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      1 /* ----------------------------------------------------------------
      2  *
      3  *
      4  * File Name:  omxVCM4P10_DecodeChromaDcCoeffsToPairCAVLC.c
      5  * OpenMAX DL: v1.0.2
      6  * Revision:   9641
      7  * Date:       Thursday, February 7, 2008
      8  *
      9  * (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
     10  *
     11  *
     12  *
     13  * H.264 decode coefficients module
     14  *
     15  */
     16 
     17 #include "omxtypes.h"
     18 #include "armOMX.h"
     19 #include "omxVC.h"
     20 
     21 #include "armCOMM.h"
     22 #include "armVC.h"
     23 
     24 /**
     25  * Function:  omxVCM4P10_DecodeChromaDcCoeffsToPairCAVLC   (6.3.4.1.1)
     26  *
     27  * Description:
     28  * Performs CAVLC decoding and inverse raster scan for a 2x2 block of
     29  * ChromaDCLevel.  The decoded coefficients in the packed position-coefficient
     30  * buffer are stored in reverse zig-zag order, i.e., the first buffer element
     31  * contains the last non-zero postion-coefficient pair of the block. Within
     32  * each position-coefficient pair, the position entry indicates the
     33  * raster-scan position of the coefficient, while the coefficient entry
     34  * contains the coefficient value.
     35  *
     36  * Input Arguments:
     37  *
     38  *   ppBitStream - Double pointer to current byte in bit stream buffer
     39  *   pOffset - Pointer to current bit position in the byte pointed to by
     40  *            *ppBitStream; valid in the range [0,7].
     41  *
     42  * Output Arguments:
     43  *
     44  *   ppBitStream - *ppBitStream is updated after each block is decoded
     45  *   pOffset - *pOffset is updated after each block is decoded
     46  *   pNumCoeff - Pointer to the number of nonzero coefficients in this block
     47  *   ppPosCoefBuf - Double pointer to destination residual
     48  *            coefficient-position pair buffer.  Buffer position
     49  *            (*ppPosCoefBuf) is updated upon return, unless there are only
     50  *            zero coefficients in the currently decoded block.  In this case
     51  *            the caller is expected to bypass the transform/dequantization of
     52  *            the empty blocks.
     53  *
     54  * Return Value:
     55  *
     56  *    OMX_Sts_NoErr, if the function runs without error.
     57  *
     58  *    OMX_Sts_BadArgErr - bad arguments: if one of the following cases occurs:
     59  *    -    ppBitStream or pOffset is NULL.
     60  *    -    ppPosCoefBuf or pNumCoeff is NULL.
     61  *    OMX_Sts_Err - if one of the following is true:
     62  *    -    an illegal code is encountered in the bitstream
     63  *
     64  */
     65 
     66 OMXResult omxVCM4P10_DecodeChromaDcCoeffsToPairCAVLC (
     67      const OMX_U8** ppBitStream,
     68      OMX_S32* pOffset,
     69      OMX_U8* pNumCoeff,
     70      OMX_U8** ppPosCoefbuf
     71  )
     72 
     73 {
     74     armRetArgErrIf(ppBitStream==NULL   , OMX_Sts_BadArgErr);
     75     armRetArgErrIf(*ppBitStream==NULL  , OMX_Sts_BadArgErr);
     76     armRetArgErrIf(pOffset==NULL       , OMX_Sts_BadArgErr);
     77     armRetArgErrIf(*pOffset<0          , OMX_Sts_BadArgErr);
     78     armRetArgErrIf(*pOffset>7          , OMX_Sts_BadArgErr);
     79     armRetArgErrIf(pNumCoeff==NULL     , OMX_Sts_BadArgErr);
     80     armRetArgErrIf(ppPosCoefbuf==NULL  , OMX_Sts_BadArgErr);
     81     armRetArgErrIf(*ppPosCoefbuf==NULL , OMX_Sts_BadArgErr);
     82 
     83     return armVCM4P10_DecodeCoeffsToPair(ppBitStream, pOffset, pNumCoeff,
     84                                          ppPosCoefbuf, 4, 4);
     85 
     86 }
     87