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;*******************************************************************************
;* x86-optimized H.264 CABAC decoding (non-SIMD)
;* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
;* Copyright (c) 2020 Anton Khirnov <anton@khirnov.net>
;*
;* 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/x86/x86util.asm"
%define H264_NORM_SHIFT_OFFSET 0
%define H264_LPS_RANGE_OFFSET 512
%define H264_MLPS_STATE_OFFSET 1024
%define H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET 1280
%define CC_OFF_LOW 0
%define CC_OFF_RANGE 4
%define CC_OFF_BYTESTREAM 24
%define CC_OFF_BYTESTREAM_END 32
cextern h264_cabac_tables
SECTION .text
%macro GET_CABAC 0
push rcx
movzx bitd, byte [statep]
mov tmpd, ranged
and ranged, 0xc0
lea ecx, [bitd + ranged * 2]
movzx ranged, byte [tablesq + rcx + H264_LPS_RANGE_OFFSET]
sub tmpd, ranged
mov ecx, tmpd
shl tmpd, 17
cmp tmpd, lowd
cmova ranged, ecx
sbb rcx, rcx
and tmpd, ecx
xor bitq, rcx
sub lowd, tmpd
movzx ecx, byte [tablesq + H264_NORM_SHIFT_OFFSET + rangeq]
shl ranged, cl
shl lowd, cl
movzx tmpd, byte [tablesq + H264_MLPS_STATE_OFFSET + 128 + bitq]
mov [statep], tmpb
test loww, loww
jnz %%finish
movzx tmpd, word [bytestreamq]
cmp bytestreamq, bytestream_endq
jge %%skip_bs_advance
add bytestreamq, 2
%%skip_bs_advance:
lea ecx, [lowd - 1]
xor ecx, lowd
shr ecx, 15
bswap tmpd
shr tmpd, 15
movzx ecx, byte [tablesq + rcx + H264_NORM_SHIFT_OFFSET]
sub tmpd, 0xffff
neg ecx
add ecx, 7
shl tmpd, cl
add lowd, tmpd
%%finish:
pop rcx
%endmacro
%macro DECODE_SIGNIFICANCE 1
; store the values we won't need until the end on stack
mov qword [rsp], 4
sub [rsp], indexq
mov qword [rsp + gprsize], ccq
; load CABACContext fields
mov lowd, [ccq + CC_OFF_LOW]
mov ranged, [ccq + CC_OFF_RANGE]
mov bytestreamq, [ccq + CC_OFF_BYTESTREAM]
mov bytestream_endq, [ccq + CC_OFF_BYTESTREAM_END]
; recycle the cabac context register for tables
%define tablesq ccq
lea tablesq, [h264_cabac_tables]
%if %1
%define loop_count 63
%define statep stateq
%else
sub max_coeffd, 1
%define loop_count max_coeffd
%define statep significant_coeff_ctx_baseq + counterq
%endif
xor counterq, counterq
.loop:
%if %1
movzx stated, byte [sig_offq + counterq]
add stateq, significant_coeff_ctx_baseq
%endif
GET_CABAC
test bitq, 1
jz .continue
%if %1
movzx stated, byte [tablesq + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET + counterq]
add stateq, last_coeff_ctx_baseq
%else
add significant_coeff_ctx_baseq, last_offq
%endif
GET_CABAC
%if !%1
sub significant_coeff_ctx_baseq, last_offq
%endif
mov [indexq], counterd
test bitq, 1
jnz .finish
add indexq, 4
.continue:
add counterd, 1
cmp counterd, loop_count
jb .loop
mov [indexq], counterd
.finish:
; update CABACContext
mov ccq, [rsp + gprsize]
mov [ccq + CC_OFF_LOW], lowd
mov [ccq + CC_OFF_RANGE], ranged
mov [ccq + CC_OFF_BYTESTREAM], bytestreamq
add indexq, [rsp]
shr indexq, 2
movifnidn rax, indexq
RET
%endmacro
; int ff_h264_decode_significance_x86(CABACContext *cc, int max_coeff,
; uint8_t *significant_coeff_ctx_base, int *index, ptrdiff_t last_off)
cglobal h264_decode_significance_x86, 5, 12, 0, gprsize * 2, \
cc, max_coeff, significant_coeff_ctx_base, index, last_off, \
bytestream, bytestream_end, low, range, bit, counter, tmp
DECODE_SIGNIFICANCE 0
cglobal h264_decode_significance_8x8_x86, 5, 13, 0, gprsize * 2, \
cc, significant_coeff_ctx_base, index, last_coeff_ctx_base, sig_off, \
bytestream, bytestream_end, low, range, bit, counter, tmp, state
DECODE_SIGNIFICANCE 1
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