Flatten arrays

versions/flattened_array.c

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