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/* -*-arm64-*-
* vim: syntax=arm64asm
*
* AArch64 NEON optimised SAO functions for HEVC decoding
*
* Copyright (c) 2020 Josh Dekker <josh@itanimul.li>
*
* 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 "libavutil/aarch64/asm.S"
// void sao_band_filter(uint8_t *_dst, uint8_t *_src,
// ptrdiff_t stride_dst, ptrdiff_t stride_src,
// int16_t *sao_offset_val, int sao_left_class,
// int width, int height)
function ff_hevc_sao_band_filter_8x8_8_neon, export=1
sub sp, sp, #64
stp xzr, xzr, [sp]
stp xzr, xzr, [sp, #16]
stp xzr, xzr, [sp, #32]
stp xzr, xzr, [sp, #48]
mov w8, #4
0: ldrsh x9, [x4, x8, lsl #1] // sao_offset_val[k+1]
subs w8, w8, #1
add w10, w8, w5 // k + sao_left_class
and w10, w10, #0x1F
strh w9, [sp, x10, lsl #1]
bne 0b
ld1 {v16.16b-v19.16b}, [sp], #64
movi v20.8h, #1
1: mov w8, w6 // beginning of line
2: // Simple layout for accessing 16bit values
// with 8bit LUT.
//
// 00 01 02 03 04 05 06 07
// +----------------------------------->
// |xDE#xAD|xCA#xFE|xBE#xEF|xFE#xED|....
// +----------------------------------->
// i-0 i-1 i-2 i-3
ld1 {v2.8b}, [x1] // dst[x] = av_clip_pixel(src[x] + offset_table[src[x] >> shift]);
uxtl v0.8h, v2.8b // load src[x]
ushr v2.8h, v0.8h, #3 // >> BIT_DEPTH - 3
shl v1.8h, v2.8h, #1 // low (x2, accessing short)
add v3.8h, v1.8h, v20.8h // +1 access upper short
sli v1.8h, v3.8h, #8 // shift insert index to upper byte
tbx v2.16b, {v16.16b-v19.16b}, v1.16b // table
add v1.8h, v0.8h, v2.8h // src[x] + table
sqxtun v4.8b, v1.8h // clip + narrow
st1 {v4.8b}, [x0] // store
subs w8, w8, #8 // done 8 pixels
bne 2b
subs w7, w7, #1 // finished line, prep. new
add x0, x0, x2 // dst += stride_dst
add x1, x1, x3 // src += stride_src
bne 1b
ret
endfunc
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