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Contents of /trunk/3rdparty/wxWidgets/src/common/extended.c

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Revision 31 - (show annotations) (download)
Tue Sep 7 03:24:11 2010 UTC (10 years, 2 months ago) by william
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committing r3113 initial commit again...
1 /*****************************************************************************
2 ** Name: extended.c
3 ** Purpose: IEEE Extended<->Double routines to save floats to file
4 ** Maintainer: Ryan Norton
5 ** Modified by:
6 ** Created: 11/24/04
7 ** RCS-ID: $Id: extended.c 36952 2006-01-18 10:25:04Z JS $
8 *****************************************************************************/
9
10
11 #if defined(_WIN32_WCE)
12 /* eVC cause warnings in its own headers: stdlib.h and winnt.h */
13 #pragma warning (disable:4115)
14 #pragma warning (disable:4214)
15 #endif
16
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <ctype.h>
20 #include <limits.h>
21 #include <string.h>
22 #include "wx/defs.h"
23
24 #if defined(_WIN32_WCE)
25 #pragma warning (default:4115)
26 #pragma warning (default:4214)
27 #endif
28
29 #if wxUSE_APPLE_IEEE
30
31 #include "wx/math.h"
32
33 /* Copyright (C) 1989-1991 Ken Turkowski. <turk@computer.org>
34 *
35 * All rights reserved.
36 *
37 * Warranty Information
38 * Even though I have reviewed this software, I make no warranty
39 * or representation, either express or implied, with respect to this
40 * software, its quality, accuracy, merchantability, or fitness for a
41 * particular purpose. As a result, this software is provided "as is,"
42 * and you, its user, are assuming the entire risk as to its quality
43 * and accuracy.
44 *
45 * This code may be used and freely distributed as long as it includes
46 * this copyright notice and the above warranty information.
47 *
48 * Machine-independent I/O routines for IEEE floating-point numbers.
49 *
50 * NaN's and infinities are converted to HUGE_VAL or HUGE, which
51 * happens to be infinity on IEEE machines. Unfortunately, it is
52 * impossible to preserve NaN's in a machine-independent way.
53 * Infinities are, however, preserved on IEEE machines.
54 *
55 * These routines have been tested on the following machines:
56 * Apple Macintosh, MPW 3.1 C compiler
57 * Apple Macintosh, THINK C compiler
58 * Silicon Graphics IRIS, MIPS compiler
59 * Cray X/MP and Y/MP
60 * Digital Equipment VAX
61 * Sequent Balance (Multiprocesor 386)
62 * NeXT
63 *
64 *
65 * Implemented by Malcolm Slaney and Ken Turkowski.
66 *
67 * Malcolm Slaney contributions during 1988-1990 include big- and little-
68 * endian file I/O, conversion to and from Motorola's extended 80-bit
69 * floating-point format, and conversions to and from IEEE single-
70 * precision floating-point format.
71 *
72 * In 1991, Ken Turkowski implemented the conversions to and from
73 * IEEE double-precision format, added more precision to the extended
74 * conversions, and accommodated conversions involving +/- infinity,
75 * NaN's, and denormalized numbers.
76 */
77
78 #ifndef HUGE_VAL
79 # define HUGE_VAL HUGE
80 #endif /*HUGE_VAL*/
81
82
83 /****************************************************************
84 * The following two routines make up for deficiencies in many
85 * compilers to convert properly between unsigned integers and
86 * floating-point. Some compilers which have this bug are the
87 * THINK_C compiler for the Macintosh and the C compiler for the
88 * Silicon Graphics MIPS-based Iris.
89 ****************************************************************/
90
91 #ifdef applec /* The Apple C compiler works */
92 # define FloatToUnsigned(f) ((wxUint32)(f))
93 # define UnsignedToFloat(u) ((wxFloat64)(u))
94 #else /*applec*/
95 # define FloatToUnsigned(f) ((wxUint32)(((wxInt32)((f) - 2147483648.0)) + 2147483647L) + 1)
96 # define UnsignedToFloat(u) (((wxFloat64)((wxInt32)((u) - 2147483647L - 1))) + 2147483648.0)
97 #endif /*applec*/
98
99
100
101 /****************************************************************
102 * Extended precision IEEE floating-point conversion routines.
103 * Extended is an 80-bit number as defined by Motorola,
104 * with a sign bit, 15 bits of exponent (offset 16383?),
105 * and a 64-bit mantissa, with no hidden bit.
106 ****************************************************************/
107
108 wxFloat64 ConvertFromIeeeExtended(const wxInt8 *bytes)
109 {
110 wxFloat64 f;
111 wxInt32 expon;
112 wxUint32 hiMant, loMant;
113
114 expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF);
115 hiMant = ((wxUint32)(bytes[2] & 0xFF) << 24)
116 | ((wxUint32)(bytes[3] & 0xFF) << 16)
117 | ((wxUint32)(bytes[4] & 0xFF) << 8)
118 | ((wxUint32)(bytes[5] & 0xFF));
119 loMant = ((wxUint32)(bytes[6] & 0xFF) << 24)
120 | ((wxUint32)(bytes[7] & 0xFF) << 16)
121 | ((wxUint32)(bytes[8] & 0xFF) << 8)
122 | ((wxUint32)(bytes[9] & 0xFF));
123
124 if (expon == 0 && hiMant == 0 && loMant == 0) {
125 f = 0;
126 }
127 else {
128 if (expon == 0x7FFF) { /* Infinity or NaN */
129 f = HUGE_VAL;
130 }
131 else {
132 expon -= 16383;
133 f = ldexp(UnsignedToFloat(hiMant), expon-=31);
134 f += ldexp(UnsignedToFloat(loMant), expon-=32);
135 }
136 }
137
138 if (bytes[0] & 0x80)
139 return -f;
140 else
141 return f;
142 }
143
144
145 /****************************************************************/
146
147
148 void ConvertToIeeeExtended(wxFloat64 num, wxInt8 *bytes)
149 {
150 wxInt32 sign;
151 wxInt32 expon;
152 wxFloat64 fMant, fsMant;
153 wxUint32 hiMant, loMant;
154
155 if (num < 0) {
156 sign = 0x8000;
157 num *= -1;
158 } else {
159 sign = 0;
160 }
161
162 if (num == 0) {
163 expon = 0; hiMant = 0; loMant = 0;
164 }
165 else {
166 fMant = frexp(num, &expon);
167 if ((expon > 16384) || !(fMant < 1)) { /* Infinity or NaN */
168 expon = sign|0x7FFF; hiMant = 0; loMant = 0; /* infinity */
169 }
170 else { /* Finite */
171 expon += 16382;
172 if (expon < 0) { /* denormalized */
173 fMant = ldexp(fMant, expon);
174 expon = 0;
175 }
176 expon |= sign;
177 fMant = ldexp(fMant, 32); fsMant = floor(fMant); hiMant = FloatToUnsigned(fsMant);
178 fMant = ldexp(fMant - fsMant, 32); fsMant = floor(fMant); loMant = FloatToUnsigned(fsMant);
179 }
180 }
181
182 bytes[0] = expon >> 8;
183 bytes[1] = expon;
184 bytes[2] = hiMant >> 24;
185 bytes[3] = hiMant >> 16;
186 bytes[4] = hiMant >> 8;
187 bytes[5] = hiMant;
188 bytes[6] = loMant >> 24;
189 bytes[7] = loMant >> 16;
190 bytes[8] = loMant >> 8;
191 bytes[9] = loMant;
192 }
193
194
195
196 #endif /* wxUSE_APPLE_IEEE */

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