source: mainline/softfloat/generic/conversion.c@ afffa1e

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since afffa1e was afffa1e, checked in by Josef Cejka <malyzelenyhnus@…>, 19 years ago

Conversion functions from float to int added.
Files arch.h and types.h from arch subdirectory should be replaced later with equivalent files from libc.
  • Property mode set to 100644
File size: 5.1 KB
Line 
1/*
2 * Copyright (C) 2005 Josef Cejka
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - 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 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include "sftypes.h"
30#include "conversion.h"
31#include "comparison.h"
32
33float64 convertFloat32ToFloat64(float32 a)
34{
35 float64 result;
36 __u64 frac;
37
38 result.parts.sign = a.parts.sign;
39 result.parts.fraction = a.parts.fraction;
40 result.parts.fraction <<= (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE );
41
42 if ((isFloat32Infinity(a))||(isFloat32NaN(a))) {
43 result.parts.exp = 0x7FF;
44 /* TODO; check if its correct for SigNaNs*/
45 return result;
46 };
47
48 result.parts.exp = a.parts.exp + ( (int)FLOAT64_BIAS - FLOAT32_BIAS );
49 if (a.parts.exp == 0) {
50 /* normalize denormalized numbers */
51
52 if (result.parts.fraction == 0ll) { /* fix zero */
53 result.parts.exp = 0ll;
54 return result;
55 }
56
57 frac = result.parts.fraction;
58
59 while (!(frac & (0x10000000000000ll))) {
60 frac <<= 1;
61 --result.parts.exp;
62 };
63
64 ++result.parts.exp;
65 result.parts.fraction = frac;
66 };
67
68 return result;
69
70}
71
72float32 convertFloat64ToFloat32(float64 a)
73{
74 float32 result;
75 __s32 exp;
76 __u64 frac;
77
78 result.parts.sign = a.parts.sign;
79
80 if (isFloat64NaN(a)) {
81
82 result.parts.exp = 0xFF;
83
84 if (isFloat64SigNaN(a)) {
85 result.parts.fraction = 0x800000; /* set first bit of fraction nonzero */
86 return result;
87 }
88
89 result.parts.fraction = 0x1; /* fraction nonzero but its first bit is zero */
90 return result;
91 };
92
93 if (isFloat64Infinity(a)) {
94 result.parts.fraction = 0;
95 result.parts.exp = 0xFF;
96 return result;
97 };
98
99 exp = (int)a.parts.exp - FLOAT64_BIAS + FLOAT32_BIAS;
100
101 if (exp >= 0xFF) {
102 /*FIXME: overflow*/
103 result.parts.fraction = 0;
104 result.parts.exp = 0xFF;
105 return result;
106
107 } else if (exp <= 0 ) {
108
109 /* underflow or denormalized */
110
111 result.parts.exp = 0;
112
113 exp *= -1;
114 if (exp > FLOAT32_FRACTION_SIZE ) {
115 /* FIXME: underflow */
116 result.parts.fraction = 0;
117 return result;
118 };
119
120 /* denormalized */
121
122 frac = a.parts.fraction;
123 frac |= 0x10000000000000ll; /* denormalize and set hidden bit */
124
125 frac >>= (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE + 1);
126
127 while (exp > 0) {
128 --exp;
129 frac >>= 1;
130 };
131 result.parts.fraction = frac;
132
133 return result;
134 };
135
136 result.parts.exp = exp;
137 result.parts.fraction = a.parts.fraction >> (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE);
138 return result;
139}
140
141
142/** Helping procedure for converting float32 to uint32
143 * @param a floating point number in normalized form (no NaNs or Inf are checked )
144 * @return unsigned integer
145 */
146static __u32 _float32_to_uint32_helper(float32 a)
147{
148 __u32 frac;
149
150 if (a.parts.exp < FLOAT32_BIAS) {
151 /*TODO: rounding*/
152 return 0;
153 }
154
155 frac = a.parts.fraction;
156
157 frac |= FLOAT32_HIDDEN_BIT_MASK;
158 /* shift fraction to left so hidden bit will be the most significant bit */
159 frac <<= 32 - FLOAT32_FRACTION_SIZE - 1;
160
161 frac >>= 32 - (a.parts.exp - FLOAT32_BIAS) - 1;
162 if ((a.parts.sign == 1) && (frac != 0)) {
163 frac = ~frac;
164 ++frac;
165 }
166
167 return frac;
168}
169
170/* Convert float to unsigned int32
171 * FIXME: Im not sure what to return if overflow/underflow happens
172 * - now its the biggest or the smallest int
173 */
174__u32 float32_to_uint32(float32 a)
175{
176 if (isFloat32NaN(a)) {
177 return MAX_UINT32;
178 }
179
180 if (isFloat32Infinity(a) || (a.parts.exp >= (32 + FLOAT32_BIAS))) {
181 if (a.parts.sign) {
182 return MIN_UINT32;
183 }
184 return MAX_UINT32;
185 }
186
187 return _float32_to_uint32_helper(a);
188}
189
190/* Convert float to signed int32
191 * FIXME: Im not sure what to return if overflow/underflow happens
192 * - now its the biggest or the smallest int
193 */
194__s32 float32_to_int32(float32 a)
195{
196 if (isFloat32NaN(a)) {
197 return MAX_INT32;
198 }
199
200 if (isFloat32Infinity(a) || (a.parts.exp >= (32 + FLOAT32_BIAS))) {
201 if (a.parts.sign) {
202 return MIN_INT32;
203 }
204 return MAX_INT32;
205 }
206 return _float32_to_uint32_helper(a);
207}
208
209
210
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