lib/libc/gdtoa/gethex.c

   1 /* $NetBSD: gethex.c,v 1.4 2008/03/21 23:13:48 christos Exp $ */
   2
   3 /****************************************************************
   4
   5 The author of this software is David M. Gay.
   6
   7 Copyright (C) 1998 by Lucent Technologies
   8 All Rights Reserved
   9
  10 Permission to use, copy, modify, and distribute this software and
  11 its documentation for any purpose and without fee is hereby
  12 granted, provided that the above copyright notice appear in all
  13 copies and that both that the copyright notice and this
  14 permission notice and warranty disclaimer appear in supporting
  15 documentation, and that the name of Lucent or any of its entities
  16 not be used in advertising or publicity pertaining to
  17 distribution of the software without specific, written prior
  18 permission.
  19
  20 LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  21 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
  22 IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
  23 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  24 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
  25 IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  26 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
  27 THIS SOFTWARE.
  28
  29 ****************************************************************/
  30
  31 /* Please send bug reports to David M. Gay (dmg at acm dot org,
  32  * with " at " changed at "@" and " dot " changed to ".").      */
  33
  34 #include "gdtoaimp.h"
  35
  36 #ifdef USE_LOCALE
  37 #include "locale.h"
  38 #endif
  39
  40  int
  41 #ifdef KR_headers
  42 gethex(sp, fpi, expt, bp, sign)
  43         CONST char **sp; CONST FPI *fpi; Long *expt; Bigint **bp; int sign;
  44 #else
  45 gethex( CONST char **sp, CONST FPI *fpi, Long *expt, Bigint **bp, int sign)
  46 #endif
  47 {
  48         Bigint *b;
  49         CONST unsigned char *decpt, *s0, *s, *s1;
  50         int esign, havedig, irv, k, n, nbits, up, zret;
  51         ULong L, lostbits, *x;
  52         Long e, e1;
  53 #ifdef USE_LOCALE
  54         unsigned char decimalpoint = *localeconv()->decimal_point;
  55 #else
  56 #define decimalpoint '.'
  57 #endif
  58
  59         if (!hexdig['0'])
  60                 hexdig_init_D2A();
  61         havedig = 0;
  62         s0 = *(CONST unsigned char **)sp + 2;
  63         while(s0[havedig] == '0')
  64                 havedig++;
  65         s0 += havedig;
  66         s = s0;
  67         decpt = 0;
  68         zret = 0;
  69         e = 0;
  70         if (!hexdig[*s]) {
  71                 zret = 1;
  72                 if (*s != decimalpoint)
  73                         goto pcheck;
  74                 decpt = ++s;
  75                 if (!hexdig[*s])
  76                         goto pcheck;
  77                 while(*s == '0')
  78                         s++;
  79                 if (hexdig[*s])
  80                         zret = 0;
  81                 havedig = 1;
  82                 s0 = s;
  83                 }
  84         while(hexdig[*s])
  85                 s++;
  86         if (*s == decimalpoint && !decpt) {
  87                 decpt = ++s;
  88                 while(hexdig[*s])
  89                         s++;
  90                 }
  91         if (decpt)
  92                 e = -(((Long)(s-decpt)) << 2);
  93  pcheck:
  94         s1 = s;
  95         switch(*s) {
  96           case 'p':
  97           case 'P':
  98                 esign = 0;
  99                 switch(*++s) {
 100                   case '-':
 101                         esign = 1;
 102                         /* FALLTHROUGH */
 103                   case '+':
 104                         s++;
 105                   }
 106                 if ((n = hexdig[*s]) == 0 || n > 0x19) {
 107                         s = s1;
 108                         break;
 109                         }
 110                 e1 = n - 0x10;
 111                 while((n = hexdig[*++s]) !=0 && n <= 0x19)
 112                         e1 = 10*e1 + n - 0x10;
 113                 if (esign)
 114                         e1 = -e1;
 115                 e += e1;
 116           }
 117         *sp = __UNCONST(s);
 118         if (zret)
 119                 return havedig ? STRTOG_Zero : STRTOG_NoNumber;
 120         n = s1 - s0 - 1;
 121         for(k = 0; n > 7; n = (unsigned int)n >> 1)
 122                 k++;
 123         b = Balloc(k);
 124         if (b == NULL)
 125                 return STRTOG_NoMemory;
 126         x = b->x;
 127         n = 0;
 128         L = 0;
 129         while(s1 > s0) {
 130                 if (*--s1 == decimalpoint)
 131                         continue;
 132                 if (n == 32) {
 133                         *x++ = L;
 134                         L = 0;
 135                         n = 0;
 136                         }
 137                 L |= (hexdig[*s1] & 0x0f) << n;
