lavc/ac3: add R-V Zbb extract_exponents

libavcodec/ac3dsp.c

@@ -395,5 +395,7 @@ av_cold void ff_ac3dsp_init(AC3DSPContext *c)
     ff_ac3dsp_init_x86(c);
 #elif ARCH_MIPS
     ff_ac3dsp_init_mips(c);
+#elif ARCH_RISCV
+    ff_ac3dsp_init_riscv(c);
 #endif
 }

libavcodec/ac3dsp.h

@@ -109,6 +109,7 @@ void ff_ac3dsp_init    (AC3DSPContext *c);
 void ff_ac3dsp_init_arm(AC3DSPContext *c);
 void ff_ac3dsp_init_x86(AC3DSPContext *c);
 void ff_ac3dsp_init_mips(AC3DSPContext *c);
+void ff_ac3dsp_init_riscv(AC3DSPContext *c);
 
 void ff_ac3dsp_downmix(AC3DSPContext *c, float **samples, float **matrix,
                        int out_ch, int in_ch, int len);

libavcodec/riscv/Makefile

@@ -1,5 +1,7 @@
 OBJS-$(CONFIG_AAC_DECODER) += riscv/aacpsdsp_init.o
 RVV-OBJS-$(CONFIG_AAC_DECODER) += riscv/aacpsdsp_rvv.o
+OBJS-$(CONFIG_AC3DSP) += riscv/ac3dsp_init.o \
+                         riscv/ac3dsp_rvb.o
 OBJS-$(CONFIG_ALAC_DECODER) += riscv/alacdsp_init.o
 RVV-OBJS-$(CONFIG_ALAC_DECODER) += riscv/alacdsp_rvv.o
 OBJS-$(CONFIG_AUDIODSP) += riscv/audiodsp_init.o \

libavcodec/riscv/ac3dsp_init.c

@@ -0,0 +1,38 @@
+/*
+ * Copyright © 2023 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 <stdint.h>
+
+#include "config.h"
+#include "libavutil/attributes.h"
+#include "libavutil/cpu.h"
+#include "libavcodec/ac3dsp.h"
+
+void ff_extract_exponents_rvb(uint8_t *exp, int32_t *coef, int nb_coefs);
+
+av_cold void ff_ac3dsp_init_riscv(AC3DSPContext *c)
+{
+    int flags = av_get_cpu_flags();
+
+    if (flags & AV_CPU_FLAG_RVB_ADDR) {
+        if (flags & AV_CPU_FLAG_RVB_BASIC)
+            c->extract_exponents = ff_extract_exponents_rvb;
+    }
+}

libavcodec/riscv/ac3dsp_rvb.S

@@ -0,0 +1,38 @@
+/*
+ * Copyright © 2023 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 "libavutil/riscv/asm.S"
+
+func ff_extract_exponents_rvb, zbb
+1:
+        lw       t0, (a1)
+        addi     a0, a0, 1
+        neg      t1, t0
+        addi     a1, a1, 4
+        max      t0, t0, t1
+        addi     a2, a2, -1
+        clz      t0, t0
+        addi     t0, t0, 24 - __riscv_xlen
+        sb       t0, -1(a0)
+        bgtz    a2, 1b
+
+        ret
+endfunc