NASM 0.98

[nasm.git] / preproc.c

/* preproc.c   macro preprocessor for the Netwide Assembler
 *
 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 *
 * initial version 18/iii/97 by Simon Tatham
 */

/* Typical flow of text through preproc
 *
 * pp_getline gets tokenised lines, either
 *
 *   from a macro expansion
 *
 * or
 *   {
 *   read_line  gets raw text from stdmacpos, or predef, or current input file
 *   tokenise   converts to tokens
 *   }
 *
 * expand_mmac_params is used to expand %1 etc., unless a macro is being
 * defined or a false conditional is being processed
 * (%0, %1, %+1, %-1, %%foo
 *
 * do_directive checks for directives
 *
 * expand_smacro is used to expand single line macros
 *
 * expand_mmacro is used to expand multi-line macros
 *
 * detoken is used to convert the line back to text
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>

#include "nasm.h"
#include "nasmlib.h"

typedef struct SMacro SMacro;
typedef struct MMacro MMacro;
typedef struct Context Context;
typedef struct Token Token;
typedef struct Line Line;
typedef struct Include Include;
typedef struct Cond Cond;
typedef struct IncPath IncPath;

/*
 * Store the definition of a single-line macro.
 */
struct SMacro {
    SMacro *next;
    char *name;
    int casesense;
    int nparam;
    int in_progress;
    Token *expansion;
};

/*
 * Store the definition of a multi-line macro. This is also used to
 * store the interiors of `%rep...%endrep' blocks, which are
 * effectively self-re-invoking multi-line macros which simply
 * don't have a name or bother to appear in the hash tables. %rep
 * blocks are signified by having a NULL `name' field.
 *
 * In a MMacro describing a `%rep' block, the `in_progress' field
 * isn't merely boolean, but gives the number of repeats left to
 * run.
 *
 * The `next' field is used for storing MMacros in hash tables; the
 * `next_active' field is for stacking them on istk entries.
 *
 * When a MMacro is being expanded, `params', `iline', `nparam',
 * `paramlen', `rotate' and `unique' are local to the invocation.
 */
struct MMacro {
    MMacro *next;
    char *name;
    int casesense;
    int nparam_min, nparam_max;
    int plus;                          /* is the last parameter greedy? */
    int nolist;                        /* is this macro listing-inhibited? */
    int in_progress;
    Token *dlist;                      /* All defaults as one list */
    Token **defaults;                  /* Parameter default pointers */
    int ndefs;                         /* number of default parameters */
    Line *expansion;

    MMacro *next_active;
    MMacro *rep_nest;                  /* used for nesting %rep */
    Token **params;                    /* actual parameters */
    Token *iline;                      /* invocation line */
    int nparam, rotate, *paramlen;
    unsigned long unique;
};

/*
 * The context stack is composed of a linked list of these.
 */
struct Context {
    Context *next;
    SMacro *localmac;
    char *name;
    unsigned long number;
};

/*
 * This is the internal form which we break input lines up into.
 * Typically stored in linked lists.
 *
 * Note that `type' serves a double meaning: TOK_SMAC_PARAM is not
 * necessarily used as-is, but is intended to denote the number of
 * the substituted parameter. So in the definition
 *
 *     %define a(x,y) ( (x) & ~(y) )
 * 
 * the token representing `x' will have its type changed to
 * TOK_SMAC_PARAM, but the one representing `y' will be
 * TOK_SMAC_PARAM+1.
 *
 * TOK_INTERNAL_STRING is a dirty hack: it's a single string token
 * which doesn't need quotes around it. Used in the pre-include
 * mechanism as an alternative to trying to find a sensible type of
 * quote to use on the filename we were passed.
 */
struct Token {
    Token *next;
    char *text;
    SMacro *mac;                       /* associated macro for TOK_SMAC_END */
    int type;
};
enum {
    TOK_WHITESPACE = 1, TOK_COMMENT, TOK_ID, TOK_PREPROC_ID, TOK_STRING,
    TOK_NUMBER, TOK_SMAC_END, TOK_OTHER, TOK_SMAC_PARAM,
    TOK_INTERNAL_STRING
};

/*
 * Multi-line macro definitions are stored as a linked list of
 * these, which is essentially a container to allow several linked
 * lists of Tokens.
 * 
 * Note that in this module, linked lists are treated as stacks
 * wherever possible. For this reason, Lines are _pushed_ on to the
 * `expansion' field in MMacro structures, so that the linked list,
 * if walked, would give the macro lines in reverse order; this
 * means that we can walk the list when expanding a macro, and thus
 * push the lines on to the `expansion' field in _istk_ in reverse
 * order (so that when popped back off they are in the right
 * order). It may seem cockeyed, and it relies on my design having
 * an even number of steps in, but it works...
 *
 * Some of these structures, rather than being actual lines, are
 * markers delimiting the end of the expansion of a given macro.
 * This is for use in the cycle-tracking and %rep-handling code.
 * Such structures have `finishes' non-NULL, and `first' NULL. All
 * others have `finishes' NULL, but `first' may still be NULL if
 * the line is blank.
 */
struct Line {
    Line *next;
    MMacro *finishes;
    Token *first;
};

/*
 * To handle an arbitrary level of file inclusion, we maintain a
 * stack (ie linked list) of these things.
 */
struct Include {
    Include *next;
    FILE *fp;
    Cond *conds;
    Line *expansion;
    char *fname;
    int lineno, lineinc;
    MMacro *mstk;                      /* stack of active macros/reps */
};

/*
 * Include search path. This is simply a list of strings which get
 * prepended, in turn, to the name of an include file, in an
 * attempt to find the file if it's not in the current directory.
 */
struct IncPath {
    IncPath *next;
    char *path;
};

/*
 * Conditional assembly: we maintain a separate stack of these for
 * each level of file inclusion. (The only reason we keep the
 * stacks separate is to ensure that a stray `%endif' in a file
 * included from within the true branch of a `%if' won't terminate
 * it and cause confusion: instead, rightly, it'll cause an error.)
 */
struct Cond {
    Cond *next;
    int state;
};
enum {
    /*
     * These states are for use just after %if or %elif: IF_TRUE
     * means the condition has evaluated to truth so we are
     * currently emitting, whereas IF_FALSE means we are not
     * currently emitting but will start doing so if a %else comes
     * up. In these states, all directives are admissible: %elif,
     * %else and %endif. (And of course %if.)
     */
    COND_IF_TRUE, COND_IF_FALSE,
    /*
     * These states come up after a %else: ELSE_TRUE means we're
     * emitting, and ELSE_FALSE means we're not. In ELSE_* states,
     * any %elif or %else will cause an error.
     */
    COND_ELSE_TRUE, COND_ELSE_FALSE,
    /*
     * This state means that we're not emitting now, and also that
     * nothing until %endif will be emitted at all. It's for use in
     * two circumstances: (i) when we've had our moment of emission
     * and have now started seeing %elifs, and (ii) when the
     * condition construct in question is contained within a
     * non-emitting branch of a larger condition construct.
     */
    COND_NEVER
};
#define emitting(x) ( (x) == COND_IF_TRUE || (x) == COND_ELSE_TRUE )

/*
 * Condition codes. Note that we use c_ prefix not C_ because C_ is
 * used in nasm.h for the "real" condition codes. At _this_ level,
 * we treat CXZ and ECXZ as condition codes, albeit non-invertible
 * ones, so we need a different enum...
 */
static char *conditions[] = {
    "a", "ae", "b", "be", "c", "cxz", "e", "ecxz", "g", "ge", "l", "le",
    "na", "nae", "nb", "nbe", "nc", "ne", "ng", "nge", "nl", "nle", "no",
    "np", "ns", "nz", "o", "p", "pe", "po", "s", "z"
};
enum {
    c_A, c_AE, c_B, c_BE, c_C, c_CXZ, c_E, c_ECXZ, c_G, c_GE, c_L, c_LE,
    c_NA, c_NAE, c_NB, c_NBE, c_NC, c_NE, c_NG, c_NGE, c_NL, c_NLE, c_NO,
    c_NP, c_NS, c_NZ, c_O, c_P, c_PE, c_PO, c_S, c_Z
};
static int inverse_ccs[] = {
    c_NA, c_NAE, c_NB, c_NBE, c_NC, -1, c_NE, -1, c_NG, c_NGE, c_NL, c_NLE,
    c_A, c_AE, c_B, c_BE, c_C, c_E, c_G, c_GE, c_L, c_LE, c_O, c_P, c_S,
    c_Z, c_NO, c_NP, c_PO, c_PE, c_NS, c_NZ
};

/*
 * Directive names.
 */
static char *directives[] = {
    "%assign", "%clear", "%define", "%elif", "%elifctx", "%elifdef",
    "%elifid", "%elifidn", "%elifidni", "%elifnctx", "%elifndef",
    "%elifnid", "%elifnidn", "%elifnidni", "%elifnnum", "%elifnstr",
    "%elifnum", "%elifstr", "%else", "%endif", "%endm", "%endmacro",
    "%endrep", "%error", "%exitrep", "%iassign", "%idefine", "%if",
    "%ifctx", "%ifdef", "%ifid", "%ifidn", "%ifidni", "%ifnctx",
    "%ifndef", "%ifnid", "%ifnidn", "%ifnidni", "%ifnnum",
    "%ifnstr", "%ifnum", "%ifstr", "%imacro", "%include", "%line",
    "%macro", "%pop", "%push", "%rep", "%repl", "%rotate", "%undef"
};
enum {
    PP_ASSIGN, PP_CLEAR, PP_DEFINE, PP_ELIF, PP_ELIFCTX, PP_ELIFDEF,
    PP_ELIFID, PP_ELIFIDN, PP_ELIFIDNI, PP_ELIFNCTX, PP_ELIFNDEF,
    PP_ELIFNID, PP_ELIFNIDN, PP_ELIFNIDNI, PP_ELIFNNUM, PP_ELIFNSTR,
    PP_ELIFNUM, PP_ELIFSTR, PP_ELSE, PP_ENDIF, PP_ENDM, PP_ENDMACRO,
    PP_ENDREP, PP_ERROR, PP_EXITREP, PP_IASSIGN, PP_IDEFINE, PP_IF,
    PP_IFCTX, PP_IFDEF, PP_IFID, PP_IFIDN, PP_IFIDNI, PP_IFNCTX,
    PP_IFNDEF, PP_IFNID, PP_IFNIDN, PP_IFNIDNI, PP_IFNNUM,
    PP_IFNSTR, PP_IFNUM, PP_IFSTR, PP_IMACRO, PP_INCLUDE, PP_LINE,
    PP_MACRO, PP_POP, PP_PUSH, PP_REP, PP_REPL, PP_ROTATE, PP_UNDEF
};


static Context *cstk;
static Include *istk;
static IncPath *ipath = NULL;

static efunc error;
static evalfunc evaluate;

static int pass;                /* HACK: pass 0 = generate dependencies only */

static unsigned long unique;           /* unique identifier numbers */

static Line *predef = NULL;

static ListGen *list;

/*
 * The number of hash values we use for the macro lookup tables.
 * FIXME: We should *really* be able to configure this at run time,
 * or even have the hash table automatically expanding when necessary.
 */
#define NHASH 31

/*
 * The current set of multi-line macros we have defined.
 */
static MMacro *mmacros[NHASH];

/*
 * The current set of single-line macros we have defined.
 */
static SMacro *smacros[NHASH];

/*
 * The multi-line macro we are currently defining, or the %rep
 * block we are currently reading, if any.
 */
static MMacro *defining;

/*
 * The number of macro parameters to allocate space for at a time.
 */
#define PARAM_DELTA 16

/*
 * The standard macro set: defined as `static char *stdmac[]'. Also
 * gives our position in the macro set, when we're processing it.
 */
#include "macros.c"
static char **stdmacpos;

/*
 * The extra standard macros that come from the object format, if
 * any.
 */
static char **extrastdmac = NULL;
int any_extrastdmac;

