FFmpeg: libavcodec/alpha/pixblockdsp_alpha.c Source File

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pixblockdsp_alpha.c

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1 /*

2 * SIMD-optimized pixel operations

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 */

21 #include "libavutil/attributes.h"

22 #include "libavcodec/pixblockdsp.h"

23 #include "asm.h"

25 static void get_pixels_mvi(int16_t *restrict block,

26 const uint8_t *restrict pixels, ptrdiff_t stride)

27 {

28 int h = 8;

30 do {

31 uint64_t p;

33 p = ldq(pixels);

34 stq(unpkbw(p), block);

35 stq(unpkbw(p >> 32), block + 4);

37 pixels += stride;

38 block += 8;

39 } while (--h);

40 }

42 static void diff_pixels_mvi(int16_t *block, const uint8_t *s1, const uint8_t *s2,

43 ptrdiff_t stride)

44 {

45 int h = 8;

46 uint64_t mask = 0x4040;

48 mask |= mask << 16;

49 mask |= mask << 32;

50 do {

51 uint64_t x, y, c, d, a;

52 uint64_t signs;

54 x = ldq(s1);

55 y = ldq(s2);

56 c = cmpbge(x, y);

57 d = x - y;

58 a = zap(mask, c); /* We use 0x4040404040404040 here... */

59 d += 4 * a; /* ...so we can use s4addq here. */

60 signs = zap(-1, c);

62 stq(unpkbw(d) | (unpkbw(signs) << 8), block);

63 stq(unpkbw(d >> 32) | (unpkbw(signs >> 32) << 8), block + 4);

65 s1 += stride;

66 s2 += stride;

67 block += 8;

68 } while (--h);

69 }

71 av_cold void ff_pixblockdsp_init_alpha(PixblockDSPContext *c, AVCodecContext *avctx,

72 unsigned high_bit_depth)

73 {

74 if (amask(AMASK_MVI) == 0) {

75 if (!high_bit_depth)

76 c->get_pixels = get_pixels_mvi;

77 c->diff_pixels = diff_pixels_mvi;

78 }

79 }

get_pixels_mvi

static void get_pixels_mvi(int16_t *restrict block, const uint8_t *restrict pixels, ptrdiff_t stride)

Definition: pixblockdsp_alpha.c:25

diff_pixels_mvi

static void diff_pixels_mvi(int16_t *block, const uint8_t *s1, const uint8_t *s2, ptrdiff_t stride)

Definition: pixblockdsp_alpha.c:42

ldq

#define ldq(p)

Definition: asm.h:59

AMASK_MVI

#define AMASK_MVI

Definition: asm.h:40

asm.h

av_cold

#define av_cold

Definition: attributes.h:90

mask

static const uint16_t mask[17]

Definition: lzw.c:38

#define s1

Definition: regdef.h:38

zap

#define zap(a, b)

Definition: asm.h:111

PixblockDSPContext

Definition: pixblockdsp.h:26

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 s2

Definition: regdef.h:39

cmpbge

#define cmpbge(a, b)

Definition: asm.h:107

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:41

attributes.h

ff_pixblockdsp_init_alpha

av_cold void ff_pixblockdsp_init_alpha(PixblockDSPContext *c, AVCodecContext *avctx, unsigned high_bit_depth)

Definition: pixblockdsp_alpha.c:71

amask

#define amask(a)

Definition: asm.h:113

stride

#define stride

Definition: h264pred_template.c:537

stq