daedalus-fourier/tests/test_chroma_dc_hadamard.c

/*
 * Tests the H.264 chroma DC 2x2 Hadamard primitive against
 * spec-derived expected outputs.
 *
 *   f[0,0] = c[0,0] + c[0,1] + c[1,0] + c[1,1]    "sum"
 *   f[0,1] = c[0,0] - c[0,1] + c[1,0] - c[1,1]    "col-diff"
 *   f[1,0] = c[0,0] + c[0,1] - c[1,0] - c[1,1]    "row-diff"
 *   f[1,1] = c[0,0] - c[0,1] - c[1,0] + c[1,1]    "anti-diag"
 */
#include <stdint.h>
#include <stdio.h>
#include <string.h>

extern void daedalus_h264_chroma_dc_hadamard_2x2_ref(int16_t c[4]);
extern void daedalus_h264_chroma_dc_hadamard_2x2(int16_t c[4]);  /* public API */

static int check(const char *name, int16_t in[4], int16_t expect[4])
{
    int16_t c[4]; memcpy(c, in, sizeof(c));
    daedalus_h264_chroma_dc_hadamard_2x2_ref(c);
    int fail = 0;
    for (int i = 0; i < 4; i++) {
        if (c[i] != expect[i]) {
            fprintf(stderr, "%s: c[%d] = %d, expected %d\n",
                    name, i, c[i], expect[i]);
            fail = 1;
        }
    }
    if (!fail) printf("  %-32s PASS\n", name);
    else       printf("  %-32s FAIL\n", name);
    return fail;
}

int main(void)
{
    int fail = 0;

    /* Test 1: All-same input.
     *   c = [5, 5, 5, 5]
     *   f[0,0] = 20, f[0,1] = 0, f[1,0] = 0, f[1,1] = 0
     */
    { int16_t in[4] = { 5, 5, 5, 5 };
      int16_t ex[4] = { 20, 0, 0, 0 };
      fail |= check("all-uniform 5", in, ex); }

    /* Test 2: Single-axis variation (col 1 = 0, col 2 = 10).
     *   c = [0, 10, 0, 10]
     *   f[0,0] = 0+10+0+10 = 20
     *   f[0,1] = 0-10+0-10 = -20
     *   f[1,0] = 0+10-0-10 = 0
     *   f[1,1] = 0-10-0+10 = 0
     */
    { int16_t in[4] = { 0, 10, 0, 10 };
      int16_t ex[4] = { 20, -20, 0, 0 };
      fail |= check("col gradient [0,10,0,10]", in, ex); }

    /* Test 3: Row gradient.
     *   c = [0, 0, 10, 10]
     *   f[0,0] = 20, f[0,1] = 0, f[1,0] = 0-20 = -20, f[1,1] = 0
     */
    { int16_t in[4] = { 0, 0, 10, 10 };
      int16_t ex[4] = { 20, 0, -20, 0 };
      fail |= check("row gradient [0,0,10,10]", in, ex); }

    /* Test 4: Anti-diagonal pattern.
     *   c = [10, 0, 0, 10]
     *   f[0,0] = 20
     *   f[0,1] = 10-0+0-10 = 0
     *   f[1,0] = 10+0-0-10 = 0
     *   f[1,1] = 10-0-0+10 = 20
     */
    { int16_t in[4] = { 10, 0, 0, 10 };
      int16_t ex[4] = { 20, 0, 0, 20 };
      fail |= check("anti-diagonal [10,0,0,10]", in, ex); }

    /* Test 5: Asymmetric — all bands non-zero.
     *   c = [1, 2, 3, 4]
     *   f[0,0] = 10
     *   f[0,1] = 1-2+3-4 = -2
     *   f[1,0] = 1+2-3-4 = -4
     *   f[1,1] = 1-2-3+4 = 0
     */
    { int16_t in[4] = { 1, 2, 3, 4 };
      int16_t ex[4] = { 10, -2, -4, 0 };
      fail |= check("asymmetric [1,2,3,4]", in, ex); }

    /* Test 6: Negative inputs (Hadamard is linear, so signs preserve).
     *   c = [-5, 5, -5, 5]
     *   f[0,0] = -5+5-5+5 = 0
     *   f[0,1] = -5-5-5-5 = -20
     *   f[1,0] = -5+5+5-5 = 0
     *   f[1,1] = -5-5+5+5 = 0
     */
    { int16_t in[4] = { -5, 5, -5, 5 };
      int16_t ex[4] = { 0, -20, 0, 0 };
      fail |= check("sign-alternating [-5,5,-5,5]", in, ex); }

    /* Test 7: Inverse-property check.  H * H = 4*I for the unscaled
     * 2x2 Hadamard.  So applying twice multiplies each by 4.
     *   c = [1, 2, 3, 4]
     *   First Hadamard:  [10, -2, -4, 0]
     *   Second Hadamard: [4, 8, 12, 16]
     */
    { int16_t in[4] = { 1, 2, 3, 4 };
      int16_t ex[4] = { 4, 8, 12, 16 };
      int16_t c[4]; memcpy(c, in, sizeof(c));
      daedalus_h264_chroma_dc_hadamard_2x2_ref(c);
      daedalus_h264_chroma_dc_hadamard_2x2_ref(c);
      int local_fail = 0;
      for (int i = 0; i < 4; i++) if (c[i] != ex[i]) local_fail = 1;
      printf("  %-32s %s\n", "double-Hadamard = 4*orig",
             local_fail ? "FAIL" : "PASS");
      fail |= local_fail;
    }

    /* Test 8: public API parity.  The public symbol must produce
     * byte-identical output to the test-only ref for the same input.
     * If the src/ Hadamard ever drifts from the spec, this catches it. */
    {
        int16_t input[4] = { 7, -11, 23, -42 };
        int16_t a[4], b[4];
        memcpy(a, input, sizeof(a));
        memcpy(b, input, sizeof(b));
        daedalus_h264_chroma_dc_hadamard_2x2_ref(a);
        daedalus_h264_chroma_dc_hadamard_2x2(b);
        int local_fail = 0;
        for (int i = 0; i < 4; i++) if (a[i] != b[i]) local_fail = 1;
        printf("  %-32s %s\n", "public API parity vs _ref",
               local_fail ? "FAIL" : "PASS");
        fail |= local_fail;
    }

    if (fail == 0) printf("\nALL chroma DC Hadamard tests PASS\n");
    else           fprintf(stderr, "\n%d test(s) FAILED\n", fail);
    return fail ? 1 : 0;
}