FFmpeg
hscale_fast_bilinear.c
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1 /*
2  * Copyright (C) 2001-2011 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 #include "swscale_internal.h"
22 
23 void ff_hyscale_fast_c(SwsContext *c, int16_t *dst, int dstWidth,
24  const uint8_t *src, int srcW, int xInc)
25 {
26  int i;
27  unsigned int xpos = 0;
28  for (i = 0; i < dstWidth; i++) {
29  register unsigned int xx = xpos >> 16;
30  register unsigned int xalpha = (xpos & 0xFFFF) >> 9;
31  dst[i] = (src[xx] << 7) + (src[xx + 1] - src[xx]) * xalpha;
32  xpos += xInc;
33  }
34  for (i=dstWidth-1; (i*xInc)>>16 >=srcW-1; i--)
35  dst[i] = src[srcW-1]*128;
36 }
37 
38 void ff_hcscale_fast_c(SwsContext *c, int16_t *dst1, int16_t *dst2,
39  int dstWidth, const uint8_t *src1,
40  const uint8_t *src2, int srcW, int xInc)
41 {
42  int i;
43  unsigned int xpos = 0;
44  for (i = 0; i < dstWidth; i++) {
45  register unsigned int xx = xpos >> 16;
46  register unsigned int xalpha = (xpos & 0xFFFF) >> 9;
47  dst1[i] = (src1[xx] * (xalpha ^ 127) + src1[xx + 1] * xalpha);
48  dst2[i] = (src2[xx] * (xalpha ^ 127) + src2[xx + 1] * xalpha);
49  xpos += xInc;
50  }
51  for (i=dstWidth-1; (i*xInc)>>16 >=srcW-1; i--) {
52  dst1[i] = src1[srcW-1]*128;
53  dst2[i] = src2[srcW-1]*128;
54  }
55 }
#define src
Definition: vp8dsp.c:254
uint8_t
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
void ff_hcscale_fast_c(SwsContext *c, int16_t *dst1, int16_t *dst2, int dstWidth, const uint8_t *src1, const uint8_t *src2, int srcW, int xInc)
#define src1
Definition: h264pred.c:139
void ff_hyscale_fast_c(SwsContext *c, int16_t *dst, int dstWidth, const uint8_t *src, int srcW, int xInc)