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 * 20 * File Name: omxVCM4P10_DecodeCoeffsToPairCAVLC.c 21 * OpenMAX DL: v1.0.2 22 * Revision: 9641 23 * Date: Thursday, February 7, 2008 24 * 25 * 26 * 27 * 28 * H.264 decode coefficients module 29 * 30 */ 31 32#include "omxtypes.h" 33#include "armOMX.h" 34#include "omxVC.h" 35#include "armCOMM.h" 36#include "armVC.h" 37 38/** 39 * Function: omxVCM4P10_DecodeCoeffsToPairCAVLC (6.3.4.1.2) 40 * 41 * Description: 42 * Performs CAVLC decoding and inverse zigzag scan for 4x4 block of 43 * Intra16x16DCLevel, Intra16x16ACLevel, LumaLevel, and ChromaACLevel. Inverse 44 * field scan is not supported. The decoded coefficients in the packed 45 * position-coefficient buffer are stored in reverse zig-zag order, i.e., the 46 * first buffer element contains the last non-zero postion-coefficient pair of 47 * the block. Within each position-coefficient pair, the position entry 48 * indicates the raster-scan position of the coefficient, while the 49 * coefficient entry contains the coefficient value. 50 * 51 * Input Arguments: 52 * 53 * ppBitStream -Double pointer to current byte in bit stream buffer 54 * pOffset - Pointer to current bit position in the byte pointed to by 55 * *ppBitStream; valid in the range [0,7]. 56 * sMaxNumCoeff - Maximum the number of non-zero coefficients in current 57 * block 58 * sVLCSelect - VLC table selector, obtained from the number of non-zero 59 * coefficients contained in the above and left 4x4 blocks. It is 60 * equivalent to the variable nC described in H.264 standard table 61 * 9 5, except its value can t be less than zero. 62 * 63 * Output Arguments: 64 * 65 * ppBitStream - *ppBitStream is updated after each block is decoded. 66 * Buffer position (*ppPosCoefBuf) is updated upon return, unless 67 * there are only zero coefficients in the currently decoded block. 68 * In this case the caller is expected to bypass the 69 * transform/dequantization of the empty blocks. 70 * pOffset - *pOffset is updated after each block is decoded 71 * pNumCoeff - Pointer to the number of nonzero coefficients in this block 72 * ppPosCoefBuf - Double pointer to destination residual 73 * coefficient-position pair buffer 74 * 75 * Return Value: 76 * OMX_Sts_NoErr, if the function runs without error. 77 * 78 * OMX_Sts_BadArgErr - bad arguments: if one of the following cases occurs: 79 * - ppBitStream or pOffset is NULL. 80 * - ppPosCoefBuf or pNumCoeff is NULL. 81 * - sMaxNumCoeff is not equal to either 15 or 16. 82 * - sVLCSelect is less than 0. 83 * 84 * OMX_Sts_Err - if one of the following is true: 85 * - an illegal code is encountered in the bitstream 86 * 87 */ 88 89OMXResult omxVCM4P10_DecodeCoeffsToPairCAVLC( 90 const OMX_U8** ppBitStream, 91 OMX_S32* pOffset, 92 OMX_U8* pNumCoeff, 93 OMX_U8**ppPosCoefbuf, 94 OMX_INT sVLCSelect, 95 OMX_INT sMaxNumCoeff 96 ) 97{ 98 int nTable; 99 100 armRetArgErrIf(ppBitStream==NULL , OMX_Sts_BadArgErr); 101 armRetArgErrIf(*ppBitStream==NULL , OMX_Sts_BadArgErr); 102 armRetArgErrIf(pOffset==NULL , OMX_Sts_BadArgErr); 103 armRetArgErrIf(*pOffset<0 , OMX_Sts_BadArgErr); 104 armRetArgErrIf(*pOffset>7 , OMX_Sts_BadArgErr); 105 armRetArgErrIf(pNumCoeff==NULL , OMX_Sts_BadArgErr); 106 armRetArgErrIf(ppPosCoefbuf==NULL , OMX_Sts_BadArgErr); 107 armRetArgErrIf(*ppPosCoefbuf==NULL , OMX_Sts_BadArgErr); 108 armRetArgErrIf(sVLCSelect<0 , OMX_Sts_BadArgErr); 109 armRetArgErrIf(sMaxNumCoeff<15 , OMX_Sts_BadArgErr); 110 armRetArgErrIf(sMaxNumCoeff>16 , OMX_Sts_BadArgErr); 111 112 /* Find VLC table number */ 113 if (sVLCSelect<2) 114 { 115 nTable = 0; 116 } 117 else if (sVLCSelect<4) 118 { 119 nTable = 1; 120 } 121 else if (sVLCSelect<8) 122 { 123 nTable = 2; 124 } 125 else /* sVLCSelect >= 8 */ 126 { 127 nTable = 3; 128 } 129 130 return armVCM4P10_DecodeCoeffsToPair(ppBitStream, pOffset, pNumCoeff, 131 ppPosCoefbuf, nTable, sMaxNumCoeff); 132} 133