mirror of https://github.com/FFmpeg/FFmpeg.git
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.pull/293/head
Janne Grunau
11 years ago
parent
dfe224f377
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634d9d8b39
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/*
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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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