add example how to use rtcd

Just use vp8_sixtap_predict as example but have not
implemented it actually.

Test:
$ CROSS=riscv64-unknown-linux-gnu- ../libvpx/configure --target=riscv64-linux-gcc
$ make

Check if vp8_sixtap_predict functions have been replaced with those
suffixed with "_rvv":
$ riscv64-unknown-linux-gnu-nm ./vp8/decoder/decodeframe.c.o | grep vp8_sixtap_predict16x16
                 U vp8_sixtap_predict16x16_rvv

Check if vp8_sixtap_predictMxN_rvv work.
$ qemu-riscv64 -L $SYSROOT_RV64  ./build-test/test_libvpx --gtest_filter="RVV/SixtapPredictTest.TestWithPresetData/*"
You should see print log output such as: "--> vp8_sixtap_predict4x4_rvv"
"FAILED" is expected due to we have not implemented the actual
algorithm.

Signed-off-by: Wang Chen <wangchen20@iscas.ac.cn>
Co-authored-by: sun min <sunmin89@outlook.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/vp8/common/riscv/sixtap_predict_rvv.c b/vp8/common/riscv/sixtap_predict_rvv.c
new file mode 100644
index 000000000..0345d026e
--- /dev/null
+++ b/vp8/common/riscv/sixtap_predict_rvv.c
@@ -0,0 +1,63 @@
+#include <riscv_vector.h>
+#include <stdio.h>
+#include "./vpx_config.h"
+#include "./vp8_rtcd.h"
+
+#define UNUSED(x) (void)(x)
+
+void vp8_sixtap_predict4x4_rvv(unsigned char *src_ptr, int src_pixels_per_line,
+                                int xoffset, int yoffset,
+                                unsigned char *dst_ptr, int dst_pitch)
+{
+  UNUSED(src_ptr);
+  UNUSED(src_pixels_per_line);
+  UNUSED(xoffset);
+  UNUSED(yoffset);
+  UNUSED(dst_ptr);
+  UNUSED(dst_pitch);
+
+  printf("--> vp8_sixtap_predict4x4_rvv\n");
+}
+
+void vp8_sixtap_predict8x4_rvv(unsigned char *src_ptr, int src_pixels_per_line,
+                                int xoffset, int yoffset,
+                                unsigned char *dst_ptr, int dst_pitch)
+{
+  UNUSED(src_ptr);
+  UNUSED(src_pixels_per_line);
+  UNUSED(xoffset);
+  UNUSED(yoffset);
+  UNUSED(dst_ptr);
+  UNUSED(dst_pitch);
+
+  printf("--> vp8_sixtap_predict8x4_rvv\n");
+}
+
+void vp8_sixtap_predict8x8_rvv(unsigned char *src_ptr, int src_pixels_per_line,
+                                int xoffset, int yoffset,
+                                unsigned char *dst_ptr, int dst_pitch)
+{
+  UNUSED(src_ptr);
+  UNUSED(src_pixels_per_line);
+  UNUSED(xoffset);
+  UNUSED(yoffset);
+  UNUSED(dst_ptr);
+  UNUSED(dst_pitch);
+
+  printf("--> vp8_sixtap_predict8x8_rvv\n");
+}
+
+void vp8_sixtap_predict16x16_rvv(unsigned char *src_ptr,
+                                  int src_pixels_per_line, int xoffset,
+                                  int yoffset, unsigned char *dst_ptr,
+                                  int dst_pitch)
+{
+  UNUSED(src_ptr);
+  UNUSED(src_pixels_per_line);
+  UNUSED(xoffset);
+  UNUSED(yoffset);
+  UNUSED(dst_ptr);
+  UNUSED(dst_pitch);
+
+  printf("--> vp8_sixtap_predict16x16_rvv\n");
+}