[FFmpeg-devel] [PATCH 2/2] lavc/aarch64: Add pix_abs16_x2 neon implementation
Hubert Mazur
hum at semihalf.com
Wed Jun 29 11:24:40 EEST 2022
Provide neon implementation for pix_abs16_x2 function.
Performance tests of implementation are below.
- pix_abs_0_1_c: 291.9
- pix_abs_0_1_neon: 73.7
Benchmarks and tests run with checkasm tool on AWS Graviton 3.
Signed-off-by: Hubert Mazur <hum at semihalf.com>
---
libavcodec/aarch64/me_cmp_init_aarch64.c | 3 +
libavcodec/aarch64/me_cmp_neon.S | 134 +++++++++++++++++++++++
2 files changed, 137 insertions(+)
diff --git a/libavcodec/aarch64/me_cmp_init_aarch64.c b/libavcodec/aarch64/me_cmp_init_aarch64.c
index bec9148a1a..136b008eb7 100644
--- a/libavcodec/aarch64/me_cmp_init_aarch64.c
+++ b/libavcodec/aarch64/me_cmp_init_aarch64.c
@@ -27,6 +27,8 @@ int ff_pix_abs16_neon(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
ptrdiff_t stride, int h);
int ff_pix_abs16_xy2_neon(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
ptrdiff_t stride, int h);
+int ff_pix_abs16_x2_neon(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+ ptrdiff_t stride, int h);
av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
{
@@ -34,6 +36,7 @@ av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
if (have_neon(cpu_flags)) {
c->pix_abs[0][0] = ff_pix_abs16_neon;
+ c->pix_abs[0][1] = ff_pix_abs16_x2_neon;
c->pix_abs[0][3] = ff_pix_abs16_xy2_neon;
c->sad[0] = ff_pix_abs16_neon;
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index a7937bd8be..c2fd94f4b3 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -203,3 +203,137 @@ function ff_pix_abs16_xy2_neon, export=1
fmov w0, s0 // copy result to general purpose register
ret
endfunc
+
+function ff_pix_abs16_x2_neon, export=1
+ // x0 unused
+ // x1 uint8_t *pix1
+ // x2 uint8_t *pix2
+ // x3 ptrdiff_t stride
+ // x4 int h
+
+ // preserve value of v8-v12 registers
+ stp d10, d11, [sp, #-0x10]!
+ stp d8, d9, [sp, #-0x10]!
+
+ // initialize buffers
+ movi d18, #0
+ movi v20.8h, #1
+ add x5, x2, #1 // pix2 + 1
+ cmp w4, #4
+ b.lt 2f
+
+// make 4 iterations at once
+1:
+ // v0 - pix1
+ // v1 - pix2
+ // v2 - pix2 + 1
+ ld1 {v0.16b}, [x1], x3
+ ld1 {v1.16b}, [x2], x3
+ ld1 {v2.16b}, [x5], x3
+
+ ld1 {v3.16b}, [x1], x3
+ ld1 {v4.16b}, [x2], x3
+ ld1 {v5.16b}, [x5], x3
+
+ ld1 {v6.16b}, [x1], x3
+ ld1 {v7.16b}, [x2], x3
+ ld1 {v8.16b}, [x5], x3
+
+ ld1 {v9.16b}, [x1], x3
+ ld1 {v10.16b}, [x2], x3
+ ld1 {v11.16b}, [x5], x3
+
+ // abs(pix1[0] - avg2(pix2[0], pix2[1]))
+ // avg2(a,b) = (((a) + (b) + 1) >> 1)
+ // abs(x) = (x < 0 ? -x : x)
+
+ // pix2[0] + pix2[1]
+ uaddl v30.8h, v1.8b, v2.8b
+ uaddl2 v29.8h, v1.16b, v2.16b
+ // add one to each element
+ add v30.8h, v30.8h, v20.8h
+ add v29.8h, v29.8h, v20.8h
+ // divide by 2, narrow width and store in v30
+ uqshrn v30.8b, v30.8h, #1
+ uqshrn2 v30.16b, v29.8h, #1
+
+ // abs(pix1[0] - avg2(pix2[0], pix2[1]))
+ uabd v16.16b, v0.16b, v30.16b
+ uaddlv h16, v16.16b
+
+ // 2nd iteration
+ uaddl v28.8h, v4.8b, v5.8b
+ uaddl2 v27.8h, v4.16b, v5.16b
+ add v28.8h, v28.8h, v20.8h
+ add v27.8h, v27.8h, v20.8h
+
+ uqshrn v28.8b, v28.8h, #1
+ uqshrn2 v28.16b, v27.8h, #1
+
+ uabd v17.16b, v3.16b, v28.16b
+ uaddlv h17, v17.16b
+
+ // 3rd iteration
+ uaddl v26.8h, v7.8b, v8.8b
+ uaddl2 v25.8h, v7.16b, v8.16b
+ add v26.8h, v26.8h, v20.8h
+ add v25.8h, v25.8h, v20.8h
+
+ uqshrn v26.8b, v26.8h, #1
+ uqshrn2 v26.16b, v25.8h, #1
+
+ uabd v19.16b, v6.16b, v26.16b
+ uaddlv h19, v19.16b
+
+ // 4th iteration
+ uaddl v24.8h, v10.8b, v11.8b
+ uaddl2 v23.8h, v10.16b, v11.16b
+ add v24.8h, v24.8h, v20.8h
+ add v23.8h, v23.8h, v20.8h
+
+ uqshrn v24.8b, v24.8h, #1
+ uqshrn2 v24.16b, v23.8h, #1
+
+ uabd v21.16b, v9.16b, v24.16b
+ uaddlv h21, v21.16b
+
+ sub w4, w4, #4
+
+ // accumulate the result in d18
+ add d18, d18, d16
+ add d18, d18, d17
+ add d18, d18, d19
+ add d18, d18, d21
+
+ cmp w4, #4
+ b.ge 1b
+ cbz w4, 3f
+
+// iterate by one
+2:
+ ld1 {v0.16b}, [x1], x3
+ ld1 {v1.16b}, [x2], x3
+ ld1 {v2.16b}, [x5], x3
+
+ uaddl v30.8h, v1.8b, v2.8b
+ uaddl2 v29.8h, v1.16b, v2.16b
+ add v30.8h, v30.8h, v20.8h
+ add v29.8h, v29.8h, v20.8h
+
+ uqshrn v30.8b, v30.8h, #1
+ uqshrn2 v30.16b, v20.8h, #1
+
+ uabd v28.16b, v0.16b, v30.16b
+ uaddlv h28, v28.16b
+
+ add d18, d18, d28
+ subs w4, w4, #1
+ b.ne 2b
+
+3:
+ fmov w0, s18
+ ldp d8, d9, [sp], 0x10
+ ldp d10, d11, [sp], 0x10
+
+ ret
+endfunc
--
2.34.1
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