1 /* $OpenBSD: ldtoa.c,v 1.4 2016/03/09 16:28:47 deraadt Exp $ */
2 /*-
3 * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/types.h>
29 #include <machine/ieee.h>
30 #include <float.h>
31 #include <stdint.h>
32 #include <limits.h>
33 #include <math.h>
34 #include <stdlib.h>
35 #include "gdtoaimp.h"
36
37 #if (LDBL_MANT_DIG > DBL_MANT_DIG)
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 *
__ldtoa(long double * ld,int mode,int ndigits,int * decpt,int * sign,char ** rve)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 struct ieee_ext *p = (struct ieee_ext *)ld;
64 uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
65 void *vbits = bits;
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 = p->ext_sign;
73 fpi.rounding ^= (fpi.rounding >> 1) & p->ext_sign;
74
75 be = p->ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
76 EXT_TO_ARRAY32(p, bits);
77
78 switch (fpclassify(*ld)) {
79 case FP_NORMAL:
80 kind = STRTOG_Normal;
81 #ifdef EXT_IMPLICIT_NBIT
82 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
83 #endif /* EXT_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 DEF_STRONG(__ldtoa);
108
109 #else /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
110
111 char *
__ldtoa(long double * ld,int mode,int ndigits,int * decpt,int * sign,char ** rve)112 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
113 char **rve)
114 {
115 char *ret;
116
117 ret = dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
118 if (*decpt == 9999)
119 *decpt = INT_MAX;
120 return ret;
121 }
122 DEF_STRONG(__ldtoa);
123
124 #endif /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
125