FFmpeg
ops_backend.h
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1 /**
2  * Copyright (C) 2025 Niklas Haas
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 SWSCALE_OPS_BACKEND_H
22 #define SWSCALE_OPS_BACKEND_H
23 
24 /**
25  * Helper macros for the C-based backend.
26  *
27  * To use these macros, the following types must be defined:
28  * - PIXEL_TYPE should be one of SWS_PIXEL_*
29  * - pixel_t should be the type of pixels
30  * - block_t should be the type of blocks (groups of pixels)
31  */
32 
33 #include <assert.h>
34 #include <float.h>
35 #include <stdint.h>
36 
37 #include "libavutil/attributes.h"
38 #include "libavutil/mem.h"
39 
40 #include "ops_chain.h"
41 
42 /**
43  * Internal context holding per-iter execution data. The data pointers will be
44  * directly incremented by the corresponding read/write functions.
45  */
46 typedef struct SwsOpIter {
47  const uint8_t *in[4];
48  uint8_t *out[4];
49  int x, y;
50 } SwsOpIter;
51 
52 #ifdef __clang__
53 # define SWS_FUNC
54 # define SWS_LOOP AV_PRAGMA(clang loop vectorize(assume_safety))
55 #elif defined(__GNUC__)
56 # define SWS_FUNC __attribute__((optimize("tree-vectorize")))
57 # define SWS_LOOP AV_PRAGMA(GCC ivdep)
58 #else
59 # define SWS_FUNC
60 # define SWS_LOOP
61 #endif
62 
63 /* Miscellaneous helpers */
64 #define bitfn2(name, ext) name ## _ ## ext
65 #define bitfn(name, ext) bitfn2(name, ext)
66 
67 #define FN_SUFFIX AV_JOIN(FMT_CHAR, BIT_DEPTH)
68 #define fn(name) bitfn(name, FN_SUFFIX)
69 
70 #define av_q2pixel(q) ((q).den ? (pixel_t) (q).num / (q).den : 0)
71 
72 /* Helper macros to make writing common function signatures less painful */
73 #define DECL_FUNC(NAME, ...) \
74  static av_always_inline void fn(NAME)(SwsOpIter *restrict iter, \
75  const SwsOpImpl *restrict impl, \
76  block_t x, block_t y, \
77  block_t z, block_t w, \
78  __VA_ARGS__)
79 
80 #define DECL_READ(NAME, ...) \
81  DECL_FUNC(NAME, const pixel_t *restrict in0, const pixel_t *restrict in1, \
82  const pixel_t *restrict in2, const pixel_t *restrict in3, \
83  __VA_ARGS__)
84 
85 #define DECL_WRITE(NAME, ...) \
86  DECL_FUNC(NAME, pixel_t *restrict out0, pixel_t *restrict out1, \
87  pixel_t *restrict out2, pixel_t *restrict out3, \
88  __VA_ARGS__)
89 
90 /* Helper macros to call into functions declared with DECL_FUNC_* */
91 #define CALL(FUNC, ...) \
92  fn(FUNC)(iter, impl, x, y, z, w, __VA_ARGS__)
93 
94 #define CALL_READ(FUNC, ...) \
95  CALL(FUNC, (const pixel_t *) iter->in[0], (const pixel_t *) iter->in[1], \
96  (const pixel_t *) iter->in[2], (const pixel_t *) iter->in[3], \
97  __VA_ARGS__)
98 
99 #define CALL_WRITE(FUNC, ...) \
100  CALL(FUNC, (pixel_t *) iter->out[0], (pixel_t *) iter->out[1], \
101  (pixel_t *) iter->out[2], (pixel_t *) iter->out[3], __VA_ARGS__)
102 
103 /* Helper macros to declare continuation functions */
104 #define DECL_IMPL(NAME) \
105  static SWS_FUNC void fn(NAME)(SwsOpIter *restrict iter, \
106  const SwsOpImpl *restrict impl, \
107  block_t x, block_t y, \
108  block_t z, block_t w)
109 
110 /* Helper macro to call into the next continuation with a given type */
111 #define CONTINUE(TYPE, ...) \
112  ((void (*)(SwsOpIter *, const SwsOpImpl *, \
113  TYPE x, TYPE y, TYPE z, TYPE w)) impl->cont) \
114  (iter, &impl[1], __VA_ARGS__)
115 
116 /* Helper macros for common op setup code */
117 #define DECL_SETUP(NAME) \
118  static int fn(NAME)(const SwsOp *op, SwsOpPriv *out)
119 
120 #define SETUP_MEMDUP(c) ff_setup_memdup(&(c), sizeof(c), out)
121 static inline int ff_setup_memdup(const void *c, size_t size, SwsOpPriv *out)
122 {
123  out->ptr = av_memdup(c, size);
124  return out->ptr ? 0 : AVERROR(ENOMEM);
125 }
126 
127 /* Helper macro for declaring op table entries */
128 #define DECL_ENTRY(NAME, ...) \
129  static const SwsOpEntry fn(op_##NAME) = { \
130  .func = (SwsFuncPtr) fn(NAME), \
131  .type = PIXEL_TYPE, \
132  __VA_ARGS__ \
133  }
134 
135 /* Helpers to define functions for common subsets of components */
136 #define DECL_PATTERN(NAME) \
137  DECL_FUNC(NAME, const bool X, const bool Y, const bool Z, const bool W)
138 
139 #define WRAP_PATTERN(FUNC, X, Y, Z, W, ...) \
140  DECL_IMPL(FUNC##_##X##Y##Z##W) \
141  { \
142  CALL(FUNC, X, Y, Z, W); \
143  } \
144  \
145  DECL_ENTRY(FUNC##_##X##Y##Z##W, \
146  .unused = { !X, !Y, !Z, !W }, \
147  __VA_ARGS__ \
148  )
149 
150 #define WRAP_COMMON_PATTERNS(FUNC, ...) \
151  WRAP_PATTERN(FUNC, 1, 0, 0, 0, __VA_ARGS__); \
152  WRAP_PATTERN(FUNC, 1, 0, 0, 1, __VA_ARGS__); \
153  WRAP_PATTERN(FUNC, 1, 1, 1, 0, __VA_ARGS__); \
154  WRAP_PATTERN(FUNC, 1, 1, 1, 1, __VA_ARGS__)
155 
156 #define REF_COMMON_PATTERNS(NAME) \
157  &fn(op_##NAME##_1000), \
158  &fn(op_##NAME##_1001), \
159  &fn(op_##NAME##_1110), \
160  &fn(op_##NAME##_1111)
161 
162 #endif
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
out
static FILE * out
Definition: movenc.c:55
float.h
SwsOpIter
Copyright (C) 2025 Niklas Haas.
Definition: ops_backend.h:46
ff_setup_memdup
static int ff_setup_memdup(const void *c, size_t size, SwsOpPriv *out)
Definition: ops_backend.h:121
SwsOpIter::out
uint8_t * out[4]
Definition: ops_backend.h:48
SwsOpIter::x
int x
Definition: ops_backend.h:49
av_memdup
void * av_memdup(const void *p, size_t size)
Duplicate a buffer with av_malloc().
Definition: mem.c:304
ops_chain.h
c
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
size
int size
Definition: twinvq_data.h:10344
attributes.h
mem.h
SwsOpIter::in
const uint8_t * in[4]
Definition: ops_backend.h:47
SwsOpPriv
Copyright (C) 2025 Niklas Haas.
Definition: ops_chain.h:42
SwsOpIter::y
int y
Definition: ops_backend.h:49
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