stdio/hexfloat.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25
  26 #ifdef HEXFLOAT
  27
  28 /*
  29  * hexfloat.c provides routines that vfprintf and vfwprintf can call to convert
  30  * floating point numbers to hexidecimal, as used by the %a and %A conversions.
  31  * This is necessarily dependent not only on the floating point data format,
  32  * but also byte order and existence of long double type.
  33  *
  34  * The union hexdouble represents the IEEE-754 double precision format, while
  35  * union hexlongdouble represents the IEEE-754 extended double precision
  36  * format.
  37  */
  38
  39 #include <stdio.h>
  40 #include <math.h>
  41 #include <limits.h>
  42
  43 #define EXPBIAS         1023
  44 #define EXPMIN          -1022
  45 #define EXPSPECIAL      2047
  46 #define FRACTHEX        13
  47
  48 union hexdouble {
  49         double d;
  50         struct {
  51 #if defined(__ppc__)
  52                 unsigned int sign:1;
  53                 unsigned int exp:11;
  54                 unsigned long long fract:52;
  55 #elif defined(__i386__)
  56                 unsigned long long fract:52;
  57                 unsigned int exp:11;
  58                 unsigned int sign:1;
  59 #else
  60 #error Unsupported architecture
  61 #endif
  62         } s;
  63 };
  64
  65 #if !__TYPE_LONGDOUBLE_IS_DOUBLE
  66 #ifdef __i386__
  67
  68 #define LEXPBIAS        16383
  69 #define LEXPMIN         -16382
  70 #define LEXPSPECIAL     32767
  71 #define LFRACTHEX       16
  72
  73 union hexlongdouble {
  74         long double d;
  75         struct {
  76                 unsigned long long fract:63;
  77                 unsigned int i:1;
  78                 unsigned int exp:15;
  79                 unsigned int sign:1;
  80         } s;
  81 };
  82 #endif /* __i386__ */
  83 #endif /* !__TYPE_LONGDOUBLE_IS_DOUBLE */
  84
  85 int
  86 __hdtoa(double d, const char *xdigs, int prec, char *cp,
  87     int *expt, int *signflag, char **dtoaend)
  88 {
  89         union hexdouble u;
  90         char buf[FRACTHEX];
  91         char *hp;
  92         int i;
  93         long long fract;
  94         //char *start = cp; //DEBUG
  95
  96         u.d = d;
  97         //printf("\nsign=%d exp=%x fract=%llx\n", u.s.sign, u.s.exp, u.s.fract); //DEBUG
  98         *signflag = u.s.sign;
  99         fract = u.s.fract;
 100         switch (u.s.exp) {
 101         case EXPSPECIAL:        /* NaN or Inf */
 102                 *expt = INT_MAX;
 103                 *cp = (fract ? 'N' : 'I');
 104                 return 0;
 105         case 0:                 /* Zero or denormalized */
 106                 *cp++ = '0';
 107                 *expt = (fract ? EXPMIN : 0);
 108                 break;
 109         default:                /* Normal numbers */
 110                 *cp++ = '1';
 111                 *expt = u.s.exp - EXPBIAS;
 112                 break;
 113         }
 114         if (prec < 0)
 115                 prec = FRACTHEX;
 116         //printf("prec=%d expt=%d\n", prec, *expt); //DEBUG
 117         if (prec > 0) {
 118                 int dig = (prec > FRACTHEX ? FRACTHEX : prec);
 119                 int zero = prec - dig;
 120                 int shift = FRACTHEX - dig;
 121                 if (shift > 0)
 122                     fract >>= (shift << 2);
 123                 for (hp = buf + dig, i = dig; i > 0; i--) {
 124                         *--hp = xdigs[fract & 0xf];
 125                         fract >>= 4;
 126                 }
 127                 strncpy(cp, hp, dig);
 128                 cp += dig;
 129                 while(zero-- > 0)
 130                         *cp++ = '0';
 131         }
 132         *dtoaend = cp;
 133         //while (start < cp) putchar(*start++); //DEBUG
 134         //putchar('\n'); //DEBUG
 135         return prec;
 136 }
 137
 138 #if !__TYPE_LONGDOUBLE_IS_DOUBLE
 139 #ifdef __i386__
 140 int
 141 __hldtoa(long double d, const char *xdigs, int prec, char *cp,
 142     int *expt, int *signflag, char **dtoaend)
 143 {
 144         union hexlongdouble u;
 145         char buf[LFRACTHEX];
 146         char *hp;
 147         int i;
 148         unsigned long long fract;
 149         //char *start = cp; //DEBUG
 150
 151         u.d = d;
 152         //printf("d=%Lg u.d=%Lg\n", d, u.d); //DEBUG
 153         //printf("\nsign=%d exp=%x fract=%llx\n", u.s.sign, u.s.exp, u.s.fract); //DEBUG
 154         *signflag = u.s.sign;
 155         fract = (u.s.fract << 1);
 156         switch (u.s.exp) {
 157         case LEXPSPECIAL:       /* NaN or Inf */
 158                 *expt = INT_MAX;
 159                 *cp = (fract ? 'N' : 'I');
 160                 return 0;
 161         default:                /* Normal or denormalized */
 162                 *cp++ = u.s.i ? '1' : '0';
 163                 *expt = u.s.exp - LEXPBIAS;
 164                 break;
 165         }
 166         if (prec < 0)
 167                 prec = LFRACTHEX;
 168         //printf("prec=%d expt=%d\n", prec, *expt); //DEBUG
 169         if (prec > 0) {
 170                 int dig = (prec > LFRACTHEX ? LFRACTHEX : prec);
 171                 int zero = prec - dig;
 172                 int shift = LFRACTHEX - dig;
 173                 if (shift > 0)
 174                     fract >>= (shift << 2);
 175                 for (hp = buf + dig, i = dig; i > 0; i--) {
 176                         *--hp = xdigs[fract & 0xf];
 177                         fract >>= 4;
 178                 }
 179                 strncpy(cp, hp, dig);
 180                 cp += dig;
 181                 while(zero-- > 0)
 182                         *cp++ = '0';
 183         }
 184         *dtoaend = cp;
 185         //while (start < cp) putchar(*start++); //DEBUG
 186         //putchar('\n'); //DEBUG
 187         return prec;
 188 }
 189 #endif /* __i386__ */
 190 #endif /* !__TYPE_LONGDOUBLE_IS_DOUBLE */
 191
 192 #endif /* HEXFLOAT */