text: /* ***** 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 
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   * 
   * Technology Compatibility Kit Test Suite(s) Location: 
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   * 
   * Contributor(s): 
   *  
   * ***** END LICENSE BLOCK ***** */ 
  
  /**************************************************************************************
   * Fixed-point MP3 decoder
   * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com)
   * July 2003
   *
   * huffman.c - Huffman decoding of transform coefficients
   **************************************************************************************/
  
  #include "coder.h"
  
  /* helper macros - see comments in hufftabs.c about the format of the huffman tables */
  #define GetMaxbits(x)   ((int)( (((unsigned short)(x)) >>  0) & 0x000f))
  #define GetHLen(x)      ((int)( (((unsigned short)(x)) >> 12) & 0x000f))
  #define GetCWY(x)       ((int)( (((unsigned short)(x)) >>  8) & 0x000f))
  #define GetCWX(x)       ((int)( (((unsigned short)(x)) >>  4) & 0x000f))
  #define GetSignBits(x)  ((int)( (((unsigned short)(x)) >>  0) & 0x000f))
  
  #define GetHLenQ(x)     ((int)( (((unsigned char)(x)) >> 4) & 0x0f))
  #define GetCWVQ(x)      ((int)( (((unsigned char)(x)) >> 3) & 0x01))
  #define GetCWWQ(x)      ((int)( (((unsigned char)(x)) >> 2) & 0x01))
  #define GetCWXQ(x)      ((int)( (((unsigned char)(x)) >> 1) & 0x01))
  #define GetCWYQ(x)      ((int)( (((unsigned char)(x)) >> 0) & 0x01))
  
  /* apply sign of s to the positive number x (save in MSB, will do two's complement in dequant) */
  #define ApplySign(x, s)	{ (x) |= ((s) & 0x80000000); }
  
  /**************************************************************************************
   * Function:    DecodeHuffmanPairs
   *
   * Description: decode 2-way vector Huffman codes in the "bigValues" region of spectrum
   *
   * Inputs:      valid BitStreamInfo struct, pointing to start of pair-wise codes
   *              pointer to xy buffer to received decoded values
   *              number of codewords to decode
   *              index of Huffman table to use
   *              number of bits remaining in bitstream
   *
   * Outputs:     pairs of decoded coefficients in vwxy
   *              updated BitStreamInfo struct
   *
   * Return:      number of bits used, or -1 if out of bits
   *
   * Notes:       assumes that nVals is an even number
   *              si_huff.bit tests every Huffman codeword in every table (though not
   *                necessarily all linBits outputs for x,y > 15)
   **************************************************************************************/
  static int DecodeHuffmanPairs(int *xy, int nVals, int tabIdx, int bitsLeft, unsigned char *buf, int bitOffset)
  {
  	int i, x, y;
  	int cachedBits, padBits, len, startBits, linBits, maxBits, minBits;
  	HuffTabType tabType;
  	unsigned short cw, *tBase, *tCurr;
  	unsigned int cache;
  
  	if(nVals <= 0) 
  		return 0;
  
  	if (bitsLeft < 0)
  		return -1;
  	startBits = bitsLeft;
  
  	tBase = (unsigned short *)(huffTable + huffTabOffset[tabIdx]);
  	linBits = huffTabLookup[tabIdx].linBits;
  	tabType = huffTabLookup[tabIdx].tabType;
  
  	ASSERT(!(nVals & 0x01));
  	ASSERT(tabIdx < HUFF_PAIRTABS);
  	ASSERT(tabIdx >= 0);
  	ASSERT(tabType != invalidTab);
  
  	/* initially fill cache with any partial byte */
  	cache = 0;
  	cachedBits = (8 - bitOffset) & 0x07;
  	if (cachedBits)
  		cache = (unsigned int)(*buf++) << (32 - cachedBits);
  	bitsLeft -= cachedBits;
  
  	if (tabType == noBits) {
  		/* table 0, no data, x = y = 0 */
  		for (i = 0; i < nVals; i+=2) {
  			xy[i+0] = 0;
  			xy[i+1] = 0;
  		}
  		return 0;
  	} else if (tabType == oneShot) {
  		/* single lookup, no escapes */
  		maxBits = GetMaxbits(tBase[0]);
  		tBase++;
  		padBits = 0;
  		while (nVals > 0) {
  			/* refill cache - assumes cachedBits <= 16 */
  			if (bitsLeft >= 16) {
  				/* load 2 new bytes into left-justified cache */
  				cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  				cache |= (unsigned int)(*buf++) << (16 - cachedBits);
  				cachedBits += 16;
  				bitsLeft -= 16;
  			} else {
  				/* last time through, pad cache with zeros and drain cache */
  				if (cachedBits + bitsLeft <= 0)	return -1;
  				if (bitsLeft > 0)	cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  				if (bitsLeft > 8)	cache |= (unsigned int)(*buf++) << (16 - cachedBits);
  				cachedBits += bitsLeft;
  				bitsLeft = 0;
  
  				cache &= (signed int)0x80000000 >> (cachedBits - 1);
  				padBits = 11;
  				cachedBits += padBits;	/* okay if this is > 32 (0's automatically shifted in from right) */
  			}
  