 138                 n += 4;
 139                 }
 140         *x++ = L;
 141         b->wds = n = x - b->x;
 142         n = 32*n - hi0bits(L);
 143         nbits = fpi->nbits;
 144         lostbits = 0;
 145         x = b->x;
 146         if (n > nbits) {
 147                 n -= nbits;
 148                 if (any_on(b,n)) {
 149                         lostbits = 1;
 150                         k = n - 1;
 151                         if (x[(unsigned int)k>>kshift] & 1 << (k & kmask)) {
 152                                 lostbits = 2;
 153                                 if (k > 1 && any_on(b,k-1))
 154                                         lostbits = 3;
 155                                 }
 156                         }
 157                 rshift(b, n);
 158                 e += n;
 159                 }
 160         else if (n < nbits) {
 161                 n = nbits - n;
 162                 b = lshift(b, n);
 163                 if (b == NULL)
 164                         return STRTOG_NoMemory;
 165                 e -= n;
 166                 x = b->x;
 167                 }
 168         if (e > fpi->emax) {
 169  ovfl:
 170                 Bfree(b);
 171                 *bp = 0;
 172                 return STRTOG_Infinite | STRTOG_Overflow | STRTOG_Inexhi;
 173                 }
 174         irv = STRTOG_Normal;
 175         if (e < fpi->emin) {
 176                 irv = STRTOG_Denormal;
 177                 n = fpi->emin - e;
 178                 if (n >= nbits) {
 179                         switch (fpi->rounding) {
 180                           case FPI_Round_near:
 181                                 if (n == nbits && (n < 2 || any_on(b,n-1)))
 182                                         goto one_bit;
 183                                 break;
 184                           case FPI_Round_up:
 185                                 if (!sign)
 186                                         goto one_bit;
 187                                 break;
 188                           case FPI_Round_down:
 189                                 if (sign) {
 190  one_bit:
 191                                         *expt = fpi->emin;
 192                                         x[0] = b->wds = 1;
 193                                         *bp = b;
 194                                         return STRTOG_Denormal | STRTOG_Inexhi
 195                                                 | STRTOG_Underflow;
 196                                         }
 197                           }
 198                         Bfree(b);
 199                         *bp = 0;
 200                         return STRTOG_Zero | STRTOG_Inexlo | STRTOG_Underflow;
 201                         }
 202                 k = n - 1;
 203                 if (lostbits)
 204                         lostbits = 1;
 205                 else if (k > 0)
 206                         lostbits = any_on(b,k);
 207                 if (x[(unsigned int)k>>kshift] & 1 << (k & kmask))
 208                         lostbits |= 2;
 209                 nbits -= n;
 210                 rshift(b,n);
 211                 e = fpi->emin;
 212                 }
 213         if (lostbits) {
 214                 up = 0;
 215                 switch(fpi->rounding) {
 216                   case FPI_Round_zero:
 217                         break;
 218                   case FPI_Round_near:
 219                         if (lostbits & 2
 220                          && (lostbits & 1) | (x[0] & 1))
 221                                 up = 1;
 222                         break;
 223                   case FPI_Round_up:
 224                         up = 1 - sign;
 225                         break;
 226                   case FPI_Round_down:
 227                         up = sign;
 228                   }
 229                 if (up) {
 230                         k = b->wds;
 231                         b = increment(b);
 232                         x = b->x;
 233                         if (irv == STRTOG_Denormal) {
 234                                 if (nbits == fpi->nbits - 1
 235                                  && x[(unsigned int)nbits >> kshift] & 1 << (nbits & kmask))
 236                                         irv =  STRTOG_Normal;
 237                                 }
 238                         else if (b->wds > k
 239                          || ((n = nbits & kmask) !=0
 240                              && hi0bits(x[k-1]) < 32-n)) {
 241                                 rshift(b,1);
 242                                 if (++e > fpi->emax)
 243                                         goto ovfl;
 244                                 }
 245                         irv |= STRTOG_Inexhi;
 246                         }
 247                 else
 248                         irv |= STRTOG_Inexlo;
 249                 }
 250         *bp = b;
 251         *expt = e;
 252         return irv;
 253         }