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Since the horizontal and vertical filters are identical except for a transposition, this uses a common subprocedure with an ad-hoc ABI. To preserve return-address stack prediction, a link register has to be used (c.f. the "Control Transfer Instructions" from the RISC-V ISA Manual). The alternate/temporary link register T0 is used here, so that the normal RA is preserved (something Arm cannot do!). To load the strength value based on `qscale`, the shortest possible and PIC-compatible sequence is used: AUIPC; ADD; LBU. The classic LLA; ADD; LBU sequence would add one more instruction since LLA is a convenience alias for AUIPC; ADDI. To ensure that this trick works, relocation relaxation is disabled. To implement the two signed divisions by a power of two toward zero: (x / (1 << SHIFT)) the code relies on the small range of integers involved, computing: (x + (x >> (16 - SHIFT))) >> SHIFT rather than the more general: (x + ((x >> (16 - 1)) & ((1 << SHIFT) - 1))) >> SHIFT Thus one ANDI instruction is avoided. T-Head C908: h263dsp.h_loop_filter_c: 228.2 h263dsp.h_loop_filter_rvv_i32: 144.0 h263dsp.v_loop_filter_c: 242.7 h263dsp.v_loop_filter_rvv_i32: 114.0 (C is probably worse in real use due to less predictible branches.) |
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| .. | ||
| aacencdsp_init.c | ||
| aacencdsp_rvv.S | ||
| aacpsdsp_init.c | ||
| aacpsdsp_rvv.S | ||
| ac3dsp_init.c | ||
| ac3dsp_rvb.S | ||
| ac3dsp_rvv.S | ||
| ac3dsp_rvvb.S | ||
| alacdsp_init.c | ||
| alacdsp_rvv.S | ||
| audiodsp_init.c | ||
| audiodsp_rvf.S | ||
| audiodsp_rvv.S | ||
| blockdsp_init.c | ||
| blockdsp_rvv.S | ||
| bswapdsp_init.c | ||
| bswapdsp_rvb.S | ||
| bswapdsp_rvv.S | ||
| exrdsp_init.c | ||
| exrdsp_rvv.S | ||
| flacdsp_init.c | ||
| flacdsp_rvv.S | ||
| fmtconvert_init.c | ||
| fmtconvert_rvv.S | ||
| g722dsp_init.c | ||
| g722dsp_rvv.S | ||
| h263dsp_init.c | ||
| h263dsp_rvv.S | ||
| h264_chroma_init_riscv.c | ||
| h264_mc_chroma.S | ||
| h264dsp_init.c | ||
| huffyuvdsp_init.c | ||
| huffyuvdsp_rvv.S | ||
| idctdsp_init.c | ||
| idctdsp_rvv.S | ||
| jpeg2000dsp_init.c | ||
| jpeg2000dsp_rvv.S | ||
| llauddsp_init.c | ||
| llauddsp_rvv.S | ||
| llviddsp_init.c | ||
| llviddsp_rvv.S | ||
| llvidencdsp_init.c | ||
| llvidencdsp_rvv.S | ||
| lpc_init.c | ||
| lpc_rvv.S | ||
| Makefile | ||
| me_cmp_init.c | ||
| me_cmp_rvv.S | ||
| opusdsp_init.c | ||
| opusdsp_rvv.S | ||
| pixblockdsp_init.c | ||
| pixblockdsp_rvi.S | ||
| pixblockdsp_rvv.S | ||
| rv34dsp_init.c | ||
| rv34dsp_rvv.S | ||
| rv40dsp_init.c | ||
| rv40dsp_rvv.S | ||
| sbrdsp_init.c | ||
| sbrdsp_rvv.S | ||
| startcode_rvb.S | ||
| startcode_rvv.S | ||
| svqenc_init.c | ||
| svqenc_rvv.S | ||
| takdsp_init.c | ||
| takdsp_rvv.S | ||
| utvideodsp_init.c | ||
| utvideodsp_rvv.S | ||
| vc1dsp_init.c | ||
| vc1dsp_rvi.S | ||
| vc1dsp_rvv.S | ||
| vorbisdsp_init.c | ||
| vorbisdsp_rvv.S | ||
| vp8dsp_init.c | ||
| vp8dsp_rvi.S | ||
| vp8dsp_rvv.S | ||
| vp8dsp.h | ||
| vp9_intra_rvi.S | ||
| vp9_intra_rvv.S | ||
| vp9_mc_rvi.S | ||
| vp9_mc_rvv.S | ||
| vp9dsp_init.c | ||
| vp9dsp.h | ||