[FFmpeg-cvslog] lavc/startcode: add R-V Zbb startcode_find_candidate
Rémi Denis-Courmont
git at videolan.org
Sun May 19 10:07:21 EEST 2024
ffmpeg | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Thu May 16 17:13:22 2024 +0300| [4ad5b9c8db737f3018360e179121fc0a9b7e7d1b] | committer: Rémi Denis-Courmont
lavc/startcode: add R-V Zbb startcode_find_candidate
The main loop processes 8 bytes in 5 instructions.
For comparison, the optimal plain strnlen() requires 4 instructions per
byte (6.4x worse): LBU; ADDI; BEQZ; BNE. The current libavcodec C code
involves 5 instructions per byte (8x worse). Actual benchmarks may be
slightly less favourable due to latency from ORC.B to BNE.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4ad5b9c8db737f3018360e179121fc0a9b7e7d1b
---
libavcodec/h264dsp.c | 2 +
libavcodec/h264dsp.h | 2 +
libavcodec/riscv/Makefile | 2 +
libavcodec/riscv/h264dsp_init.c | 40 +++++++++++++++++++
libavcodec/riscv/startcode_rvb.S | 83 ++++++++++++++++++++++++++++++++++++++++
libavcodec/riscv/vc1dsp_init.c | 7 +++-
6 files changed, 134 insertions(+), 2 deletions(-)
diff --git a/libavcodec/h264dsp.c b/libavcodec/h264dsp.c
index 4d2ee10bab..1ba936be1c 100644
--- a/libavcodec/h264dsp.c
+++ b/libavcodec/h264dsp.c
@@ -158,6 +158,8 @@ av_cold void ff_h264dsp_init(H264DSPContext *c, const int bit_depth,
ff_h264dsp_init_arm(c, bit_depth, chroma_format_idc);
#elif ARCH_PPC
ff_h264dsp_init_ppc(c, bit_depth, chroma_format_idc);
+#elif ARCH_RISCV
+ ff_h264dsp_init_riscv(c, bit_depth, chroma_format_idc);
#elif ARCH_X86
ff_h264dsp_init_x86(c, bit_depth, chroma_format_idc);
#elif ARCH_MIPS
diff --git a/libavcodec/h264dsp.h b/libavcodec/h264dsp.h
index e0880c4d88..4a9cb1568d 100644
--- a/libavcodec/h264dsp.h
+++ b/libavcodec/h264dsp.h
@@ -125,6 +125,8 @@ void ff_h264dsp_init_arm(H264DSPContext *c, const int bit_depth,
const int chroma_format_idc);
void ff_h264dsp_init_ppc(H264DSPContext *c, const int bit_depth,
const int chroma_format_idc);
+void ff_h264dsp_init_riscv(H264DSPContext *c, const int bit_depth,
+ const int chroma_format_idc);
void ff_h264dsp_init_x86(H264DSPContext *c, const int bit_depth,
const int chroma_format_idc);
void ff_h264dsp_init_mips(H264DSPContext *c, const int bit_depth,
diff --git a/libavcodec/riscv/Makefile b/libavcodec/riscv/Makefile
index f7a3bf76f1..697c10269a 100644
--- a/libavcodec/riscv/Makefile
+++ b/libavcodec/riscv/Makefile
@@ -28,6 +28,7 @@ OBJS-$(CONFIG_JPEG2000_DECODER) += riscv/jpeg2000dsp_init.o
RVV-OBJS-$(CONFIG_JPEG2000_DECODER) += riscv/jpeg2000dsp_rvv.o
OBJS-$(CONFIG_H264CHROMA) += riscv/h264_chroma_init_riscv.o
RVV-OBJS-$(CONFIG_H264CHROMA) += riscv/h264_mc_chroma.o
+OBJS-$(CONFIG_H264DSP) += riscv/h264dsp_init.o
OBJS-$(CONFIG_HUFFYUV_DECODER) += riscv/huffyuvdsp_init.o
RVV-OBJS-$(CONFIG_HUFFYUV_DECODER) += riscv/huffyuvdsp_rvv.o
OBJS-$(CONFIG_IDCTDSP) += riscv/idctdsp_init.o
@@ -51,6 +52,7 @@ OBJS-$(CONFIG_RV34DSP) += riscv/rv34dsp_init.o
RVV-OBJS-$(CONFIG_RV34DSP) += riscv/rv34dsp_rvv.o
OBJS-$(CONFIG_RV40_DECODER) += riscv/rv40dsp_init.o
RVV-OBJS-$(CONFIG_RV40_DECODER) += riscv/rv40dsp_rvv.o
+RV-OBJS-$(CONFIG_STARTCODE) += riscv/startcode_rvb.o
OBJS-$(CONFIG_SVQ1_ENCODER) += riscv/svqenc_init.o
RVV-OBJS-$(CONFIG_SVQ1_ENCODER) += riscv/svqenc_rvv.o
OBJS-$(CONFIG_TAK_DECODER) += riscv/takdsp_init.o
diff --git a/libavcodec/riscv/h264dsp_init.c b/libavcodec/riscv/h264dsp_init.c
new file mode 100644
