lavc/h264dsp: R-V V high-depth h264_idct8_add

Unlike the 8-bit version, we need two iterations to process this within
128-bit vectors. This adds some extra complexity for pointer arithmetic
and counting down which is unnecessary in the 8-bit variant.

Accordingly the gain relative to C are just slight better than half as
good with 128-bit vectors as with 256-bit ones.

T-Head C908 (2 iterations):
h264_idct8_add_9bpp_c:       17.5
h264_idct8_add_9bpp_rvv_i32: 10.0
h264_idct8_add_10bpp_c:      17.5
h264_idct8_add_10bpp_rvv_i32: 9.7
h264_idct8_add_12bpp_c:      17.7
h264_idct8_add_12bpp_rvv_i32: 9.7
h264_idct8_add_14bpp_c:      17.7
h264_idct8_add_14bpp_rvv_i32: 9.7

SpacemiT X60 (single iteration):
h264_idct8_add_9bpp_c:       15.2
h264_idct8_add_9bpp_rvv_i32:  5.0
h264_idct8_add_10bpp_c:      15.2
h264_idct8_add_10bpp_rvv_i32: 5.0
h264_idct8_add_12bpp_c:      14.7
h264_idct8_add_12bpp_rvv_i32: 5.0
h264_idct8_add_14bpp_c:      14.7
h264_idct8_add_14bpp_rvv_i32: 4.7

0 files changed, 0 insertions, 0 deletions