1 /*
2 * Copyright (c) 2016 Umair Khan <omerjerk@gmail.com>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #ifndef AVUTIL_SOFTFLOAT_IEEE754_H
22 #define AVUTIL_SOFTFLOAT_IEEE754_H
23
24 #include <stdint.h>
25
26 #define EXP_BIAS 127
27 #define MANT_BITS 23
28
29 typedef struct SoftFloat_IEEE754 {
30 int32_t sign;
31 uint64_t mant;
32 int32_t exp;
33 } SoftFloat_IEEE754;
34
35 static const SoftFloat_IEEE754 FLOAT_0 = {0, 0, -126};
36 static const SoftFloat_IEEE754 FLOAT_1 = {0, 0, 0};
37
38 /** Normalize the softfloat as defined by IEEE 754 single-recision floating
39 * point specification
40 */
av_normalize_sf_ieee754(SoftFloat_IEEE754 sf)41 static inline SoftFloat_IEEE754 av_normalize_sf_ieee754(SoftFloat_IEEE754 sf) {
42 while( sf.mant >= 0x1000000UL ) {
43 sf.exp++;
44 sf.mant >>= 1;
45 }
46 sf.mant &= 0x007fffffUL;
47 return sf;
48 }
49
50 /** Convert integer to softfloat.
51 * @return softfloat with value n * 2^e
52 */
av_int2sf_ieee754(int64_t n,int e)53 static inline SoftFloat_IEEE754 av_int2sf_ieee754(int64_t n, int e) {
54 int sign = 0;
55
56 if (n < 0) {
57 sign = 1;
58 n *= -1;
59 }
60 return av_normalize_sf_ieee754((SoftFloat_IEEE754) {sign, n << MANT_BITS, 0 + e});
61 }
62
63 /** Make a softfloat out of the bitstream. Assumes the bits are in the form as defined
64 * by the IEEE 754 spec.
65 */
av_bits2sf_ieee754(uint32_t n)66 static inline SoftFloat_IEEE754 av_bits2sf_ieee754(uint32_t n) {
67 return ((SoftFloat_IEEE754) { (n & 0x80000000UL) >> 31, (n & 0x7FFFFFUL), (int8_t)((n & 0x7F800000UL) >> 23)});
68 }
69
70 /** Convert the softfloat to integer
71 */
av_sf2int_ieee754(SoftFloat_IEEE754 a)72 static inline int av_sf2int_ieee754(SoftFloat_IEEE754 a) {
73 if(a.exp >= 0) return a.mant << a.exp ;
74 else return a.mant >>(-a.exp);
75 }
76
77 /** Divide a by b. b should not be zero.
78 * @return normalized result
79 */
av_div_sf_ieee754(SoftFloat_IEEE754 a,SoftFloat_IEEE754 b)80 static inline SoftFloat_IEEE754 av_div_sf_ieee754(SoftFloat_IEEE754 a, SoftFloat_IEEE754 b) {
81 int32_t mant, exp, sign;
82 a = av_normalize_sf_ieee754(a);
83 b = av_normalize_sf_ieee754(b);
84 sign = a.sign ^ b.sign;
85 mant = ((((uint64_t) (a.mant | 0x00800000UL)) << MANT_BITS) / (b.mant| 0x00800000UL));
86 exp = a.exp - b.exp;
87 return av_normalize_sf_ieee754((SoftFloat_IEEE754) {sign, mant, exp});
88 }
89
90 /** Multiply a with b
91 * #return normalized result
92 */
av_mul_sf_ieee754(SoftFloat_IEEE754 a,SoftFloat_IEEE754 b)93 static inline SoftFloat_IEEE754 av_mul_sf_ieee754(SoftFloat_IEEE754 a, SoftFloat_IEEE754 b) {
94 int32_t sign, mant, exp;
95 a = av_normalize_sf_ieee754(a);
96 b = av_normalize_sf_ieee754(b);
97 sign = a.sign ^ b.sign;
98 mant = (((uint64_t)(a.mant|0x00800000UL) * (uint64_t)(b.mant|0x00800000UL))>>MANT_BITS);
99 exp = a.exp + b.exp;
100 return av_normalize_sf_ieee754((SoftFloat_IEEE754) {sign, mant, exp});
101 }
102
103 /** Compare a with b strictly
104 * @returns 1 if the a and b are equal, 0 otherwise.
105 */
av_cmp_sf_ieee754(SoftFloat_IEEE754 a,SoftFloat_IEEE754 b)106 static inline int av_cmp_sf_ieee754(SoftFloat_IEEE754 a, SoftFloat_IEEE754 b) {
107 a = av_normalize_sf_ieee754(a);
108 b = av_normalize_sf_ieee754(b);
109 if (a.sign != b.sign) return 0;
110 if (a.mant != b.mant) return 0;
111 if (a.exp != b.exp ) return 0;
112 return 1;
113 }
114
115 #endif /*AVUTIL_SOFTFLOAT_IEEE754_H*/
116