index 0000000000..60c84734cd
--- /dev/null
+++ b/libavcodec/riscv/h264dsp_init.c
@@ -0,0 +1,40 @@
+/*
+ * 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 "config.h"
+
+#include <stdint.h>
+
+#include "libavutil/attributes.h"
+#include "libavutil/cpu.h"
+#include "libavcodec/h264dsp.h"
+
+extern int ff_startcode_find_candidate_rvb(const uint8_t *, int);
+
+av_cold void ff_h264dsp_init_riscv(H264DSPContext *dsp, const int bit_depth,
+ const int chroma_format_idc)
+{
+#if HAVE_RV
+ int flags = av_get_cpu_flags();
+
+ if (flags & AV_CPU_FLAG_RVB_BASIC)
+ dsp->startcode_find_candidate = ff_startcode_find_candidate_rvb;
+#endif
+}
diff --git a/libavcodec/riscv/startcode_rvb.S b/libavcodec/riscv/startcode_rvb.S
new file mode 100644
index 0000000000..c043d59809
--- /dev/null
+++ b/libavcodec/riscv/startcode_rvb.S
@@ -0,0 +1,83 @@
+/*
+ * Copyright © 2024 Rémi Denis-Courmont.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "libavutil/riscv/asm.S"
+
+ .macro lx rd, addr
+#if (__riscv_xlen == 32)
+ lw \rd, \addr
+#elif (__riscv_xlen == 64)
+ ld \rd, \addr
+#else
+ lq \rd, \addr
+#endif
+ .endm
+
+func ff_startcode_find_candidate_rvb, zbb
+ add a1, a0, a1
+
+ // Potentially unaligned head
+ andi t0, a0, -(__riscv_xlen / 8)
+ beq a0, a1, 2f
+
+ andi t1, a0, (__riscv_xlen / 8) - 1
+ lx t2, (t0)
+ li t3, __riscv_xlen
+ orc.b t2, t2
+ slli t1, t1, 3
+ not t2, t2
+ sub t3, t3, t1
+ srl t2, t2, t1
+ addi t0, t0, __riscv_xlen / 8
+ sll t2, t2, t1
+ bnez t2, 4f
+
+ // Main loop (including potentially short tail)
+ bge t0, a1, 2f
+ li t3, -1
+1:
+ lx t2, (t0)
+ addi t0, t0, __riscv_xlen / 8
+ orc.b t2, t2
+ bne t2, t3, 3f // t2 != -1 iff (at least one) zero byte
+ blt t0, a1, 1b
+
+2: // No zero byte found
+ sub a0, a1, a0
+ ret
+
+3: // Zero byte found in main loop
+ not t2, t2
+4: // Zero byte found in head
+ ctz t2, t2
+ addi t0, t0, -(__riscv_xlen / 8) // back-track
+ srl t2, t2, 3
+ add t0, t0, t2
+ // Uncomment the following line for exact POSIX C strnlen() semantics.
+ //minu t0, t0, a1 // ignore zero byte in tail
+ sub a0, t0, a0
+ ret
+endfunc
diff --git a/libavcodec/riscv/vc1dsp_init.c b/libavcodec/riscv/vc1dsp_init.c
index e1dd374a4a..d82f7efbc2 100644
--- a/libavcodec/riscv/vc1dsp_init.c
+++ b/libavcodec/riscv/vc1dsp_init.c
@@ -33,6 +33,7 @@ void ff_put_pixels16x16_rvi(uint8_t *dst, const uint8_t *src, ptrdiff_t line_siz
void ff_put_pixels8x8_rvi(uint8_t *dst, const uint8_t *src, ptrdiff_t line_size, int rnd);
void ff_avg_pixels16x16_rvv(uint8_t *dst, const uint8_t *src, ptrdiff_t line_size, int rnd);
void ff_avg_pixels8x8_rvv(uint8_t *dst, const uint8_t *src, ptrdiff_t line_size, int rnd);
+int ff_startcode_find_candidate_rvb(const uint8_t *, int);
av_cold void ff_vc1dsp_init_riscv(VC1DSPContext *dsp)
{
@@ -45,7 +46,9 @@ av_cold void ff_vc1dsp_init_riscv(VC1DSPContext *dsp)
dsp->put_vc1_mspel_pixels_tab[0][0] = ff_put_pixels16x16_rvi;
}
# endif
-#if HAVE_RVV
+ if (flags & AV_CPU_FLAG_RVB_BASIC)
+ dsp->startcode_find_candidate = ff_startcode_find_candidate_rvb;
+# if HAVE_RVV
if (flags & AV_CPU_FLAG_RVV_I32 && ff_rv_vlen_least(128)) {
dsp->vc1_inv_trans_4x8_dc = ff_vc1_inv_trans_4x8_dc_rvv;
dsp->vc1_inv_trans_4x4_dc = ff_vc1_inv_trans_4x4_dc_rvv;
@@ -56,6 +59,6 @@ av_cold void ff_vc1dsp_init_riscv(VC1DSPContext *dsp)
dsp->avg_vc1_mspel_pixels_tab[1][0] = ff_avg_pixels8x8_rvv;
}
}
-#endif
+# endif
#endif
}
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