[FFmpeg-devel] [PATCH] lavc/llvidencdsp: R-V V sub_left_predict (PR #21159)

["Rémi Denis-Courmont via ffmpeg-devel" <ffmpeg-devel@ffmpeg.org>]

PR #21159 opened by Rémi Denis-Courmont (Courmisch)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21159
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21159.patch

SpacemiT X60:
sub_left_predict_c:                                  51836.0 ( 1.00x)
sub_left_predict_rvv_i32:                             5843.1 ( 8.87x)


From 0909d13e178a492c5ef57f46922ac51a3f36b023 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Denis-Courmont?= <remi@remlab.net>
Date: Wed, 10 Dec 2025 20:35:59 +0200
Subject: [PATCH] lavc/llvidencdsp: R-V V sub_left_predict

SpacemiT X60:
sub_left_predict_c:                                  51836.0 ( 1.00x)
sub_left_predict_rvv_i32:                             5843.1 ( 8.87x)
---
 libavcodec/riscv/llvidencdsp_init.c |  4 ++++
 libavcodec/riscv/llvidencdsp_rvv.S  | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/libavcodec/riscv/llvidencdsp_init.c b/libavcodec/riscv/llvidencdsp_init.c
index e35406dc41..bd2ffef42f 100644
--- a/libavcodec/riscv/llvidencdsp_init.c
+++ b/libavcodec/riscv/llvidencdsp_init.c
@@ -26,6 +26,9 @@
 
 void ff_llvidenc_diff_bytes_rvv(uint8_t *dst, const uint8_t *src1,
                                 const uint8_t *src2, intptr_t w);
+void ff_llvidenc_sub_left_predict_rvv(uint8_t *dst, const uint8_t *src,
+                                      ptrdiff_t stride, ptrdiff_t width,
+                                      int height);
 
 av_cold void ff_llvidencdsp_init_riscv(LLVidEncDSPContext *c)
 {
@@ -34,6 +37,7 @@ av_cold void ff_llvidencdsp_init_riscv(LLVidEncDSPContext *c)
 
     if (flags & AV_CPU_FLAG_RVV_I32) {
         c->diff_bytes = ff_llvidenc_diff_bytes_rvv;
+        c->sub_left_predict = ff_llvidenc_sub_left_predict_rvv;
     }
 #endif
 }
diff --git a/libavcodec/riscv/llvidencdsp_rvv.S b/libavcodec/riscv/llvidencdsp_rvv.S
index 44bf3ac7e5..506e62d1e1 100644
--- a/libavcodec/riscv/llvidencdsp_rvv.S
+++ b/libavcodec/riscv/llvidencdsp_rvv.S
@@ -36,3 +36,30 @@ func ff_llvidenc_diff_bytes_rvv, zve32x
 
         ret
 endfunc
+
+func ff_llvidenc_sub_left_predict_rvv, zve32x
+        lpad    0
+        li      a5, 0x80
+        sub     a2, a2, a3
+1:
+        mv      t3, a3
+        addi    a4, a4, -1
+2:
+        vsetvli t0, t3, e8, m8, ta, ma
+        vle8.v  v16, (a1)
+        sub     t3, t3, t0
+        vle8.v  v8, (a0)
+        add     a1, a1, t0
+        vslide1up.vx    v24, v16, a5
+        vadd.vv v8, v8, v16
+        lb      a5, -1(a1)
+        vsub.vv v8, v8, v24
+        vse8.v  v8, (a0)
+        add     a0, a0, t0
+        bnez    t3, 2b
+
+        add     a1, a1, a2
+        bnez    a4, 1b
+
+        ret
+endfunc
-- 
2.49.1

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