lavc/lpc: R-V V apply_welch_window

apply_welch_window_even_c:       617.5
apply_welch_window_even_rvv_f64: 235.0
apply_welch_window_odd_c:        709.0
apply_welch_window_odd_rvv_f64:  256.5

libavcodec/lpc.c

@@ -320,7 +320,9 @@ av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
     s->lpc_apply_welch_window = lpc_apply_welch_window_c;
     s->lpc_compute_autocorr   = lpc_compute_autocorr_c;
 
-#if ARCH_X86
+#if ARCH_RISCV
+    ff_lpc_init_riscv(s);
+#elif ARCH_X86
     ff_lpc_init_x86(s);
 #endif
 

libavcodec/lpc.h

@@ -109,6 +109,7 @@ double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
  */
 int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
                 enum FFLPCType lpc_type);
+void ff_lpc_init_riscv(LPCContext *s);
 void ff_lpc_init_x86(LPCContext *s);
 
 /**

libavcodec/riscv/Makefile

@@ -33,6 +33,8 @@ OBJS-$(CONFIG_LLVIDDSP) += riscv/llviddsp_init.o
 RVV-OBJS-$(CONFIG_LLVIDDSP) += riscv/llviddsp_rvv.o
 OBJS-$(CONFIG_LLVIDENCDSP) += riscv/llvidencdsp_init.o
 RVV-OBJS-$(CONFIG_LLVIDENCDSP) += riscv/llvidencdsp_rvv.o
+OBJS-$(CONFIG_LPC) += riscv/lpc_init.o
+RVV-OBJS-$(CONFIG_LPC) += riscv/lpc_rvv.o
 OBJS-$(CONFIG_OPUS_DECODER) += riscv/opusdsp_init.o
 RVV-OBJS-$(CONFIG_OPUS_DECODER) += riscv/opusdsp_rvv.o
 OBJS-$(CONFIG_PIXBLOCKDSP) += riscv/pixblockdsp_init.o

libavcodec/riscv/lpc_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/lpc.h"
+
+void ff_lpc_apply_welch_window_rvv(const int32_t *, ptrdiff_t, double *);
+
+av_cold void ff_lpc_init_riscv(LPCContext *c)
+{
+#if HAVE_RVV && (__riscv_xlen >= 64)
+    int flags = av_get_cpu_flags();
+
+    if ((flags & AV_CPU_FLAG_RVV_F64) && (flags & AV_CPU_FLAG_RVB_ADDR))
+        c->lpc_apply_welch_window = ff_lpc_apply_welch_window_rvv;
+#endif
+}

libavcodec/riscv/lpc_rvv.S

@@ -0,0 +1,88 @@
+/*
+ * 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 "libavutil/riscv/asm.S"
+
+#if __riscv_xlen >= 64
+func ff_lpc_apply_welch_window_rvv, zve64d
+        vsetvli   t0, zero, e64, m8, ta, ma
+        vid.v     v0
+        addi      t2, a1, -1
+        vfcvt.f.xu.v v0, v0
+        li        t3, 2
+        fcvt.d.l  ft2, t2
+        srai      t1, a1, 1
+        fcvt.d.l  ft3, t3
+        li        t4, 1
+        fdiv.d    ft0, ft3, ft2    # ft0 = c = 2. / (len - 1)
+        fcvt.d.l  fa1, t4         # fa1 = 1.
+        fsub.d    ft1, ft0, fa1
+        vfrsub.vf v0, v0, ft1    # v0[i] = c - i - 1.
+1:
+        vsetvli   t0, t1, e64, m8, ta, ma
+        vfmul.vv  v16, v0, v0  # no fused multipy-add as v0 is reused
+        sub       t1, t1, t0
+        vle32.v   v8, (a0)
+        fcvt.d.l  ft2, t0
+        vfrsub.vf v16, v16, fa1  # v16 = 1. - w * w
+        sh2add    a0, t0, a0
+        vsetvli   zero, zero, e32, m4, ta, ma
+        vfwcvt.f.x.v v24, v8
+        vsetvli   zero, zero, e64, m8, ta, ma
+        vfsub.vf  v0, v0, ft2     # v0 -= vl
+        vfmul.vv  v8, v24, v16
+        vse64.v   v8, (a2)
+        sh3add    a2, t0, a2
+        bnez      t1, 1b
+
+        andi      t1, a1, 1
+        beqz      t1, 2f
+
+        sd        zero, (a2)
+        addi      a0, a0, 4
+        addi      a2, a2, 8
+2:
+        vsetvli   t0, zero, e64, m8, ta, ma
+        vid.v     v0
+        srai      t1, a1, 1
+        vfcvt.f.xu.v v0, v0
+        fcvt.d.l  ft1, t1
+        fsub.d    ft1, ft0, ft1    # ft1 = c - (len / 2)
+        vfadd.vf  v0, v0, ft1     # v0[i] = c - (len / 2) + i
+3:
+        vsetvli   t0, t1, e64, m8, ta, ma
+        vfmul.vv  v16, v0, v0
+        sub       t1, t1, t0
+        vle32.v   v8, (a0)
+        fcvt.d.l  ft2, t0
+        vfrsub.vf v16, v16, fa1  # v16 = 1. - w * w
+        sh2add    a0, t0, a0
+        vsetvli   zero, zero, e32, m4, ta, ma
+        vfwcvt.f.x.v v24, v8
+        vsetvli   zero, zero, e64, m8, ta, ma
+        vfadd.vf  v0, v0, ft2     # v0 += vl
+        vfmul.vv  v8, v24, v16
+        vse64.v   v8, (a2)
+        sh3add    a2, t0, a2
+        bnez      t1, 3b
+
+        ret
+endfunc
+#endif