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gethex.c

/****************************************************************

The author of this software is David M. Gay.

Copyright (C) 1998 by Lucent Technologies
All Rights Reserved

Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name of Lucent or any of its entities
not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.

****************************************************************/

/* Please send bug reports to David M. Gay (dmg at acm dot org,
 * with " at " changed at "@" and " dot " changed to ".").  */

#include "gdtoaimp.h"

#ifdef USE_LOCALE
#include "locale.h"
#endif

int gethex (const char **sp, FPI *fpi, Long *expo, Bigint **bp, int sign)
{
      Bigint *b;
      const unsigned char *decpt, *s0, *s, *s1;
      int big, esign, havedig, irv, j, k, n, n0, nbits, up, zret;
      ULong L, lostbits, *x;
      Long e, e1;
#ifdef USE_LOCALE
      int i;
      const unsigned char *decimalpoint;
#ifdef NO_LOCALE_CACHE
      decimalpoint = (unsigned char *)localeconv()->decimal_point;
#else
      static unsigned char *decimalpoint_cache;
      if (!(s0 = decimalpoint_cache)) {
            s0 = (unsigned char *)localeconv()->decimal_point;
            decimalpoint_cache = (unsigned char *)
                              MALLOC(strlen((char *)s0) + 1);
            if (decimalpoint_cache) {
                  strcpy((char *)decimalpoint_cache, (char *)s0);
                  s0 = decimalpoint_cache;
            }
      }
      decimalpoint = s0;
#endif
#endif

