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ffmpeg / libavcodec / costablegen.c @ 7087ce08

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/*
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 * Generate a header file for hardcoded ff_cos_* tables
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 *
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 * Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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#define BITS 16
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#define FLOATFMT "%.18e"
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#define FIXEDFMT "%6d"
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static int clip_f15(int v)
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{
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    return v < -32767 ? -32767 :
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           v >  32767 ?  32767 :
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           v;
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}
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static void printval(double val, int fixed)
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{
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    if (fixed)
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        printf(" "FIXEDFMT",", clip_f15(lrint(val * (double)(1<<15))));
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    else
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        printf(" "FLOATFMT",", val);
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}
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int main(int argc, char *argv[])
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{
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    int i, j;
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    int do_sin = argc > 1 && !strcmp(argv[1], "sin");
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    int fixed  = argc > 2 && !strcmp(argv[2], "fixed");
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    double (*func)(double) = do_sin ? sin : cos;
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    printf("/* This file was generated by libavcodec/costablegen */\n");
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    printf("#define CONFIG_FFT_FLOAT %d\n", !fixed);
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    printf("#include \"libavcodec/%s\"\n", do_sin ? "rdft.h" : "fft.h");
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    for (i = 4; i <= BITS; i++) {
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        int m = 1 << i;
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        double freq = 2*M_PI/m;
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        printf("%s(%i) = {\n   ", do_sin ? "SINTABLE" : "COSTABLE", m);
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        for (j = 0; j < m/2 - 1; j++) {
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            int idx = j > m/4 ? m/2 - j : j;
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            if (do_sin && j >= m/4)
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                idx = m/4 - j;
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            printval(func(idx*freq), fixed);
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            if ((j & 3) == 3)
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                printf("\n   ");
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        }
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        printval(func(do_sin ? -(m/4 - 1)*freq : freq), fixed);
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        printf("\n};\n");
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    }
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    return 0;
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}