/*
 * Forward declarations.
 */
static Token *expand_mmac_params (Token *tline);
static Token *expand_smacro (Token *tline);
static void   make_tok_num(Token *tok, long val);

/*
 * Macros for safe checking of token pointers, avoid *(NULL)
 */
#define tok_type_(x,t) ((x) && (x)->type == (t))
#define skip_white_(x) if (tok_type_((x), TOK_WHITESPACE)) (x)=(x)->next
#define tok_is_(x,v) (tok_type_((x), TOK_OTHER) && !strcmp((x)->text,(v)))
#define tok_isnt_(x,v) ((x) && ((x)->type!=TOK_OTHER || strcmp((x)->text,(v))))

/*
 * The pre-preprocessing stage... This function translates line
 * number indications as they emerge from GNU cpp (`# lineno "file"
 * flags') into NASM preprocessor line number indications (`%line
 * lineno file').
 */
static char *prepreproc(char *line) 
{
    int lineno, fnlen;
    char *fname, *oldline;

    if (line[0] == '#' && line[1] == ' ') {
        oldline = line;
        fname = oldline+2;
        lineno = atoi(fname);
        fname += strspn(fname, "0123456789 ");
        if (*fname == '"')
            fname++;
        fnlen = strcspn(fname, "\"");
        line = nasm_malloc(20+fnlen);
        sprintf(line, "%%line %d %.*s", lineno, fnlen, fname);
        nasm_free (oldline);
    }
    return line;
}

/*
 * The hash function for macro lookups. Note that due to some
 * macros having case-insensitive names, the hash function must be
 * invariant under case changes. We implement this by applying a
 * perfectly normal hash function to the uppercase of the string.
 */
static int hash(char *s) 
{
    unsigned int h = 0;
    int i = 0;
    /*
     * Powers of three, mod 31.
     */
    static const int multipliers[] = {
        1, 3, 9, 27, 19, 26, 16, 17, 20, 29, 25, 13, 8, 24, 10,
        30, 28, 22, 4, 12, 5, 15, 14, 11, 2, 6, 18, 23, 7, 21
    };


    while (*s) {
        h += multipliers[i] * (unsigned char) (toupper(*s));
        s++;
        if (++i >= sizeof(multipliers)/sizeof(*multipliers))
            i = 0;
    }
    h %= NHASH;
    return h;
}

/*
 * Free a linked list of tokens.
 */
static void free_tlist (Token *list) 
{
    Token *t;
    while (list) {
        t = list;
        list = list->next;
        nasm_free (t->text);
        nasm_free (t);
    }
}

/*
 * Free a linked list of lines.
 */
static void free_llist (Line *list) 
{
    Line *l;
    while (list) {
        l = list;
        list = list->next;
        free_tlist (l->first);
        nasm_free (l);
    }
}

/*
 * Free an MMacro
 */
static void free_mmacro (MMacro *m) 
{
    nasm_free (m->name);
    free_tlist (m->dlist);
    nasm_free (m->defaults);
    free_llist (m->expansion);
    nasm_free (m);
}

/*
 * Pop the context stack.
 */
static void ctx_pop (void) 
{
    Context *c = cstk;
    SMacro *smac, *s;

    cstk = cstk->next;
    smac = c->localmac;
    while (smac) {
        s = smac;
        smac = smac->next;
        nasm_free (s->name);
        free_tlist (s->expansion);
        nasm_free (s);
    }
    nasm_free (c->name);
    nasm_free (c);
}

#define BUF_DELTA 512
/*
 * Read a line from the top file in istk, handling multiple CR/LFs
 * at the end of the line read, and handling spurious ^Zs. Will
 * return lines from the standard macro set if this has not already
 * been done.
 */
static char *read_line (void) 
{
    char *buffer, *p, *q;
    int bufsize;

    if (stdmacpos) {
        if (*stdmacpos) {
            char *ret = nasm_strdup(*stdmacpos++);
            if (!*stdmacpos && any_extrastdmac) 
            {
                stdmacpos = extrastdmac;
                any_extrastdmac = FALSE;
                return ret;
            }
            /*
             * Nasty hack: here we push the contents of `predef' on
             * to the top-level expansion stack, since this is the
             * most convenient way to implement the pre-include and
             * pre-define features.
             */
            if (!*stdmacpos) 
            {
                Line *pd, *l;
                Token *head, **tail, *t, *tt;

                for (pd = predef; pd; pd = pd->next) {
                    head = NULL;
                    tail = &head;
                    for (t = pd->first; t; t = t->next) {
                        tt = *tail = nasm_malloc(sizeof(Token));
                        tt->next = NULL;
                        tail = &tt->next;
                        tt->type = t->type;
                        tt->text = nasm_strdup(t->text);
                        tt->mac = t->mac;   /* always NULL here, in fact */
                    }
                    l = nasm_malloc(sizeof(Line));
                    l->next = istk->expansion;
                    l->first = head;
                    l->finishes = FALSE;
                    istk->expansion = l;
                }
            }
            return ret;
        } 
        else {
            stdmacpos = NULL;
        }
    }

    bufsize = BUF_DELTA;
    buffer = nasm_malloc(BUF_DELTA);
    p = buffer;
    while (1) {
        q = fgets(p, bufsize-(p-buffer), istk->fp);
        if (!q)
            break;
        p += strlen(p);
        if (p > buffer && p[-1] == '\n') {
            break;
        }
        if (p-buffer > bufsize-10) {
            long offset = p-buffer;
            bufsize += BUF_DELTA;
            buffer = nasm_realloc(buffer, bufsize);
            p = buffer+offset;         /* prevent stale-pointer problems */
        }
    }

    if (!q && p == buffer) {
        nasm_free (buffer);
        return NULL;
    }

    src_set_linnum(src_get_linnum() + istk->lineinc);

    /*
     * Play safe: remove CRs as well as LFs, if any of either are
     * present at the end of the line.
     */
    while (--p >= buffer && (*p == '\n' || *p == '\r'))
        *p = '\0';

    /*
     * Handle spurious ^Z, which may be inserted into source files
     * by some file transfer utilities.
     */
    buffer[strcspn(buffer, "\032")] = '\0';

    list->line (LIST_READ, buffer);

    return buffer;
}

/*
 * Tokenise a line of text. This is a very simple process since we
 * don't need to parse the value out of e.g. numeric tokens: we
 * simply split one string into many.
 */
static Token *tokenise (char *line) 
{
    char *p = line;
    int type;
    Token *list = NULL;
    Token *t, **tail = &list;

    while (*line) {
        p = line;
        if (*p == '%' && ( isdigit(p[1]) || 
              ((p[1] == '-' || p[1] == '+') && isdigit(p[2]))))
        {
            p++;
            do {
                p++;
            } while (isdigit(*p));
            type = TOK_PREPROC_ID;
        }
        else if (*p == '%' && p[1] == '{') {
            p += 2;
            while (*p && *p != '}') {
                p[-1] = *p;
                p++;
            }
            p[-1] = '\0';
            if (*p) p++;
            type = TOK_PREPROC_ID;
        }
        else if (*p == '%' && (isidchar(p[1]) ||
                  ((p[1] == '!' || p[1] == '%' || p[1] == '$') &&
                  isidchar(p[2]))))
        {
            p++;
            do {
                p++;
            } while (isidchar(*p));
            type = TOK_PREPROC_ID;
        }
        else if (isidstart(*p) || (*p == '$' && isidstart(p[1]))) {
            type = TOK_ID;
            p++;
            while (*p && isidchar(*p))
                p++;
        }
        else if (*p == '\'' || *p == '"') {
            /*
             * A string token.
             */
            char c = *p;
            p++;
            type = TOK_STRING;
            while (*p && *p != c)
                p++;
            if (*p) p++;
        } 
        else if (isnumstart(*p)) {
            /*
             * A number token.
             */
            type = TOK_NUMBER;
            p++;
            while (*p && isnumchar(*p))
                p++;
        } 
        else if (isspace(*p)) {
            type = TOK_WHITESPACE;
            p++;
            while (*p && isspace(*p))
                p++;
            /*
             * Whitespace just before end-of-line is discarded by
             * pretending it's a comment; whitespace just before a
             * comment gets lumped into the comment.
             */
            if (!*p || *p == ';') {
                type = TOK_COMMENT;
                while (*p) p++;
            }
        } 
        else if (*p == ';') {
            type = TOK_COMMENT;
            while (*p) p++;
        } 
        else {
            /*
             * Anything else is an operator of some kind. We check
             * for all the double-character operators (>>, <<, //,
             * %%, <=, >=, ==, !=, <>, &&, ||, ^^), but anything
             * else is a single-character operator.
             */
            type = TOK_OTHER;
            if ((p[0] == '>' && p[1] == '>') ||
                (p[0] == '<' && p[1] == '<') ||
                (p[0] == '/' && p[1] == '/') ||
                (p[0] == '%' && p[1] == '%') ||
                (p[0] == '<' && p[1] == '=') ||
                (p[0] == '>' && p[1] == '=') ||
                (p[0] == '=' && p[1] == '=') ||
                (p[0] == '!' && p[1] == '=') ||
                (p[0] == '<' && p[1] == '>') ||
                (p[0] == '&' && p[1] == '&') ||
                (p[0] == '|' && p[1] == '|') ||
                (p[0] == '^' && p[1] == '^'))
            {
                p++;
            }
            p++;
        }
        if (type != TOK_COMMENT) {
            *tail = t = nasm_malloc (sizeof(Token));
            tail = &t->next;
            t->next = NULL;
            t->type = type;
            t->text = nasm_malloc(1+p-line);
            strncpy(t->text, line, p-line);
            t->text[p-line] = '\0';
        }
        line = p;
    }

    return list;
}

/*
 * Convert a line of tokens back into text.
 */
char *detoken (Token *tlist) 
{
    Token *t;
    int len;
    char *line, *p;

    len = 0;
    for (t = tlist; t; t = t->next) {
        if (t->type == TOK_PREPROC_ID && t->text[1] == '!') {
            char *p = getenv(t->text+2);
            nasm_free (t->text);
            if (p)
                t->text = nasm_strdup(p);
            else
                t->text = NULL;
        }
        if (t->text)
            len += strlen(t->text);
    }
    p = line = nasm_malloc(len+1);
    for (t = tlist; t; t = t->next) {
        if (t->text) {
            strcpy (p, t->text);
            p += strlen(p);
        }
    }
    *p = '\0';
    return line;
}

/*
 * A scanner, suitable for use by the expression evaluator, which
 * operates on a line of Tokens. Expects a pointer to a pointer to
 * the first token in the line to be passed in as its private_data
 * field.
 */
static int ppscan(void *private_data, struct tokenval *tokval) 
{
    Token **tlineptr = private_data;
    Token *tline;

    do {
        tline = *tlineptr;
        *tlineptr = tline ? tline->next : NULL;
    } while (tline && (tline->type == TOK_WHITESPACE ||
                       tline->type == TOK_COMMENT));

    if (!tline)
        return tokval->t_type = TOKEN_EOS;

    if (tline->text[0] == '$' && !tline->text[1])
        return tokval->t_type = TOKEN_HERE;
    if (tline->text[0] == '$' && tline->text[1] == '$' && !tline->text[1])
        return tokval->t_type = TOKEN_BASE;

    if (tline->type == TOK_ID) {
        tokval->t_charptr = tline->text;
        if (tline->text[0] == '$') {
            tokval->t_charptr++;
            return tokval->t_type = TOKEN_ID;
        }

