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)
  27  *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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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 "nctype.h"
  41
  42 #include "nasmlib.h"
  43 #include "error.h"
  44 #include "nasm.h"               /* For globalbits */
  45
  46 #define lib_isnumchar(c)    (nasm_isalnum(c) || (c) == '$' || (c) == '_')
  47
  48 static int radix_letter(char c)
  49 {
  50     switch (c) {
  51     case 'b': case 'B':
  52     case 'y': case 'Y':
  53         return 2;               /* Binary */
  54     case 'o': case 'O':
  55     case 'q': case 'Q':
  56         return 8;               /* Octal */
  57     case 'h': case 'H':
  58     case 'x': case 'X':
  59         return 16;              /* Hexadecimal */
  60     case 'd': case 'D':
  61     case 't': case 'T':
  62         return 10;              /* Decimal */
  63     default:
  64         return 0;               /* Not a known radix letter */
  65     }
  66 }
  67
  68 int64_t readnum(const char *str, bool *error)
  69 {
  70     const char *r = str, *q;
  71     int32_t pradix, sradix, radix;
  72     int plen, slen, len;
  73     uint64_t result, checklimit;
  74     int digit, last;
  75     bool warn = false;
  76     int sign = 1;
  77
  78     *error = false;
  79
  80     while (nasm_isspace(*r))
  81         r++;                    /* find start of number */
  82
  83     /*
  84      * If the number came from make_tok_num (as a result of an %assign), it
  85      * might have a '-' built into it (rather than in a preceeding token).
  86      */
  87     if (*r == '-') {
  88         r++;
  89         sign = -1;
  90     }
  91
  92     q = r;
  93
  94     while (lib_isnumchar(*q))
  95         q++;                    /* find end of number */
  96
  97     len = q-r;
  98     if (!len) {
  99         /* Not numeric */
 100         *error = true;
 101         return 0;
 102     }
 103
 104     /*
 105      * Handle radix formats:
 106      *
 107      * 0<radix-letter><string>
 108      * $<string>                (hexadecimal)
 109      * <string><radix-letter>
 110      */
 111     pradix = sradix = 0;
 112     plen = slen = 0;
 113
 114     if (len > 2 && *r == '0' && (pradix = radix_letter(r[1])) != 0)
 115         plen = 2;
 116     else if (len > 1 && *r == '$')
 117         pradix = 16, plen = 1;
 118
 119     if (len > 1 && (sradix = radix_letter(q[-1])) != 0)
 120         slen = 1;
 121
 122     if (pradix > sradix) {
 123         radix = pradix;
 124         r += plen;
 125     } else if (sradix > pradix) {
 126         radix = sradix;
 127         q -= slen;
 128     } else {
 129         /* Either decimal, or invalid -- if invalid, we'll trip up
 130            further down. */
 131         radix = 10;
 132     }
 133
 134     /*
 135      * `checklimit' must be 2**64 / radix. We can't do that in
 136      * 64-bit arithmetic, which we're (probably) using, so we
 137      * cheat: since we know that all radices we use are even, we
 138      * can divide 2**63 by radix/2 instead.
 139      */
 140     checklimit = UINT64_C(0x8000000000000000) / (radix >> 1);
 141
 142     /*
 143      * Calculate the highest allowable value for the last digit of a
 144      * 64-bit constant... in radix 10, it is 6, otherwise it is 0
 145      */
 146     last = (radix == 10 ? 6 : 0);
 147
 148     result = 0;
 149     while (*r && r < q) {
 150         if (*r != '_') {
 151             if (*r < '0' || (*r > '9' && *r < 'A')
 152                 || (digit = numvalue(*r)) >= radix) {
 153                 *error = true;
 154                 return 0;
 155             }
 156             if (result > checklimit ||
 157                 (result == checklimit && digit >= last)) {
 158                 warn = true;
 159             }
 160
 161             result = radix * result + digit;
 162         }
 163         r++;
 164     }
 165
 166     if (warn) {
 167         /*!
 168          *!number-overflow [on] numeric constant does not fit
 169          *!    covers warnings about numeric constants which
 170          *!    don't fit in 64 bits.
 171          */
 172         nasm_warn(WARN_NUMBER_OVERFLOW,
 173                    "numeric constant %s does not fit in 64 bits",
 174                    str);
 175     }
 176
 177     return result * sign;
 178 }