lavc/aarch64: add hevc sao edge 16x16

bench on AWS Graviton:

hevc_sao_edge_16x16_8_c: 1857.0
hevc_sao_edge_16x16_8_neon: 211.0
hevc_sao_edge_32x32_8_c: 7802.2
hevc_sao_edge_32x32_8_neon: 808.2
hevc_sao_edge_48x48_8_c: 16764.2
hevc_sao_edge_48x48_8_neon: 1796.5
hevc_sao_edge_64x64_8_c: 32647.5
hevc_sao_edge_64x64_8_neon: 3118.5

Signed-off-by: J. Dekker <jdek@itanimul.li>

libavcodec/aarch64/hevcdsp_init_aarch64.c

@@ -57,8 +57,8 @@ void ff_hevc_sao_band_filter_8x8_8_neon(uint8_t *_dst, uint8_t *_src,
                                   ptrdiff_t stride_dst, ptrdiff_t stride_src,
                                   int16_t *sao_offset_val, int sao_left_class,
                                   int width, int height);
-
+void ff_hevc_sao_edge_filter_16x16_8_neon(uint8_t *dst, uint8_t *src, ptrdiff_t stride_dst,
-
+                                          int16_t *sao_offset_val, int eo, int width, int height);
 
 av_cold void ff_hevc_dsp_init_aarch64(HEVCDSPContext *c, const int bit_depth)
 {
@@ -80,6 +80,10 @@ av_cold void ff_hevc_dsp_init_aarch64(HEVCDSPContext *c, const int bit_depth)
         c->sao_band_filter[2]          =
         c->sao_band_filter[3]          =
         c->sao_band_filter[4]          = ff_hevc_sao_band_filter_8x8_8_neon;
+        c->sao_edge_filter[1]          =
+        c->sao_edge_filter[2]          =
+        c->sao_edge_filter[3]          =
+        c->sao_edge_filter[4]          = ff_hevc_sao_edge_filter_16x16_8_neon;
     }
     if (bit_depth == 10) {
         c->add_residual[0]             = ff_hevc_add_residual_4x4_10_neon;

libavcodec/aarch64/hevcdsp_sao_neon.S

@@ -74,3 +74,69 @@ function ff_hevc_sao_band_filter_8x8_8_neon, export=1
         bne             1b
         ret
 endfunc
+
+// ASSUMES STRIDE_SRC = 192
+.Lsao_edge_pos:
+.word 1 // horizontal
+.word 192 // vertical
+.word 192 + 1 // 45 degree
+.word 192 - 1 // 135 degree
+
+// ff_hevc_sao_edge_filter_16x16_8_neon(char *dst, char *src, ptrdiff stride_dst,
+//                                      int16 *sao_offset_val, int eo, int width, int height)
+function ff_hevc_sao_edge_filter_16x16_8_neon, export=1
+        adr             x7, .Lsao_edge_pos
+        ld1             {v3.8h}, [x3]              // load sao_offset_val
+        add             w5,  w5,  #0xF
+        bic             w5,  w5,  #0xF
+        ldr             w4, [x7, w4, uxtw #2]      // stride_src
+        mov             v3.h[7], v3.h[0]           // reorder to [1,2,0,3,4]
+        mov             v3.h[0], v3.h[1]
+        mov             v3.h[1], v3.h[2]
+        mov             v3.h[2], v3.h[7]
+        // split 16bit values into two tables
+        uzp2            v1.16b, v3.16b, v3.16b     // sao_offset_val -> upper
+        uzp1            v0.16b, v3.16b, v3.16b     // sao_offset_val -> lower
+        movi            v2.16b, #2
+        mov             x15, #192
+        // strides between end of line and next src/dst
+        sub             x15, x15, x5               // stride_src - width
+        sub             x16, x2, x5                // stride_dst - width
+        mov             x11, x1                    // copy base src
+1:      // new line
+        mov             x14, x5                    // copy width
+        sub             x12, x11, x4               // src_a (prev) = src - sao_edge_pos
+        add             x13, x11, x4               // src_b (next) = src + sao_edge_pos
+2:      // process 16 bytes
+        ld1             {v3.16b}, [x11], #16       // load src
+        ld1             {v4.16b}, [x12], #16       // load src_a (prev)
+        ld1             {v5.16b}, [x13], #16       // load src_b (next)
+        cmhi            v16.16b, v4.16b, v3.16b    // (prev > cur)
+        cmhi            v17.16b, v3.16b, v4.16b    // (cur > prev)
+        cmhi            v18.16b, v5.16b, v3.16b    // (next > cur)
+        cmhi            v19.16b, v3.16b, v5.16b    // (cur > next)
+        sub             v20.16b, v16.16b, v17.16b  // diff0 = CMP(cur, prev) = (cur > prev) - (cur < prev)
+        sub             v21.16b, v18.16b, v19.16b  // diff1 = CMP(cur, next) = (cur > next) - (cur < next)
+        add             v20.16b, v20.16b, v21.16b  // diff = diff0 + diff1
+        add             v20.16b, v20.16b, v2.16b   // offset_val = diff + 2
+        tbl             v16.16b, {v0.16b}, v20.16b
+        tbl             v17.16b, {v1.16b}, v20.16b
+        uxtl            v20.8h, v3.8b              // src[0:7]
+        uxtl2           v21.8h, v3.16b             // src[7:15]
+        zip1            v18.16b, v16.16b, v17.16b  // sao_offset_val lower ->
+        zip2            v19.16b, v16.16b, v17.16b  // sao_offset_val upper ->
+        sqadd           v20.8h, v18.8h, v20.8h     // + sao_offset_val
+        sqadd           v21.8h, v19.8h, v21.8h
+        sqxtun          v3.8b, v20.8h
+        sqxtun2         v3.16b, v21.8h
+        st1             {v3.16b}, [x0], #16
+        subs            x14, x14, #16              // filtered 16 bytes
+        b.ne            2b                         // do we have width to filter?
+        // no width to filter, setup next line
+        add             x11, x11, x15              // stride src to next line
+        add             x0, x0, x16                // stride dst to next line
+        subs            w6, w6, #1                 // filtered line
+        b.ne            1b                         // do we have lines to process?
+        // no lines to filter
+        ret
+endfunc