[FFmpeg-devel,PATCHv3,1/3] sws/input: R-V V rgb24ToY & bgr24ToY

diff --git a/libswscale/riscv/Makefile b/libswscale/riscv/Makefile
index 48afaf62aa..d1b0eae367 100644
--- a/libswscale/riscv/Makefile
+++ b/libswscale/riscv/Makefile
@@ -1,3 +1,5 @@ 
-OBJS += riscv/rgb2rgb.o
+OBJS += riscv/rgb2rgb.o \
+        riscv/swscale.o
 RV-OBJS += riscv/rgb2rgb_rvb.o
-RVV-OBJS += riscv/rgb2rgb_rvv.o
+RVV-OBJS += riscv/input.o \
+            riscv/rgb2rgb_rvv.o
diff --git a/libswscale/riscv/input.S b/libswscale/riscv/input.S
new file mode 100644
index 0000000000..323f650bc9
--- /dev/null
+++ b/libswscale/riscv/input.S
@@ -0,0 +1,55 @@ 
+/*
+ * Copyright © 2024 Rémi Denis-Courmont.
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/riscv/asm.S"
+
+func ff_bgr24ToY_rvv, zve32x
+        lw      t1, 8(a5) # BY
+        lw      t3, 0(a5) # RY
+        j       1f
+endfunc
+
+func ff_rgb24ToY_rvv, zve32x
+        lw      t1, 0(a5) # RY
+        lw      t3, 8(a5) # BY
+1:
+        lw      t2, 4(a5) # GY
+        li      t4, (32 << (15 - 1)) + (1 << (15 - 7))
+2:
+        vsetvli    t0, a4, e32, m8, ta, ma
+        vlseg3e8.v v0, (a1)
+        sub        a4, a4, t0
+        vzext.vf4  v8, v0
+        sh1add     t5, t0, t0 # t1 = 3 * t0
+        vzext.vf4  v16, v2
+        vzext.vf4  v24, v4
+        add        a1, t5, a1
+        vmul.vx    v8, v8, t1
+        vmacc.vx   v8, t2, v16
+        vmacc.vx   v8, t3, v24
+        vadd.vx    v8, v8, t4
+        vsetvli    zero, zero, e16, m4, ta, ma
+        vnsra.wi   v0, v8, 15 - 6
+        vse16.v    v0, (a0)
+        sh1add     a0, t0, a0
+        bnez       a4, 2b
+
+        ret
+endfunc
diff --git a/libswscale/riscv/swscale.c b/libswscale/riscv/swscale.c
new file mode 100644
index 0000000000..187b3fce58
--- /dev/null
+++ b/libswscale/riscv/swscale.c
@@ -0,0 +1,46 @@ 
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "config.h"
+#include "libavutil/attributes.h"
+#include "libavutil/riscv/cpu.h"
+#include "libswscale/swscale_internal.h"
+
+void ff_bgr24ToY_rvv(uint8_t *dst, const uint8_t *src, const uint8_t *,
+                     const uint8_t *, int width, uint32_t *coeffs, void *);
+void ff_rgb24ToY_rvv(uint8_t *dst, const uint8_t *src, const uint8_t *,
+                     const uint8_t *, int width, uint32_t *coeffs, void *);
+
+av_cold void ff_sws_init_swscale_riscv(SwsContext *c)
+{
+#if HAVE_RVV
+    int flags = av_get_cpu_flags();
+
+    if ((flags & AV_CPU_FLAG_RVV_I32) && (flags & AV_CPU_FLAG_RVB_ADDR)) {
+        switch (c->srcFormat) {
+            case AV_PIX_FMT_BGR24:
+                c->lumToYV12 = ff_bgr24ToY_rvv;
+                break;
+
+            case AV_PIX_FMT_RGB24:
+                c->lumToYV12 = ff_rgb24ToY_rvv;
+                break;
+        }
+    }
+#endif
+}
diff --git a/libswscale/swscale.c b/libswscale/swscale.c
index 2795429b6c..9736734881 100644
--- a/libswscale/swscale.c
+++ b/libswscale/swscale.c
@@ -602,6 +602,8 @@  void ff_sws_init_scale(SwsContext *c)
     ff_sws_init_swscale_arm(c);
 #elif ARCH_LOONGARCH64
     ff_sws_init_swscale_loongarch(c);
+#elif ARCH_RISCV
+    ff_sws_init_swscale_riscv(c);
 #endif
 }
 
diff --git a/libswscale/swscale_internal.h b/libswscale/swscale_internal.h
index d4b0c3cee2..5007dd422f 100644
--- a/libswscale/swscale_internal.h
+++ b/libswscale/swscale_internal.h
@@ -988,6 +988,7 @@  void ff_sws_init_swscale_x86(SwsContext *c);
 void ff_sws_init_swscale_aarch64(SwsContext *c);
 void ff_sws_init_swscale_arm(SwsContext *c);
 void ff_sws_init_swscale_loongarch(SwsContext *c);
+void ff_sws_init_swscale_riscv(SwsContext *c);
 
 void ff_hyscale_fast_c(SwsContext *c, int16_t *dst, int dstWidth,
                        const uint8_t *src, int srcW, int xInc);