        /*
         * This is the only special case we actually need to worry
         * about in this restricted context.
         */
        if (!nasm_stricmp(tline->text, "seg"))
            return tokval->t_type = TOKEN_SEG;

        return tokval->t_type = TOKEN_ID;
    }

    if (tline->type == TOK_NUMBER) {
        int rn_error;

        tokval->t_integer = readnum(tline->text, &rn_error);
        if (rn_error)
            return tokval->t_type = TOKEN_ERRNUM;
        tokval->t_charptr = NULL;
        return tokval->t_type = TOKEN_NUM;
    }

    if (tline->type == TOK_STRING) {
        int rn_warn;
        char q, *r;
        int l;

        r = tline->text;
        q = *r++;
        l = strlen(r);

        if (l == 0 || r[l-1] != q)
            return tokval->t_type = TOKEN_ERRNUM;
        tokval->t_integer = readstrnum(r, l-1, &rn_warn);
        if (rn_warn)
            error(ERR_WARNING|ERR_PASS1,
                  "character constant too long");
        tokval->t_charptr = NULL;
        return tokval->t_type = TOKEN_NUM;
    }

    if (tline->type == TOK_OTHER) {
        if (!strcmp(tline->text, "<<")) return tokval->t_type = TOKEN_SHL;
        if (!strcmp(tline->text, ">>")) return tokval->t_type = TOKEN_SHR;
        if (!strcmp(tline->text, "//")) return tokval->t_type = TOKEN_SDIV;
        if (!strcmp(tline->text, "%%")) return tokval->t_type = TOKEN_SMOD;
        if (!strcmp(tline->text, "==")) return tokval->t_type = TOKEN_EQ;
        if (!strcmp(tline->text, "<>")) return tokval->t_type = TOKEN_NE;
        if (!strcmp(tline->text, "!=")) return tokval->t_type = TOKEN_NE;
        if (!strcmp(tline->text, "<=")) return tokval->t_type = TOKEN_LE;
        if (!strcmp(tline->text, ">=")) return tokval->t_type = TOKEN_GE;
        if (!strcmp(tline->text, "&&")) return tokval->t_type = TOKEN_DBL_AND;
        if (!strcmp(tline->text, "^^")) return tokval->t_type = TOKEN_DBL_XOR;
        if (!strcmp(tline->text, "||")) return tokval->t_type = TOKEN_DBL_OR;
    }

    /*
     * We have no other options: just return the first character of
     * the token text.
     */
    return tokval->t_type = tline->text[0];
}

/*
 * Return the Context structure associated with a %$ token. Return
 * NULL, having _already_ reported an error condition, if the
 * context stack isn't deep enough for the supplied number of $
 * signs.
 */
static Context *get_ctx (char *name) 
{
    Context *ctx;
    int i;

    if (!cstk) {
        error (ERR_NONFATAL, "`%s': context stack is empty", name);
        return NULL;
    }

    i = 1;
    ctx = cstk;
    while (name[i+1] == '$') {
        i++;
        ctx = ctx->next;
        if (!ctx) {
            error (ERR_NONFATAL, "`%s': context stack is only"
                   " %d level%s deep", name, i-1, (i==2 ? "" : "s"));
            return NULL;
        }
    }
    return ctx;
}

/*
 * Compare a string to the name of an existing macro; this is a
 * simple wrapper which calls either strcmp or nasm_stricmp
 * depending on the value of the `casesense' parameter.
 */
static int mstrcmp(char *p, char *q, int casesense) 
{
    return casesense ? strcmp(p,q) : nasm_stricmp(p,q);
}

/*
 * Open an include file. This routine must always return a valid
 * file pointer if it returns - it's responsible for throwing an
 * ERR_FATAL and bombing out completely if not. It should also try
 * the include path one by one until it finds the file or reaches
 * the end of the path.
 */
static FILE *inc_fopen(char *file) 
{
    FILE *fp;
    char *prefix = "", *combine;
    IncPath *ip = ipath;
    static int namelen = 0;

    while (1) {
        combine = nasm_strcat(prefix,file);
        fp = fopen(combine, "r");
        if (pass == 0 && fp)
        {
          namelen += strlen(combine) + 1;
          if (namelen > 62)
          {
            printf(" \\\n  ");
            namelen = 2;
          }
          printf(" %s", combine);
        }
        nasm_free (combine);
        if (fp)
            return fp;
        if (!ip)
            break;
        prefix = ip->path;
        ip = ip->next;
    }

    error (ERR_FATAL,
           "unable to open include file `%s'", file);
    return NULL;                       /* never reached - placate compilers */
}

/*
 * Determine if we should warn on defining a single-line macro of
 * name `name', with `nparam' parameters. If nparam is 0 or -1, will
 * return TRUE if _any_ single-line macro of that name is defined.
 * Otherwise, will return TRUE if a single-line macro with either
 * `nparam' or no parameters is defined.
 *
 * If a macro with precisely the right number of parameters is
 * defined, or nparam is -1, the address of the definition structure
 * will be returned in `defn'; otherwise NULL will be returned. If `defn'
 * is NULL, no action will be taken regarding its contents, and no
 * error will occur.
 *
 * Note that this is also called with nparam zero to resolve
 * `ifdef'.
 */
static int smacro_defined (char *name, int nparam, SMacro **defn, int nocase) 
{
    SMacro *m;
    Context *ctx;
    char *p;

    if (name[0] == '%' && name[1] == '$') {
        ctx = get_ctx (name);
        if (!ctx)
            return FALSE;              /* got to return _something_ */
        m = ctx->localmac;
        p = name+1;
        p += strspn(p, "$");
    } else {
        m = smacros[hash(name)];
        p = name;
    }

    while (m) {
        if (!mstrcmp(m->name, p, m->casesense & nocase) &&
            (nparam <= 0 || m->nparam == 0 || nparam == m->nparam)) {
            if (defn) {
                if (nparam == m->nparam || nparam == -1)
                    *defn = m;
                else
                    *defn = NULL;
            }
            return TRUE;
        }
        m = m->next;
    }
    return FALSE;
}

/*
 * Count and mark off the parameters in a multi-line macro call.
 * This is called both from within the multi-line macro expansion
 * code, and also to mark off the default parameters when provided
 * in a %macro definition line.
 */
static void count_mmac_params (Token *t, int *nparam, Token ***params) 
{
    int paramsize, brace;

    *nparam = paramsize = 0;
    *params = NULL;
    while (t) {
        if (*nparam >= paramsize) {
            paramsize += PARAM_DELTA;
            *params = nasm_realloc(*params, sizeof(**params) * paramsize);
        }
        skip_white_(t);
        brace = FALSE;
        if (tok_is_(t, "{"))
            brace = TRUE;
        (*params)[(*nparam)++] = t;
        while (tok_isnt_(t, brace ? "}" : ","))
            t = t->next;
        if (t) {                       /* got a comma/brace */
            t = t->next;
            if (brace) {
                /*
                 * Now we've found the closing brace, look further
                 * for the comma.
                 */
                skip_white_(t);
                if (tok_isnt_(t, ",")) {
                    error (ERR_NONFATAL,
                           "braces do not enclose all of macro parameter");
                    while (tok_isnt_(t, ","))
                        t = t->next;
                }
                if (t)
                    t = t->next;               /* eat the comma */
            }
        }
    }
}

/*
 * Determine whether one of the various `if' conditions is true or
 * not.
 *
 * We must free the tline we get passed.
 */
static int if_condition (Token *tline, int i) 
{
    int    j, casesense;
    Token  * t, * tt, ** tptr, * origline;
    struct tokenval tokval;
    expr   * evalresult;

    origline = tline;

    switch (i) {
      case PP_IFCTX: case PP_ELIFCTX:
      case PP_IFNCTX: case PP_ELIFNCTX:
        j = FALSE;                     /* have we matched yet? */
        if (!cstk)
            error(ERR_FATAL,
                  "`%s': context stack is empty", directives[i]);
        else while (tline) {
            skip_white_(tline);
            if (!tline || tline->type != TOK_ID) {
                error(ERR_NONFATAL,
                      "`%s' expects context identifiers", directives[i]);
                free_tlist (origline);
                return -1;
            }
            if (!nasm_stricmp(tline->text, cstk->name))
                j = TRUE;
            tline = tline->next;
        }
        if (i == PP_IFNCTX || i == PP_ELIFNCTX)
            j = !j;
        free_tlist (origline);
        return j;

      case PP_IFDEF: case PP_ELIFDEF:
      case PP_IFNDEF: case PP_ELIFNDEF:
        j = FALSE;                     /* have we matched yet? */
        while (tline) {
            skip_white_(tline);
            if (!tline || (tline->type != TOK_ID &&
                           (tline->type != TOK_PREPROC_ID ||
                            tline->text[1] != '$'))) {
                error(ERR_NONFATAL,
                      "`%%if%sdef' expects macro identifiers",
                      (i==PP_ELIFNDEF ? "n" : ""));
                free_tlist (origline);
                return -1;
            }
            if (smacro_defined(tline->text, 0, NULL, 1))
                j = TRUE;
                tline = tline->next;
        }
        if (i == PP_IFNDEF || i == PP_ELIFNDEF)
            j = !j;
        free_tlist (origline);
        return j;

      case PP_IFIDN: case PP_ELIFIDN: case PP_IFNIDN: case PP_ELIFNIDN:
      case PP_IFIDNI: case PP_ELIFIDNI: case PP_IFNIDNI: case PP_ELIFNIDNI:
        tline = expand_smacro(tline);
        t = tt = tline;
        while (tok_isnt_(tt, ","))
            tt = tt->next;
        if (!tt) {
            error(ERR_NONFATAL, "`%s' expects two comma-separated arguments",
                  directives[i]);
            free_tlist (tline);
            return -1;
        }
        tt = tt->next;
        casesense = (i == PP_IFIDN || i == PP_ELIFIDN ||
                     i == PP_IFNIDN || i == PP_ELIFNIDN);
        j = TRUE;                      /* assume equality unless proved not */
        while ((t->type != TOK_OTHER || strcmp(t->text, ",")) && tt) {
            if (tt->type == TOK_OTHER && !strcmp(tt->text, ",")) {
                error(ERR_NONFATAL, "`%s': more than one comma on line",
                      directives[i]);
                free_tlist (tline);
                return -1;
            }
            if (t->type == TOK_WHITESPACE) {
                t = t->next;
                continue;
            } else if (tt->type == TOK_WHITESPACE) {
                tt = tt->next;
                continue;
            } else if (tt->type != t->type ||
                       (casesense ? strcmp(tt->text, t->text) :
                        nasm_stricmp(tt->text, t->text))) {
                j = FALSE;             /* found mismatching tokens */
                break;
            } else {
                t = t->next;
                tt = tt->next;
                continue;
            }
        }
        if ((t->type != TOK_OTHER || strcmp(t->text, ",")) || tt)
            j = FALSE;                 /* trailing gunk on one end or other */
        if (i == PP_IFNIDN || i == PP_ELIFNIDN ||
            i == PP_IFNIDNI || i == PP_ELIFNIDNI)
            j = !j;
        free_tlist (tline);
        return j;

      case PP_IFID: case PP_ELIFID: case PP_IFNID: case PP_ELIFNID:
      case PP_IFNUM: case PP_ELIFNUM: case PP_IFNNUM: case PP_ELIFNNUM:
      case PP_IFSTR: case PP_ELIFSTR: case PP_IFNSTR: case PP_ELIFNSTR:
        tline = expand_smacro(tline);
        t = tline;
        while (tok_type_(t, TOK_WHITESPACE))
            t = t->next;
        j = FALSE;                     /* placate optimiser */
        if (t) switch (i) {
          case PP_IFID: case PP_ELIFID: case PP_IFNID: case PP_ELIFNID:
            j = (t->type == TOK_ID);
            break;
          case PP_IFNUM: case PP_ELIFNUM: case PP_IFNNUM: case PP_ELIFNNUM:
            j = (t->type == TOK_NUMBER);
            break;
          case PP_IFSTR: case PP_ELIFSTR: case PP_IFNSTR: case PP_ELIFNSTR:
            j = (t->type == TOK_STRING);
            break;
        }
        if (i == PP_IFNID || i == PP_ELIFNID ||
            i == PP_IFNNUM || i == PP_ELIFNNUM ||
            i == PP_IFNSTR || i == PP_ELIFNSTR)
            j = !j;
        free_tlist (tline);
        return j;

      case PP_IF: case PP_ELIF:
        t = tline = expand_smacro(tline);
        tptr = &t;
        tokval.t_type = TOKEN_INVALID;
        evalresult = evaluate (ppscan, tptr, &tokval,
                               NULL, pass | 0x10, error, NULL);
        free_tlist (tline);
        if (!evalresult)
            return -1;
        if (tokval.t_type)
            error(ERR_WARNING,
                  "trailing garbage after expression ignored");
        if (!is_simple(evalresult)) {
            error(ERR_NONFATAL,
                  "non-constant value given to `%s'", directives[i]);
            return -1;
        }
        return reloc_value(evalresult) != 0;

      default:
        error(ERR_FATAL,
              "preprocessor directive `%s' not yet implemented",
              directives[i]);
        free_tlist (origline);
        return -1;                     /* yeah, right */
    }
}

