1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 __FBSDID("$FreeBSD$"); 31 32 #include <float.h> 33 #include <inttypes.h> 34 #include <limits.h> 35 #include <math.h> 36 #include <stdlib.h> 37 #include "../stdio/floatio.h" 38 #include "fpmath.h" 39 #include "gdtoaimp.h" 40 41 /* 42 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(), 43 * except that the floating point argument is passed by reference. 44 * When dtoa() is passed a NaN or infinity, it sets expt to 9999. 45 * However, a long double could have a valid exponent of 9999, so we 46 * use INT_MAX in ldtoa() instead. 47 */ 48 char * 49 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign, 50 char **rve) 51 { 52 FPI fpi = { 53 LDBL_MANT_DIG, /* nbits */ 54 LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */ 55 LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */ 56 FLT_ROUNDS, /* rounding */ 57 #ifdef Sudden_Underflow /* unused, but correct anyway */ 58 1 59 #else 60 0 61 #endif 62 }; 63 int be, kind; 64 char *ret; 65 union IEEEl2bits u; 66 uint32_t bits[(LDBL_MANT_DIG + 31) / 32]; 67 void *vbits = bits; 68 69 u.e = *ld; 70 71 /* 72 * gdtoa doesn't know anything about the sign of the number, so 73 * if the number is negative, we need to swap rounding modes of 74 * 2 (upwards) and 3 (downwards). 75 */ 76 *sign = u.bits.sign; 77 fpi.rounding ^= (fpi.rounding >> 1) & u.bits.sign; 78 79 be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1); 80 LDBL_TO_ARRAY32(u, bits); 81 82 switch (fpclassify(u.e)) { 83 case FP_NORMAL: 84 kind = STRTOG_Normal; 85 #ifdef LDBL_IMPLICIT_NBIT 86 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32); 87 #endif /* LDBL_IMPLICIT_NBIT */ 88 break; 89 case FP_ZERO: 90 kind = STRTOG_Zero; 91 break; 92 case FP_SUBNORMAL: 93 kind = STRTOG_Denormal; 94 be++; 95 break; 96 case FP_INFINITE: 97 kind = STRTOG_Infinite; 98 break; 99 case FP_NAN: 100 kind = STRTOG_NaN; 101 break; 102 default: 103 abort(); 104 } 105 106 ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve); 107 if (*decpt == -32768) 108 *decpt = INT_MAX; 109 return ret; 110 } 111