huffman.c
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上传日期:2007-06-06
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- /* ***** BEGIN LICENSE BLOCK *****
- * Version: RCSL 1.0/RPSL 1.0
- *
- * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved.
- *
- * The contents of this file, and the files included with this file, are
- * subject to the current version of the RealNetworks Public Source License
- * Version 1.0 (the "RPSL") available at
- * http://www.helixcommunity.org/content/rpsl unless you have licensed
- * the file under the RealNetworks Community Source License Version 1.0
- * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl,
- * in which case the RCSL will apply. You may also obtain the license terms
- * directly from RealNetworks. You may not use this file except in
- * compliance with the RPSL or, if you have a valid RCSL with RealNetworks
- * applicable to this file, the RCSL. Please see the applicable RPSL or
- * RCSL for the rights, obligations and limitations governing use of the
- * contents of the file.
- *
- * This file is part of the Helix DNA Technology. RealNetworks is the
- * developer of the Original Code and owns the copyrights in the portions
- * it created.
- *
- * This file, and the files included with this file, is distributed and made
- * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
- * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES,
- * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS
- * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
- *
- * Technology Compatibility Kit Test Suite(s) Location:
- * http://www.helixcommunity.org/content/tck
- *
- * Contributor(s):
- *
- * ***** END LICENSE BLOCK ***** */
- /**************************************************************************************
- * Fixed-point MP3 decoder using Intel IPP libraries
- * June 2003
- *
- * huffman.c - wrapper for IPP primitive which decodes Huffman codewords
- **************************************************************************************/
- #include "coder.h"
- /**************************************************************************************
- * Function: DecodeHuffman
- *
- * Description: decode one granule, one channel worth of Huffman codes
- *
- * Inputs: MP3DecInfo structure filled by UnpackFrameHeader(), UnpackSideInfo(),
- * and UnpackScaleFactors() (for this granule)
- * buffer pointing to start of Huffman data in MP3 frame
- * pointer to bit offset (0-7) indicating starting bit in buf[0]
- * number of bits in the Huffman data section of the frame
- * (could include padding bits)
- * index of current granule and channel
- *
- * Outputs: decoded coefficients in hi->huffDecBuf[ch] (hi pointer in mp3DecInfo)
- * updated bitOffset
- *
- * Return: length (in bytes) of frame header (for caller to calculate offset to
- * first byte following frame header)
- * bitOffset also returned in parameter (0 = MSB, 7 = LSB of
- * byte located at buf + offset)
- * -1 if null input pointers
- **************************************************************************************/
- int DecodeHuffman(MP3DecInfo *mp3DecInfo, unsigned char *buf, int *bitOffset, int huffBlockBits, int gr, int ch)
- {
- Ipp8u *pBitStream;
- FrameHeader *fh;
- IppMP3FrameHeader *fhIPP;
- SideInfo *si;
- IppMP3SideInfo *siIPP;
- HuffmanInfo *hi;
- /* validate pointers */
- if (!mp3DecInfo || !mp3DecInfo->FrameHeaderPS || !mp3DecInfo->SideInfoPS || !mp3DecInfo->HuffmanInfoPS)
- return -1;
- pBitStream = (Ipp8u *)buf;
- fh = (FrameHeader *)(mp3DecInfo->FrameHeaderPS);
- fhIPP = &(fh->fhIPP);
- /* si is an array of up to 4 structs, stored as gr0ch0, gr0ch1, gr1ch0, gr1ch1 */
- si = (SideInfo *)(mp3DecInfo->SideInfoPS);
- siIPP = &(si->siIPP[0]);
- siIPP += (gr*mp3DecInfo->nChans + ch);
- hi = (HuffmanInfo*)(mp3DecInfo->HuffmanInfoPS);
- /* IPP primitive #4 - Huffman decoding */
- ippsHuffmanDecode_MP3_1u32s(&pBitStream, bitOffset, hi->huffDecBuf[ch], &(hi->nonZeroBound[ch]),
- siIPP, fhIPP, huffBlockBits);
- /* IPP primitive updated pBitStream, return the offset to start of next block in bitstream */
- return (pBitStream - buf);
- }