strtopdd.c revision 1.4 
1/* $NetBSD: strtopdd.c,v 1.4 2019/08/01 02:27:43 riastradh Exp $ */
2
3/****************************************************************
4
5The author of this software is David M. Gay.
6
7Copyright (C) 1998, 2000 by Lucent Technologies
8All Rights Reserved
9
10Permission to use, copy, modify, and distribute this software and
11its documentation for any purpose and without fee is hereby
12granted, provided that the above copyright notice appear in all
13copies and that both that the copyright notice and this
14permission notice and warranty disclaimer appear in supporting
15documentation, and that the name of Lucent or any of its entities
16not be used in advertising or publicity pertaining to
17distribution of the software without specific, written prior
18permission.
19
20LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
21INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
22IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
23SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
24WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
25IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
26ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
27THIS SOFTWARE.
28
29****************************************************************/
30
31/* Please send bug reports to David M. Gay (dmg at acm dot org,
32 * with " at " changed at "@" and " dot " changed to ".").	*/
33
34#include "gdtoaimp.h"
35
36 int
37#ifdef KR_headers
38strtopdd(s, sp, dd) CONST char *s; char **sp; double *dd;
39#else
40strtopdd(CONST char *s, char **sp, double *dd)
41#endif
42{
43#ifdef Sudden_Underflow
44	static CONST FPI fpi0 = { 106, 1-1023, 2046-1023-106+1, 1, 1 };
45#else
46	static CONST FPI fpi0 = { 106, 1-1023-53+1, 2046-1023-106+1, 1, 0 };
47#endif
48	ULong bits[4];
49	Long expt;
50	int i, j, rv;
51	typedef union {
52		double d[2];
53		ULong L[4];
54		} U;
55	U *u;
56#ifdef Honor_FLT_ROUNDS
57#include "gdtoa_fltrnds.h"
58#else
59#define fpi &fpi0
60#endif
61
62	rv = strtodg(s, sp, fpi, &expt, bits);
63	if (rv == STRTOG_NoMemory)
64		return rv;
65	u = (U*)dd;
66	switch(rv & STRTOG_Retmask) {
67	  case STRTOG_NoNumber:
68	  case STRTOG_Zero:
69		u->d[0] = u->d[1] = 0.;
70		break;
71
72	  case STRTOG_Normal:
73		u->L[_1] = (bits[1] >> 21 | bits[2] << 11) & 0xffffffffL;
74		u->L[_0] = (bits[2] >> 21) | ((bits[3] << 11) & 0xfffff)
75			  | ((expt + 0x3ff + 105) << 20);
76		expt += 0x3ff + 52;
77		if (bits[1] &= 0x1fffff) {
78			i = hi0bits(bits[1]) - 11;
79			if (i >= expt) {
80				i = expt - 1;
81				expt = 0;
82				}
83			else
84				expt -= i;
85			if (i > 0) {
86				bits[1] = bits[1] << i | bits[0] >> (32-i);
87				bits[0] = bits[0] << i & 0xffffffffL;
88				}
89			}
90		else if (bits[0]) {
91			i = hi0bits(bits[0]) + 21;
92			if (i >= expt) {
93				i = expt - 1;
94				expt = 0;
95				}
96			else
97				expt -= i;
98			if (i < 32) {
99				bits[1] = bits[0] >> (32 - i);
100				bits[0] = bits[0] << i & 0xffffffffL;
101				}
102			else {
103				bits[1] = bits[0] << (i - 32);
104				bits[0] = 0;
105				}
106			}
107		else {
108			u->L[2] = u->L[3] = 0;
109			break;
110			}
111		u->L[2+_1] = bits[0];
112		u->L[2+_0] = (bits[1] & 0xfffff) | (expt << 20);
113		break;
114
115	  case STRTOG_Denormal:
116		if (bits[3])
117			goto nearly_normal;
118		if (bits[2])
119			goto partly_normal;
120		if (bits[1] & 0xffe00000)
121			goto hardly_normal;
122		/* completely denormal */
123		u->L[2] = u->L[3] = 0;
124		u->L[_1] = bits[0];
125		u->L[_0] = bits[1];
126		break;
127
128	  nearly_normal:
129		i = hi0bits(bits[3]) - 11;	/* i >= 12 */
130		j = 32 - i;
131		u->L[_0] = ((bits[3] << i | bits[2] >> j) & 0xfffff)
132			| ((65 - i) << 20);
133		u->L[_1] = (bits[2] << i | bits[1] >> j) & 0xffffffffL;
134		u->L[2+_0] = bits[1] & ((1L << j) - 1);
135		u->L[2+_1] = bits[0];
136		break;
137
138	  partly_normal:
139		i = hi0bits(bits[2]) - 11;
140		if (i < 0) {
141			j = -i;
142			i += 32;
143			u->L[_0] = (bits[2] >> j & 0xfffff) | (33 + j) << 20;
144			u->L[_1] = ((bits[2] << i) | (bits[1] >> j)) & 0xffffffffL;
145			u->L[2+_0] = bits[1] & ((1L << j) - 1);
146			u->L[2+_1] = bits[0];
147			break;
148			}
149		if (i == 0) {
150			u->L[_0] = (bits[2] & 0xfffff) | (33 << 20);
151			u->L[_1] = bits[1];
152			u->L[2+_0] = 0;
153			u->L[2+_1] = bits[0];
154			break;
155			}
156		j = 32 - i;
157		u->L[_0] = (((bits[2] << i) | (bits[1] >> j)) & 0xfffff)
158				| ((j + 1) << 20);
159		u->L[_1] = (bits[1] << i | bits[0] >> j) & 0xffffffffL;
160		u->L[2+_0] = 0;
161		u->L[2+_1] = bits[0] & ((1L << j) - 1);
162		break;
163
164	  hardly_normal:
165		j = 11 - hi0bits(bits[1]);
166		i = 32 - j;
167		u->L[_0] = (bits[1] >> j & 0xfffff) | ((j + 1) << 20);
168		u->L[_1] = (bits[1] << i | bits[0] >> j) & 0xffffffffL;
169		u->L[2+_0] = 0;
170		u->L[2+_1] = bits[0] & ((1L << j) - 1);
171		break;
172
173	  case STRTOG_Infinite:
174		u->L[_0] = u->L[2+_0] = 0x7ff00000;
175		u->L[_1] = u->L[2+_1] = 0;
176		break;
177
178	  case STRTOG_NaN:
179		u->L[0] = u->L[2] = d_QNAN0;
180		u->L[1] = u->L[3] = d_QNAN1;
181	  }
182	if (rv & STRTOG_Neg) {
183		u->L[  _0] |= 0x80000000L;
184		u->L[2+_0] |= 0x80000000L;
185		}
186	return rv;
187	}
188