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   1 /*
   2  * This file is part of FFmpeg.
   3  *
   4  * FFmpeg is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * FFmpeg is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with FFmpeg; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #ifndef AVCODEC_ARM_CABAC_H
  20 #define AVCODEC_ARM_CABAC_H
  21
  22 #include "config.h"
  23 #if HAVE_ARMV6T2_INLINE
  24
  25 #include "libavutil/attributes.h"
  26 #include "libavutil/internal.h"
  27 #include "libavcodec/cabac.h"
  28
  29 #define get_cabac_inline get_cabac_inline_arm
  30 static av_always_inline int get_cabac_inline_arm(CABACContext *c,
  31                                                  uint8_t *const state)
  32 {
  33     int bit;
  34     void *reg_b, *reg_c, *tmp;
  35
  36     __asm__ volatile(
  37         "ldrb       %[bit]        , [%[state]]                  \n\t"
  38         "add        %[r_b]        , %[tables]   , %[lps_off]    \n\t"
  39         "mov        %[tmp]        , %[range]                    \n\t"
  40         "and        %[range]      , %[range]    , #0xC0         \n\t"
  41         "add        %[r_b]        , %[r_b]      , %[bit]        \n\t"
  42         "ldrb       %[range]      , [%[r_b], %[range], lsl #1]  \n\t"
  43         "add        %[r_b]        , %[tables]   , %[norm_off]   \n\t"
  44         "sub        %[r_c]        , %[tmp]      , %[range]      \n\t"
  45         "lsl        %[tmp]        , %[r_c]      , #17           \n\t"
  46         "cmp        %[tmp]        , %[low]                      \n\t"
  47         "it         gt                                          \n\t"
  48         "movgt      %[range]      , %[r_c]                      \n\t"
  49         "itt        cc                                          \n\t"
  50         "mvncc      %[bit]        , %[bit]                      \n\t"
  51         "subcc      %[low]        , %[low]      , %[tmp]        \n\t"
  52         "add        %[r_c]        , %[tables]   , %[mlps_off]   \n\t"
  53         "ldrb       %[tmp]        , [%[r_b], %[range]]          \n\t"
  54         "ldrb       %[r_b]        , [%[r_c], %[bit]]            \n\t"
  55         "lsl        %[low]        , %[low]      , %[tmp]        \n\t"
  56         "lsl        %[range]      , %[range]    , %[tmp]        \n\t"
  57         "uxth       %[r_c]        , %[low]                      \n\t"
  58         "strb       %[r_b]        , [%[state]]                  \n\t"
  59         "tst        %[r_c]        , %[r_c]                      \n\t"
  60         "bne        2f                                          \n\t"
  61         "ldr        %[r_c]        , [%[c], %[byte]]             \n\t"
  62 #if UNCHECKED_BITSTREAM_READER
  63         "ldrh       %[tmp]        , [%[r_c]]                    \n\t"
  64         "add        %[r_c]        , %[r_c]      , #2            \n\t"
  65         "str        %[r_c]        , [%[c], %[byte]]             \n\t"
  66 #else
  67         "ldr        %[r_b]        , [%[c], %[end]]              \n\t"
  68         "ldrh       %[tmp]        , [%[r_c]]                    \n\t"
  69         "cmp        %[r_c]        , %[r_b]                      \n\t"
  70         "itt        lt                                          \n\t"
  71         "addlt      %[r_c]        , %[r_c]      , #2            \n\t"
  72         "strlt      %[r_c]        , [%[c], %[byte]]             \n\t"
  73 #endif
  74         "sub        %[r_c]        , %[low]      , #1            \n\t"
  75         "add        %[r_b]        , %[tables]   , %[norm_off]   \n\t"
  76         "eor        %[r_c]        , %[low]      , %[r_c]        \n\t"
  77         "rev        %[tmp]        , %[tmp]                      \n\t"
  78         "lsr        %[r_c]        , %[r_c]      , #15           \n\t"
  79         "lsr        %[tmp]        , %[tmp]      , #15           \n\t"
  80         "ldrb       %[r_c]        , [%[r_b], %[r_c]]            \n\t"
  81         "movw       %[r_b]        , #0xFFFF                     \n\t"
  82         "sub        %[tmp]        , %[tmp]      , %[r_b]        \n\t"
  83         "rsb        %[r_c]        , %[r_c]      , #7            \n\t"
  84         "lsl        %[tmp]        , %[tmp]      , %[r_c]        \n\t"
  85         "add        %[low]        , %[low]      , %[tmp]        \n\t"
  86         "2:                                                     \n\t"
  87         :    [bit]"=&r"(bit),
  88              [low]"+&r"(c->low),
  89            [range]"+&r"(c->range),
  90              [r_b]"=&r"(reg_b),
  91              [r_c]"=&r"(reg_c),
  92              [tmp]"=&r"(tmp)
  93         :        [c]"r"(c),
  94              [state]"r"(state),
  95             [tables]"r"(ff_h264_cabac_tables),
  96               [byte]"M"(offsetof(CABACContext, bytestream)),
  97                [end]"M"(offsetof(CABACContext, bytestream_end)),
  98           [norm_off]"I"(H264_NORM_SHIFT_OFFSET),
  99            [lps_off]"I"(H264_LPS_RANGE_OFFSET),
 100           [mlps_off]"I"(H264_MLPS_STATE_OFFSET + 128)
 101         : "memory", "cc"
 102         );
 103
 104     return bit & 1;
 105 }
 106 #endif /* HAVE_ARMV6T2_INLINE */
 107
 108 #endif /* AVCODEC_ARM_CABAC_H */