/*
 * Find out if a line contains a preprocessor directive, and deal
 * with it if so.
 * 
 * If a directive _is_ found, we are expected to free_tlist() the
 * line.
 *
 * Return values go like this:
 * 
 * bit 0 is set if a directive was found (so the line gets freed)
 */
static int do_directive (Token *tline) 
{
    int i, j, k, m, nparam, nolist;
    char *p, *mname;
    Include *inc;
    Context *ctx;
    Cond *cond;
    SMacro *smac, **smhead;
    MMacro *mmac;
    Token *t, *tt, *param_start, *macro_start, *last, **tptr, *origline;
    Line *l;
    struct tokenval tokval;
    expr *evalresult;
    MMacro *tmp_defining;       /* Used when manipulating rep_nest */

    origline = tline;

    skip_white_(tline);
    if (!tok_type_(tline, TOK_PREPROC_ID) ||
        (tline->text[1]=='%' || tline->text[1]=='$' || tline->text[1]=='!'))
        return 0;

    i = -1;
    j = sizeof(directives)/sizeof(*directives);
    while (j-i > 1) {
        k = (j+i) / 2;
        m = nasm_stricmp(tline->text, directives[k]);
        if (m == 0) {
            i = k;
            j = -2;
            break;
        } else if (m < 0) {
            j = k;
        } else
            i = k;
    }

    /*
     * If we're in a non-emitting branch of a condition construct,
     * or walking to the end of an already terminated %rep block,
     * we should ignore all directives except for condition
     * directives.
     */
    if (((istk->conds && !emitting(istk->conds->state)) ||
         (istk->mstk && !istk->mstk->in_progress)) &&
        i != PP_IF && i != PP_ELIF &&
        i != PP_IFCTX && i != PP_ELIFCTX &&
        i != PP_IFDEF && i != PP_ELIFDEF &&
        i != PP_IFID && i != PP_ELIFID &&
        i != PP_IFIDN && i != PP_ELIFIDN &&
        i != PP_IFIDNI && i != PP_ELIFIDNI &&
        i != PP_IFNCTX && i != PP_ELIFNCTX &&
        i != PP_IFNDEF && i != PP_ELIFNDEF &&
        i != PP_IFNID && i != PP_ELIFNID &&
        i != PP_IFNIDN && i != PP_ELIFNIDN &&
        i != PP_IFNIDNI && i != PP_ELIFNIDNI &&
        i != PP_IFNNUM && i != PP_ELIFNNUM &&
        i != PP_IFNSTR && i != PP_ELIFNSTR &&
        i != PP_IFNUM && i != PP_ELIFNUM &&
        i != PP_IFSTR && i != PP_ELIFSTR &&
        i != PP_ELSE && i != PP_ENDIF)
    {
        return 0;
    }

    /*
     * If we're defining a macro or reading a %rep block, we should
     * ignore all directives except for %macro/%imacro (which
     * generate an error), %endm/%endmacro, and (only if we're in a
     * %rep block) %endrep. If we're in a %rep block, another %rep
     * causes an error, so should be let through.
     */
    if (defining && i != PP_MACRO && i != PP_IMACRO &&
        i != PP_ENDMACRO && i != PP_ENDM &&
        (defining->name || (i != PP_ENDREP && i != PP_REP)))
    {
        return 0;
    }

    if (j != -2) {
        error(ERR_NONFATAL, "unknown preprocessor directive `%s'",
              tline->text);
        return 0;                      /* didn't get it */
    }

    switch (i) {

      case PP_CLEAR:
        if (tline->next)
            error(ERR_WARNING,
                  "trailing garbage after `%%clear' ignored");
        for (j=0; j<NHASH; j++) {
            while (mmacros[j]) {
                MMacro *m = mmacros[j];
                mmacros[j] = m->next;
                free_mmacro(m);
            }
            while (smacros[j]) {
                SMacro *s = smacros[j];
                smacros[j] = smacros[j]->next;
                nasm_free (s->name);
                free_tlist (s->expansion);
                nasm_free (s);
            }
        }
        free_tlist (origline);
        return 3;

      case PP_INCLUDE:
        tline = tline->next;
        skip_white_(tline);
        if (!tline || (tline->type != TOK_STRING &&
                       tline->type != TOK_INTERNAL_STRING)) 
        {
            error(ERR_NONFATAL, "`%%include' expects a file name");
            free_tlist (origline);
            return 3;                  /* but we did _something_ */
        }
        if (tline->next)
            error(ERR_WARNING,
                  "trailing garbage after `%%include' ignored");
        if (tline->type != TOK_INTERNAL_STRING) {
            p = tline->text+1;         /* point past the quote to the name */
            p[strlen(p)-1] = '\0';     /* remove the trailing quote */
        } else
            p = tline->text;           /* internal_string is easier */
        inc = nasm_malloc(sizeof(Include));
        inc->next = istk;
        inc->conds = NULL;
        inc->fp = inc_fopen(p);
        inc->fname = src_set_fname(nasm_strdup(p));
        inc->lineno = src_set_linnum(0);
        inc->lineinc = 1;
        inc->expansion = NULL;
        inc->mstk = NULL;
        istk = inc;
        list->uplevel (LIST_INCLUDE);
        free_tlist (origline);
        return 5;

      case PP_PUSH:
        tline = tline->next;
        skip_white_(tline);
        if (!tok_type_(tline, TOK_ID)) {
            error(ERR_NONFATAL,
                  "`%%push' expects a context identifier");
            free_tlist (origline);
            return 3;                  /* but we did _something_ */
        }
        if (tline->next)
            error(ERR_WARNING,
                  "trailing garbage after `%%push' ignored");
        ctx = nasm_malloc(sizeof(Context));
        ctx->next = cstk;
        ctx->localmac = NULL;
        ctx->name = nasm_strdup(tline->text);
        ctx->number = unique++;
        cstk = ctx;
        free_tlist (origline);
        break;

      case PP_REPL:
        tline = tline->next;
        skip_white_(tline);
        if (!tok_type_(tline, TOK_ID)) {
            error(ERR_NONFATAL,
                  "`%%repl' expects a context identifier");
            free_tlist (origline);
            return 3;                  /* but we did _something_ */
        }
        if (tline->next)
            error(ERR_WARNING,
                  "trailing garbage after `%%repl' ignored");
        if (!cstk)
            error(ERR_NONFATAL,
                  "`%%repl': context stack is empty");
        else {
            nasm_free (cstk->name);
            cstk->name = nasm_strdup(tline->text);
        }
        free_tlist (origline);
        break;

      case PP_POP:
        if (tline->next)
            error(ERR_WARNING,
                  "trailing garbage after `%%pop' ignored");
        if (!cstk)
            error(ERR_NONFATAL,
                  "`%%pop': context stack is already empty");
        else
            ctx_pop();
        free_tlist (origline);
        break;

      case PP_ERROR:
        tline->next = expand_smacro (tline->next);
        tline = tline->next;
        skip_white_(tline);
        if (tok_type_(tline, TOK_STRING)) {
            p = tline->text+1;         /* point past the quote to the name */
            p[strlen(p)-1] = '\0';     /* remove the trailing quote */
            error(ERR_NONFATAL, "user error: %s", p);
        } else {
            p = detoken(tline);
            error(ERR_WARNING, "user error: %s", p);
            nasm_free(p);
        }
        free_tlist (origline);
        break;

      case PP_IF:
      case PP_IFCTX:
      case PP_IFDEF:
      case PP_IFID:
      case PP_IFIDN:
      case PP_IFIDNI:
      case PP_IFNCTX:
      case PP_IFNDEF:
      case PP_IFNID:
      case PP_IFNIDN:
      case PP_IFNIDNI:
      case PP_IFNNUM:
      case PP_IFNSTR:
      case PP_IFNUM:
      case PP_IFSTR:
        if (istk->conds && !emitting(istk->conds->state))
            j = COND_NEVER;
        else {
            j = if_condition(tline->next, i);
            tline->next = NULL;        /* it got freed */
            free_tlist (origline);
            if (j < 0)
                /*
                 * Bogus expression in %if, but we should pretend
                 * it was OK anyway, so that we don't get an error
                 * cascade on the subsequent %else / %endif.
                 */
                j = COND_NEVER;
            else
                j = j ? COND_IF_TRUE : COND_IF_FALSE;
        }
        cond = nasm_malloc(sizeof(Cond));
        cond->next = istk->conds;
        cond->state = j;
        istk->conds = cond;
        return (j == COND_IF_TRUE ? 3 : 1);

      case PP_ELIF:
      case PP_ELIFCTX:
      case PP_ELIFDEF:
      case PP_ELIFID:
      case PP_ELIFIDN:
      case PP_ELIFIDNI:
      case PP_ELIFNCTX:
      case PP_ELIFNDEF:
      case PP_ELIFNID:
      case PP_ELIFNIDN:
      case PP_ELIFNIDNI:
      case PP_ELIFNNUM:
      case PP_ELIFNSTR:
      case PP_ELIFNUM:
      case PP_ELIFSTR:
        if (!istk->conds)
            error(ERR_FATAL, "`%s': no matching `%%if'",
                  directives[i]);
        if (emitting(istk->conds->state) || istk->conds->state == COND_NEVER)
            istk->conds->state = COND_NEVER;
        else {
            j = if_condition(expand_mmac_params(tline->next), i);
            tline->next = NULL;        /* it got freed */
            free_tlist (origline);
            if (j < 0)
                /*
                 * The expression was bogus, but let's make
                 * %endif not complain about missing %if
                 */
                j = COND_NEVER;
            else
                istk->conds->state = j ? COND_IF_TRUE : COND_IF_FALSE;
        }
        return (istk->conds->state == COND_IF_TRUE ? 5 : 1);

      case PP_ELSE:
        if (tline->next)
            error(ERR_WARNING,
                  "trailing garbage after `%%else' ignored");
        if (!istk->conds)
            error(ERR_FATAL,
                  "`%%else': no matching `%%if'");
        if (emitting(istk->conds->state) || istk->conds->state == COND_NEVER)
            istk->conds->state = COND_ELSE_FALSE;
        else
            istk->conds->state = COND_ELSE_TRUE;
        free_tlist (origline);
        return 5;

      case PP_ENDIF:
        if (tline->next)
            error(ERR_WARNING,
                  "trailing garbage after `%%endif' ignored");
        if (!istk->conds)
            error(ERR_FATAL,
                  "`%%endif': no matching `%%if'");
        cond = istk->conds;
        istk->conds = cond->next;
        nasm_free (cond);
        free_tlist (origline);
        return 5;

