summaryrefslogtreecommitdiff
path: root/libavutil/softfloat.h (plain)
blob: fa91d1e1cbf2760def88c3bfdaa56039640bf9f4
1/*
2 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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_H
22#define AVUTIL_SOFTFLOAT_H
23
24#include <stdint.h>
25#include "common.h"
26
27#include "avassert.h"
28#include "softfloat_tables.h"
29
30#define MIN_EXP -149
31#define MAX_EXP 126
32#define ONE_BITS 29
33
34typedef struct SoftFloat{
35 int32_t mant;
36 int32_t exp;
37}SoftFloat;
38
39static const SoftFloat FLOAT_0 = { 0, MIN_EXP}; ///< 0.0
40static const SoftFloat FLOAT_05 = { 0x20000000, 0}; ///< 0.5
41static const SoftFloat FLOAT_1 = { 0x20000000, 1}; ///< 1.0
42static const SoftFloat FLOAT_EPSILON = { 0x29F16B12, -16}; ///< A small value
43static const SoftFloat FLOAT_1584893192 = { 0x32B771ED, 1}; ///< 1.584893192 (10^.2)
44static const SoftFloat FLOAT_100000 = { 0x30D40000, 17}; ///< 100000
45static const SoftFloat FLOAT_0999999 = { 0x3FFFFBCE, 0}; ///< 0.999999
46
47
48/**
49 * Convert a SoftFloat to a double precision float.
50 */
51static inline av_const double av_sf2double(SoftFloat v) {
52 v.exp -= ONE_BITS +1;
53 if(v.exp > 0) return (double)v.mant * (double)(1 << v.exp);
54 else return (double)v.mant / (double)(1 << (-v.exp));
55}
56
57static av_const SoftFloat av_normalize_sf(SoftFloat a){
58 if(a.mant){
59#if 1
60 while((a.mant + 0x1FFFFFFFU)<0x3FFFFFFFU){
61 a.mant += a.mant;
62 a.exp -= 1;
63 }
64#else
65 int s=ONE_BITS - av_log2(FFABS(a.mant));
66 a.exp -= s;
67 a.mant <<= s;
68#endif
69 if(a.exp < MIN_EXP){
70 a.exp = MIN_EXP;
71 a.mant= 0;
72 }
73 }else{
74 a.exp= MIN_EXP;
75 }
76 return a;
77}
78
79static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){
80#if 1
81 if((int32_t)(a.mant + 0x40000000U) <= 0){
82 a.exp++;
83 a.mant>>=1;
84 }
85 av_assert2(a.mant < 0x40000000 && a.mant > -0x40000000);
86 av_assert2(a.exp <= MAX_EXP);
87 return a;
88#elif 1
89 int t= a.mant + 0x40000000 < 0;
90 return (SoftFloat){ a.mant>>t, a.exp+t};
91#else
92 int t= (a.mant + 0x3FFFFFFFU)>>31;
93 return (SoftFloat){a.mant>>t, a.exp+t};
94#endif
95}
96
97/**
98 * @return Will not be more denormalized than a*b. So if either input is
99 * normalized, then the output will not be worse then the other input.
100 * If both are normalized, then the output will be normalized.
101 */
102static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){
103 a.exp += b.exp;
104 av_assert2((int32_t)((a.mant * (int64_t)b.mant) >> ONE_BITS) == (a.mant * (int64_t)b.mant) >> ONE_BITS);
105 a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;
106 a = av_normalize1_sf((SoftFloat){a.mant, a.exp - 1});
107 if (!a.mant || a.exp < MIN_EXP)
108 return FLOAT_0;
109 return a;
110}
111
112/**
113 * b has to be normalized and not zero.
114 * @return Will not be more denormalized than a.
115 */
116static inline av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){
117 a.exp -= b.exp;
118 a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;
119 a = av_normalize1_sf(a);
120 if (!a.mant || a.exp < MIN_EXP)
121 return FLOAT_0;
122 return a;
123}
124
125/**
126 * Compares two SoftFloats.
127 * @returns < 0 if the first is less
128 * > 0 if the first is greater
129 * 0 if they are equal
130 */
131static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){
132 int t= a.exp - b.exp;
133 if (t <-31) return - b.mant ;
134 else if (t < 0) return (a.mant >> (-t)) - b.mant ;
135 else if (t < 32) return a.mant - (b.mant >> t);
136 else return a.mant ;
137}
138
139/**
140 * Compares two SoftFloats.
141 * @returns 1 if a is greater than b, 0 otherwise
142 */
143static inline av_const int av_gt_sf(SoftFloat a, SoftFloat b)
144{
145 int t= a.exp - b.exp;
146 if (t <-31) return 0 > b.mant ;
147 else if (t < 0) return (a.mant >> (-t)) > b.mant ;
148 else if (t < 32) return a.mant > (b.mant >> t);
149 else return a.mant > 0 ;
150}
151
152/**
153 * @returns the sum of 2 SoftFloats.
