include/bout.h

   1 /*
   2  * This file is a modified version of 'a.out.h'.  It is to be used in all
   3  * GNU tools modified to support the i80960 (or tools that operate on
   4  * object files created by such tools).
   5  *
   6  * All i80960 development is done in a CROSS-DEVELOPMENT environment.  I.e.,
   7  * object code is generated on, and executed under the direction of a symbolic
   8  * debugger running on, a host system.  We do not want to be subject to the
   9  * vagaries of which host it is or whether it supports COFF or a.out format,
  10  * or anything else.  We DO want to:
  11  *
  12  *      o always generate the same format object files, regardless of host.
  13  *
  14  *      o have an 'a.out' header that we can modify for our own purposes
  15  *        (the 80960 is typically an embedded processor and may require
  16  *        enhanced linker support that the normal a.out.h header can't
  17  *        accommodate).
  18  *
  19  * As for byte-ordering, the following rules apply:
  20  *
  21  *      o Text and data that is actually downloaded to the target is always
  22  *        in i80960 (little-endian) order.
  23  *
  24  *      o All other numbers (in the header, symbols, relocation directives)
  25  *        are in host byte-order:  object files CANNOT be lifted from a
  26  *        little-end host and used on a big-endian (or vice versa) without
  27  *        modification.
  28  * ==> THIS IS NO LONGER TRUE USING BFD.  WE CAN GENERATE ANY BYTE ORDER
  29  *     FOR THE HEADER, AND READ ANY BYTE ORDER.  PREFERENCE WOULD BE TO
  30  *     USE LITTLE-ENDIAN BYTE ORDER THROUGHOUT, REGARDLESS OF HOST.  <==
  31  *
  32  *      o The downloader ('comm960') takes care to generate a pseudo-header
  33  *        with correct (i80960) byte-ordering before shipping text and data
  34  *        off to the NINDY monitor in the target systems.  Symbols and
  35  *        relocation info are never sent to the target.
  36  */
  37
  38
  39 #define BMAGIC  0415
  40 /* We don't accept the following (see N_BADMAG macro).
  41  * They're just here so GNU code will compile.
  42  */
  43 #define OMAGIC  0407            /* old impure format */
  44 #define NMAGIC  0410            /* read-only text */
  45 #define ZMAGIC  0413            /* demand load format */
  46
  47 /* FILE HEADER
  48  *      All 'lengths' are given as a number of bytes.
  49  *      All 'alignments' are for relinkable files only;  an alignment of
  50  *              'n' indicates the corresponding segment must begin at an
  51  *              address that is a multiple of (2**n).
  52  */
  53 struct external_exec {
  54         /* Standard stuff */
  55         unsigned char e_info[4];        /* Identifies this as a b.out file */
  56         unsigned char e_text[4];        /* Length of text */
  57         unsigned char e_data[4];        /* Length of data */
  58         unsigned char e_bss[4];         /* Length of uninitialized data area */
  59         unsigned char e_syms[4];        /* Length of symbol table */
  60         unsigned char e_entry[4];       /* Runtime start address */
  61         unsigned char e_trsize[4];      /* Length of text relocation info */
  62         unsigned char e_drsize[4];      /* Length of data relocation info */
  63
  64         /* Added for i960 */
  65         unsigned char e_tload[4];       /* Text runtime load address */
  66         unsigned char e_dload[4];       /* Data runtime load address */
  67         unsigned char e_talign[1];      /* Alignment of text segment */
  68         unsigned char e_dalign[1];      /* Alignment of data segment */
  69         unsigned char e_balign[1];      /* Alignment of bss segment */
  70         unsigned char e_relaxable[1];   /* Assembled with enough info to allow linker to relax */
  71 };
  72
  73 #define EXEC_BYTES_SIZE (sizeof (struct external_exec))
  74
  75 /* These macros use the a_xxx field names, since they operate on the exec
  76    structure after it's been byte-swapped and realigned on the host machine. */
  77 #define N_BADMAG(x)     (((x).a_info)!=BMAGIC)
  78 #define N_TXTOFF(x)     EXEC_BYTES_SIZE
  79 #define N_DATOFF(x)     ( N_TXTOFF(x) + (x).a_text )
  80 #define N_TROFF(x)      ( N_DATOFF(x) + (x).a_data )
  81 #define N_TRELOFF       N_TROFF
  82 #define N_DROFF(x)      ( N_TROFF(x) + (x).a_trsize )
  83 #define N_DRELOFF       N_DROFF
  84 #define N_SYMOFF(x)     ( N_DROFF(x) + (x).a_drsize )
  85 #define N_STROFF(x)     ( N_SYMOFF(x) + (x).a_syms )
  86 #define N_DATADDR(x)    ( (x).a_dload )
  87
  88 /* Address of text segment in memory after it is loaded.  */
