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 1.5 2007/12/09 19:48:57 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 */ 45char * 46__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign, 47 char **rve) 48{ 49#if defined(__arm__) 50 /* On arm, double == long double, so short circuit this */ 51 char * ret = __dtoa((double)*ld, mode, ndigits, decpt, sign, rve); 52 if (*decpt == 9999) 53 *decpt = INT_MAX; 54 return ret; 55#else 56 FPI fpi = { 57 LDBL_MANT_DIG, /* nbits */ 58 LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */ 59 LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */ 60 FLT_ROUNDS, /* rounding */ 61#ifdef Sudden_Underflow /* unused, but correct anyway */ 62 1 63#else 64 0 65#endif 66 }; 67 int be, kind; 68 char *ret; 69 union IEEEl2bits u; 70 uint32_t bits[(LDBL_MANT_DIG + 31) / 32]; 71 void *vbits = bits; 72 int type; 73 74 u.e = *ld; 75 type = fpclassify(u.e); 76 77 /* 78 * gdtoa doesn't know anything about the sign of the number, so 79 * if the number is negative, we need to swap rounding modes of 80 * 2 (upwards) and 3 (downwards). 81 */ 82 *sign = u.bits.sign; 83 fpi.rounding ^= (fpi.rounding >> 1) & u.bits.sign; 84 85 be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1); 86 LDBL_TO_ARRAY32(u, bits); 87 88 switch (type) { 89 case FP_NORMAL: 90 case FP_SUPERNORMAL: 91 kind = STRTOG_Normal; 92#ifdef LDBL_IMPLICIT_NBIT 93 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32); 94#endif /* LDBL_IMPLICIT_NBIT */ 95 break; 96 case FP_ZERO: 97 kind = STRTOG_Zero; 98 break; 99 case FP_SUBNORMAL: 100 kind = STRTOG_Denormal; 101 be++; 102 break; 103 case FP_INFINITE: 104 kind = STRTOG_Infinite; 105 break; 106 case FP_NAN: 107 kind = STRTOG_NaN; 108 break; 109 default: 110 LIBC_ABORT("fpclassify returned %d", type); 111 } 112 113 ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve); 114 if (*decpt == -32768) 115 *decpt = INT_MAX; 116 return ret; 117#endif 118} 119