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/* -*-arm64-*-
* vim: syntax=arm64asm
*
* AArch64 NEON optimised SAO functions for HEVC decoding
*
* Copyright (c) 2022 J. Dekker <jdek@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"
#define MAX_PB_SIZE 64
#define AV_INPUT_BUFFER_PADDING_SIZE 64
#define SAO_STRIDE (2*MAX_PB_SIZE + AV_INPUT_BUFFER_PADDING_SIZE)
// 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
add w6, w6, #7
bic w6, w6, #7
ld1 {v16.16b-v19.16b}, [sp], #64
sub x2, x2, x6
sub x3, x3, x6
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], #8 // dst[x] = av_clip_pixel(src[x] + offset_table[src[x] >> shift]);
subs w8, w8, #8
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], #8 // store
// 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
.Lsao_edge_pos:
.word 1 // horizontal
.word SAO_STRIDE // vertical
.word SAO_STRIDE + 1 // 45 degree
.word SAO_STRIDE - 1 // 135 degree
// ff_hevc_sao_edge_filter_16x16_8_neon(char *dst, char *src, ptrdiff stride_dst,
// int16 *sao_offset_val, int eo, int width, int height)
function ff_hevc_sao_edge_filter_16x16_8_neon, export=1
adr x7, .Lsao_edge_pos
ld1 {v3.8h}, [x3] // load sao_offset_val
add w5, w5, #0xF
bic w5, w5, #0xF
ldr w4, [x7, w4, uxtw #2] // stride_src
mov v3.h[7], v3.h[0] // reorder to [1,2,0,3,4]
mov v3.h[0], v3.h[1]
mov v3.h[1], v3.h[2]
mov v3.h[2], v3.h[7]
// split 16bit values into two tables
uzp2 v1.16b, v3.16b, v3.16b // sao_offset_val -> upper
uzp1 v0.16b, v3.16b, v3.16b // sao_offset_val -> lower
movi v2.16b, #2
mov x15, #SAO_STRIDE
// strides between end of line and next src/dst
sub x15, x15, x5 // stride_src - width
sub x16, x2, x5 // stride_dst - width
mov x11, x1 // copy base src
1: // new line
mov x14, x5 // copy width
sub x12, x11, x4 // src_a (prev) = src - sao_edge_pos
add x13, x11, x4 // src_b (next) = src + sao_edge_pos
2: // process 16 bytes
ld1 {v3.16b}, [x11], #16 // load src
ld1 {v4.16b}, [x12], #16 // load src_a (prev)
ld1 {v5.16b}, [x13], #16 // load src_b (next)
subs x14, x14, #16
cmhi v16.16b, v4.16b, v3.16b // (prev > cur)
cmhi v17.16b, v3.16b, v4.16b // (cur > prev)
cmhi v18.16b, v5.16b, v3.16b // (next > cur)
cmhi v19.16b, v3.16b, v5.16b // (cur > next)
sub v20.16b, v16.16b, v17.16b // diff0 = CMP(cur, prev) = (cur > prev) - (cur < prev)
sub v21.16b, v18.16b, v19.16b // diff1 = CMP(cur, next) = (cur > next) - (cur < next)
add v20.16b, v20.16b, v21.16b // diff = diff0 + diff1
add v20.16b, v20.16b, v2.16b // offset_val = diff + 2
tbl v16.16b, {v0.16b}, v20.16b
tbl v17.16b, {v1.16b}, v20.16b
uxtl v20.8h, v3.8b // src[0:7]
uxtl2 v21.8h, v3.16b // src[7:15]
zip1 v18.16b, v16.16b, v17.16b // sao_offset_val lower ->
zip2 v19.16b, v16.16b, v17.16b // sao_offset_val upper ->
sqadd v20.8h, v18.8h, v20.8h // + sao_offset_val
sqadd v21.8h, v19.8h, v21.8h
sqxtun v3.8b, v20.8h
sqxtun2 v3.16b, v21.8h
st1 {v3.16b}, [x0], #16
// filtered 16 bytes
b.ne 2b // do we have width to filter?
// no width to filter, setup next line
subs w6, w6, #1 // filtered line
add x11, x11, x15 // stride src to next line
add x0, x0, x16 // stride dst to next line
b.ne 1b // do we have lines to process?
// no lines to filter
ret
endfunc
// ff_hevc_sao_edge_filter_8x8_8_neon(char *dst, char *src, ptrdiff stride_dst,
// int16 *sao_offset_val, int eo, int width, int height)
function ff_hevc_sao_edge_filter_8x8_8_neon, export=1
adr x7, .Lsao_edge_pos
ldr w4, [x7, w4, uxtw #2]
ld1 {v3.8h}, [x3]
mov v3.h[7], v3.h[0]
mov v3.h[0], v3.h[1]
mov v3.h[1], v3.h[2]
mov v3.h[2], v3.h[7]
uzp2 v1.16b, v3.16b, v3.16b
uzp1 v0.16b, v3.16b, v3.16b
movi v2.16b, #2
add x16, x0, x2
lsl x2, x2, #1
mov x15, #SAO_STRIDE
mov x8, x1
sub x9, x1, x4
add x10, x1, x4
1: ld1 {v3.d}[0], [ x8], x15
ld1 {v4.d}[0], [ x9], x15
ld1 {v5.d}[0], [x10], x15
ld1 {v3.d}[1], [ x8], x15
ld1 {v4.d}[1], [ x9], x15
ld1 {v5.d}[1], [x10], x15
subs w6, w6, #2
cmhi v16.16b, v4.16b, v3.16b
cmhi v17.16b, v3.16b, v4.16b
cmhi v18.16b, v5.16b, v3.16b
cmhi v19.16b, v3.16b, v5.16b
sub v20.16b, v16.16b, v17.16b
sub v21.16b, v18.16b, v19.16b
add v20.16b, v20.16b, v21.16b
add v20.16b, v20.16b, v2.16b
tbl v16.16b, {v0.16b}, v20.16b
tbl v17.16b, {v1.16b}, v20.16b
uxtl v20.8h, v3.8b
uxtl2 v21.8h, v3.16b
zip1 v18.16b, v16.16b, v17.16b
zip2 v19.16b, v16.16b, v17.16b
sqadd v20.8h, v18.8h, v20.8h
sqadd v21.8h, v19.8h, v21.8h
sqxtun v6.8b, v20.8h
sqxtun v7.8b, v21.8h
st1 {v6.8b}, [ x0], x2
st1 {v7.8b}, [x16], x2
b.ne 1b
ret
endfunc