1/* 2 * Copyright (C) 2007-2008 ARM Limited 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/** 18 * 19 * File Name: omxVCM4P2_DecodeVLCZigzag_IntraACVLC.c 20 * OpenMAX DL: v1.0.2 21 * Revision: 9641 22 * Date: Thursday, February 7, 2008 23 * 24 * 25 * 26 * 27 * Description: 28 * Contains modules for zigzag scanning and VLC decoding 29 * for intra block. 30 * 31 */ 32 33#include "omxtypes.h" 34#include "armOMX.h" 35#include "omxVC.h" 36 37#include "armVC.h" 38#include "armCOMM.h" 39 40 41 42/** 43 * Function: omxVCM4P2_DecodeVLCZigzag_IntraACVLC (6.2.5.2.2) 44 * 45 * Description: 46 * Performs VLC decoding and inverse zigzag scan of AC and DC coefficients 47 * for one intra block. Two versions of the function (DCVLC and ACVLC) are 48 * provided in order to support the two different methods of processing DC 49 * coefficients, as described in [ISO14496-2], subclause 7.4.1.4, Intra DC 50 * Coefficient Decoding for the Case of Switched VLC Encoding. 51 * 52 * Input Arguments: 53 * 54 * ppBitStream - pointer to the pointer to the current byte in the 55 * bitstream buffer 56 * pBitOffset - pointer to the bit position in the current byte referenced 57 * by *ppBitStream. The parameter *pBitOffset is valid in the 58 * range [0-7]. Bit Position in one byte: |Most Least| *pBitOffset 59 * |0 1 2 3 4 5 6 7| 60 * predDir - AC prediction direction; used to select the zigzag scan 61 * pattern; takes one of the following values: OMX_VC_NONE - AC 62 * prediction not used; performs classical zigzag scan. 63 * OMX_VC_HORIZONTAL - Horizontal prediction; performs 64 * alternate-vertical zigzag scan; OMX_VC_VERTICAL - Vertical 65 * prediction; performs alternate-horizontal zigzag scan. 66 * shortVideoHeader - binary flag indicating presence of 67 * short_video_header; escape modes 0-3 are used if 68 * shortVideoHeader==0, and escape mode 4 is used when 69 * shortVideoHeader==1. 70 * videoComp - video component type (luminance or chrominance) of the 71 * current block 72 * 73 * Output Arguments: 74 * 75 * ppBitStream - *ppBitStream is updated after the block is decoded such 76 * that it points to the current byte in the bit stream buffer 77 * pBitOffset - *pBitOffset is updated such that it points to the current 78 * bit position in the byte pointed by *ppBitStream 79 * pDst - pointer to the coefficient buffer of current block; must be 80 * 4-byte aligned. 81 * 82 * Return Value: 83 * 84 * OMX_Sts_NoErr - no error 85 * OMX_Sts_BadArgErr - bad arguments At least one of the following 86 * pointers is NULL: ppBitStream, *ppBitStream, pBitOffset, pDst, 87 * or At least one of the following conditions is true: 88 * *pBitOffset exceeds [0,7], preDir exceeds [0,2], or pDst is 89 * not 4-byte aligned 90 * OMX_Sts_Err In DecodeVLCZigzag_IntraDCVLC, dc_size > 12 At least one of 91 * mark bits equals zero Illegal stream encountered; code cannot 92 * be located in VLC table Forbidden code encountered in the VLC 93 * FLC table The number of coefficients is greater than 64 94 * 95 */ 96 97 98OMXResult omxVCM4P2_DecodeVLCZigzag_IntraACVLC( 99 const OMX_U8 ** ppBitStream, 100 OMX_INT * pBitOffset, 101 OMX_S16 * pDst, 102 OMX_U8 predDir, 103 OMX_INT shortVideoHeader 104) 105{ 106 OMX_U8 start = 0; 107 108 return armVCM4P2_DecodeVLCZigzag_Intra( 109 ppBitStream, 110 pBitOffset, 111 pDst, 112 predDir, 113 shortVideoHeader, 114 start); 115} 116 117/* End of file */ 118 119