      if (!hexdig['0'])
            hexdig_init_D2A();
      *bp = 0;
      havedig = 0;
      s0 = *(const unsigned char **)sp + 2;
      while(s0[havedig] == '0')
            havedig++;
      s0 += havedig;
      s = s0;
      decpt = 0;
      zret = 0;
      e = 0;
      if (hexdig[*s])
            havedig++;
      else {
            zret = 1;
#ifdef USE_LOCALE
            for(i = 0; decimalpoint[i]; ++i) {
                  if (s[i] != decimalpoint[i])
                        goto pcheck;
            }
            decpt = s += i;
#else
            if (*s != '.')
                  goto pcheck;
            decpt = ++s;
#endif
            if (!hexdig[*s])
                  goto pcheck;
            while(*s == '0')
                  s++;
            if (hexdig[*s])
                  zret = 0;
            havedig = 1;
            s0 = s;
      }
      while(hexdig[*s])
            s++;
#ifdef USE_LOCALE
      if (*s == *decimalpoint && !decpt) {
            for(i = 1; decimalpoint[i]; ++i) {
                  if (s[i] != decimalpoint[i])
                        goto pcheck;
            }
            decpt = s += i;
#else
      if (*s == '.' && !decpt) {
            decpt = ++s;
#endif
            while(hexdig[*s])
                  s++;
      }/*}*/
      if (decpt)
            e = -(((Long)(s-decpt)) << 2);
 pcheck:
      s1 = s;
      big = esign = 0;
      switch(*s) {
        case 'p':
        case 'P':
            switch(*++s) {
              case '-':
                  esign = 1;
                  /* no break */
              case '+':
                  s++;
            }
            if ((n = hexdig[*s]) == 0 || n > 0x19) {
                  s = s1;
                  break;
            }
            e1 = n - 0x10;
            while((n = hexdig[*++s]) !=0 && n <= 0x19) {
                  if (e1 & 0xf8000000)
                        big = 1;
                  e1 = 10*e1 + n - 0x10;
            }
            if (esign)
                  e1 = -e1;
            e += e1;
      }
      *sp = (char*)s;
      if (!havedig)
            *sp = (char*)s0 - 1;
      if (zret)
            return STRTOG_Zero;
      if (big) {
            if (esign) {
                  switch(fpi->rounding) {
                    case FPI_Round_up:
                        if (sign)
                              break;
                        goto ret_tiny;
                    case FPI_Round_down:
                        if (!sign)
                              break;
                        goto ret_tiny;
                  }
                  goto retz;
 ret_tiny:
                  b = Balloc(0);
                  b->wds = 1;
                  b->x[0] = 1;
                  goto dret;
            }
            switch(fpi->rounding) {
              case FPI_Round_near:
                  goto ovfl1;
              case FPI_Round_up:
                  if (!sign)
                        goto ovfl1;
                  goto ret_big;
              case FPI_Round_down:
                  if (sign)
                        goto ovfl1;
                  goto ret_big;
            }
 ret_big:
            nbits = fpi->nbits;
            n0 = n = nbits >> kshift;
            if (nbits & kmask)
                  ++n;
            for(j = n, k = 0; j >>= 1; ++k);
            *bp = b = Balloc(k);
            b->wds = n;
            for(j = 0; j < n0; ++j)
                  b->x[j] = ALL_ON;
            if (n > n0)
                  b->x[j] = ULbits >> (ULbits - (nbits & kmask));
            *expo = fpi->emin;
            return STRTOG_Normal | STRTOG_Inexlo;
      }
      n = s1 - s0 - 1;
      for(k = 0; n > (1 << (kshift-2)) - 1; n >>= 1)
            k++;
      b = Balloc(k);
      x = b->x;
      n = 0;
      L = 0;
#ifdef USE_LOCALE
      for(i = 0; decimalpoint[i+1]; ++i);
#endif
      while(s1 > s0) {
#ifdef USE_LOCALE
            if (*--s1 == decimalpoint[i]) {
                  s1 -= i;
                  continue;
            }
#else
            if (*--s1 == '.')
                  continue;
#endif
            if (n == ULbits) {
                  *x++ = L;
                  L = 0;
                  n = 0;
            }
            L |= (hexdig[*s1] & 0x0f) << n;
            n += 4;
      }
      *x++ = L;
      b->wds = n = x - b->x;
      n = ULbits*n - hi0bits(L);
      nbits = fpi->nbits;
      lostbits = 0;
      x = b->x;
      if (n > nbits) {
            n -= nbits;
            if (any_on(b,n)) {
                  lostbits = 1;
                  k = n - 1;
                  if (x[k>>kshift] & 1 << (k & kmask)) {
                        lostbits = 2;
                        if (k > 0 && any_on(b,k))
                              lostbits = 3;
                  }
            }
            rshift(b, n);
            e += n;
      }
      else if (n < nbits) {
            n = nbits - n;
            b = lshift(b, n);
            e -= n;
            x = b->x;
      }
      if (e > fpi->emax) {
 ovfl:
            Bfree(b);
 ovfl1:
            SET_ERRNO(ERANGE);
            return STRTOG_Infinite | STRTOG_Overflow | STRTOG_Inexhi;
      }
      irv = STRTOG_Normal;
      if (e < fpi->emin) {
            irv = STRTOG_Denormal;
            n = fpi->emin - e;
            if (n >= nbits) {
                  switch (fpi->rounding) {
                    case FPI_Round_near:
                        if (n == nbits && (n < 2 || any_on(b,n-1)))
                              goto one_bit;
                        break;
                    case FPI_Round_up:
                        if (!sign)
                              goto one_bit;
                        break;
                    case FPI_Round_down:
                        if (sign) {
 one_bit:
                              x[0] = b->wds = 1;
 dret:
                              *bp = b;
                              *expo = fpi->emin;
                              SET_ERRNO(ERANGE);
                              return STRTOG_Denormal | STRTOG_Inexhi
                                    | STRTOG_Underflow;
                        }
                  }
                  Bfree(b);
 retz:
                  SET_ERRNO(ERANGE);
                  return STRTOG_Zero | STRTOG_Inexlo | STRTOG_Underflow;
            }
            k = n - 1;
            if (lostbits)
                  lostbits = 1;
            else if (k > 0)
                  lostbits = any_on(b,k);
            if (x[k>>kshift] & 1 << (k & kmask))
                  lostbits |= 2;
            nbits -= n;
            rshift(b,n);
            e = fpi->emin;
      }
      if (lostbits) {
            up = 0;
            switch(fpi->rounding) {
              case FPI_Round_zero:
                  break;
              case FPI_Round_near:
                  if (lostbits & 2
                   && (lostbits | x[0]) & 1)
                        up = 1;
                  break;
              case FPI_Round_up:
                  up = 1 - sign;
                  break;
              case FPI_Round_down:
                  up = sign;
            }
            if (up) {
                  k = b->wds;
                  b = increment(b);
                  x = b->x;
                  if (irv == STRTOG_Denormal) {
                        if (nbits == fpi->nbits - 1
                         && x[nbits >> kshift] & 1 << (nbits & kmask))
                              irv =  STRTOG_Normal;
                  }
                  else if (b->wds > k
                   || ((n = nbits & kmask) !=0
                        && hi0bits(x[k-1]) < 32-n)) {
                        rshift(b,1);
                        if (++e > fpi->emax)
                              goto ovfl;
                  }
                  irv |= STRTOG_Inexhi;
            }
            else
                  irv |= STRTOG_Inexlo;
      }
      *bp = b;
      *expo = e;
      return irv;
}

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