88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
#include <stdint.h>
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#include <stdlib.h>
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#include <stdio.h>
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#define DCT_SIZE 8
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#define TOTAL_DCT_BLOCKS 100
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#define element_t int16_t
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#define real_t double
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#define DCT_COS_TABLE_SIZE 32
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// DCT_COS_TABLE[i] = cos(i * PI / (2 * DCT_SIZE))
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#define DCT_COS_TABLE (double[DCT_COS_TABLE_SIZE]) { \
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1, 0.980785, 0.92388, 0.83147, 0.707107, 0.55557, 0.382683, \
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0.19509, 0, -0.19509, -0.382683, -0.55557, -0.707107, -0.83147, \
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-0.92388, -0.980785, -1, -0.980785, -0.92388, -0.83147, -0.707107, \
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-0.55557, -0.382683, -0.19509, 0, 0.19509, 0.382683, 0.55557, \
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0.707107, 0.83147, 0.92388, 0.980785 }
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#define INV_SQRTDCT_SIZE (real_t) 0.3535533906
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#define SQRT2_INV_SQRTDCT (real_t) 0.5
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void dct_2d(element_t* matrix_in, element_t* matrix_out) {
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real_t cu, cv, sum, cos_u, cos_v;
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int u, v, i, j;
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for (u = 0; u < DCT_SIZE; u++) {
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cu = u == 0 ? INV_SQRTDCT_SIZE : SQRT2_INV_SQRTDCT;
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for (v = 0; v < DCT_SIZE; v++) {
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cv = v == 0 ? INV_SQRTDCT_SIZE : SQRT2_INV_SQRTDCT;
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sum = 0;
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for (i = 0; i < DCT_SIZE; i++) {
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cos_u = DCT_COS_TABLE[((2 * i + 1) * u) % DCT_COS_TABLE_SIZE];
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for (j = 0; j < DCT_SIZE; j++) {
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cos_v = DCT_COS_TABLE[((2 * j + 1) * v) % DCT_COS_TABLE_SIZE];
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sum += matrix_in[i * DCT_SIZE + j] * cos_u * cos_v;
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}
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}
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matrix_out[u * DCT_SIZE + v] = cu * cv * sum;
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}
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}
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}
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void populate_mock_matrices(element_t** mock_matrices) {
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for (long i = 0; i < TOTAL_DCT_BLOCKS; i++) {
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for (int j = 0; j < DCT_SIZE; j++) {
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for (int k = 0; k < DCT_SIZE; k++) {
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mock_matrices[i][j * DCT_SIZE + k] = j + k;
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}
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}
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}
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}
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element_t** generate_mock_matrices() {
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element_t **mock_matrices = (element_t **) malloc(TOTAL_DCT_BLOCKS * sizeof(element_t*));
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for (int i = 0; i < TOTAL_DCT_BLOCKS; i++) {
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mock_matrices[i] = (element_t *) malloc(DCT_SIZE * DCT_SIZE * sizeof(element_t));
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}
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populate_mock_matrices(mock_matrices);
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return mock_matrices;
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}
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void free_mock_matrices(element_t** mock_matrices) {
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for (int i = 0; i < TOTAL_DCT_BLOCKS; i++) {
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free(mock_matrices[i]);
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}
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free(mock_matrices);
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}
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int main() {
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element_t **mock_matrices = generate_mock_matrices();
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int i;
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element_t* matrix_out = (element_t *) malloc(DCT_SIZE * DCT_SIZE * sizeof(element_t));
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for(i = 0; i < TOTAL_DCT_BLOCKS; i++) {
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dct_2d(mock_matrices[i], matrix_out);
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}
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free_mock_matrices(mock_matrices);
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free(matrix_out);
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return 0;
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}
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