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      1 /* ///////////////////////////////////////////////////////////////////////
      2 //
      3 //               INTEL CORPORATION PROPRIETARY INFORMATION
      4 //  This software is supplied under the terms of a license agreement or
      5 //  nondisclosure agreement with Intel Corporation and may not be copied
      6 //  or disclosed except in accordance with the terms of that agreement.
      7 //        Copyright (c) 2008 Intel Corporation. All Rights Reserved.
      8 //
      9 //  Description: Parses VLC syntax elements within VC-1 bitstream.
     10 //
     11 */
     12 
     13 #include "vc1parse.h"
     14 
     15 /*----------------------------------------------------------------------------*/
     16 
     17 vc1_Status vc1_DecodeHuffmanOne(void* ctxt, int32_t *pDst, const int32_t *pDecodeTable)
     18 {
     19     uint32_t tempValue;
     20     const int32_t *pTable = pDecodeTable;
     21     vc1_Status status = VC1_STATUS_OK;
     22     int32_t i, j, maxBits, loopCount, totalBits, value;
     23 
     24     maxBits = *pTable++;
     25     loopCount = *pTable++;
     26     totalBits = 0;
     27     for (i = 0; i < loopCount; i++)
     28         totalBits += *pTable++;
     29 
     30     if (totalBits != maxBits)
     31         return VC1_STATUS_PARSE_ERROR;
     32 
     33     value = 0;
     34     for (i = 0; i < maxBits; i++)
     35     {
     36         VC1_GET_BITS9(1, tempValue);
     37         value = (value << 1) | tempValue;
     38         loopCount = *pTable++;
     39         if (loopCount == -1)
     40             break;
     41         for (j = 0; j < loopCount; j++)
     42         {
     43             if (value == *pTable++)
     44             {
     45                 *pDst = *pTable;
     46                 return status;
     47             }
     48             else
     49                 pTable++;
     50         }
     51     }
     52 
     53     return status;
     54 }
     55 
     56 /*----------------------------------------------------------------------------*/
     57 
     58 vc1_Status vc1_DecodeHuffmanPair(void* ctxt, const int32_t *pDecodeTable,
     59                                  int8_t *pFirst, int16_t *pSecond)
     60 {
     61     uint32_t tempValue;
     62     const int32_t *pTable = pDecodeTable;
     63     vc1_Status status = VC1_STATUS_OK;
     64     int32_t i, j, maxBits, loopCount, totalBits, value;
     65 
     66     maxBits = *pTable++;
     67     loopCount = *pTable++;
     68     totalBits = 0;
     69     for (i = 0; i < loopCount; i++)
     70         totalBits += *pTable++;
     71 
     72     if (totalBits != maxBits)
     73         return VC1_STATUS_PARSE_ERROR;
     74 
     75     value = 0;
     76     for (i = 0; i < maxBits; i++)
     77     {
     78         VC1_GET_BITS9(1, tempValue);
     79         value = (value << 1) | tempValue;
     80         loopCount = *pTable++;
     81         if (loopCount == -1)
     82             break;
     83         for (j = 0; j < loopCount; j++)
     84         {
     85             if (value == *pTable++)
     86             {
     87                 *pFirst = *pTable++;
     88                 *pSecond = *pTable;
     89                 return status;
     90             }
     91             else
     92                 pTable += 2;
     93         }
     94     }
     95 
     96     return status;
     97 }
     98