1 /*- 2 * Copyright (c) 2003 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/_ldtoa.c,v 1.5 2007/12/09 19:48:57 das Exp $ 27 */ 28 29 #include <float.h> 30 #include <inttypes.h> 31 #include <limits.h> 32 #include <math.h> 33 #include <stdlib.h> 34 #include "fpmath.h" 35 #include "gdtoaimp.h" 36 37 /* 38 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(), 39 * except that the floating point argument is passed by reference. 40 * When dtoa() is passed a NaN or infinity, it sets expt to 9999. 41 * However, a long double could have a valid exponent of 9999, so we 42 * use INT_MAX in ldtoa() instead. 43 */ 44 char * 45 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign, 46 char **rve) 47 { 48 FPI fpi = { 49 LDBL_MANT_DIG, /* nbits */ 50 LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */ 51 LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */ 52 FLT_ROUNDS, /* rounding */ 53 #ifdef Sudden_Underflow /* unused, but correct anyway */ 54 1 55 #else 56 0 57 #endif 58 }; 59 int be, kind; 60 char *ret; 61 union IEEEl2bits u; 62 uint32_t bits[(LDBL_MANT_DIG + 31) / 32]; 63 void *vbits = bits; 64 65 u.e = *ld; 66 67 /* 68 * gdtoa doesn't know anything about the sign of the number, so 69 * if the number is negative, we need to swap rounding modes of 70 * 2 (upwards) and 3 (downwards). 71 */ 72 *sign = u.bits.sign; 73 fpi.rounding ^= (fpi.rounding >> 1) & u.bits.sign; 74 75 be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1); 76 LDBL_TO_ARRAY32(u, bits); 77 78 switch (fpclassify(u.e)) { 79 case FP_NORMAL: 80 kind = STRTOG_Normal; 81 #ifdef LDBL_IMPLICIT_NBIT 82 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32); 83 #endif /* LDBL_IMPLICIT_NBIT */ 84 break; 85 case FP_ZERO: 86 kind = STRTOG_Zero; 87 break; 88 case FP_SUBNORMAL: 89 kind = STRTOG_Denormal; 90 be++; 91 break; 92 case FP_INFINITE: 93 kind = STRTOG_Infinite; 94 break; 95 case FP_NAN: 96 kind = STRTOG_NaN; 97 break; 98 default: 99 abort(); 100 } 101 102 ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve); 103 if (*decpt == -32768) 104 *decpt = INT_MAX; 105 return ret; 106 } 107