634d9d8b39
Based on the aarch64 asm. CPU cycle counts on cortex-a9 compared to gcc 4.8.2: before: 475 decicycles in get_cabac_noinline, 67106035 runs, 2829 skips after: 393 decicycles in get_cabac_noinline, 67106474 runs, 2390 skips Overall speedup is above 2%. Code generated by clang 3.4 is slower on the same hardware and the relative change is a little larger.
103 lines
4.9 KiB
C
103 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_ARM_CABAC_H
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#define AVCODEC_ARM_CABAC_H
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#include "config.h"
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#if HAVE_ARMV6T2_INLINE
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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_arm
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static av_always_inline int get_cabac_inline_arm(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_b, *reg_c, *tmp;
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__asm__ volatile(
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"ldrb %[bit] , [%[state]] \n\t"
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"add %[r_b] , %[tables] , %[lps_off] \n\t"
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"mov %[tmp] , %[range] \n\t"
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"and %[range] , %[range] , #0xC0 \n\t"
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"add %[r_b] , %[r_b] , %[bit] \n\t"
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"ldrb %[range] , [%[r_b], %[range], lsl #1] \n\t"
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"add %[r_b] , %[tables] , %[norm_off] \n\t"
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"sub %[r_c] , %[tmp] , %[range] \n\t"
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"lsl %[tmp] , %[r_c] , #17 \n\t"
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"cmp %[tmp] , %[low] \n\t"
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"it gt \n\t"
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"movgt %[range] , %[r_c] \n\t"
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"itt cc \n\t"
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"mvncc %[bit] , %[bit] \n\t"
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"subcc %[low] , %[low] , %[tmp] \n\t"
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"add %[r_c] , %[tables] , %[mlps_off] \n\t"
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"ldrb %[tmp] , [%[r_b], %[range]] \n\t"
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"ldrb %[r_b] , [%[r_c], %[bit]] \n\t"
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"lsl %[low] , %[low] , %[tmp] \n\t"
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"lsl %[range] , %[range] , %[tmp] \n\t"
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"uxth %[r_c] , %[low] \n\t"
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"strb %[r_b] , [%[state]] \n\t"
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"tst %[r_c] , %[r_c] \n\t"
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"bne 2f \n\t"
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"ldr %[r_c] , [%[c], %[byte]] \n\t"
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"ldr %[r_b] , [%[c], %[end]] \n\t"
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"ldrh %[tmp] , [%[r_c]] \n\t"
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"cmp %[r_c] , %[r_b] \n\t"
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"itt lt \n\t"
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"addlt %[r_c] , %[r_c] , #2 \n\t"
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"strlt %[r_c] , [%[c], %[byte]] \n\t"
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"sub %[r_c] , %[low] , #1 \n\t"
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"add %[r_b] , %[tables] , %[norm_off] \n\t"
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"eor %[r_c] , %[low] , %[r_c] \n\t"
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"rev %[tmp] , %[tmp] \n\t"
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"lsr %[r_c] , %[r_c] , #15 \n\t"
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"lsr %[tmp] , %[tmp] , #15 \n\t"
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"ldrb %[r_c] , [%[r_b], %[r_c]] \n\t"
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"movw %[r_b] , #0xFFFF \n\t"
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"sub %[tmp] , %[tmp] , %[r_b] \n\t"
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"rsb %[r_c] , %[r_c] , #7 \n\t"
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"lsl %[tmp] , %[tmp] , %[r_c] \n\t"
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"add %[low] , %[low] , %[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_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]"M"(offsetof(CABACContext, bytestream)),
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[end]"M"(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_ARMV6T2_INLINE */
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#endif /* AVCODEC_ARM_CABAC_H */
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