      case PP_MACRO:
      case PP_IMACRO:
        if (defining)
            error (ERR_FATAL,
                   "`%%%smacro': already defining a macro",
                   (i == PP_IMACRO ? "i" : ""));
        tline = tline->next;
        skip_white_(tline);
        if (!tok_type_(tline, TOK_ID)) {
            error (ERR_NONFATAL,
                   "`%%%smacro' expects a macro name",
                   (i == PP_IMACRO ? "i" : ""));
            return 3;
        }
        defining = nasm_malloc(sizeof(MMacro));
        defining->name = nasm_strdup(tline->text);
        defining->casesense = (i == PP_MACRO);
        defining->plus = FALSE;
        defining->nolist = FALSE;
        defining->in_progress = FALSE;
        defining->rep_nest = NULL;
        tline = tline->next;
        skip_white_(tline);
        if (!tok_type_(tline, TOK_NUMBER)) {
            error (ERR_NONFATAL,
                   "`%%%smacro' expects a parameter count",
                   (i == PP_IMACRO ? "i" : ""));
            defining->nparam_min = defining->nparam_max = 0;
        } else {
            defining->nparam_min = defining->nparam_max =
                readnum(tline->text, &j);
            if (j)
                error (ERR_NONFATAL,
                       "unable to parse parameter count `%s'", tline->text);
        }
        if (tline && tok_is_(tline->next, "-")) {
            tline = tline->next->next;
            if (tok_is_(tline, "*"))
                defining->nparam_max = INT_MAX;
            else if (!tok_type_(tline, TOK_NUMBER))
                error (ERR_NONFATAL,
                       "`%%%smacro' expects a parameter count after `-'",
                       (i == PP_IMACRO ? "i" : ""));
            else {
                defining->nparam_max = readnum(tline->text, &j);
                if (j)
                    error (ERR_NONFATAL,
                           "unable to parse parameter count `%s'",
                           tline->text);
                if (defining->nparam_min > defining->nparam_max)
                    error (ERR_NONFATAL,
                           "minimum parameter count exceeds maximum");
            }
        }
        if (tline && tok_is_(tline->next, "+")) {
            tline = tline->next;
            defining->plus = TRUE;
        }
        if (tline && tok_type_(tline->next, TOK_ID) &&
            !nasm_stricmp(tline->next->text, ".nolist")) 
        {
            tline = tline->next;
            defining->nolist = TRUE;
        }
        mmac = mmacros[hash(defining->name)];
        while (mmac) {
            if (!strcmp(mmac->name, defining->name) &&
                (mmac->nparam_min<=defining->nparam_max || defining->plus) &&
                (defining->nparam_min<=mmac->nparam_max || mmac->plus)) 
            {
                error (ERR_WARNING,
                       "redefining multi-line macro `%s'", defining->name);
                break;
            }
            mmac = mmac->next;
        }
        /*
         * Handle default parameters.
         */
        if (tline && tline->next) {
            defining->dlist = tline->next;
            tline->next = NULL;
            count_mmac_params (defining->dlist, &defining->ndefs,
                               &defining->defaults);
        } else {
            defining->dlist = NULL;
            defining->defaults = NULL;
        }
        defining->expansion = NULL;
        free_tlist (origline);
        return 1;

      case PP_ENDM:
      case PP_ENDMACRO:
        if (!defining) {
            error (ERR_NONFATAL, "`%s': not defining a macro",
                   tline->text);
            return 3;
        }
        k = hash(defining->name);
        defining->next = mmacros[k];
        mmacros[k] = defining;
        defining = NULL;
        free_tlist (origline);
        return 5;

      case PP_ROTATE:
        if (tline->next && tline->next->type == TOK_WHITESPACE)
            tline = tline->next;
        t = expand_smacro(tline->next);
        tline->next = NULL;
        free_tlist (origline);
        tline = t;
        tptr = &t;
        tokval.t_type = TOKEN_INVALID;
        evalresult = evaluate (ppscan, tptr, &tokval, NULL, pass, error, NULL);
        free_tlist (tline);
        if (!evalresult)
            return 3;
        if (tokval.t_type)
            error(ERR_WARNING,
                  "trailing garbage after expression ignored");
        if (!is_simple(evalresult)) {
            error(ERR_NONFATAL,
                  "non-constant value given to `%%rotate'");
            return 3;
        }
        mmac = istk->mstk;
        while (mmac && !mmac->name)    /* avoid mistaking %reps for macros */
            mmac = mmac->next_active;
        if (!mmac)
            error(ERR_NONFATAL, "`%%rotate' invoked outside a macro call");
        mmac->rotate = mmac->rotate + reloc_value(evalresult);
        if (mmac->rotate < 0)
            mmac->rotate = mmac->nparam - (-mmac->rotate) % mmac->nparam;
        mmac->rotate %= mmac->nparam;
        return 1;

      case PP_REP:
        nolist = FALSE;
        tline = tline->next;
        if (tline->next && tline->next->type == TOK_WHITESPACE)
            tline = tline->next;
        if (tline->next && tline->next->type == TOK_ID &&
            !nasm_stricmp(tline->next->text, ".nolist")) {
            tline = tline->next;
            nolist = TRUE;
        }
        t = expand_smacro(tline->next);
        tline->next = NULL;
        free_tlist (origline);
        tline = t;
        tptr = &t;
        tokval.t_type = TOKEN_INVALID;
        evalresult = evaluate (ppscan, tptr, &tokval, NULL, pass, error, NULL);
        free_tlist (tline);
        if (!evalresult)
            return 3;
        if (tokval.t_type)
            error(ERR_WARNING,
                  "trailing garbage after expression ignored");
        if (!is_simple(evalresult)) {
            error(ERR_NONFATAL,
                  "non-constant value given to `%%rep'");
            return 3;
        }
        tmp_defining = defining;
        defining = nasm_malloc(sizeof(MMacro));
        defining->name = NULL;         /* flags this macro as a %rep block */
        defining->casesense = 0;
        defining->plus = FALSE;
        defining->nolist = nolist;
        defining->in_progress = reloc_value(evalresult) + 1;
        defining->nparam_min = defining->nparam_max = 0;
        defining->defaults = NULL;
        defining->dlist = NULL;
        defining->expansion = NULL;
        defining->next_active = istk->mstk;
        defining->rep_nest = tmp_defining;
        return 1;

      case PP_ENDREP:
        if (!defining || defining->name) {
            error (ERR_NONFATAL,
                   "`%%endrep': no matching `%%rep'");
            return 3;
        }

        /*
         * Now we have a "macro" defined - although it has no name
         * and we won't be entering it in the hash tables - we must
         * push a macro-end marker for it on to istk->expansion.
         * After that, it will take care of propagating itself (a
         * macro-end marker line for a macro which is really a %rep
         * block will cause the macro to be re-expanded, complete
         * with another macro-end marker to ensure the process
         * continues) until the whole expansion is forcibly removed
         * from istk->expansion by a %exitrep.
         */
        l = nasm_malloc(sizeof(Line));
        l->next = istk->expansion;
        l->finishes = defining;
        l->first = NULL;
        istk->expansion = l;

        istk->mstk = defining;

        list->uplevel (defining->nolist ? LIST_MACRO_NOLIST : LIST_MACRO);
        tmp_defining = defining;
        defining = defining->rep_nest;
        free_tlist (origline);
        return 1;

      case PP_EXITREP:
        /*
         * We must search along istk->expansion until we hit a
         * macro-end marker for a macro with no name. Then we set
         * its `in_progress' flag to 0.
         */
        for (l = istk->expansion; l; l = l->next)
            if (l->finishes && !l->finishes->name)
                break;

        if (l)
            l->finishes->in_progress = 0;
        else
            error (ERR_NONFATAL, "`%%exitrep' not within `%%rep' block");
        free_tlist (origline);
        return 1;

      case PP_DEFINE:
      case PP_IDEFINE:
        tline = tline->next;
        skip_white_(tline);
        if (!tline || (tline->type != TOK_ID &&
                       (tline->type != TOK_PREPROC_ID ||
                        tline->text[1] != '$'))) {
            error (ERR_NONFATAL,
                   "`%%%sdefine' expects a macro identifier",
                   (i == PP_IDEFINE ? "i" : ""));
            free_tlist (origline);
            return 3;
        }
        mname = tline->text;
        if (tline->type == TOK_ID) {
            p = tline->text;
            smhead = &smacros[hash(mname)];
        } else {
            ctx = get_ctx (tline->text);
            if (ctx == NULL)
                return 3;
            else {
                p = tline->text+1;
                p += strspn(p, "$");
                smhead = &ctx->localmac;
            }
        }
        last = tline;
        param_start = tline = tline->next;
        nparam = 0;
        if (tok_is_(tline, "(")) {
            /*
             * This macro has parameters.
             */

            tline = tline->next;
            while (1) {
                skip_white_(tline);
                if (!tline) {
                    error (ERR_NONFATAL,
                           "parameter identifier expected");
                    free_tlist (origline);
                    return 3;
                }
                if (tline->type != TOK_ID) {
                    error (ERR_NONFATAL,
                           "`%s': parameter identifier expected",
                           tline->text);
                    free_tlist (origline);
                    return 3;
                }
                tline->type = TOK_SMAC_PARAM + nparam++;
                tline = tline->next;
                skip_white_(tline);
                if (tok_is_(tline, ",")) {
                    tline = tline->next;
                    continue;
                }
                if (!tok_is_(tline, ")")) {
                    error (ERR_NONFATAL,
                           "`)' expected to terminate macro template");
                    free_tlist (origline);
                    return 3;
                }
                break;
            }
            last = tline;
            tline = tline->next;
        }
        if (tok_type_(tline, TOK_WHITESPACE))
            last = tline, tline = tline->next;
        macro_start = NULL;
        last->next = NULL;
        t = tline;
        while (t) {
            if (t->type == TOK_ID) {
                for (tt = param_start; tt; tt = tt->next)
                    if (tt->type >= TOK_SMAC_PARAM &&
                        !strcmp(tt->text, t->text))
                        t->type = tt->type;
            }
            tt = t->next;
            t->next = macro_start;
            macro_start = t;
            t = tt;
        }
        /*
         * Good. We now have a macro name, a parameter count, and a
         * token list (in reverse order) for an expansion. We ought
         * to be OK just to create an SMacro, store it, and let
         * free_tlist have the rest of the line (which we have
         * carefully re-terminated after chopping off the expansion
         * from the end).
         */
        if (smacro_defined (mname, nparam, &smac, i==PP_DEFINE)) {
            if (!smac) {
                error (ERR_WARNING,
                       "single-line macro `%s' defined both with and"
                       " without parameters", mname);
                free_tlist (origline);
                free_tlist (macro_start);
                return 3;
            } else {
                /*
                 * We're redefining, so we have to take over an
                 * existing SMacro structure. This means freeing
                 * what was already in it.
                 */
                nasm_free (smac->name);
                free_tlist (smac->expansion);
            }
        } else {
            smac = nasm_malloc(sizeof(SMacro));
            smac->next = *smhead;
            *smhead = smac;
        }
        smac->name = nasm_strdup(p);
        smac->casesense = (i == PP_DEFINE);
        smac->nparam = nparam;
        smac->expansion = macro_start;
        smac->in_progress = FALSE;
        free_tlist (origline);
        return 3;

    case PP_UNDEF:
        tline = tline->next;
        skip_white_(tline);
        if (!tline || (tline->type != TOK_ID &&
                       (tline->type != TOK_PREPROC_ID ||
                        tline->text[1] != '$'))) {
            error (ERR_NONFATAL,
                   "`%%undef' expects a macro identifier");
            free_tlist (origline);
            return 3;
        }
        mname = tline->text;
        if (tline->type == TOK_ID) {
            p = tline->text;
            smhead = &smacros[hash(mname)];
        } else {
            ctx = get_ctx (tline->text);
            if (ctx == NULL) {
                free_tlist (origline);
                return 3;
            } else {
                p = tline->text+1;
                p += strspn(p, "$");
                smhead = &ctx->localmac;
            }
        }
        last = tline;
        tline = tline->next;
        last->next = NULL;

        if (tline)
            error(ERR_WARNING,
                  "trailing garbage after macro name ignored");

