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FFmpeg/libavcodec/riscv/bswapdsp_rvv.S
Rémi Denis-Courmont 61e5ca4ded lavc/bswapdsp: purge RISC-V V bswap32
This cannot beat the Zbb implementation, and it is unlikely that a real
meaningful CPU design would support V and not Zbb. The best loop rewrite
that I could come up with (4 shifts, 2 ands, 3 ors) is still ~40% slower
than Zbb.

A proper faster vector implementation should be feasible with the
cryptographic vector extensions, but that is a story for another time.
2023-07-19 19:29:35 +03:00

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1.2 KiB
ArmAsm

/*
* Copyright © 2022 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 "config.h"
#include "libavutil/riscv/asm.S"
func ff_bswap16_buf_rvv, zve32x
1:
vsetvli t0, a2, e16, m8, ta, ma
vle16.v v8, (a1)
sub a2, a2, t0
vsll.vi v16, v8, 8
sh1add a1, t0, a1
vsrl.vi v24, v8, 8
vor.vv v8, v16, v24
vse16.v v8, (a0)
sh1add a0, t0, a0
bnez a2, 1b
ret
endfunc