nasmlib/readnum.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2016 The NASM Authors - All Rights Reserved
   4  *   See the file AUTHORS included with the NASM distribution for
   5  *   the specific copyright holders.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following
   9  *   conditions are met:
  10  *
  11  *   * Redistributions of source code must retain the above copyright
  12  *     notice, this list of conditions and the following disclaimer.
  13  *   * Redistributions in binary form must reproduce the above
  14  *     copyright notice, this list of conditions and the following
  15  *     disclaimer in the documentation and/or other materials provided
  16  *     with the distribution.
  17  *
  18  *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  19  *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  20  *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  21  *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  22  *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  23  *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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  29  *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  30  *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * ----------------------------------------------------------------------- */
  33
  34 /*
  35  * nasmlib.c    library routines for the Netwide Assembler
  36  */
  37
  38 #include "compiler.h"
  39
  40 #include <ctype.h>
  41
  42 #include "nasmlib.h"
  43 #include "nasm.h"               /* For globalbits */
  44
  45 #define lib_isnumchar(c)    (nasm_isalnum(c) || (c) == '$' || (c) == '_')
  46
  47 static int radix_letter(char c)
  48 {
  49     switch (c) {
  50     case 'b': case 'B':
  51     case 'y': case 'Y':
  52         return 2;               /* Binary */
  53     case 'o': case 'O':
  54     case 'q': case 'Q':
  55         return 8;               /* Octal */
  56     case 'h': case 'H':
  57     case 'x': case 'X':
  58         return 16;              /* Hexadecimal */
  59     case 'd': case 'D':
  60     case 't': case 'T':
  61         return 10;              /* Decimal */
  62     default:
  63         return 0;               /* Not a known radix letter */
  64     }
  65 }
  66
  67 int64_t readnum(char *str, bool *error)
  68 {
  69     char *r = str, *q;
  70     int32_t pradix, sradix, radix;
  71     int plen, slen, len;
  72     uint64_t result, checklimit;
  73     int digit, last;
  74     bool warn = false;
  75     int sign = 1;
  76
  77     *error = false;
  78
  79     while (nasm_isspace(*r))
  80         r++;                    /* find start of number */
  81
  82     /*
  83      * If the number came from make_tok_num (as a result of an %assign), it
  84      * might have a '-' built into it (rather than in a preceeding token).
  85      */
  86     if (*r == '-') {
  87         r++;
  88         sign = -1;
  89     }
  90
  91     q = r;
  92
  93     while (lib_isnumchar(*q))
  94         q++;                    /* find end of number */
  95
  96     len = q-r;
  97     if (!len) {
  98         /* Not numeric */
  99         *error = true;
 100         return 0;
 101     }
 102
 103     /*
 104      * Handle radix formats:
 105      *
 106      * 0<radix-letter><string>
 107      * $<string>                (hexadecimal)
 108      * <string><radix-letter>
 109      */
 110     pradix = sradix = 0;
 111     plen = slen = 0;
 112
 113     if (len > 2 && *r == '0' && (pradix = radix_letter(r[1])) != 0)
 114         plen = 2;
 115     else if (len > 1 && *r == '$')
 116         pradix = 16, plen = 1;
 117
 118     if (len > 1 && (sradix = radix_letter(q[-1])) != 0)
 119         slen = 1;
 120
 121     if (pradix > sradix) {
 122         radix = pradix;
 123         r += plen;
 124     } else if (sradix > pradix) {
 125         radix = sradix;
 126         q -= slen;
 127     } else {
 128         /* Either decimal, or invalid -- if invalid, we'll trip up
 129            further down. */
 130         radix = 10;
 131     }
 132
 133     /*
 134      * `checklimit' must be 2**64 / radix. We can't do that in
 135      * 64-bit arithmetic, which we're (probably) using, so we
 136      * cheat: since we know that all radices we use are even, we
 137      * can divide 2**63 by radix/2 instead.
 138      */
 139     checklimit = UINT64_C(0x8000000000000000) / (radix >> 1);
 140
 141     /*
 142      * Calculate the highest allowable value for the last digit of a
 143      * 64-bit constant... in radix 10, it is 6, otherwise it is 0
 144      */
 145     last = (radix == 10 ? 6 : 0);
 146
 147     result = 0;
 148     while (*r && r < q) {
 149         if (*r != '_') {
 150             if (*r < '0' || (*r > '9' && *r < 'A')
 151                 || (digit = numvalue(*r)) >= radix) {
 152                 *error = true;
 153                 return 0;
 154             }
 155             if (result > checklimit ||
 156                 (result == checklimit && digit >= last)) {
 157                 warn = true;
 158             }
 159
 160             result = radix * result + digit;
 161         }
 162         r++;
 163     }
 164
 165     if (warn)
 166         nasm_error(ERR_WARNING | ERR_PASS1 | ERR_WARN_NOV,
 167                    "numeric constant %s does not fit in 64 bits",
 168                    str);
 169
 170     return result * sign;
 171 }