daedalus-fourier/tests/test_intra_pred_16x16.c

/*
 * Tests the 4 H.264 Intra_16x16 luma prediction modes against
 * spec-derived expected patterns.  Same layout as the 4x4 test:
 * a buffer that holds the 16x16 output plus 1-pixel top/left
 * context and 1-pixel top-left corner.
 *
 *   row  0: [tl][t0..t15]
 *   row  1: [l0][output row 0]
 *   row  2: [l1][output row 1]
 *   ...
 *   row 16: [l15][output row 15]
 *
 * Buffer dimensions: 17 rows × 17 cols, total 289 bytes.
 * dst (passed to the pred fns) points at row 1 col 1.
 */
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>

extern void daedalus_h264_pred_16x16_vertical_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_16x16_horizontal_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_16x16_dc_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_16x16_plane_ref(uint8_t *dst, ptrdiff_t stride);

#define STRIDE 17
#define ROWS   17

static void set_ctx(uint8_t buf[ROWS][STRIDE], int tl,
                     const int t[16], const int l[16])
{
    for (int r = 0; r < ROWS; r++)
        for (int c = 0; c < STRIDE; c++) buf[r][c] = 0xff;
    buf[0][0] = (uint8_t) tl;
    for (int c = 0; c < 16; c++) buf[0][1 + c] = (uint8_t) t[c];
    for (int r = 0; r < 16; r++) buf[1 + r][0] = (uint8_t) l[r];
}

static int check(const uint8_t buf[ROWS][STRIDE], const char *name,
                  uint8_t (*expect_at)(int r, int c, void *), void *cookie)
{
    int diff = 0;
    int first_r = 0, first_c = 0, first_got = 0, first_exp = 0;
    for (int r = 0; r < 16; r++) {
        for (int c = 0; c < 16; c++) {
            uint8_t got = buf[1 + r][1 + c];
            uint8_t exp = expect_at(r, c, cookie);
            if (got != exp) {
                if (diff == 0) {
                    first_r = r; first_c = c;
                    first_got = got; first_exp = exp;
                }
                diff++;
            }
        }
    }
    if (diff == 0)
        printf("  %-30s PASS\n", name);
    else
        printf("  %-30s FAIL (%d/256 wrong, first r=%d c=%d got=%u exp=%u)\n",
               name, diff, first_r, first_c, first_got, first_exp);
    return diff == 0 ? 0 : 1;
}

/* Expectation helpers for each mode. */
static uint8_t expect_uniform(int r, int c, void *cookie)
{ (void)r; (void)c; return *(uint8_t *)cookie; }

struct vertical_ctx { const int *t; };
static uint8_t expect_vertical(int r, int c, void *cookie)
{ (void)r; return (uint8_t) ((struct vertical_ctx *)cookie)->t[c]; }

struct horizontal_ctx { const int *l; };
static uint8_t expect_horizontal(int r, int c, void *cookie)
{ (void)c; return (uint8_t) ((struct horizontal_ctx *)cookie)->l[r]; }

int main(void)
{
    int fail = 0;

    /* --- Mode 0 Vertical: each col = top[col] --- */
    {
        uint8_t buf[ROWS][STRIDE];
        int t[16], l[16];
        for (int i = 0; i < 16; i++) { t[i] = 10 + i; l[i] = 0; }
        set_ctx(buf, 0, t, l);
        daedalus_h264_pred_16x16_vertical_ref(&buf[1][1], STRIDE);
        struct vertical_ctx vc = { t };
        fail |= check(buf, "Vertical (mode 0)", expect_vertical, &vc);
    }

    /* --- Mode 1 Horizontal: each row = left[row] --- */
    {
        uint8_t buf[ROWS][STRIDE];
        int t[16] = {0}, l[16];
        for (int i = 0; i < 16; i++) l[i] = 50 + i;
        set_ctx(buf, 0, t, l);
        daedalus_h264_pred_16x16_horizontal_ref(&buf[1][1], STRIDE);
        struct horizontal_ctx hc = { l };
        fail |= check(buf, "Horizontal (mode 1)", expect_horizontal, &hc);
    }

