gdtoa/_ldtoa-fbsd.c

   1 /*-
   2  * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD: src/lib/libc/gdtoa/_ldtoa.c,v 1.2 2004/01/18 07:53:49 das Exp $");
  29
  30 #include <float.h>
  31 #include <inttypes.h>
  32 #include <limits.h>
  33 #include <math.h>
  34 #include <stdlib.h>
  35 #include "fpmath.h"
  36 #include "gdtoaimp.h"
  37
  38 /*
  39  * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
  40  * except that the floating point argument is passed by reference.
  41  * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
  42  * However, a long double could have a valid exponent of 9999, so we
  43  * use INT_MAX in ldtoa() instead.
  44  */
  45 char *
  46 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
  47     char **rve)
  48 {
  49         static FPI fpi0 = {
  50                 LDBL_MANT_DIG,                  /* nbits */
  51                 LDBL_MIN_EXP - LDBL_MANT_DIG,   /* emin */
  52                 LDBL_MAX_EXP - LDBL_MANT_DIG,   /* emax */
  53                 FPI_Round_near,                 /* rounding */
  54 #ifdef Sudden_Underflow /* unused, but correct anyway */
  55                 1
  56 #else
  57                 0
  58 #endif
  59         };
  60         int be, kind;
  61         char *ret;
  62         union IEEEl2bits u;
  63         uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
  64         FPI *fpi = &fpi0, fpi1;
  65 #ifdef Honor_FLT_ROUNDS
  66         int rounding = Flt_Rounds;
  67 #endif
  68 #if defined(__ppc__) || defined(__ppc64__)
  69         int type;
  70 #endif /* defined(__ppc__) || defined(__ppc64__) */
  71
  72         u.e = *ld;
  73 #if defined(__ppc__) || defined(__ppc64__)
  74         /*
  75          * Subnormal head-tail doubles don't seem to be converted correctly
  76          * by gdtoa.  So we multiply by 10^32 to make them normal then
  77          * subtract 32 from the exponent later.
  78          */
  79         if ((type = __fpclassify(u.e)) == FP_NORMAL && __fpclassifyd(u.d[1]) == FP_SUBNORMAL)
  80                 type = FP_SUBNORMAL;
  81         if (type == FP_SUBNORMAL)
  82                 u.e *= 1.0e32L;
  83 #endif /* defined(__ppc__) || defined(__ppc64__) */
  84         *sign = u.bits.sign;
  85         be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
  86         LDBL_TO_ARRAY32(u, bits);
  87
  88 #if defined(__ppc__) || defined(__ppc64__)
  89         switch (type) {
  90         case FP_SUBNORMAL:
  91 #else /* !defined(__ppc__) && !defined(__ppc64__) */
  92         switch (fpclassify(u.e)) {
  93 #endif /* defined(__ppc__) || defined(__ppc64__) */
  94         case FP_NORMAL:
  95         case FP_SUPERNORMAL:
  96                 kind = STRTOG_Normal;
  97 /* For ppc/ppc64 and head-tail long double, the implicit bit is already there */
  98 #if !defined(__ppc__) && !defined(__ppc64__)
  99 #ifdef  LDBL_IMPLICIT_NBIT
 100                 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
 101 #endif /* LDBL_IMPLICIT_NBIT */
 102 #endif /* !defined(__ppc__) && !defined(__ppc64__) */
 103                 break;
 104         case FP_ZERO:
 105                 kind = STRTOG_Zero;
 106                 break;
 107 #if !defined(__ppc__) && !defined(__ppc64__)
 108         case FP_SUBNORMAL:
 109                 kind = STRTOG_Denormal;
 110                 be++;
 111                 break;
 112 #endif /* !defined(__ppc__) && !defined(__ppc64__) */
 113         case FP_INFINITE:
 114                 kind = STRTOG_Infinite;
 115                 break;
 116         case FP_NAN:
 117                 kind = STRTOG_NaN;
 118                 break;
 119         default:
 120                 abort();
 121         }
 122
 123 #ifdef Honor_FLT_ROUNDS
 124         if (rounding != fpi0.rounding) {
 125                 fpi1 = fpi0; /* for thread safety */
 126                 fpi1.rounding = rounding;
 127                 fpi = &fpi1;
 128                 }
 129 #endif /* Honor_FLT_ROUNDS */
 130         ret = gdtoa(fpi, be, (ULong *)bits, &kind, mode, ndigits, decpt, rve);
 131         if (*decpt == -32768)
 132                 *decpt = INT_MAX;
 133 #if defined(__ppc__) || defined(__ppc64__)
 134         else if (type == FP_SUBNORMAL)
 135                 *decpt -= 32;
 136 #endif /* defined(__ppc__) || defined(__ppc64__) */
 137         return ret;
 138 }