        /*
         * We now have a macro name... go hunt for it.
         */
        while (smacro_defined (mname, -1, &smac, 1)) {
          /* Defined, so we need to find its predecessor and nuke it */
          SMacro **s;
          for ( s = smhead ; *s && *s != smac ; s = &(*s)->next );
          if ( *s ) {
            *s = smac->next;
            nasm_free(smac->name);
            free_tlist(smac->expansion);
            nasm_free(smac);
          }
        }
        return 3;

      case PP_ASSIGN:
      case PP_IASSIGN:
        tline = tline->next;
        skip_white_(tline);
        if (!tline || (tline->type != TOK_ID &&
                       (tline->type != TOK_PREPROC_ID ||
                        tline->text[1] != '$'))) {
            error (ERR_NONFATAL,
                   "`%%%sassign' expects a macro identifier",
                   (i == PP_IASSIGN ? "i" : ""));
            free_tlist (origline);
            return 3;
        }
        mname = tline->text;
        if (tline->type == TOK_ID) {
            p = tline->text;
            smhead = &smacros[hash(mname)];
        } else {
            ctx = get_ctx (tline->text);
            if (ctx == NULL) {
                free_tlist (origline);
                return 3;
            } else {
                p = tline->text+1;
                p += strspn(p, "$");
                smhead = &ctx->localmac;
            }
        }
        last = tline;
        tline = tline->next;
        last->next = NULL;

        tline = expand_smacro (tline);
        t = tline;
        tptr = &t;
        tokval.t_type = TOKEN_INVALID;
        evalresult = evaluate (ppscan, tptr, &tokval, NULL, pass, error, NULL);
        free_tlist (tline);
        if (!evalresult) {
            free_tlist (origline);
            return 3;
        }

        if (tokval.t_type)
            error(ERR_WARNING,
                  "trailing garbage after expression ignored");

        if (!is_simple(evalresult)) {
            error(ERR_NONFATAL,
                  "non-constant value given to `%%%sassign'",
                  (i == PP_IASSIGN ? "i" : ""));
            free_tlist (origline);
            return 3;
        }

        macro_start = nasm_malloc(sizeof(*macro_start));
        macro_start->next = NULL;
        make_tok_num(macro_start, reloc_value(evalresult));
        macro_start->mac = NULL;

        /*
         * We now have a macro name, an implicit parameter count of
         * zero, and a numeric token to use as an expansion. Create
         * and store an SMacro.
         */
        if (smacro_defined (mname, 0, &smac, i==PP_ASSIGN)) {
            if (!smac)
                error (ERR_WARNING,
                       "single-line macro `%s' defined both with and"
                       " without parameters", mname);
            else {
                /*
                 * We're redefining, so we have to take over an
                 * existing SMacro structure. This means freeing
                 * what was already in it.
                 */
                nasm_free (smac->name);
                free_tlist (smac->expansion);
            }
        } 
        else {
            smac = nasm_malloc(sizeof(SMacro));
            smac->next = *smhead;
            *smhead = smac;
        }
        smac->name = nasm_strdup(p);
        smac->casesense = (i == PP_ASSIGN);
        smac->nparam = 0;
        smac->expansion = macro_start;
        smac->in_progress = FALSE;
        free_tlist (origline);
        return 3;

      case PP_LINE:
        /*
         * Syntax is `%line nnn[+mmm] [filename]'
         */
        tline = tline->next;
        skip_white_(tline);
        if (!tok_type_(tline, TOK_NUMBER)) {
            error (ERR_NONFATAL, "`%%line' expects line number");
            free_tlist (origline);
            return 3;
        }
        k = readnum(tline->text, &j);
        m = 1;
        tline = tline->next;
        if (tok_is_(tline, "+")) {
            tline = tline->next;
            if (!tok_type_(tline, TOK_NUMBER)) {
                error (ERR_NONFATAL,
                       "`%%line' expects line increment");
                free_tlist (origline);
                return 3;
            }
            m = readnum(tline->text, &j);
            tline = tline->next;
        }
        skip_white_(tline);
        src_set_linnum(k);
        istk->lineinc = m;
        if (tline) {
            nasm_free ( src_set_fname ( detoken(tline) ) );
        }
        free_tlist (origline);
        return 5;

      default:
        error(ERR_FATAL,
              "preprocessor directive `%s' not yet implemented",
              directives[i]);
        break;
    }
    return 3;
}

/*
 * Ensure that a macro parameter contains a condition code and
 * nothing else. Return the condition code index if so, or -1
 * otherwise.
 */
static int find_cc (Token *t) 
{
    Token *tt;
    int i, j, k, m;

    skip_white_(t);
    if (t->type != TOK_ID)
        return -1;
    tt = t->next;
    skip_white_(tt);
    if (tt && (tt->type != TOK_OTHER || strcmp(tt->text, ",")))
        return -1;

    i = -1;
    j = sizeof(conditions)/sizeof(*conditions);
    while (j-i > 1) {
        k = (j+i) / 2;
        m = nasm_stricmp(t->text, conditions[k]);
        if (m == 0) {
            i = k;
            j = -2;
            break;
        } else if (m < 0) {
            j = k;
        } else
            i = k;
    }
    if (j != -2)
        return -1;
    return i;
}

/*
 * Expand MMacro-local things: parameter references (%0, %n, %+n,
 * %-n) and MMacro-local identifiers (%%foo).
 */
static Token *expand_mmac_params (Token *tline) 
{
    Token *t, *tt, *ttt, **tail, *thead;

    tail = &thead;
    thead = NULL;

    while (tline) {
        if (tline->type == TOK_PREPROC_ID &&
            (tline->text[1] == '+' || tline->text[1] == '-' ||
             tline->text[1] == '%' ||
             (tline->text[1] >= '0' && tline->text[1] <= '9'))) {
            char *text = NULL;
            int type = 0, cc;          /* type = 0 to placate optimisers */
            char tmpbuf[30];
            int n, i;
            MMacro *mac;

            t = tline;
            tline = tline->next;

            mac = istk->mstk;
            while (mac && !mac->name)  /* avoid mistaking %reps for macros */
                mac = mac->next_active;
            if (!mac)
                error(ERR_NONFATAL, "`%s': not in a macro call", t->text);
            else switch (t->text[1]) {
                /*
                 * We have to make a substitution of one of the
                 * forms %1, %-1, %+1, %%foo, %0.
                 */
              case '0':
                type = TOK_NUMBER;
                sprintf(tmpbuf, "%d", mac->nparam);
                text = nasm_strdup(tmpbuf);
                break;
              case '%':
                type = TOK_ID;
                sprintf(tmpbuf, "..@%lu.", mac->unique);
                text = nasm_strcat(tmpbuf, t->text+2);
                break;
              case '-':
                n = atoi(t->text+2)-1;
                if (n >= mac->nparam)
                    tt = NULL;
                else {
                    if (mac->nparam > 1)
                        n = (n + mac->rotate) % mac->nparam;
                    tt = mac->params[n];
                }
                cc = find_cc (tt);
                if (cc == -1) {
                    error (ERR_NONFATAL,
                           "macro parameter %d is not a condition code",
                           n+1);
                    text = NULL;
                } else {
                    type = TOK_ID;
                    if (inverse_ccs[cc] == -1) {
                        error (ERR_NONFATAL,
                               "condition code `%s' is not invertible",
                               conditions[cc]);
                        text = NULL;
                    } else
                        text = nasm_strdup(conditions[inverse_ccs[cc]]);
                }
                break;
              case '+':
                n = atoi(t->text+2)-1;
                if (n >= mac->nparam)
                    tt = NULL;
                else {
                    if (mac->nparam > 1)
                        n = (n + mac->rotate) % mac->nparam;
                    tt = mac->params[n];
                }
                cc = find_cc (tt);
                if (cc == -1) {
                    error (ERR_NONFATAL,
                           "macro parameter %d is not a condition code",
                           n+1);
                    text = NULL;
                } else {
                    type = TOK_ID;
                    text = nasm_strdup(conditions[cc]);
                }
                break;
              default:
                n = atoi(t->text+1)-1;
                if (n >= mac->nparam)
                    tt = NULL;
                else {
                    if (mac->nparam > 1)
                        n = (n + mac->rotate) % mac->nparam;
                    tt = mac->params[n];
                }
                if (tt) {
                    for (i=0; i<mac->paramlen[n]; i++) {
                        ttt = *tail = nasm_malloc(sizeof(Token));
                        tail = &ttt->next;
                        ttt->type = tt->type;
                        ttt->text = nasm_strdup(tt->text);
                        ttt->mac = NULL;
                        tt = tt->next;
                    }
                }
                text = NULL;       /* we've done it here */
                break;
            }
            nasm_free (t->text);
            if (!text) {
                nasm_free (t);
            } else {
                *tail = t;
                tail = &t->next;
                t->type = type;
                t->text = text;
                t->mac = NULL;
            }
            continue;
        } else {
            t = *tail = tline;
            tline = tline->next;
            t->mac = NULL;
            tail = &t->next;
        }
    }
    *tail = NULL;
    t = thead;
    for (; t && (tt=t->next)!=NULL ; t = t->next)
        switch (t->type) {
        case TOK_WHITESPACE:
            if (tt->type == TOK_WHITESPACE) {
                t->next = tt->next;
                nasm_free(tt->text);
                nasm_free(tt); 
            }
            break;
        case TOK_ID:
            if (tt->type == TOK_ID || tt->type == TOK_NUMBER) {
                char *tmp = nasm_strcat(t->text, tt->text);
                nasm_free(t->text);
                t->text = tmp;
                t->next = tt->next;
                nasm_free(tt->text);
                nasm_free(tt); 
            }
            break;
        case TOK_NUMBER:
            if (tt->type == TOK_NUMBER) {
                char *tmp = nasm_strcat(t->text, tt->text);
                nasm_free(t->text);
                t->text = tmp;
                t->next = tt->next;
                nasm_free(tt->text);
                nasm_free(tt); 
            }
            break;
        }
                
    return thead;
}

/*
 * Expand all single-line macro calls made in the given line.
 * Return the expanded version of the line. The original is deemed
 * to be destroyed in the process. (In reality we'll just move
 * Tokens from input to output a lot of the time, rather than
 * actually bothering to destroy and replicate.)
 */
static Token *expand_smacro (Token *tline) 
{
    Token *t, *tt, *mstart, **tail, *thead;
    SMacro *head = NULL, *m;
    Token **params;
    int *paramsize;
    int nparam, sparam, brackets;
    char *p;

    tail = &thead;
    thead = NULL;

