1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004-2008 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 __FBSDID("$FreeBSD$"); 31 32 #include <float.h> 33 #include <limits.h> 34 #include <math.h> 35 #include <stdint.h> 36 37 #ifdef __i386__ 38 #include <ieeefp.h> 39 #endif 40 41 #include "../stdio/floatio.h" 42 #include "fpmath.h" 43 #include "gdtoaimp.h" 44 45 #if (LDBL_MANT_DIG > DBL_MANT_DIG) 46 47 /* Strings values used by dtoa() */ 48 #define INFSTR "Infinity" 49 #define NANSTR "NaN" 50 51 #ifdef LDBL_IMPLICIT_NBIT 52 #define MANH_SIZE LDBL_MANH_SIZE 53 #else 54 #define MANH_SIZE (LDBL_MANH_SIZE - 1) 55 #endif 56 57 #if MANH_SIZE > 32 58 typedef uint64_t manh_t; 59 #else 60 typedef uint32_t manh_t; 61 #endif 62 63 #if LDBL_MANL_SIZE > 32 64 typedef uint64_t manl_t; 65 #else 66 typedef uint32_t manl_t; 67 #endif 68 69 #define LDBL_ADJ (LDBL_MAX_EXP - 2) 70 #define SIGFIGS ((LDBL_MANT_DIG + 3) / 4 + 1) 71 72 static const float one[] = { 1.0f, -1.0f }; 73 74 /* 75 * This is the long double version of __hdtoa(). 76 */ 77 char * 78 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign, 79 char **rve) 80 { 81 union IEEEl2bits u; 82 char *s, *s0; 83 manh_t manh; 84 manl_t manl; 85 int bufsize; 86 #ifdef __i386__ 87 fp_prec_t oldprec; 88 #endif 89 90 u.e = e; 91 *sign = u.bits.sign; 92 93 switch (fpclassify(e)) { 94 case FP_NORMAL: 95 *decpt = u.bits.exp - LDBL_ADJ; 96 break; 97 case FP_ZERO: 98 *decpt = 1; 99 return (nrv_alloc("0", rve, 1)); 100 case FP_SUBNORMAL: 101 #ifdef __i386__ 102 oldprec = fpsetprec(FP_PE); 103 #endif 104 u.e *= 0x1p514L; 105 *decpt = u.bits.exp - (514 + LDBL_ADJ); 106 #ifdef __i386__ 107 fpsetprec(oldprec); 108 #endif 109 break; 110 case FP_INFINITE: 111 *decpt = INT_MAX; 112 return (nrv_alloc(INFSTR, rve, sizeof(INFSTR) - 1)); 113 default: /* FP_NAN or unrecognized */ 114 *decpt = INT_MAX; 115 return (nrv_alloc(NANSTR, rve, sizeof(NANSTR) - 1)); 116 } 117 118 /* FP_NORMAL or FP_SUBNORMAL */ 119 120 if (ndigits == 0) /* dtoa() compatibility */ 121 ndigits = 1; 122 123 /* 124 * If ndigits < 0, we are expected to auto-size, so we allocate 125 * enough space for all the digits. 126 */ 127 bufsize = (ndigits > 0) ? ndigits : SIGFIGS; 128 s0 = rv_alloc(bufsize); 129 130 /* Round to the desired number of digits. */ 131 if (SIGFIGS > ndigits && ndigits > 0) { 132 float redux = one[u.bits.sign]; 133 int offset = 4 * ndigits + LDBL_MAX_EXP - 4 - LDBL_MANT_DIG; 134 #ifdef __i386__ 135 oldprec = fpsetprec(FP_PE); 136 #endif 137 u.bits.exp = offset; 138 u.e += redux; 139 u.e -= redux; 140 *decpt += u.bits.exp - offset; 141 #ifdef __i386__ 142 fpsetprec(oldprec); 143 #endif 144 } 145 146 mask_nbit_l(u); 147 manh = u.bits.manh; 148 manl = u.bits.manl; 149 *s0 = '1'; 150 for (s = s0 + 1; s < s0 + bufsize; s++) { 151 *s = xdigs[(manh >> (MANH_SIZE - 4)) & 0xf]; 152 manh = (manh << 4) | (manl >> (LDBL_MANL_SIZE - 4)); 153 manl <<= 4; 154 } 155 156 /* If ndigits < 0, we are expected to auto-size the precision. */ 157 if (ndigits < 0) { 158 for (ndigits = SIGFIGS; s0[ndigits - 1] == '0'; ndigits--) 159 ; 160 } 161 162 s = s0 + ndigits; 163 *s = '\0'; 164 if (rve != NULL) 165 *rve = s; 166 return (s0); 167 } 168 169 #else /* (LDBL_MANT_DIG == DBL_MANT_DIG) */ 170 171 char * 172 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign, 173 char **rve) 174 { 175 176 return (__hdtoa((double)e, xdigs, ndigits, decpt, sign, rve)); 177 } 178 179 #endif /* (LDBL_MANT_DIG == DBL_MANT_DIG) */ 180