shithub: dav1d

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Add dc-only path to C-implementation of IDCT

--- a/src/itx_tmpl.c

+++ b/src/itx_tmpl.c

@@ -46,21 +46,40 @@

 inv_txfm_add_c(pixel *dst, const ptrdiff_t stride,

                coef *const coeff, const int eob,

                const int w, const int h, const int shift1, const int shift2,

-               const itx_1d_fn first_1d_fn, const itx_1d_fn second_1d_fn

-               HIGHBD_DECL_SUFFIX)

+               const itx_1d_fn first_1d_fn, const itx_1d_fn second_1d_fn,

+               const int has_dconly HIGHBD_DECL_SUFFIX)

 {

     int i, j;

-    const ptrdiff_t sh = imin(h, 32), sw = imin(w, 32);

     assert((h >= 4 || h <= 64) && (w >= 4 || w <= 64));

-    // Maximum value for h and w is 64

-    coef tmp[4096 /* w * h */], out[64 /* h */], in_mem[64 /* w */];

     const int is_rect2 = w * 2 == h || h * 2 == w;

     const int bitdepth = bitdepth_from_max(bitdepth_max);

+    const int rnd1 = (1 << shift1) >> 1;

+    const int rnd2 = (1 << shift2) >> 1;

+

+    if (has_dconly && eob == 0) {

+        int dc = coeff[0];

+        coeff[0] = 0;

+        if (is_rect2)

+            dc = (dc * 2896 + 2048) >> 12;

+        dc = (dc * 2896 + 2048) >> 12;

+        dc = (dc + rnd1) >> shift1;

+        dc = (dc * 2896 + 2048) >> 12;

+        dc = (dc + rnd2) >> shift2;

+        for (j = 0; j < h; j++)

+            for (i = 0; i < w; i++)

+                dst[i + j * PXSTRIDE(stride)] =

+                    iclip_pixel(dst[i + j * PXSTRIDE(stride)] + dc);

+        return;

+    }

+    assert(eob > 0 || (eob == 0 && !has_dconly));

+

+    const ptrdiff_t sh = imin(h, 32), sw = imin(w, 32);

+    // Maximum value for h and w is 64

+    coef tmp[4096 /* w * h */], out[64 /* h */], in_mem[64 /* w */];

     const int row_clip_max = (1 << (bitdepth + 8 - 1)) - 1;

     const int col_clip_max = (1 << (imax(bitdepth + 6, 16) - 1)) -1;

     if (w != sw) memset(&in_mem[sw], 0, (w - sw) * sizeof(*in_mem));

-    const int rnd1 = (1 << shift1) >> 1;

     for (i = 0; i < sh; i++) {

         if (w != sw || is_rect2) {

             for (j = 0; j < sw; j++) {

@@ -82,7 +101,6 @@

     }

     if (h != sh) memset(&tmp[sh * w], 0, w * (h - sh) * sizeof(*tmp));

-    const int rnd2 = (1 << shift2) >> 1;

     for (i = 0; i < w; i++) {

         second_1d_fn(&tmp[i], w, out, 1, col_clip_max);

         for (j = 0; j < h; j++)

@@ -93,7 +111,7 @@

     memset(coeff, 0, sizeof(*coeff) * sh * sw);

 }

-#define inv_txfm_fn(type1, type2, w, h, shift1, shift2) \

+#define inv_txfm_fn(type1, type2, w, h, shift1, shift2, has_dconly) \

 static void \

 inv_txfm_add_##type1##_##type2##_##w##x##h##_c(pixel *dst, \

                                                const ptrdiff_t stride, \

@@ -102,36 +120,36 @@

                                                HIGHBD_DECL_SUFFIX) \

 { \

     inv_txfm_add_c(dst, stride, coeff, eob, w, h, shift1, shift2, \

-                   inv_##type1##w##_1d, inv_##type2##h##_1d \

+                   inv_##type1##w##_1d, inv_##type2##h##_1d, has_dconly \

                    HIGHBD_TAIL_SUFFIX); \

 }

 #define inv_txfm_fn64(w, h, shift1, shift2) \

-inv_txfm_fn(dct, dct, w, h, shift1, shift2)

+inv_txfm_fn(dct, dct, w, h, shift1, shift2, 1)

 #define inv_txfm_fn32(w, h, shift1, shift2) \

 inv_txfm_fn64(w, h, shift1, shift2) \

-inv_txfm_fn(identity, identity, w, h, shift1, shift2)

+inv_txfm_fn(identity, identity, w, h, shift1, shift2, 0)

 #define inv_txfm_fn16(w, h, shift1, shift2) \

 inv_txfm_fn32(w, h, shift1, shift2) \

-inv_txfm_fn(adst,     dct,      w, h, shift1, shift2) \

-inv_txfm_fn(dct,      adst,     w, h, shift1, shift2) \

-inv_txfm_fn(adst,     adst,     w, h, shift1, shift2) \

-inv_txfm_fn(dct,      flipadst, w, h, shift1, shift2) \

-inv_txfm_fn(flipadst, dct,      w, h, shift1, shift2) \

-inv_txfm_fn(adst,     flipadst, w, h, shift1, shift2) \

-inv_txfm_fn(flipadst, adst,     w, h, shift1, shift2) \

-inv_txfm_fn(flipadst, flipadst, w, h, shift1, shift2) \

-inv_txfm_fn(identity, dct,      w, h, shift1, shift2) \

-inv_txfm_fn(dct,      identity, w, h, shift1, shift2) \

+inv_txfm_fn(adst,     dct,      w, h, shift1, shift2, 0) \

+inv_txfm_fn(dct,      adst,     w, h, shift1, shift2, 0) \

+inv_txfm_fn(adst,     adst,     w, h, shift1, shift2, 0) \

+inv_txfm_fn(dct,      flipadst, w, h, shift1, shift2, 0) \

+inv_txfm_fn(flipadst, dct,      w, h, shift1, shift2, 0) \

+inv_txfm_fn(adst,     flipadst, w, h, shift1, shift2, 0) \

+inv_txfm_fn(flipadst, adst,     w, h, shift1, shift2, 0) \

+inv_txfm_fn(flipadst, flipadst, w, h, shift1, shift2, 0) \

+inv_txfm_fn(identity, dct,      w, h, shift1, shift2, 0) \

+inv_txfm_fn(dct,      identity, w, h, shift1, shift2, 0) \

 #define inv_txfm_fn84(w, h, shift1, shift2) \

 inv_txfm_fn16(w, h, shift1, shift2) \

-inv_txfm_fn(identity, flipadst, w, h, shift1, shift2) \

-inv_txfm_fn(flipadst, identity, w, h, shift1, shift2) \

-inv_txfm_fn(identity, adst,     w, h, shift1, shift2) \

-inv_txfm_fn(adst,     identity, w, h, shift1, shift2) \

+inv_txfm_fn(identity, flipadst, w, h, shift1, shift2, 0) \

+inv_txfm_fn(flipadst, identity, w, h, shift1, shift2, 0) \

+inv_txfm_fn(identity, adst,     w, h, shift1, shift2, 0) \

+inv_txfm_fn(adst,     identity, w, h, shift1, shift2, 0) \

 inv_txfm_fn84( 4,  4, 0, 4)

 inv_txfm_fn84( 4,  8, 0, 4)