1 /* $OpenBSD: ldtoa.c,v 1.2 2014/08/10 02:15:18 guenther 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 #ifndef __vax__
30 #include <machine/ieee.h>
31 #endif /* !__vax__ */
32 #include <float.h>
33 #include <stdint.h>
34 #include <limits.h>
35 #include <math.h>
36 #include <stdlib.h>
37 #include "gdtoaimp.h"
38
39 #if (LDBL_MANT_DIG > DBL_MANT_DIG)
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 *
__ldtoa(long double * ld,int mode,int ndigits,int * decpt,int * sign,char ** rve)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 struct ieee_ext *p = (struct ieee_ext *)ld;
66 uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
67 void *vbits = bits;
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 = p->ext_sign;
75 fpi.rounding ^= (fpi.rounding >> 1) & p->ext_sign;
76
77 be = p->ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
78 EXT_TO_ARRAY32(p, bits);
79
80 switch (fpclassify(*ld)) {
81 case FP_NORMAL:
82 kind = STRTOG_Normal;
83 #ifdef EXT_IMPLICIT_NBIT
84 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
85 #endif /* EXT_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
110 #else /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
111
112 char *
__ldtoa(long double * ld,int mode,int ndigits,int * decpt,int * sign,char ** rve)113 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
114 char **rve)
115 {
116 char *ret;
117
118 ret = dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
119 if (*decpt == 9999)
120 *decpt = INT_MAX;
121 return ret;
122 }
123
124 #endif /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
125