1124667Sdas/*- 2178140Sdas * Copyright (c) 2004-2008 David Schultz <das@FreeBSD.ORG> 3124667Sdas * All rights reserved. 4124667Sdas * 5124667Sdas * Redistribution and use in source and binary forms, with or without 6124667Sdas * modification, are permitted provided that the following conditions 7124667Sdas * are met: 8124667Sdas * 1. Redistributions of source code must retain the above copyright 9124667Sdas * notice, this list of conditions and the following disclaimer. 10124667Sdas * 2. Redistributions in binary form must reproduce the above copyright 11124667Sdas * notice, this list of conditions and the following disclaimer in the 12124667Sdas * documentation and/or other materials provided with the distribution. 13124667Sdas * 14124667Sdas * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15124667Sdas * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16124667Sdas * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17124667Sdas * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18124667Sdas * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19124667Sdas * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20124667Sdas * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21124667Sdas * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22124667Sdas * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23124667Sdas * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24124667Sdas * SUCH DAMAGE. 25124667Sdas */ 26124667Sdas 27124667Sdas#include <sys/cdefs.h> 28124667Sdas__FBSDID("$FreeBSD$"); 29124667Sdas 30124667Sdas#include <float.h> 31124667Sdas#include <limits.h> 32124667Sdas#include <math.h> 33178154Sdas 34178154Sdas#include "../stdio/floatio.h" 35124667Sdas#include "fpmath.h" 36124667Sdas#include "gdtoaimp.h" 37124667Sdas 38124667Sdas/* Strings values used by dtoa() */ 39124667Sdas#define INFSTR "Infinity" 40124667Sdas#define NANSTR "NaN" 41124667Sdas 42178140Sdas#define DBL_ADJ (DBL_MAX_EXP - 2) 43178140Sdas#define SIGFIGS ((DBL_MANT_DIG + 3) / 4 + 1) 44124667Sdas 45178140Sdasstatic const float one[] = { 1.0f, -1.0f }; 46124667Sdas 47124667Sdas/* 48124667Sdas * This procedure converts a double-precision number in IEEE format 49124667Sdas * into a string of hexadecimal digits and an exponent of 2. Its 50124667Sdas * behavior is bug-for-bug compatible with dtoa() in mode 2, with the 51124667Sdas * following exceptions: 52124667Sdas * 53124667Sdas * - An ndigits < 0 causes it to use as many digits as necessary to 54124667Sdas * represent the number exactly. 55124667Sdas * - The additional xdigs argument should point to either the string 56124667Sdas * "0123456789ABCDEF" or the string "0123456789abcdef", depending on 57124667Sdas * which case is desired. 58124667Sdas * - This routine does not repeat dtoa's mistake of setting decpt 59124667Sdas * to 9999 in the case of an infinity or NaN. INT_MAX is used 60124667Sdas * for this purpose instead. 61124667Sdas * 62124667Sdas * Note that the C99 standard does not specify what the leading digit 63124667Sdas * should be for non-zero numbers. For instance, 0x1.3p3 is the same 64178140Sdas * as 0x2.6p2 is the same as 0x4.cp3. This implementation always makes 65178140Sdas * the leading digit a 1. This ensures that the exponent printed is the 66178140Sdas * actual base-2 exponent, i.e., ilogb(d). 67124667Sdas * 68124667Sdas * Inputs: d, xdigs, ndigits 69124667Sdas * Outputs: decpt, sign, rve 70124667Sdas */ 71124667Sdaschar * 72124667Sdas__hdtoa(double d, const char *xdigs, int ndigits, int *decpt, int *sign, 73124667Sdas char **rve) 74124667Sdas{ 75124667Sdas union IEEEd2bits u; 76124667Sdas char *s, *s0; 77124667Sdas int bufsize; 78178140Sdas uint32_t manh, manl; 79124667Sdas 80124667Sdas u.d = d; 81124667Sdas *sign = u.bits.sign; 82124667Sdas 83124667Sdas switch (fpclassify(d)) { 84124667Sdas case FP_NORMAL: 85140430Sdas *decpt = u.bits.exp - DBL_ADJ; 86124667Sdas break; 87124667Sdas case FP_ZERO: 88124667Sdas *decpt = 1; 89124667Sdas return (nrv_alloc("0", rve, 1)); 90124667Sdas case FP_SUBNORMAL: 91140430Sdas u.d *= 0x1p514; 92140430Sdas *decpt = u.bits.exp - (514 + DBL_ADJ); 93124667Sdas break; 94124667Sdas case FP_INFINITE: 95124667Sdas *decpt = INT_MAX; 96124667Sdas return (nrv_alloc(INFSTR, rve, sizeof(INFSTR) - 1)); 97178140Sdas default: /* FP_NAN or unrecognized */ 98124667Sdas *decpt = INT_MAX; 99124667Sdas return (nrv_alloc(NANSTR, rve, sizeof(NANSTR) - 1)); 100124667Sdas } 101124667Sdas 102124667Sdas /* FP_NORMAL or FP_SUBNORMAL */ 103124667Sdas 104124667Sdas if (ndigits == 0) /* dtoa() compatibility */ 105124667Sdas ndigits = 1; 106124667Sdas 107124667Sdas /* 108178140Sdas * If ndigits < 0, we are expected to auto-size, so we allocate 109178140Sdas * enough space for all the digits. 110124667Sdas */ 111178140Sdas bufsize = (ndigits > 0) ? ndigits : SIGFIGS; 112124667Sdas s0 = rv_alloc(bufsize); 113124667Sdas 114178140Sdas /* Round to the desired number of digits. */ 115178140Sdas if (SIGFIGS > ndigits && ndigits > 0) { 116178140Sdas float redux = one[u.bits.sign]; 117178140Sdas int offset = 4 * ndigits + DBL_MAX_EXP - 4 - DBL_MANT_DIG; 118178140Sdas u.bits.exp = offset; 119178140Sdas u.d += redux; 120178140Sdas u.d -= redux; 121178140Sdas *decpt += u.bits.exp - offset; 122124667Sdas } 123124667Sdas 124178140Sdas manh = u.bits.manh; 125178140Sdas manl = u.bits.manl; 126178140Sdas *s0 = '1'; 127178140Sdas for (s = s0 + 1; s < s0 + bufsize; s++) { 128178140Sdas *s = xdigs[(manh >> (DBL_MANH_SIZE - 4)) & 0xf]; 129178140Sdas manh = (manh << 4) | (manl >> (DBL_MANL_SIZE - 4)); 130178140Sdas manl <<= 4; 131124667Sdas } 132124667Sdas 133124667Sdas /* If ndigits < 0, we are expected to auto-size the precision. */ 134124667Sdas if (ndigits < 0) { 135178140Sdas for (ndigits = SIGFIGS; s0[ndigits - 1] == '0'; ndigits--) 136124667Sdas ; 137124667Sdas } 138124667Sdas 139124667Sdas s = s0 + ndigits; 140178140Sdas *s = '\0'; 141124667Sdas if (rve != NULL) 142124667Sdas *rve = s; 143124667Sdas return (s0); 144124667Sdas} 145