154 */
155static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){
156 int t= a.exp - b.exp;
157 if (t <-31) return b;
158 else if (t < 0) return av_normalize_sf(av_normalize1_sf((SoftFloat){ b.mant + (a.mant >> (-t)), b.exp}));
159 else if (t < 32) return av_normalize_sf(av_normalize1_sf((SoftFloat){ a.mant + (b.mant >> t ), a.exp}));
160 else return a;
161}
162
163/**
164 * @returns the difference of 2 SoftFloats.
165 */
166static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){
167 return av_add_sf(a, (SoftFloat){ -b.mant, b.exp});
168}
169
170//FIXME log, exp, pow
171
172/**
173 * Converts a mantisse and exponent to a SoftFloat
174 * @returns a SoftFloat with value v * 2^frac_bits
175 */
176static inline av_const SoftFloat av_int2sf(int v, int frac_bits){
177 int exp_offset = 0;
178 if(v <= INT_MIN + 1){
179 exp_offset = 1;
180 v>>=1;
181 }
182 return av_normalize_sf(av_normalize1_sf((SoftFloat){v, ONE_BITS + 1 - frac_bits + exp_offset}));
183}
184
185/**
186 * Converts a SoftFloat to an integer.
187 * Rounding is to -inf.
188 */
189static inline av_const int av_sf2int(SoftFloat v, int frac_bits){
190 v.exp += frac_bits - (ONE_BITS + 1);
191 if(v.exp >= 0) return v.mant << v.exp ;
192 else return v.mant >>(-v.exp);
193}
194
195/**
196 * Rounding-to-nearest used.
197 */
198static av_always_inline SoftFloat av_sqrt_sf(SoftFloat val)
199{
200 int tabIndex, rem;
201
202 if (val.mant == 0)
203 val.exp = MIN_EXP;
204 else if (val.mant < 0)
205 abort();
206 else
207 {
208 tabIndex = (val.mant - 0x20000000) >> 20;
209
210 rem = val.mant & 0xFFFFF;
211 val.mant = (int)(((int64_t)av_sqrttbl_sf[tabIndex] * (0x100000 - rem) +
212 (int64_t)av_sqrttbl_sf[tabIndex + 1] * rem +
213 0x80000) >> 20);
214 val.mant = (int)(((int64_t)av_sqr_exp_multbl_sf[val.exp & 1] * val.mant +
215 0x10000000) >> 29);
216
217 if (val.mant < 0x40000000)
218 val.exp -= 2;
219 else
220 val.mant >>= 1;
221
222 val.exp = (val.exp >> 1) + 1;
223 }
224
225 return val;
226}
227
228/**
229 * Rounding-to-nearest used.
230 */
231static av_unused void av_sincos_sf(int a, int *s, int *c)
232{
233 int idx, sign;
234 int sv, cv;
235 int st, ct;
236
237 idx = a >> 26;
238 sign = (idx << 27) >> 31;
239 cv = av_costbl_1_sf[idx & 0xf];
240 cv = (cv ^ sign) - sign;
241
242 idx -= 8;
243 sign = (idx << 27) >> 31;
244 sv = av_costbl_1_sf[idx & 0xf];
245 sv = (sv ^ sign) - sign;
246
247 idx = a >> 21;
248 ct = av_costbl_2_sf[idx & 0x1f];
249 st = av_sintbl_2_sf[idx & 0x1f];
250
251 idx = (int)(((int64_t)cv * ct - (int64_t)sv * st + 0x20000000) >> 30);
252
253 sv = (int)(((int64_t)cv * st + (int64_t)sv * ct + 0x20000000) >> 30);
254
255 cv = idx;
256
257 idx = a >> 16;
258 ct = av_costbl_3_sf[idx & 0x1f];
259 st = av_sintbl_3_sf[idx & 0x1f];
260
261 idx = (int)(((int64_t)cv * ct - (int64_t)sv * st + 0x20000000) >> 30);
262
263 sv = (int)(((int64_t)cv * st + (int64_t)sv * ct + 0x20000000) >> 30);
264 cv = idx;
265
266 idx = a >> 11;
267
268 ct = (int)(((int64_t)av_costbl_4_sf[idx & 0x1f] * (0x800 - (a & 0x7ff)) +
269 (int64_t)av_costbl_4_sf[(idx & 0x1f)+1]*(a & 0x7ff) +
270 0x400) >> 11);
271 st = (int)(((int64_t)av_sintbl_4_sf[idx & 0x1f] * (0x800 - (a & 0x7ff)) +
272 (int64_t)av_sintbl_4_sf[(idx & 0x1f) + 1] * (a & 0x7ff) +
273 0x400) >> 11);
274
275 *c = (int)(((int64_t)cv * ct + (int64_t)sv * st + 0x20000000) >> 30);
276
277 *s = (int)(((int64_t)cv * st + (int64_t)sv * ct + 0x20000000) >> 30);
278}
279
280#endif /* AVUTIL_SOFTFLOAT_H */
281
generated by cgit at 2024-05-17 03:07:33 (GMT)