daedalus-fourier/tests/test_intra_pred_4x4.c

/*
 * Tests the 9 H.264 Intra_4x4 luma prediction modes against
 * spec-derived expected patterns.  Goal: catch any mistake in
 * the reference (sign / shift / table mapping) before it lands
 * downstream.  Each mode is exercised with a deterministic
 * neighbour context and checked against a hand-computed (or
 * spec-derived) expected 4x4 output.
 *
 * The test buffer layout reserves a 1-pixel top/left context border
 * + a 4-pixel top-right (for modes 3 / 7):
 *
 *   row 0: [tl][t0 t1 t2 t3 t4 t5 t6 t7]   <- TOP_STRIDE = 9 bytes
 *   row 1: [l0][  4x4 output goes here   ]
 *   row 2: [l1][                         ]
 *   row 3: [l2][                         ]
 *   row 4: [l3][                         ]
 *
 * 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_4x4_vertical_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_horizontal_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_dc_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_ddl_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_ddr_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_vr_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_hd_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_vl_ref(uint8_t *dst, ptrdiff_t stride);
extern void daedalus_h264_pred_4x4_hu_ref(uint8_t *dst, ptrdiff_t stride);

#define STRIDE 9
typedef void (*pred_fn)(uint8_t *dst, ptrdiff_t stride);

/* Set up the buffer: 5 rows × STRIDE cols.
 * top-left = tl, top[0..7] = t[0..7], left[0..3] = l[0..3].
 * The 4x4 output region (rows 1..4, cols 1..4) is filled with 0xff
 * sentinels so any unwritten cell shows up as 255 in the compare. */
static void set_ctx(uint8_t buf[5][STRIDE], int tl, const int t[8], const int l[4])
{
    for (int r = 0; r < 5; r++) for (int c = 0; c < STRIDE; c++) buf[r][c] = 0xff;
    buf[0][0] = (uint8_t) tl;
    for (int c = 0; c < 8; c++) buf[0][1 + c] = (uint8_t) t[c];
    for (int r = 0; r < 4; r++) buf[1 + r][0] = (uint8_t) l[r];
}

static int check(const uint8_t buf[5][STRIDE], const char *name,
                  const uint8_t expect[4][4])
{
    int diff = 0;
    for (int r = 0; r < 4; r++) {
        for (int c = 0; c < 4; c++) {
            uint8_t got = buf[1 + r][1 + c];
            uint8_t exp = expect[r][c];
            if (got != exp) {
                if (diff == 0)
                    fprintf(stderr,
                            "%s: first mismatch r=%d c=%d got=%u exp=%u\n",
                            name, r, c, got, exp);
                diff++;
            }
        }
    }
    if (diff == 0)
        printf("  %-26s PASS\n", name);
    else
        printf("  %-26s FAIL (%d/16 bytes wrong)\n", name, diff);
    return diff == 0 ? 0 : 1;
}

int main(void)
{
    int fail = 0;

    /* Mode 0 — Vertical: each col = top[col]. */
    {
        uint8_t buf[5][STRIDE];
        int tl = 0;
        int t[8] = { 10, 20, 30, 40,  0, 0, 0, 0 };
        int l[4] = {  0,  0,  0,  0 };
        set_ctx(buf, tl, t, l);
        daedalus_h264_pred_4x4_vertical_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {10,20,30,40}, {10,20,30,40}, {10,20,30,40}, {10,20,30,40}
        };
        fail |= check(buf, "Vertical (mode 0)", exp);
    }

    /* Mode 1 — Horizontal: each row = left[row]. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 0,0,0,0, 0,0,0,0 };
        int l[4] = { 50, 60, 70, 80 };
        set_ctx(buf, 0, t, l);
        daedalus_h264_pred_4x4_horizontal_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {50,50,50,50}, {60,60,60,60}, {70,70,70,70}, {80,80,80,80}
        };
        fail |= check(buf, "Horizontal (mode 1)", exp);
    }

    /* Mode 2 — DC: all 8 neighbours valid → ((sum + 4) >> 3) broadcast.
     * top sum = 4*1 = 4, left sum = 4*3 = 12, total 16, +4 = 20,
     * >>3 = 2. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 1,1,1,1, 0,0,0,0 };
        int l[4] = { 3,3,3,3 };
        set_ctx(buf, 99, t, l);   /* tl unused for DC */
        daedalus_h264_pred_4x4_dc_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {2,2,2,2}, {2,2,2,2}, {2,2,2,2}, {2,2,2,2}
        };
        fail |= check(buf, "DC (mode 2)", exp);
    }

    /* Mode 3 — Diagonal_Down_Left: zz[i] = avg3(t[i], t[i+1], t[i+2]);
     * dst[r][c] = zz[c + r].
     * With all t[]=100 → all zz=100 → all dst=100. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 100,100,100,100, 100,100,100,100 };
        int l[4] = { 0,0,0,0 };
        set_ctx(buf, 0, t, l);
        daedalus_h264_pred_4x4_ddl_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {100,100,100,100}, {100,100,100,100},
            {100,100,100,100}, {100,100,100,100}
        };
        fail |= check(buf, "DiagDownLeft (mode 3)", exp);
    }

