1 /* $NetBSD: ldtoa.c,v 1.6 2019/08/01 02:27:43 riastradh Exp $ */
2
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 #if 0
31 __FBSDID("$FreeBSD: src/lib/libc/gdtoa/_ldtoa.c,v 1.2 2004/01/18 07:53:49 das Exp $");
32 #else
33 __RCSID("$NetBSD: ldtoa.c,v 1.6 2019/08/01 02:27:43 riastradh Exp $");
34 #endif
35
36 #include <float.h>
37 #include <inttypes.h>
38 #include <limits.h>
39 #include <math.h>
40 #include <stdlib.h>
41 #ifndef __vax__
42 #include <machine/ieee.h>
43 #endif
44 #include "gdtoaimp.h"
45
46 /*
47 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
48 * except that the floating point argument is passed by reference.
49 * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
50 * However, a long double could have a valid exponent of 9999, so we
51 * use INT_MAX in ldtoa() instead.
52 */
53 char *
ldtoa(long double * ld,int mode,int ndigits,int * decpt,int * sign,char ** rve)54 ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign, char **rve)
55 {
56 #ifdef EXT_EXPBITS
57 static CONST FPI fpi = {
58 LDBL_MANT_DIG, /* nbits */
59 LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */
60 LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */
61 FPI_Round_near, /* rounding */
62 #ifdef Sudden_Underflow /* unused, but correct anyway */
63 1
64 #else
65 0
66 #endif
67 };
68 int be, kind;
69 char *ret;
70 union ieee_ext_u u;
71 uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
72
73 u.extu_ld = *ld;
74 *sign = u.extu_ext.ext_sign;
75 be = u.extu_ext.ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
76 EXT_TO_ARRAY32(u, bits);
77
78 switch (fpclassify(u.extu_ld)) {
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, (ULong *)bits, &kind, mode, ndigits, decpt, rve);
103 if (*decpt == -32768)
104 *decpt = INT_MAX;
105 return ret;
106 #else
107 return dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
108 #endif
109 }
110