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 <float.h> 30 #include <inttypes.h> 31 #include <limits.h> 32 #include <math.h> 33 #include <stdlib.h> 34 #include "../stdio/floatio.h" 35 #include "fpmath.h" 36 #include "gdtoaimp.h" 37 38 /* 39 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(), 40 * except that the floating point argument is passed by reference. 41 * When dtoa() is passed a NaN or infinity, it sets expt to 9999. 42 * However, a long double could have a valid exponent of 9999, so we 43 * use INT_MAX in ldtoa() instead. 44 */ 45 char * 46 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign, 47 char **rve) 48 { 49 FPI fpi = { 50 LDBL_MANT_DIG, /* nbits */ 51 LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */ 52 LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */ 53 FLT_ROUNDS, /* rounding */ 54 #ifdef Sudden_Underflow /* unused, but correct anyway */ 55 1 56 #else 57 0 58 #endif 59 }; 60 int be, kind; 61 char *ret; 62 union IEEEl2bits u; 63 uint32_t bits[(LDBL_MANT_DIG + 31) / 32]; 64 void *vbits = bits; 65 66 u.e = *ld; 67 68 /* 69 * gdtoa doesn't know anything about the sign of the number, so 70 * if the number is negative, we need to swap rounding modes of 71 * 2 (upwards) and 3 (downwards). 72 */ 73 *sign = u.bits.sign; 74 fpi.rounding ^= (fpi.rounding >> 1) & u.bits.sign; 75 76 be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1); 77 LDBL_TO_ARRAY32(u, bits); 78 79 switch (fpclassify(u.e)) { 80 case FP_NORMAL: 81 kind = STRTOG_Normal; 82 #ifdef LDBL_IMPLICIT_NBIT 83 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32); 84 #endif /* LDBL_IMPLICIT_NBIT */ 85 break; 86 case FP_ZERO: 87 kind = STRTOG_Zero; 88 break; 89 case FP_SUBNORMAL: 90 kind = STRTOG_Denormal; 91 be++; 92 break; 93 case FP_INFINITE: 94 kind = STRTOG_Infinite; 95 break; 96 case FP_NAN: 97 kind = STRTOG_NaN; 98 break; 99 default: 100 abort(); 101 } 102 103 ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve); 104 if (*decpt == -32768) 105 *decpt = INT_MAX; 106 return ret; 107 } 108