xref: /freebsd/contrib/gdtoa/strtof.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /****************************************************************
2 
3 The author of this software is David M. Gay.
4 
5 Copyright (C) 1998, 2000 by Lucent Technologies
6 All Rights Reserved
7 
8 Permission to use, copy, modify, and distribute this software and
9 its documentation for any purpose and without fee is hereby
10 granted, provided that the above copyright notice appear in all
11 copies and that both that the copyright notice and this
12 permission notice and warranty disclaimer appear in supporting
13 documentation, and that the name of Lucent or any of its entities
14 not be used in advertising or publicity pertaining to
15 distribution of the software without specific, written prior
16 permission.
17 
18 LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
19 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
20 IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
21 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
22 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
23 IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
24 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
25 THIS SOFTWARE.
26 
27 ****************************************************************/
28 
29 /* Please send bug reports to David M. Gay (dmg at acm dot org,
30  * with " at " changed at "@" and " dot " changed to ".").	*/
31 
32 /* $FreeBSD$ */
33 
34 #include "gdtoaimp.h"
35 
36  float
37 #ifdef KR_headers
38 strtof(s, sp) CONST char *s; char **sp;
39 #else
40 strtof(CONST char *s, char **sp)
41 #endif
42 {
43 	static FPI fpi = { 24, 1-127-24+1,  254-127-24+1, 1, SI };
44 	ULong bits[1];
45 	Long exp;
46 	int k;
47 	union { ULong L[1]; float f; } u;
48 
49 	k = strtodg(s, sp, &fpi, &exp, bits);
50 	switch(k & STRTOG_Retmask) {
51 	  case STRTOG_NoNumber:
52 	  case STRTOG_Zero:
53 		u.L[0] = 0;
54 		break;
55 
56 	  case STRTOG_Normal:
57 		u.L[0] = bits[0] & 0x7fffff | exp + 0x7f + 23 << 23;
58 		break;
59 
60 	  case STRTOG_NaNbits:
61 		/* FreeBSD local: always return a quiet NaN */
62 		u.L[0] = bits[0] | 0x7fc00000;
63 		break;
64 
65 	  case STRTOG_Denormal:
66 		u.L[0] = bits[0];
67 		break;
68 
69 	  case STRTOG_Infinite:
70 		u.L[0] = 0x7f800000;
71 		break;
72 
73 	  case STRTOG_NaN:
74 		u.L[0] = f_QNAN;
75 	  }
76 	if (k & STRTOG_Neg)
77 		u.L[0] |= 0x80000000L;
78 	return u.f;
79 	}
80