    while (tline) {  /* main token loop */
        p = NULL;
        if (tline->type == TOK_ID) {
            head = smacros[hash(tline->text)];
            p = tline->text;
        } else if (tline->type == TOK_PREPROC_ID && tline->text[1] == '$') {
            Context *ctx = get_ctx (tline->text);
            if (ctx) {
                head = ctx->localmac;
                p = tline->text+2;
                p += strspn(p, "$");
            }
        }
        if (p) {
        /*
         * We've hit an identifier. As in is_mmacro below, we first
         * check whether the identifier is a single-line macro at
         * all, then think about checking for parameters if
         * necessary.
         */
            for (m = head; m; m = m->next)
                if (!mstrcmp(m->name, p, m->casesense))
                    break;
            if (m) {
              mstart = tline;
              params = NULL;
              paramsize = NULL;
              if (m->nparam == 0) {
                /*
                 * Simple case: the macro is parameterless. Discard the
                 * one token that the macro call took, and push the
                 * expansion back on the to-do stack.
                 */
                if (!m->expansion) 
                {
                    if (!strcmp("__FILE__", m->name)) {
                        long num=0;
                        src_get(&num, &(tline->text));
                        nasm_quote(&(tline->text));
                        tline->type = TOK_STRING;
                        continue;
                    }
                    if (!strcmp("__LINE__", m->name)) {
                        nasm_free(tline->text);
                        make_tok_num(tline, src_get_linnum());
                        continue;
                    }
                    t = tline;
                    tline = tline->next;
                    nasm_free (t->text);
                    nasm_free (t);
                    continue;
                }
              } 
              else {
                  /*
                   * Complicated case: at least one macro with this name
                   * exists and takes parameters. We must find the
                   * parameters in the call, count them, find the SMacro
                   * that corresponds to that form of the macro call, and
                   * substitute for the parameters when we expand. What a
                   * pain.
                   */
                  tline = tline->next;
                  skip_white_(tline);
                  if (!tok_is_(tline, "(")) {
                      /*
                       * This macro wasn't called with parameters: ignore
                       * the call. (Behaviour borrowed from gnu cpp.)
                       */
                      tline = mstart;
                      m = NULL;
                  } 
                  else {
                      int paren = 0;
                      int white = 0;
                      brackets = 0;
                      nparam = 0;
                      tline = tline->next;
                      sparam = PARAM_DELTA;
                      params = nasm_malloc (sparam*sizeof(Token *));
                      params[0] = tline;
                      paramsize = nasm_malloc (sparam*sizeof(int));
                      paramsize[0] = 0;
                      for (;;tline = tline->next) {    /* parameter loop */
                          if (!tline) {
                              error(ERR_NONFATAL,
                                    "macro call expects terminating `)'");
                              break;
                          }
                          if (tline->type == TOK_WHITESPACE && brackets<=0) {
                              if (paramsize[nparam])
                                  white++;
                              else
                                  params[nparam] = tline->next;
                              continue;    /* parameter loop */
                          }
                          if (tline->type == TOK_OTHER && tline->text[1]==0) {
                              char ch = tline->text[0];
                              if (ch == ',' && !paren && brackets<=0) {
                                  if (++nparam >= sparam) {
                                      sparam += PARAM_DELTA;
                                      params = nasm_realloc (params, 
                                                     sparam*sizeof(Token *));
                                      paramsize = nasm_realloc (paramsize,
                                                     sparam*sizeof(int));
                                  }
                                  params[nparam] = tline->next;
                                  paramsize[nparam] = 0;
                                  white = 0;
                                  continue; /* parameter loop */
                              }
                              if (ch == '{' && 
                                  (brackets>0 || (brackets==0 &&
                                                  !paramsize[nparam])))
                              {
                                  if (!(brackets++))
                                  {
                                      params[nparam] = tline->next;
                                      continue; /* parameter loop */
                                  }
                              }
                              if (ch == '}' && brackets>0)
                                  if (--brackets == 0) {
                                      brackets = -1;
                                      continue; /* parameter loop */
                                  }
                              if (ch == '(' && !brackets)
                                  paren++;
                              if (ch == ')' && brackets<=0)
                                  if (--paren < 0)
                                      break;
                          }
                          if (brackets<0) {
                              brackets = 0;
                              error (ERR_NONFATAL, "braces do not "
                                     "enclose all of macro parameter");
                          }
                          paramsize[nparam] += white+1;
                          white = 0;
                      } /* parameter loop */
                      nparam++;
                      while (m && (m->nparam != nparam ||
                                   mstrcmp(m->name, p, m->casesense)))
                          m = m->next;
                      if (!m)
                          error (ERR_WARNING|ERR_WARN_MNP, 
                                 "macro `%s' exists, "
                                 "but not taking %d parameters",
                                 mstart->text, nparam);
                  }
              }
              if (m && m->in_progress)
                  m = NULL;
              if (!m)    /* in progess or didn't find '(' or wrong nparam */
              {
                  /* 
                   * Design question: should we handle !tline, which
                   * indicates missing ')' here, or expand those
                   * macros anyway, which requires the (t) test a few
                   * lines down?  
                   */
                  nasm_free (params);
                  nasm_free (paramsize);
                  tline = mstart;
              } 
              else {
                /*
                 * Expand the macro: we are placed on the last token of the
                 * call, so that we can easily split the call from the
                 * following tokens. We also start by pushing an SMAC_END
                 * token for the cycle removal.
                 */
                t = tline;
                if (t) {
                    tline = t->next;
                    t->next = NULL;
                }
                tt = nasm_malloc(sizeof(Token));
                tt->type = TOK_SMAC_END;
                tt->text = NULL;
                tt->mac = m;
                m->in_progress = TRUE;
                tt->next = tline;
                tline = tt;
                for (t = m->expansion; t; t = t->next) {
                    if (t->type >= TOK_SMAC_PARAM) {
                        Token *pcopy = tline, **ptail = &pcopy;
                        Token *ttt, *pt;
                        int i;
                        
                        ttt = params[t->type - TOK_SMAC_PARAM];
                        for (i=paramsize[t->type-TOK_SMAC_PARAM]; --i>=0;) {
                            pt = *ptail = nasm_malloc(sizeof(Token));
                            pt->next = tline;
                            ptail = &pt->next;
                            pt->text = nasm_strdup(ttt->text);
                            pt->type = ttt->type;
                            pt->mac = NULL;
                            ttt = ttt->next;
                        }
                        tline = pcopy;
                    } else {
                        tt = nasm_malloc(sizeof(Token));
                        tt->type = t->type;
                        tt->text = nasm_strdup(t->text);
                        tt->mac = NULL;
                        tt->next = tline;
                        tline = tt;
                    }
                }
        
                /*
                 * Having done that, get rid of the macro call, and clean
                 * up the parameters.
                 */
                nasm_free (params);
                nasm_free (paramsize);
                free_tlist (mstart);
                continue;  /* main token loop */
              }
            }
        }

        if (tline->type == TOK_SMAC_END) {
            tline->mac->in_progress = FALSE;
            t = tline;
            tline = tline->next;
            nasm_free (t);
        } else {
            t = *tail = tline;
            tline = tline->next;
            t->mac = NULL;
            t->next = NULL;
            tail = &t->next;
            if (t->type == TOK_PREPROC_ID && t->text[1] == '$') {
                Context *c = get_ctx (t->text);
                char *p, *q, buffer[40];

                t->type = TOK_ID;
                if (c) {
                    q = t->text+1;
                    q += strspn(q, "$");
                    sprintf(buffer, "..@%lu.", c->number);
                    p = nasm_strcat (buffer,q);
                    nasm_free (t->text);
                    t->text = p;
                }
            }
        }
    }

    return thead;
}

/*
 * Determine whether the given line constitutes a multi-line macro
 * call, and return the MMacro structure called if so. Doesn't have
 * to check for an initial label - that's taken care of in
 * expand_mmacro - but must check numbers of parameters. Guaranteed
 * to be called with tline->type == TOK_ID, so the putative macro
 * name is easy to find.
 */
static MMacro *is_mmacro (Token *tline, Token ***params_array) 
{
    MMacro *head, *m;
    Token **params;
    int nparam;

    head = mmacros[hash(tline->text)];

    /*
     * Efficiency: first we see if any macro exists with the given
     * name. If not, we can return NULL immediately. _Then_ we
     * count the parameters, and then we look further along the
     * list if necessary to find the proper MMacro.
     */
    for (m = head; m; m = m->next)
        if (!mstrcmp(m->name, tline->text, m->casesense))
            break;
    if (!m)
        return NULL;

    /*
     * OK, we have a potential macro. Count and demarcate the
     * parameters.
     */
    count_mmac_params (tline->next, &nparam, &params);

    /*
     * So we know how many parameters we've got. Find the MMacro
     * structure that handles this number.
     */
    while (m) {
        if (m->nparam_min <= nparam && (m->plus || nparam <= m->nparam_max)) {
            /*
             * This one is right. Just check if cycle removal
             * prohibits us using it before we actually celebrate...
             */
            if (m->in_progress) {
#if 0
                error (ERR_NONFATAL,
                       "self-reference in multi-line macro `%s'",
                       m->name);
#endif
                nasm_free (params);
                return NULL;
            }
            /*
             * It's right, and we can use it. Add its default
             * parameters to the end of our list if necessary.
             */
            if (m->defaults && nparam < m->nparam_min + m->ndefs) {
                params = nasm_realloc (params, ((m->nparam_min+m->ndefs+1) *
                                                sizeof(*params)));
                while (nparam < m->nparam_min + m->ndefs) {
                    params[nparam] = m->defaults[nparam - m->nparam_min];
                    nparam++;
                }
            }
            /*
             * If we've gone over the maximum parameter count (and
             * we're in Plus mode), ignore parameters beyond
             * nparam_max.
             */
            if (m->plus && nparam > m->nparam_max)
                nparam = m->nparam_max;
            /*
             * Then terminate the parameter list, and leave.
             */
            if (!params) {             /* need this special case */
                params = nasm_malloc(sizeof(*params));
                nparam = 0;
            }
            params[nparam] = NULL;
            *params_array = params;
            return m;
        }
        /*
         * This one wasn't right: look for the next one with the
         * same name.
         */
        for (m = m->next; m; m = m->next)
            if (!mstrcmp(m->name, tline->text, m->casesense))
                break;
    }

    /*
     * After all that, we didn't find one with the right number of
     * parameters. Issue a warning, and fail to expand the macro.
     */
    error (ERR_WARNING|ERR_WARN_MNP,
           "macro `%s' exists, but not taking %d parameters",
           tline->text, nparam);
    nasm_free (params);
    return NULL;
}

/*
 * Expand the multi-line macro call made by the given line, if
 * there is one to be expanded. If there is, push the expansion on
 * istk->expansion and return 1. Otherwise return 0.
 */
static int expand_mmacro (Token *tline) 
{
    Token *startline = tline;
    Token *label = NULL;
    int dont_prepend = 0;
    Token **params, *t, *tt;
    MMacro *m;
    Line *l, *ll;
    int i, nparam, *paramlen;

    t = tline;
    skip_white_(t);
    if (!tok_type_(t, TOK_ID))
        return 0;
    m = is_mmacro (t, &params);
    if (!m) {
        Token *last;
        /*
         * We have an id which isn't a macro call. We'll assume
         * it might be a label; we'll also check to see if a
         * colon follows it. Then, if there's another id after
         * that lot, we'll check it again for macro-hood.
         */
        label = last = t;
        t = t->next;
        if (tok_type_(t, TOK_WHITESPACE))
            last = t, t = t->next;
        if (tok_is_(t, ":")) {
            dont_prepend = 1;
            last = t, t = t->next;
            if (tok_type_(t, TOK_WHITESPACE))
                last = t, t = t->next;
        }
        if (!tok_type_(t, TOK_ID) || (m = is_mmacro(t, &params)) == NULL)
            return 0;
        last->next = NULL;
        tline = t;
    }

    /*
     * Fix up the parameters: this involves stripping leading and
     * trailing whitespace, then stripping braces if they are
     * present.
     */
    for (nparam = 0; params[nparam]; nparam++)
        ;
    paramlen = nparam ? nasm_malloc(nparam*sizeof(*paramlen)) : NULL;

    for (i = 0; params[i]; i++) {
        int brace = FALSE;
        int comma = (!m->plus || i < nparam-1);

        t = params[i];
        skip_white_(t);
        if (tok_is_(t, "{"))
            t = t->next, brace = TRUE, comma = FALSE;
        params[i] = t;
        paramlen[i] = 0;
        while (t) {
            if (comma && t->type == TOK_OTHER && !strcmp(t->text, ","))
                break;                 /* ... because we have hit a comma */
            if (comma && t->type == TOK_WHITESPACE && tok_is_(t->next, ","))
                break;                 /* ... or a space then a comma */
            if (brace && t->type == TOK_OTHER && !strcmp(t->text, "}"))
                break;                 /* ... or a brace */
            t = t->next;
            paramlen[i]++;
        }
    }