    /* Mode 4 — Diagonal_Down_Right: zz[c-r] with c-r ∈ {-3..+3}.
     * If all 9 surrounding pixels = 200 → all zz = 200 → all dst = 200. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 200,200,200,200, 0,0,0,0 };
        int l[4] = { 200,200,200,200 };
        set_ctx(buf, 200, t, l);
        daedalus_h264_pred_4x4_ddr_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {200,200,200,200}, {200,200,200,200},
            {200,200,200,200}, {200,200,200,200}
        };
        fail |= check(buf, "DiagDownRight (mode 4)", exp);
    }

    /* Mode 5 — Vertical_Right. With all neighbours = 80 the 3-tap
     * (a+2b+c+2)>>2 and 2-tap (a+b+1)>>1 both yield 80. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 80,80,80,80, 0,0,0,0 };
        int l[4] = { 80,80,80,80 };
        set_ctx(buf, 80, t, l);
        daedalus_h264_pred_4x4_vr_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {80,80,80,80}, {80,80,80,80}, {80,80,80,80}, {80,80,80,80}
        };
        fail |= check(buf, "VerticalRight (mode 5)", exp);
    }

    /* Mode 6 — Horizontal_Down.  Same uniform-context degenerate case. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 120,120,120,120, 0,0,0,0 };
        int l[4] = { 120,120,120,120 };
        set_ctx(buf, 120, t, l);
        daedalus_h264_pred_4x4_hd_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {120,120,120,120}, {120,120,120,120},
            {120,120,120,120}, {120,120,120,120}
        };
        fail |= check(buf, "HorizontalDown (mode 6)", exp);
    }

    /* Mode 7 — Vertical_Left.  Uniform context. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 64,64,64,64, 64,64,64,64 };
        int l[4] = { 0,0,0,0 };
        set_ctx(buf, 0, t, l);
        daedalus_h264_pred_4x4_vl_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {64,64,64,64}, {64,64,64,64}, {64,64,64,64}, {64,64,64,64}
        };
        fail |= check(buf, "VerticalLeft (mode 7)", exp);
    }

    /* Mode 8 — Horizontal_Up.  Uniform context. */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 0,0,0,0, 0,0,0,0 };
        int l[4] = { 200,200,200,200 };
        set_ctx(buf, 0, t, l);
        daedalus_h264_pred_4x4_hu_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            {200,200,200,200}, {200,200,200,200},
            {200,200,200,200}, {200,200,200,200}
        };
        fail |= check(buf, "HorizontalUp (mode 8)", exp);
    }

    /* Asymmetric Vertical_Right test: detects orientation /
     * row-vs-col confusion.  Top=10,20,30,40, Left=50,60,70,
     * top-left=5.  Spec-derived expected output computed by hand
     * from §8.3.1.4.6.
     *
     *   d[0][0] = (tl+t0+1)>>1 = (5+10+1)>>1 = 8
     *   d[0][1] = (t0+t1+1)>>1 = (10+20+1)>>1 = 15
     *   d[0][2] = (t1+t2+1)>>1 = (20+30+1)>>1 = 25
     *   d[0][3] = (t2+t3+1)>>1 = (30+40+1)>>1 = 35
     *   d[1][0] = avg3(l0,tl,t0) = (50+2*5+10+2)>>2 = 72/4 = 18
     *   d[1][1] = avg3(tl,t0,t1) = (5+20+20+2)>>2 = 47/4 = 11
     *   d[1][2] = avg3(t0,t1,t2) = (10+40+30+2)>>2 = 82/4 = 20
     *   d[1][3] = avg3(t1,t2,t3) = (20+60+40+2)>>2 = 122/4 = 30
     *   d[2][0] = avg3(tl,l0,l1) = (5+100+60+2)>>2 = 167/4 = 41
     *   d[2][1] = d[0][0] = 8
     *   d[2][2] = d[0][1] = 15
     *   d[2][3] = d[0][2] = 25
     *   d[3][0] = avg3(l0,l1,l2) = (50+120+70+2)>>2 = 242/4 = 60
     *   d[3][1] = d[1][0] = 18
     *   d[3][2] = d[1][1] = 11
     *   d[3][3] = d[1][2] = 20
     */
    {
        uint8_t buf[5][STRIDE];
        int t[8] = { 10,20,30,40, 0,0,0,0 };
        int l[4] = { 50,60,70,0 };
        set_ctx(buf, 5, t, l);
        daedalus_h264_pred_4x4_vr_ref(&buf[1][1], STRIDE);
        uint8_t exp[4][4] = {
            { 8,15,25,35},
            {18,11,20,30},
            {41, 8,15,25},
            {60,18,11,20},
        };
        fail |= check(buf, "VR asym (sanity)", exp);
    }

    if (fail == 0) printf("\nALL %d intra-4x4 mode references PASS\n", 10);
    else           fprintf(stderr, "\n%d test(s) FAILED\n", fail);
    return fail ? 1 : 0;
}