1 /*- 2 * Copyright (c) 2004-2008 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 * $FreeBSD: src/lib/libc/gdtoa/_hldtoa.c,v 1.2 2008/04/12 14:53:52 das Exp $ 27 */ 28 29 #include <float.h> 30 #include <limits.h> 31 #include <math.h> 32 #include <stdint.h> 33 34 #ifdef __i386__ 35 #include <ieeefp.h> 36 #endif 37 38 #include "../stdio/floatio.h" 39 #include "fpmath.h" 40 #include "gdtoaimp.h" 41 42 #if (LDBL_MANT_DIG > DBL_MANT_DIG) 43 44 /* Strings values used by dtoa() */ 45 #define INFSTR "Infinity" 46 #define NANSTR "NaN" 47 48 #ifdef LDBL_IMPLICIT_NBIT 49 #define MANH_SIZE LDBL_MANH_SIZE 50 #else 51 #define MANH_SIZE (LDBL_MANH_SIZE - 1) 52 #endif 53 54 #if MANH_SIZE > 32 55 typedef uint64_t manh_t; 56 #else 57 typedef uint32_t manh_t; 58 #endif 59 60 #if LDBL_MANL_SIZE > 32 61 typedef uint64_t manl_t; 62 #else 63 typedef uint32_t manl_t; 64 #endif 65 66 #define LDBL_ADJ (LDBL_MAX_EXP - 2) 67 #define SIGFIGS ((LDBL_MANT_DIG + 3) / 4 + 1) 68 69 static const float one[] = { 1.0f, -1.0f }; 70 71 /* 72 * This is the long double version of __hdtoa(). 73 */ 74 char * 75 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign, 76 char **rve) 77 { 78 union IEEEl2bits u; 79 char *s, *s0; 80 manh_t manh; 81 manl_t manl; 82 int bufsize; 83 #ifdef __i386__ 84 fp_prec_t oldprec; 85 #endif 86 87 u.e = e; 88 *sign = u.bits.sign; 89 90 switch (fpclassify(e)) { 91 case FP_NORMAL: 92 *decpt = u.bits.exp - LDBL_ADJ; 93 break; 94 case FP_ZERO: 95 *decpt = 1; 96 return (nrv_alloc("0", rve, 1)); 97 case FP_SUBNORMAL: 98 #ifdef __i386__ 99 oldprec = fpsetprec(FP_PE); 100 #endif 101 u.e *= 0x1p514L; 102 *decpt = u.bits.exp - (514 + LDBL_ADJ); 103 #ifdef __i386__ 104 fpsetprec(oldprec); 105 #endif 106 break; 107 case FP_INFINITE: 108 *decpt = INT_MAX; 109 return (nrv_alloc(INFSTR, rve, sizeof(INFSTR) - 1)); 110 default: /* FP_NAN or unrecognized */ 111 *decpt = INT_MAX; 112 return (nrv_alloc(NANSTR, rve, sizeof(NANSTR) - 1)); 113 } 114 115 /* FP_NORMAL or FP_SUBNORMAL */ 116 117 if (ndigits == 0) /* dtoa() compatibility */ 118 ndigits = 1; 119 120 /* 121 * If ndigits < 0, we are expected to auto-size, so we allocate 122 * enough space for all the digits. 123 */ 124 bufsize = (ndigits > 0) ? ndigits : SIGFIGS; 125 s0 = rv_alloc(bufsize); 126 127 /* Round to the desired number of digits. */ 128 if (SIGFIGS > ndigits && ndigits > 0) { 129 float redux = one[u.bits.sign]; 130 int offset = 4 * ndigits + LDBL_MAX_EXP - 4 - LDBL_MANT_DIG; 131 #ifdef __i386__ 132 oldprec = fpsetprec(FP_PE); 133 #endif 134 u.bits.exp = offset; 135 u.e += redux; 136 u.e -= redux; 137 *decpt += u.bits.exp - offset; 138 #ifdef __i386__ 139 fpsetprec(oldprec); 140 #endif 141 } 142 143 mask_nbit_l(u); 144 manh = u.bits.manh; 145 manl = u.bits.manl; 146 *s0 = '1'; 147 for (s = s0 + 1; s < s0 + bufsize; s++) { 148 *s = xdigs[(manh >> (MANH_SIZE - 4)) & 0xf]; 149 manh = (manh << 4) | (manl >> (LDBL_MANL_SIZE - 4)); 150 manl <<= 4; 151 } 152 153 /* If ndigits < 0, we are expected to auto-size the precision. */ 154 if (ndigits < 0) { 155 for (ndigits = SIGFIGS; s0[ndigits - 1] == '0'; ndigits--) 156 ; 157 } 158 159 s = s0 + ndigits; 160 *s = '\0'; 161 if (rve != NULL) 162 *rve = s; 163 return (s0); 164 } 165 166 #else /* (LDBL_MANT_DIG == DBL_MANT_DIG) */ 167 168 char * 169 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign, 170 char **rve) 171 { 172 173 return (__hdtoa((double)e, xdigs, ndigits, decpt, sign, rve)); 174 } 175 176 #endif /* (LDBL_MANT_DIG == DBL_MANT_DIG) */ 177