omxVCM4P10_DecodeChromaDcCoeffsToPairCAVLC.c revision 0c1bc742181ded4930842b46e9507372f0b1b963 
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
66OMXResult 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