    /* --- Mode 2 DC: ((sum + 16) >> 5) --- */
    /* All top = 2, all left = 6: sum = 32 + 96 = 128, +16 = 144,
     * >>5 = 144/32 = 4. */
    {
        uint8_t buf[ROWS][STRIDE];
        int t[16], l[16];
        for (int i = 0; i < 16; i++) { t[i] = 2; l[i] = 6; }
        set_ctx(buf, 99, t, l);
        daedalus_h264_pred_16x16_dc_ref(&buf[1][1], STRIDE);
        uint8_t exp_val = 4;
        fail |= check(buf, "DC (mode 2)", expect_uniform, &exp_val);
    }

    /* --- Mode 3 Plane: uniform neighbours → uniform output --- */
    /* H=V=0 when neighbours are uniform.  a = 16*(p+p) = 32p.
     * pred[y][x] = (32p + 0 + 0 + 16) >> 5 = (32p + 16) >> 5 = p
     * (exact integer for any p, since 32p/32 = p and +16/32 = 0).
     * Verifies the orientation-free portion of the formula. */
    {
        uint8_t buf[ROWS][STRIDE];
        int t[16], l[16];
        for (int i = 0; i < 16; i++) { t[i] = 100; l[i] = 100; }
        set_ctx(buf, 100, t, l);   /* uniform tl too — H/V sums actually zero */
        daedalus_h264_pred_16x16_plane_ref(&buf[1][1], STRIDE);
        uint8_t exp_val = 100;
        fail |= check(buf, "Plane (mode 3, uniform)", expect_uniform, &exp_val);
    }

    /* --- Mode 3 Plane: gradient sanity ---
     * Top row = 0..15 (gradient), left col = 0..15, tl = 0.
     *   H = sum_{i=0..7} (i+1) * (t[8+i] - t[6-i] for i<7; or t[15]-tl=15 for i=7)
     *     = 1*(8-6) + 2*(9-5) + 3*(10-4) + 4*(11-3) + 5*(12-2) + 6*(13-1)
     *       + 7*(14-0) + 8*(15-0)
     *     = 2 + 8 + 18 + 32 + 50 + 72 + 98 + 120 = 400
     *   V = same shape on left col = 400
     *   b = (5*400 + 32) >> 6 = 2032 >> 6 = 31
     *   c = (5*400 + 32) >> 6 = 31
     *   a = 16 * (l[15] + t[15]) = 16 * (15 + 15) = 480
     *   pred[0][0] = (480 + 31*(-7) + 31*(-7) + 16) >> 5
     *              = (480 - 217 - 217 + 16) >> 5
     *              = 62 >> 5 = 1
     *   pred[15][15] = (480 + 31*8 + 31*8 + 16) >> 5
     *                = (480 + 248 + 248 + 16) >> 5
     *                = 992 >> 5 = 31
     * Just spot-check those two corners. */
    {
        uint8_t buf[ROWS][STRIDE];
        int t[16], l[16];
        for (int i = 0; i < 16; i++) { t[i] = i; l[i] = i; }
        set_ctx(buf, 0, t, l);
        daedalus_h264_pred_16x16_plane_ref(&buf[1][1], STRIDE);
        uint8_t tl_actual = buf[1 + 0][1 + 0];
        uint8_t br_actual = buf[1 + 15][1 + 15];
        int spot_fail = 0;
        if (tl_actual != 1)  { fprintf(stderr, "Plane gradient pred[0][0] = %u, expected 1\n", tl_actual); spot_fail = 1; }
        if (br_actual != 31) { fprintf(stderr, "Plane gradient pred[15][15] = %u, expected 31\n", br_actual); spot_fail = 1; }
        if (!spot_fail) printf("  %-30s PASS (corners 1, 31)\n", "Plane (mode 3, gradient)");
        else            printf("  %-30s FAIL\n", "Plane (mode 3, gradient)");
        fail |= spot_fail;
    }

    if (fail == 0) printf("\nALL Intra_16x16 mode references PASS\n");
    else           fprintf(stderr, "\n%d test(s) FAILED\n", fail);
    return fail ? 1 : 0;
}