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