[FFmpeg-devel] lavu/lls: R-V V update_lls

diff --git a/libavutil/lls.c b/libavutil/lls.c
index c1e038daf1..d300ae7a60 100644
--- a/libavutil/lls.c
+++ b/libavutil/lls.c
@@ -117,7 +117,9 @@  av_cold void avpriv_init_lls(LLSModel *m, int indep_count)
     m->indep_count = indep_count;
     m->update_lls = update_lls;
     m->evaluate_lls = evaluate_lls;
-#if ARCH_X86
+#if ARCH_RISCV
+    ff_init_lls_riscv(m);
+#elif ARCH_X86
     ff_init_lls_x86(m);
 #endif
 }
diff --git a/libavutil/lls.h b/libavutil/lls.h
index 0709275822..7acef4eff8 100644
--- a/libavutil/lls.h
+++ b/libavutil/lls.h
@@ -57,6 +57,7 @@  typedef struct LLSModel {
 } LLSModel;
 
 void avpriv_init_lls(LLSModel *m, int indep_count);
+void ff_init_lls_riscv(LLSModel *m);
 void ff_init_lls_x86(LLSModel *m);
 void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order);
 
diff --git a/libavutil/riscv/Makefile b/libavutil/riscv/Makefile
index 1597154ba5..7e9a51194b 100644
--- a/libavutil/riscv/Makefile
+++ b/libavutil/riscv/Makefile
@@ -1,5 +1,7 @@ 
 OBJS +=     riscv/float_dsp_init.o \
             riscv/fixed_dsp_init.o \
+            riscv/lls_init.o \
             riscv/cpu.o
 RVV-OBJS += riscv/float_dsp_rvv.o \
-            riscv/fixed_dsp_rvv.o
+            riscv/fixed_dsp_rvv.o \
+            riscv/lls_rvv.o
diff --git a/libavutil/riscv/lls_init.c b/libavutil/riscv/lls_init.c
new file mode 100644
index 0000000000..b1317dc925
--- /dev/null
+++ b/libavutil/riscv/lls_init.c
@@ -0,0 +1,57 @@ 
+/*
+ * 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 <assert.h>
+#include <stdint.h>
+
+#include "config.h"
+#include "libavutil/attributes.h"
+#include "libavutil/cpu.h"
+#include "libavutil/riscv/cpu.h"
+#include "libavutil/lls.h"
+
+void ff_lls_update_covariance_rvv(double covar[][36], const double *var,
+                                  int count);
+double ff_scalarproduct_double_rvv(const double *, const double *, size_t);
+
+static void ff_lls_update_rvv(struct LLSModel *m, const double *var)
+{
+    ff_lls_update_covariance_rvv(m->covariance, var, m->indep_count + 1);
+}
+
+static double ff_lls_evaluate_rvv(struct LLSModel *m, const double *var,
+                                  int order)
+{
+    return ff_scalarproduct_double_rvv(m->coeff[order], var, order + 1);
+}
+
+av_cold void ff_init_lls_riscv(LLSModel *m)
+{
+#if HAVE_RVV
+    int flags = av_get_cpu_flags();
+
+    if ((flags & AV_CPU_FLAG_RVB_ADDR) && (flags & AV_CPU_FLAG_RVV_F64)) {
+        if ((flags & AV_CPU_FLAG_RVB_BASIC) &&
+            ff_get_rv_vlenb() > m->indep_count)
+            m->update_lls = ff_lls_update_rvv;
+        m->evaluate_lls = ff_lls_evaluate_rvv;
+    }
+#endif
+}
diff --git a/libavutil/riscv/lls_rvv.S b/libavutil/riscv/lls_rvv.S
new file mode 100644
index 0000000000..e0e6f1008e
--- /dev/null
+++ b/libavutil/riscv/lls_rvv.S
@@ -0,0 +1,39 @@ 
+/*
+ * 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 "asm.S"
+
+func ff_lls_update_covariance_rvv, zve64d, zbb
+        vtype_vli     t0, a2, t1, e64, ta, ma
+        vsetvl        zero, a2, t0
+        vle64.v       v8, (a1)
+1:
+        vfmv.f.s      ft0, v8
+        vsetvl        zero, a2, t0
+        vle64.v       v16, (a0)
+        vfmacc.vf     v16, ft0, v8
+        addi          a2, a2, -1
+        vslidedown.vi v8, v8, 1
+        vse64.v       v16, (a0)
+        addi          a0, a0, (36 + 1) * 8 # 1 row + 1 element
+        bnez          a2, 1b
+
+        ret
+endfunc