    /*
     * OK, we have a MMacro structure together with a set of
     * parameters. We must now go through the expansion and push
     * copies of each Line on to istk->expansion. Substitution of
     * parameter tokens and macro-local tokens doesn't get done
     * until the single-line macro substitution process; this is
     * because delaying them allows us to change the semantics
     * later through %rotate.
     *
     * First, push an end marker on to istk->expansion, mark this
     * macro as in progress, and set up its invocation-specific
     * variables.
     */
    ll = nasm_malloc(sizeof(Line));
    ll->next = istk->expansion;
    ll->finishes = m;
    ll->first = NULL;
    istk->expansion = ll;

    m->in_progress = TRUE;
    m->params = params;
    m->iline = tline;
    m->nparam = nparam;
    m->rotate = 0;
    m->paramlen = paramlen;
    m->unique = unique++;

    m->next_active = istk->mstk;
    istk->mstk = m;

    for (l = m->expansion; l; l = l->next) {
        Token **tail;

        ll = nasm_malloc(sizeof(Line));
        ll->finishes = NULL;
        ll->next = istk->expansion;
        istk->expansion = ll;
        tail = &ll->first;

        for (t = l->first; t; t = t->next) {
            Token *x = t;
            if (t->type == TOK_PREPROC_ID && 
                t->text[1]=='0' && t->text[2]=='0') 
            {
                dont_prepend = -1;
                x = label;
                if (!x)
                    continue;
            }
            tt = *tail = nasm_malloc(sizeof(Token));
            tail = &tt->next;
            tt->type = x->type;
            tt->text = nasm_strdup(x->text);
            tt->mac = NULL;
        }
        *tail = NULL;
    }

    /*
     * If we had a label, push it on as the first line of
     * the macro expansion.
     */
    if (label)
        if (dont_prepend<0)
            free_tlist(startline);
        else {
            ll = nasm_malloc(sizeof(Line));
            ll->finishes = NULL;
            ll->next = istk->expansion;
            istk->expansion = ll;
            ll->first = startline;
            if (!dont_prepend) {
                while (label->next)
                    label = label->next;
                label->next = tt = nasm_malloc(sizeof(Token));
                tt->next = NULL;
                tt->mac = NULL;
                tt->type = TOK_OTHER;
                tt->text = nasm_strdup(":");
            }
        }

    list->uplevel (m->nolist ? LIST_MACRO_NOLIST : LIST_MACRO);

    return 1;
}

static void pp_reset (char *file, int apass, efunc errfunc, evalfunc eval,
                      ListGen *listgen) 
{
    int h;

    error = errfunc;
    cstk = NULL;
    istk = nasm_malloc(sizeof(Include));
    istk->next = NULL;
    istk->conds = NULL;
    istk->expansion = NULL;
    istk->mstk = NULL;
    istk->fp = fopen(file, "r");
    istk->fname = NULL;
    src_set_fname(nasm_strdup(file));
    src_set_linnum(0);
    istk->lineinc = 1;
    if (!istk->fp)
        error (ERR_FATAL|ERR_NOFILE, "unable to open input file `%s'", file);
    defining = NULL;
    for (h=0; h<NHASH; h++) {
        mmacros[h] = NULL;
        smacros[h] = NULL;
    }
    unique = 0;
    stdmacpos = stdmac;
    any_extrastdmac = (extrastdmac != NULL);
    list = listgen;
    evaluate = eval;
    pass = apass;
}

static char *pp_getline (void) 
{
    char *line;
    Token *tline;
    int ret;

    while (1) {
        /*
         * Fetch a tokenised line, either from the macro-expansion
         * buffer or from the input file.
         */
        tline = NULL;
        while (istk->expansion && istk->expansion->finishes) {
            Line *l = istk->expansion;
            if (!l->finishes->name && l->finishes->in_progress > 1) {
                Line *ll;

                /*
                 * This is a macro-end marker for a macro with no
                 * name, which means it's not really a macro at all
                 * but a %rep block, and the `in_progress' field is
                 * more than 1, meaning that we still need to
                 * repeat. (1 means the natural last repetition; 0
                 * means termination by %exitrep.) We have
                 * therefore expanded up to the %endrep, and must
                 * push the whole block on to the expansion buffer
                 * again. We don't bother to remove the macro-end
                 * marker: we'd only have to generate another one
                 * if we did.
                 */
                l->finishes->in_progress--;
                for (l = l->finishes->expansion; l; l = l->next) {
                    Token *t, *tt, **tail;

                    ll = nasm_malloc(sizeof(Line));
                    ll->next = istk->expansion;
                    ll->finishes = NULL;
                    ll->first = NULL;
                    tail = &ll->first;

                    for (t = l->first; t; t = t->next) {
                        if (t->text) {
                            tt = *tail = nasm_malloc(sizeof(Token));
                            tt->next = NULL;
                            tail = &tt->next;
                            tt->type = t->type;
                            tt->text = nasm_strdup(t->text);
                            tt->mac = NULL;
                        }
                    }

                    istk->expansion = ll;
                }
            } else {
                /*
                 * Check whether a `%rep' was started and not ended
                 * within this macro expansion. This can happen and
                 * should be detected. It's a fatal error because
                 * I'm too confused to work out how to recover
                 * sensibly from it.
                 */
                if (defining) {
                    if (defining->name)
                        error (ERR_PANIC,
                               "defining with name in expansion");
                    else if (istk->mstk->name)
                        error (ERR_FATAL, "`%%rep' without `%%endrep' within"
                               " expansion of macro `%s'", istk->mstk->name);
                }

                /*
                 * FIXME:  investigate the relationship at this point between
                 * istk->mstk and l->finishes
                 */
                {
                    MMacro *m = istk->mstk;
                    istk->mstk = m->next_active;
                    if (m->name) {
                        /*
                         * This was a real macro call, not a %rep, and
                         * therefore the parameter information needs to
                         * be freed.
                         */
                        nasm_free(m->params);
                        free_tlist(m->iline);
                        nasm_free(m->paramlen);
                        l->finishes->in_progress = FALSE;
                    } 
                    else
                        free_mmacro(m);
                }
                istk->expansion = l->next;
                nasm_free (l);
                list->downlevel (LIST_MACRO);
            }
        }
        while (1) {  /* until we get a line we can use */

            if (istk->expansion) {   /* from a macro expansion */
                char *p;
                Line *l = istk->expansion;
                tline = l->first;
                istk->expansion = l->next;
                nasm_free (l);
                p = detoken(tline);
                list->line (LIST_MACRO, p);
                nasm_free(p);
                break;
            }
            line = read_line();
            if (line) {    /* from the current input file */
                line = prepreproc(line);
                tline = tokenise(line);
                nasm_free (line);
                break;
            }
            /*
             * The current file has ended; work down the istk
             */
            {
                Include *i = istk;
                fclose(i->fp);
                if (i->conds)
                    error(ERR_FATAL, "expected `%%endif' before end of file");
                istk = i->next;
                list->downlevel (LIST_INCLUDE);
                src_set_linnum(i->lineno);
                nasm_free ( src_set_fname(i->fname) );
                nasm_free (i);
                if (!istk)
                    return NULL;
            }
        }

        /*
         * We must expand MMacro parameters and MMacro-local labels
         * _before_ we plunge into directive processing, to cope
         * with things like `%define something %1' such as STRUC
         * uses. Unless we're _defining_ a MMacro, in which case
         * those tokens should be left alone to go into the
         * definition; and unless we're in a non-emitting
         * condition, in which case we don't want to meddle with
         * anything.
         */
        if (!defining && !(istk->conds && !emitting(istk->conds->state)))
            tline = expand_mmac_params(tline);

        /*
         * Check the line to see if it's a preprocessor directive.
         */
        ret = do_directive(tline);
        if (ret & 1) {
                continue;
        } else if (defining) {
            /*
             * We're defining a multi-line macro. We emit nothing
             * at all, and just
             * shove the tokenised line on to the macro definition.
             */
            Line *l = nasm_malloc(sizeof(Line));
            l->next = defining->expansion;
            l->first = tline;
            l->finishes = FALSE;
            defining->expansion = l;
            continue;
        } else if (istk->conds && !emitting(istk->conds->state)) {
            /*
             * We're in a non-emitting branch of a condition block.
             * Emit nothing at all, not even a blank line: when we
             * emerge from the condition we'll give a line-number
             * directive so we keep our place correctly.
             */
            free_tlist(tline);
            continue;
        } else if (istk->mstk && !istk->mstk->in_progress) {
            /*
             * We're in a %rep block which has been terminated, so
             * we're walking through to the %endrep without
             * emitting anything. Emit nothing at all, not even a
             * blank line: when we emerge from the %rep block we'll
             * give a line-number directive so we keep our place
             * correctly.
             */
            free_tlist(tline);
            continue;
        } else {
            tline = expand_smacro(tline);
            ret = expand_mmacro(tline);
            if (!ret) {
                /*
                 * De-tokenise the line again, and emit it.
                 */
                line = detoken(tline);
                free_tlist (tline);
                break;
            } else {
                continue;              /* expand_mmacro calls free_tlist */
            }
        }
    }

    return line;
}

static void pp_cleanup (void) 
{
    int h;

    if (defining) {
        error (ERR_NONFATAL, "end of file while still defining macro `%s'",
               defining->name);
        free_mmacro (defining);
    }
    while (cstk)
        ctx_pop();
    for (h=0; h<NHASH; h++) {
        while (mmacros[h]) {
            MMacro *m = mmacros[h];
            mmacros[h] = mmacros[h]->next;
            free_mmacro(m);
        }
        while (smacros[h]) {
            SMacro *s = smacros[h];
            smacros[h] = smacros[h]->next;
            nasm_free (s->name);
            free_tlist (s->expansion);
            nasm_free (s);
        }
    }
    while (istk) {
        Include *i = istk;
        istk = istk->next;
        fclose(i->fp);
        nasm_free (i->fname);
        nasm_free (i);
    }
    while (cstk)
        ctx_pop();
}

void pp_include_path (char *path) 
{
    IncPath *i;

    i = nasm_malloc(sizeof(IncPath));
    i->path = nasm_strdup(path);
    i->next = ipath;
    ipath = i;
}

void pp_pre_include (char *fname) 
{
    Token *inc, *space, *name;
    Line *l;

    inc = nasm_malloc(sizeof(Token));
    inc->next = space = nasm_malloc(sizeof(Token));
    space->next = name = nasm_malloc(sizeof(Token));
    name->next = NULL;

    inc->type = TOK_PREPROC_ID;
    inc->text = nasm_strdup("%include");
    space->type = TOK_WHITESPACE;
    space->text = nasm_strdup(" ");
    name->type = TOK_INTERNAL_STRING;
    name->text = nasm_strdup(fname);

    inc->mac = space->mac = name->mac = NULL;

    l = nasm_malloc(sizeof(Line));
    l->next = predef;
    l->first = inc;
    l->finishes = FALSE;
    predef = l;
}

void pp_pre_define (char *definition) 
{
    Token *def, *space;
    Line *l;
    char *equals;

    equals = strchr(definition, '=');

    def = nasm_malloc(sizeof(Token));
    def->next = space = nasm_malloc(sizeof(Token));
    if (equals)
        *equals = ' ';
    space->next = tokenise(definition);
    if (equals)
        *equals = '=';

    def->type = TOK_PREPROC_ID;
    def->text = nasm_strdup("%define");
    space->type = TOK_WHITESPACE;
    space->text = nasm_strdup(" ");

    def->mac = space->mac = NULL;

    l = nasm_malloc(sizeof(Line));
    l->next = predef;
    l->first = def;
    l->finishes = FALSE;
    predef = l;
}

void pp_pre_undefine (char *definition) 
{
    Token *def, *space;
    Line *l;

    def = nasm_malloc(sizeof(Token));
    def->next = space = nasm_malloc(sizeof(Token));
    space->next = tokenise(definition);

    def->type = TOK_PREPROC_ID;
    def->text = nasm_strdup("%undef");
    space->type = TOK_WHITESPACE;
    space->text = nasm_strdup(" ");

    def->mac = space->mac = NULL;

    l = nasm_malloc(sizeof(Line));
    l->next = predef;
    l->first = def;
    l->finishes = FALSE;
    predef = l;
}

void pp_extra_stdmac (char **macros) 
{
    extrastdmac = macros;
}

static void make_tok_num(Token *tok, long val)  
{
    char numbuf[20];
    sprintf(numbuf, "%ld", val);
    tok->text = nasm_strdup(numbuf);
    tok->type = TOK_NUMBER;
}

Preproc nasmpp = {
    pp_reset,
    pp_getline,
    pp_cleanup
};