FFmpeg
takdsp.c
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1 /*
2  * TAK decoder
3  * Copyright (c) 2015 Paul B Mahol
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/attributes.h"
23 #include "takdsp.h"
24 #include "config.h"
25 
26 static void decorrelate_ls(int32_t *p1, int32_t *p2, int length)
27 {
28  int i;
29 
30  for (i = 0; i < length; i++) {
31  int32_t a = p1[i];
32  int32_t b = p2[i];
33  p2[i] = a + b;
34  }
35 }
36 
37 static void decorrelate_sr(int32_t *p1, int32_t *p2, int length)
38 {
39  int i;
40 
41  for (i = 0; i < length; i++) {
42  int32_t a = p1[i];
43  int32_t b = p2[i];
44  p1[i] = b - a;
45  }
46 }
47 
48 static void decorrelate_sm(int32_t *p1, int32_t *p2, int length)
49 {
50  int i;
51 
52  for (i = 0; i < length; i++) {
53  int32_t a = p1[i];
54  int32_t b = p2[i];
55  a -= b >> 1;
56  p1[i] = a;
57  p2[i] = a + b;
58  }
59 }
60 
61 static void decorrelate_sf(int32_t *p1, int32_t *p2, int length, int dshift, int dfactor)
62 {
63  int i;
64 
65  for (i = 0; i < length; i++) {
66  int32_t a = p1[i];
67  int32_t b = p2[i];
68  b = dfactor * (b >> dshift) + 128 >> 8 << dshift;
69  p1[i] = b - a;
70  }
71 }
72 
74 {
79 
80  if (ARCH_X86)
82 }
av_cold void ff_takdsp_init(TAKDSPContext *c)
Definition: takdsp.c:73
void(* decorrelate_ls)(int32_t *p1, int32_t *p2, int length)
Definition: takdsp.h:25
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:36
static void decorrelate_sr(int32_t *p1, int32_t *p2, int length)
Definition: takdsp.c:37
Macro definitions for various function/variable attributes.
#define av_cold
Definition: attributes.h:82
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
GLsizei GLsizei * length
Definition: opengl_enc.c:114
#define b
Definition: input.c:41
void(* decorrelate_sr)(int32_t *p1, int32_t *p2, int length)
Definition: takdsp.h:26
int32_t
static void decorrelate_ls(int32_t *p1, int32_t *p2, int length)
Definition: takdsp.c:26
void(* decorrelate_sf)(int32_t *p1, int32_t *p2, int length, int dshift, int dfactor)
Definition: takdsp.h:28
static void decorrelate_sf(int32_t *p1, int32_t *p2, int length, int dshift, int dfactor)
Definition: takdsp.c:61
static void decorrelate_sm(int32_t *p1, int32_t *p2, int length)
Definition: takdsp.c:48
void ff_takdsp_init_x86(TAKDSPContext *c)
Definition: takdsp_init.c:30
void(* decorrelate_sm)(int32_t *p1, int32_t *p2, int length)
Definition: takdsp.h:27