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cos_tablegen.c
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1 /*
2  * Generate a header file for hardcoded ff_cos_* tables
3  *
4  * Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <stdio.h>
24 #include <string.h>
25 #include <math.h>
26 
27 #define BITS 16
28 #define FLOATFMT "%.18e"
29 #define FIXEDFMT "%6d"
30 
31 static int clip_f15(int v)
32 {
33  return v < -32767 ? -32767 :
34  v > 32767 ? 32767 :
35  v;
36 }
37 
38 static void printval(double val, int fixed)
39 {
40  if (fixed) {
41  /* lrint() isn't always available, so round and cast manually. */
42  double new_val = val * (double) (1 << 15);
43 
44  new_val = new_val >= 0 ? floor(new_val + 0.5) : ceil(new_val - 0.5);
45 
46  printf(" "FIXEDFMT",", clip_f15((long int) new_val));
47  } else {
48  printf(" "FLOATFMT",", val);
49  }
50 }
51 
52 int main(int argc, char *argv[])
53 {
54  int i, j;
55  int do_sin = argc > 1 && !strcmp(argv[1], "sin");
56  int fixed = argc > 1 && strstr(argv[1], "fixed");
57  double (*func)(double) = do_sin ? sin : cos;
58 
59  printf("/* This file was automatically generated. */\n");
60  printf("#define FFT_FLOAT %d\n", !fixed);
61  printf("#include \"libavcodec/%s\"\n", do_sin ? "rdft.h" : "fft.h");
62  for (i = 4; i <= BITS; i++) {
63  int m = 1 << i;
64  double freq = 2*3.14159265358979323846/m;
65  printf("%s(%i) = {\n ", do_sin ? "SINTABLE" : "COSTABLE", m);
66  for (j = 0; j < m/2 - 1; j++) {
67  int idx = j > m/4 ? m/2 - j : j;
68  if (do_sin && j >= m/4)
69  idx = m/4 - j;
70  printval(func(idx*freq), fixed);
71  if ((j & 3) == 3)
72  printf("\n ");
73  }
74  printval(func(do_sin ? -(m/4 - 1)*freq : freq), fixed);
75  printf("\n};\n");
76  }
77  return 0;
78 }