  89 #if !defined (N_TXTADDR)
  90 #define N_TXTADDR(x) 0
  91 #endif
  92
  93 /* A single entry in the symbol table
  94  */
  95 struct nlist {
  96         union {
  97                 char    *n_name;
  98                 struct nlist *n_next;
  99                 long    n_strx;         /* Index into string table      */
 100         } n_un;
 101         unsigned char n_type;   /* See below                            */
 102         char    n_other;        /* Used in i80960 support -- see below  */
 103         short   n_desc;
 104         unsigned long n_value;
 105 };
 106
 107
 108 /* Legal values of n_type
 109  */
 110 #define N_UNDF  0       /* Undefined symbol     */
 111 #define N_ABS   2       /* Absolute symbol      */
 112 #define N_TEXT  4       /* Text symbol          */
 113 #define N_DATA  6       /* Data symbol          */
 114 #define N_BSS   8       /* BSS symbol           */
 115 #define N_FN    31      /* Filename symbol      */
 116
 117 #define N_EXT   1       /* External symbol (OR'd in with one of above)  */
 118 #define N_TYPE  036     /* Mask for all the type bits                   */
 119 #define N_STAB  0340    /* Mask for all bits used for SDB entries       */
 120
 121 /* MEANING OF 'n_other'
 122  *
 123  * If non-zero, the 'n_other' fields indicates either a leaf procedure or
 124  * a system procedure, as follows:
 125  *
 126  *      1 <= n_other <= 32 :
 127  *              The symbol is the entry point to a system procedure.
 128  *              'n_value' is the address of the entry, as for any other
 129  *              procedure.  The system procedure number (which can be used in
 130  *              a 'calls' instruction) is (n_other-1).  These entries come from
 131  *              '.sysproc' directives.
 132  *
 133  *      n_other == N_CALLNAME
 134  *              the symbol is the 'call' entry point to a leaf procedure.
 135  *              The *next* symbol in the symbol table must be the corresponding
 136  *              'bal' entry point to the procedure (see following).  These
 137  *              entries come from '.leafproc' directives in which two different
 138  *              symbols are specified (the first one is represented here).
 139  *
 140  *
 141  *      n_other == N_BALNAME
 142  *              the symbol is the 'bal' entry point to a leaf procedure.
 143  *              These entries result from '.leafproc' directives in which only
 144  *              one symbol is specified, or in which the same symbol is
 145  *              specified twice.
 146  *
 147  * Note that an N_CALLNAME entry *must* have a corresponding N_BALNAME entry,
 148  * but not every N_BALNAME entry must have an N_CALLNAME entry.
 149  */
 150 #define N_CALLNAME      ((char)-1)
 151 #define N_BALNAME       ((char)-2)
 152 #define IS_CALLNAME(x)  (N_CALLNAME == (x))
 153 #define IS_BALNAME(x)   (N_BALNAME == (x))
 154 #define IS_OTHER(x)     ((x)>0 && (x) <=32)
 155
 156 #define b_out_relocation_info relocation_info
 157 struct relocation_info {
 158         int      r_address;     /* File address of item to be relocated */
 159         unsigned
 160 #define r_index r_symbolnum
 161                 r_symbolnum:24,/* Index of symbol on which relocation is based,
 162                                 *       if r_extern is set.  Otherwise set to
 163                                 *       either N_TEXT, N_DATA, or N_BSS to
 164                                 *       indicate section on which relocation is
 165                                 *       based.
 166                                 */
 167                 r_pcrel:1,      /* 1 => relocate PC-relative; else absolute
 168                                  *      On i960, pc-relative implies 24-bit
 169                                  *      address, absolute implies 32-bit.
 170                                  */
 171                 r_length:2,     /* Number of bytes to relocate:
 172                                  *      0 => 1 byte
 173                                  *      1 => 2 bytes -- used for 13 bit pcrel
 174                                  *      2 => 4 bytes
 175                                  */
 176                 r_extern:1,
 177                 r_bsr:1,        /* Something for the GNU NS32K assembler */
 178                 r_disp:1,       /* Something for the GNU NS32K assembler */
 179                 r_callj:1,      /* 1 if relocation target is an i960 'callj' */
 180                 r_relaxable:1;  /* 1 if enough info is left to relax
 181                                    the data */
 182 };