| /* |
| * Copyright (C) 2007-2008 ARM Limited |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| /** |
| * |
| * File Name: omxVCM4P2_DecodeVLCZigzag_IntraACVLC.c |
| * OpenMAX DL: v1.0.2 |
| * Revision: 9641 |
| * Date: Thursday, February 7, 2008 |
| * |
| * |
| * |
| * |
| * Description: |
| * Contains modules for zigzag scanning and VLC decoding |
| * for intra block. |
| * |
| */ |
| |
| #include "omxtypes.h" |
| #include "armOMX.h" |
| #include "omxVC.h" |
| |
| #include "armVC.h" |
| #include "armCOMM.h" |
| |
| |
| |
| /** |
| * Function: omxVCM4P2_DecodeVLCZigzag_IntraACVLC (6.2.5.2.2) |
| * |
| * Description: |
| * Performs VLC decoding and inverse zigzag scan of AC and DC coefficients |
| * for one intra block. Two versions of the function (DCVLC and ACVLC) are |
| * provided in order to support the two different methods of processing DC |
| * coefficients, as described in [ISO14496-2], subclause 7.4.1.4, Intra DC |
| * Coefficient Decoding for the Case of Switched VLC Encoding. |
| * |
| * Input Arguments: |
| * |
| * ppBitStream - pointer to the pointer to the current byte in the |
| * bitstream buffer |
| * pBitOffset - pointer to the bit position in the current byte referenced |
| * by *ppBitStream. The parameter *pBitOffset is valid in the |
| * range [0-7]. Bit Position in one byte: |Most Least| *pBitOffset |
| * |0 1 2 3 4 5 6 7| |
| * predDir - AC prediction direction; used to select the zigzag scan |
| * pattern; takes one of the following values: OMX_VC_NONE - AC |
| * prediction not used; performs classical zigzag scan. |
| * OMX_VC_HORIZONTAL - Horizontal prediction; performs |
| * alternate-vertical zigzag scan; OMX_VC_VERTICAL - Vertical |
| * prediction; performs alternate-horizontal zigzag scan. |
| * shortVideoHeader - binary flag indicating presence of |
| * short_video_header; escape modes 0-3 are used if |
| * shortVideoHeader==0, and escape mode 4 is used when |
| * shortVideoHeader==1. |
| * videoComp - video component type (luminance or chrominance) of the |
| * current block |
| * |
| * Output Arguments: |
| * |
| * ppBitStream - *ppBitStream is updated after the block is decoded such |
| * that it points to the current byte in the bit stream buffer |
| * pBitOffset - *pBitOffset is updated such that it points to the current |
| * bit position in the byte pointed by *ppBitStream |
| * pDst - pointer to the coefficient buffer of current block; must be |
| * 4-byte aligned. |
| * |
| * Return Value: |
| * |
| * OMX_Sts_NoErr - no error |
| * OMX_Sts_BadArgErr - bad arguments At least one of the following |
| * pointers is NULL: ppBitStream, *ppBitStream, pBitOffset, pDst, |
| * or At least one of the following conditions is true: |
| * *pBitOffset exceeds [0,7], preDir exceeds [0,2], or pDst is |
| * not 4-byte aligned |
| * OMX_Sts_Err In DecodeVLCZigzag_IntraDCVLC, dc_size > 12 At least one of |
| * mark bits equals zero Illegal stream encountered; code cannot |
| * be located in VLC table Forbidden code encountered in the VLC |
| * FLC table The number of coefficients is greater than 64 |
| * |
| */ |
| |
| |
| OMXResult omxVCM4P2_DecodeVLCZigzag_IntraACVLC( |
| const OMX_U8 ** ppBitStream, |
| OMX_INT * pBitOffset, |
| OMX_S16 * pDst, |
| OMX_U8 predDir, |
| OMX_INT shortVideoHeader |
| ) |
| { |
| OMX_U8 start = 0; |
| |
| return armVCM4P2_DecodeVLCZigzag_Intra( |
| ppBitStream, |
| pBitOffset, |
| pDst, |
| predDir, |
| shortVideoHeader, |
| start); |
| } |
| |
| /* End of file */ |
| |
