lib/libc/gdtoa/ldtoa.c

   1 /*      $NetBSD: ldtoa.c,v 1.4 2007/02/23 17:45:59 christos Exp $       */
   2
   3 /*-
   4  * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 #if 0
  31 __FBSDID("$FreeBSD: src/lib/libc/gdtoa/_ldtoa.c,v 1.2 2004/01/18 07:53:49 das Exp $");
  32 #else
  33 __RCSID("$NetBSD: ldtoa.c,v 1.4 2007/02/23 17:45:59 christos Exp $");
  34 #endif
  35
  36 #include <float.h>
  37 #include <inttypes.h>
  38 #include <limits.h>
  39 #include <math.h>
  40 #include <stdlib.h>
  41 #ifndef __vax__
  42 #include <machine/ieee.h>
  43 #endif
  44 #include "gdtoaimp.h"
  45
  46 /*
  47  * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
  48  * except that the floating point argument is passed by reference.
  49  * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
  50  * However, a long double could have a valid exponent of 9999, so we
  51  * use INT_MAX in ldtoa() instead.
  52  */
  53 char *
  54 ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign, char **rve)
  55 {
  56 #ifdef EXT_EXPBITS
  57         static FPI fpi = {
  58                 LDBL_MANT_DIG,                  /* nbits */
  59                 LDBL_MIN_EXP - LDBL_MANT_DIG,   /* emin */
  60                 LDBL_MAX_EXP - LDBL_MANT_DIG,   /* emax */
  61                 FPI_Round_near,                 /* rounding */
  62 #ifdef Sudden_Underflow /* unused, but correct anyway */
  63                 1
  64 #else
  65                 0
  66 #endif
  67         };
  68         int be, kind;
  69         char *ret;
  70         union ieee_ext_u u;
  71         uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
  72
  73         u.extu_ld = *ld;
  74         *sign = u.extu_ext.ext_sign;
  75         be = u.extu_ext.ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
  76         EXT_TO_ARRAY32(u, bits);
  77
  78         switch (fpclassify(u.extu_ld)) {
  79         case FP_NORMAL:
  80                 kind = STRTOG_Normal;
  81 #ifdef  LDBL_IMPLICIT_NBIT
  82                 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
  83 #endif /* LDBL_IMPLICIT_NBIT */
  84                 break;
  85         case FP_ZERO:
  86                 kind = STRTOG_Zero;
  87                 break;
  88         case FP_SUBNORMAL:
  89                 kind = STRTOG_Denormal;
  90 #ifdef  LDBL_IMPLICIT_NBIT
  91                 be++;
  92 #endif
  93                 break;
  94         case FP_INFINITE:
  95                 kind = STRTOG_Infinite;
  96                 break;
  97         case FP_NAN:
  98                 kind = STRTOG_NaN;
  99                 break;
 100         default:
 101                 abort();
 102         }
 103
 104         ret = gdtoa(&fpi, be, (ULong *)bits, &kind, mode, ndigits, decpt, rve);
 105         if (*decpt == -32768)
 106                 *decpt = INT_MAX;
 107         return ret;
 108 #else
 109         return dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
 110 #endif
 111 }