lavc/vorbisdsp: RISC-V V inverse_coupling

This uses the following vectorisation:

    for (i = 0; i < blocksize; i++) {
        ang[i] = mag[i] - copysignf(fmaxf(ang[i], 0.f), mag[i]);
        mag[i] = mag[i] - copysignf(fminf(ang[i], 0.f), mag[i]);
    }

libavcodec/riscv/Makefile

@@ -5,3 +5,5 @@ OBJS-$(CONFIG_FMTCONVERT) += riscv/fmtconvert_init.o
 RVV-OBJS-$(CONFIG_FMTCONVERT) += riscv/fmtconvert_rvv.o
 OBJS-$(CONFIG_PIXBLOCKDSP) += riscv/pixblockdsp_init.o \
                               riscv/pixblockdsp_rvi.o
+OBJS-$(CONFIG_VORBIS_DECODER) += riscv/vorbisdsp_init.o
+RVV-OBJS-$(CONFIG_VORBIS_DECODER) += riscv/vorbisdsp_rvv.o

libavcodec/riscv/vorbisdsp_init.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright © 2022 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/attributes.h"
+#include "libavutil/cpu.h"
+#include "libavcodec/vorbisdsp.h"
+
+void ff_vorbis_inverse_coupling_rvv(float *mag, float *ang,
+                                    ptrdiff_t blocksize);
+
+av_cold void ff_vorbisdsp_init_riscv(VorbisDSPContext *c)
+{
+#if HAVE_RVV
+    int flags = av_get_cpu_flags();
+
+    if (flags & AV_CPU_FLAG_RVV_I32)
+        c->vorbis_inverse_coupling = ff_vorbis_inverse_coupling_rvv;
+#endif
+}

libavcodec/riscv/vorbisdsp_rvv.S

@@ -0,0 +1,44 @@
+/*
+ * Copyright © 2022 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_vorbis_inverse_coupling_rvv, zve32f
+        fmv.w.x   ft0, zero
+1:
+        vsetvli   t0, a2, e32, m1, ta, ma
+        vle32.v   v16, (a1)
+        sub       a2, a2, t0
+        vle32.v   v24, (a0)
+        vfmax.vf  v8, v16, ft0
+        vfmin.vf  v16, v16, ft0
+        vfsgnj.vv v8, v8, v24
+        vfsgnj.vv v16, v16, v24
+        vfsub.vv  v8, v24, v8
+        vfsub.vv  v24, v24, v16
+        vse32.v   v8, (a1)
+        sh2add    a1, t0, a1
+        vse32.v   v24, (a0)
+        sh2add    a0, t0, a0
+        bnez      a2, 1b
+
+        ret
+endfunc

libavcodec/vorbisdsp.c

@@ -53,6 +53,8 @@ av_cold void ff_vorbisdsp_init(VorbisDSPContext *dsp)
     ff_vorbisdsp_init_arm(dsp);
 #elif ARCH_PPC
     ff_vorbisdsp_init_ppc(dsp);
+#elif ARCH_RISCV
+    ff_vorbisdsp_init_riscv(dsp);
 #elif ARCH_X86
     ff_vorbisdsp_init_x86(dsp);
 #endif

libavcodec/vorbisdsp.h

@@ -34,5 +34,6 @@ void ff_vorbisdsp_init_aarch64(VorbisDSPContext *dsp);
 void ff_vorbisdsp_init_x86(VorbisDSPContext *dsp);
 void ff_vorbisdsp_init_arm(VorbisDSPContext *dsp);
 void ff_vorbisdsp_init_ppc(VorbisDSPContext *dsp);
+void ff_vorbisdsp_init_riscv(VorbisDSPContext *dsp);
 
 #endif /* AVCODEC_VORBISDSP_H */