lavc/videodsp: RISC-V zicbop prefetch

There are currently no ways to run-time detect the CPU capability, so we
take it for granted (in the worst case, it will execute NOPs).

1 files changed, 36 insertions, 0 deletions

diff --git a/libavcodec/riscv/videodsp_init.c b/libavcodec/riscv/videodsp_init.c
new file mode 100644
index 0000000000..f2c9aae3ca
--- /dev/null
+++ b/libavcodec/riscv/videodsp_init.c
@@ -0,0 +1,36 @@
+/*
+ * 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/videodsp.h"
+
+void ff_prefetch_rv_zicbop(const uint8_t *mem, ptrdiff_t stride, int h);
+
+av_cold void ff_videodsp_init_riscv(VideoDSPContext *ctx, int bpc)
+{
+#if HAVE_RV_ZICBOP
+    /* TODO: Since we pay for the indirect function call anyway, we should
+     * only set this if Cache-Block Operation Prefetch (Zicbop) is actually
+     * supported and otherwise save a few cycles of NOPs.
+     * But so far there are no means to detect Zicbop (in user mode).
+     */
+    ctx->prefetch = ff_prefetch_rv_zicbop;
+#endif
+}