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dfe224f377
Based on the x86 branchless get_cabac asm. get_cabac_noinline() gets approximately 20% faster (no cycle counts available) compared to clang from Xcode 5.1 beta5. More than 6% faster overall. A part of the overall speedup might be explained by additional inlining of get_cabac().
105 lines
4.9 KiB
C
105 lines
4.9 KiB
C
/*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_AARCH64_CABAC_H
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#define AVCODEC_AARCH64_CABAC_H
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#include "config.h"
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#if HAVE_INLINE_ASM
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#include "libavutil/attributes.h"
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#include "libavutil/internal.h"
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#include "libavcodec/cabac.h"
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#define get_cabac_inline get_cabac_inline_aarch64
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static av_always_inline int get_cabac_inline_aarch64(CABACContext *c,
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uint8_t *const state)
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{
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int bit;
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void *reg_a, *reg_b, *reg_c, *tmp;
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__asm__ volatile(
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"ldrb %w[bit] , [%[state]] \n\t"
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"add %[r_b] , %[tables] , %[lps_off] \n\t"
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"mov %w[tmp] , %w[range] \n\t"
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"and %w[range] , %w[range] , #0xC0 \n\t"
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"lsl %w[r_c] , %w[range] , #1 \n\t"
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"add %[r_b] , %[r_b] , %w[bit], UXTW \n\t"
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"ldrb %w[range] , [%[r_b], %w[r_c], SXTW] \n\t"
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"sub %w[r_c] , %w[tmp] , %w[range] \n\t"
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"lsl %w[tmp] , %w[r_c] , #17 \n\t"
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"cmp %w[tmp] , %w[low] \n\t"
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"csel %w[tmp] , %w[tmp] , wzr , cc \n\t"
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"csel %w[range] , %w[r_c] , %w[range], gt \n\t"
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"cinv %w[bit] , %w[bit] , cc \n\t"
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"sub %w[low] , %w[low] , %w[tmp] \n\t"
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"add %[r_b] , %[tables] , %[norm_off] \n\t"
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"add %[r_a] , %[tables] , %[mlps_off] \n\t"
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"ldrb %w[tmp] , [%[r_b], %w[range], SXTW] \n\t"
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"ldrb %w[r_a] , [%[r_a], %w[bit], SXTW] \n\t"
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"lsl %w[low] , %w[low] , %w[tmp] \n\t"
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"lsl %w[range] , %w[range] , %w[tmp] \n\t"
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"uxth %w[r_c] , %w[low] \n\t"
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"strb %w[r_a] , [%[state]] \n\t"
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"cbnz %w[r_c] , 2f \n\t"
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"ldr %[r_c] , [%[c], %[byte]] \n\t"
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"ldr %[r_a] , [%[c], %[end]] \n\t"
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"ldrh %w[tmp] , [%[r_c]] \n\t"
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"cmp %[r_c] , %[r_a] \n\t"
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"b.ge 1f \n\t"
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"add %[r_a] , %[r_c] , #2 \n\t"
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"str %[r_a] , [%[c], %[byte]] \n\t"
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"1: \n\t"
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"sub %w[r_c] , %w[low] , #1 \n\t"
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"eor %w[r_c] , %w[r_c] , %w[low] \n\t"
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"rev %w[tmp] , %w[tmp] \n\t"
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"lsr %w[r_c] , %w[r_c] , #15 \n\t"
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"lsr %w[tmp] , %w[tmp] , #15 \n\t"
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"ldrb %w[r_c] , [%[r_b], %w[r_c], SXTW] \n\t"
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"mov %w[r_b] , #0xFFFF \n\t"
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"mov %w[r_a] , #7 \n\t"
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"sub %w[tmp] , %w[tmp] , %w[r_b] \n\t"
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"sub %w[r_c] , %w[r_a] , %w[r_c] \n\t"
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"lsl %w[tmp] , %w[tmp] , %w[r_c] \n\t"
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"add %w[low] , %w[low] , %w[tmp] \n\t"
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"2: \n\t"
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: [bit]"=&r"(bit),
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[low]"+&r"(c->low),
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[range]"+&r"(c->range),
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[r_a]"=&r"(reg_a),
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[r_b]"=&r"(reg_b),
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[r_c]"=&r"(reg_c),
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[tmp]"=&r"(tmp)
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: [c]"r"(c),
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[state]"r"(state),
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[tables]"r"(ff_h264_cabac_tables),
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[byte]"i"(offsetof(CABACContext, bytestream)),
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[end]"i"(offsetof(CABACContext, bytestream_end)),
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[norm_off]"I"(H264_NORM_SHIFT_OFFSET),
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[lps_off]"I"(H264_LPS_RANGE_OFFSET),
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[mlps_off]"I"(H264_MLPS_STATE_OFFSET + 128)
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: "memory", "cc"
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);
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return bit & 1;
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}
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#endif /* HAVE_INLINE_ASM */
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#endif /* AVCODEC_AARCH64_CABAC_H */
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