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dct.c
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dct.c
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/*
* Copyright 2002 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Niels Provos.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <err.h>
#include <jpeglib.h>
#include "dct.h"
static int dct_inited;
static double **D, **Dt;
static double **tmp1, **tmp2;
static double _D[8][8] = {
{0.35355339059327, 0.35355339059327, 0.35355339059327, 0.35355339059327, 0.35355339059327, 0.35355339059327, 0.35355339059327, 0.35355339059327},
{0.49039264020162, 0.41573480615127, 0.27778511650980, 0.09754516100806, -0.09754516100806, -0.27778511650980, -0.41573480615127, -0.49039264020162},
{0.46193976625564, 0.19134171618254, -0.19134171618254, -0.46193976625564, -0.46193976625564, -0.19134171618255, 0.19134171618255, 0.46193976625564},
{0.41573480615127, -0.09754516100806, -0.49039264020162, -0.27778511650980, 0.27778511650980, 0.49039264020162, 0.09754516100806, -0.41573480615127},
{0.35355339059327, -0.35355339059327, -0.35355339059327, 0.35355339059327, 0.35355339059327, -0.35355339059327, -0.35355339059327, 0.35355339059327},
{0.27778511650980, -0.49039264020162, 0.09754516100806, 0.41573480615127, -0.41573480615127, -0.09754516100806, 0.49039264020162, -0.27778511650980},
{0.19134171618254, -0.46193976625564, 0.46193976625564, -0.19134171618254, -0.19134171618255, 0.46193976625564, -0.46193976625564, 0.19134171618254},
{0.09754516100806, -0.27778511650980, 0.41573480615127, -0.49039264020162, 0.49039264020162, -0.41573480615127, 0.27778511650980, -0.09754516100806}
};
void
mat_transpose(double **out, double **in, int size)
{
int i, j;
for (i = 0; i < size; i++)
for (j = 0; j < size; j++)
out[i][j] = in[j][i];
}
double **
mat_new(int size)
{
double **mat;
int i;
if ((mat = malloc(sizeof(double) * size)) == NULL)
err(1, "malloc");
for (i = 0; i < size; i++) {
if ((mat[i] = calloc(size, sizeof(double))) == NULL)
err(1, "calloc");
}
return (mat);
}
void
mat_mul(double **out, double **a, double **b, int size)
{
int i, j, k;
for (i = 0; i < size; i++) {
for (j = 0; j < size; j++) {
double sum = 0;
for (k = 0; k < size; k++)
sum += a[i][k]*b[k][j];
out[i][j] = sum;
}
}
}
void
mat_sadd(double **out, double **in, double val, int size)
{
int i, j;
for (i = 0; i < size; i++)
for (j = 0; j < size; j++)
out[i][j] = in[i][j] + val;
}
void
dcttomat(double **mat, short *dct)
{
int i;
for (i = 0; i < DCTSIZE2; i++) {
mat[i >> 3][i & 7] = dct[i];
}
}
void
mattodct(short *dct, double **mat)
{
int i;
for (i = 0; i < DCTSIZE2; i++) {
dct[i] = mat[i >> 3][i & 7];
}
}
void
dct_init(void)
{
int i, j;
D = mat_new(DCTSIZE);
Dt = mat_new(DCTSIZE);
tmp1 = mat_new(DCTSIZE);
tmp2 = mat_new(DCTSIZE);
for (i = 0; i < DCTSIZE; i++)
for (j = 0; j < DCTSIZE; j++)
D[i][j] = _D[i][j];
mat_transpose(Dt, D, DCTSIZE);
dct_inited = 1;
}
void
idct(short *out, short *in)
{
if (!dct_inited)
dct_init();
/* Convert to internal matrix representation */
dcttomat(tmp1, in);
/* Do D' * A * D */
mat_mul(tmp2, Dt, tmp1, DCTSIZE);
mat_mul(tmp1, tmp2, D, DCTSIZE);
/* Convert back to dct representation */
mattodct(out, tmp1);
}
void
dct(short *out, short *in)
{
if (!dct_inited)
dct_init();
/* Convert to internal matrix representation */
dcttomat(tmp1, in);
/* Do D' * A * D */
mat_mul(tmp2, D, tmp1, DCTSIZE);
mat_mul(tmp1, tmp2, Dt, DCTSIZE);
/* Convert back to dct representation */
mattodct(out, tmp1);
}