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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "M4OSA_Types.h"
     18 #include "M4OSA_Debug.h"
     19 
     20 #include "M4VD_Tools.h"
     21 
     22 /**
     23  ************************************************************************
     24  * @file   M4VD_Tools.c
     25  * @brief
     26  * @note   This file implements helper functions for Bitstream parser
     27  ************************************************************************
     28  */
     29 
     30 M4OSA_UInt32 M4VD_Tools_GetBitsFromMemory(M4VS_Bitstream_ctxt* parsingCtxt,
     31      M4OSA_UInt32 nb_bits)
     32 {
     33     M4OSA_UInt32    code;
     34     M4OSA_UInt32    i;
     35     code = 0;
     36     for (i = 0; i < nb_bits; i++)
     37     {
     38         if (parsingCtxt->stream_index == 8)
     39         {
     40             //M4OSA_memcpy( (M4OSA_MemAddr8)&(parsingCtxt->stream_byte), parsingCtxt->in,
     41             //     sizeof(unsigned char));
     42             parsingCtxt->stream_byte = (unsigned char)(parsingCtxt->in)[0];
     43             parsingCtxt->in++;
     44             //fread(&stream_byte, sizeof(unsigned char),1,in);
     45             parsingCtxt->stream_index = 0;
     46         }
     47         code = (code << 1);
     48         code |= ((parsingCtxt->stream_byte & 0x80) >> 7);
     49 
     50         parsingCtxt->stream_byte = (parsingCtxt->stream_byte << 1);
     51         parsingCtxt->stream_index++;
     52     }
     53 
     54     return code;
     55 }
     56 
     57 M4OSA_ERR M4VD_Tools_WriteBitsToMemory(M4OSA_UInt32 bitsToWrite,
     58                                      M4OSA_MemAddr32 dest_bits,
     59                                      M4OSA_UInt8 offset, M4OSA_UInt8 nb_bits)
     60 {
     61     M4OSA_UInt8 i,j;
     62     M4OSA_UInt32 temp_dest = 0, mask = 0, temp = 1;
     63     M4OSA_UInt32 input = bitsToWrite;
     64     input = (input << (32 - nb_bits - offset));
     65 
     66     /* Put destination buffer to 0 */
     67     for(j=0;j<3;j++)
     68     {
     69         for(i=0;i<8;i++)
     70         {
     71             if((j*8)+i >= offset && (j*8)+i < nb_bits + offset)
     72             {
     73                 mask |= (temp << ((7*(j+1))-i+j));
     74             }
     75         }
     76     }
     77     mask = ~mask;
     78     *dest_bits &= mask;
     79 
     80     /* Parse input bits, and fill output buffer */
     81     for(j=0;j<3;j++)
     82     {
     83         for(i=0;i<8;i++)
     84         {
     85             if((j*8)+i >= offset && (j*8)+i < nb_bits + offset)
     86             {
     87                 temp = ((input & (0x80000000 >> offset)) >> (31-offset));
     88                 //*dest_bits |= (temp << (31 - i));
     89                 *dest_bits |= (temp << ((7*(j+1))-i+j));
     90                 input = (input << 1);
     91             }
     92         }
     93     }
     94 
     95     return M4NO_ERROR;
     96 }
     97 
     98 
     99 
    100