  			/* largest maxBits = 9, plus 2 for sign bits, so make sure cache has at least 11 bits */
  			while (nVals > 0 && cachedBits >= 11 ) {
  				cw = tBase[cache >> (32 - maxBits)];
  				len = GetHLen(cw);
  				cachedBits -= len;
  				cache <<= len;
  
  				x = GetCWX(cw);		if (x)	{ApplySign(x, cache); cache <<= 1; cachedBits--;}
  				y = GetCWY(cw);		if (y)	{ApplySign(y, cache); cache <<= 1; cachedBits--;}
  
  				/* ran out of bits - should never have consumed padBits */
  				if (cachedBits < padBits)
  					return -1;
  
  				*xy++ = x;
  				*xy++ = y;
  				nVals -= 2;
  			}
  		}
  		bitsLeft += (cachedBits - padBits);
  		return (startBits - bitsLeft);
  	} else if (tabType == loopLinbits || tabType == loopNoLinbits) {
  		tCurr = tBase;
  		padBits = 0;
  		while (nVals > 0) {
  			/* refill cache - assumes cachedBits <= 16 */
  			if (bitsLeft >= 16) {
  				/* load 2 new bytes into left-justified cache */
  				cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  				cache |= (unsigned int)(*buf++) << (16 - cachedBits);
  				cachedBits += 16;
  				bitsLeft -= 16;
  			} else {
  				/* last time through, pad cache with zeros and drain cache */
  				if (cachedBits + bitsLeft <= 0)	return -1;
  				if (bitsLeft > 0)	cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  				if (bitsLeft > 8)	cache |= (unsigned int)(*buf++) << (16 - cachedBits);
  				cachedBits += bitsLeft;
  				bitsLeft = 0;
  
  				cache &= (signed int)0x80000000 >> (cachedBits - 1);
  				padBits = 11;
  				cachedBits += padBits;	/* okay if this is > 32 (0's automatically shifted in from right) */
  			}
  
  			/* largest maxBits = 9, plus 2 for sign bits, so make sure cache has at least 11 bits */
  			while (nVals > 0 && cachedBits >= 11 ) {
  				maxBits = GetMaxbits(tCurr[0]);
  				cw = tCurr[(cache >> (32 - maxBits)) + 1];
  				len = GetHLen(cw);
  				if (!len) {
  					cachedBits -= maxBits;
  					cache <<= maxBits;
  					tCurr += cw;
  					continue;
  				}
  				cachedBits -= len;
  				cache <<= len;
  			
  				x = GetCWX(cw);
  				y = GetCWY(cw);
  
  				if (x == 15 && tabType == loopLinbits) {
  					minBits = linBits + 1 + (y ? 1 : 0);
  					if (cachedBits + bitsLeft < minBits)
  						return -1;
  					while (cachedBits < minBits) {
  						cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  						cachedBits += 8;
  						bitsLeft -= 8;
  					}
  					if (bitsLeft < 0) {
  						cachedBits += bitsLeft;
  						bitsLeft = 0;
  						cache &= (signed int)0x80000000 >> (cachedBits - 1);
  					}
  					x += (int)(cache >> (32 - linBits));
  					cachedBits -= linBits;
  					cache <<= linBits;
  				}
  				if (x)	{ApplySign(x, cache); cache <<= 1; cachedBits--;}
  
  				if (y == 15 && tabType == loopLinbits) {
  					minBits = linBits + 1;
  					if (cachedBits + bitsLeft < minBits)
  						return -1;
  					while (cachedBits < minBits) {
  						cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  						cachedBits += 8;
  						bitsLeft -= 8;
  					}
  					if (bitsLeft < 0) {
  						cachedBits += bitsLeft;
  						bitsLeft = 0;
  						cache &= (signed int)0x80000000 >> (cachedBits - 1);
  					}
  					y += (int)(cache >> (32 - linBits));
  					cachedBits -= linBits;
  					cache <<= linBits;
  				}
  				if (y)	{ApplySign(y, cache); cache <<= 1; cachedBits--;}
  
  				/* ran out of bits - should never have consumed padBits */
  				if (cachedBits < padBits)
  					return -1;
  
  				*xy++ = x;
  				*xy++ = y;
  				nVals -= 2;
  				tCurr = tBase;
  			}
  		}
  		bitsLeft += (cachedBits - padBits);
  		return (startBits - bitsLeft);
  	}
  
  	/* error in bitstream - trying to access unused Huffman table */
  	return -1;
  }
  
  /**************************************************************************************
   * Function:    DecodeHuffmanQuads
   *
   * Description: decode 4-way vector Huffman codes in the "count1" region of spectrum
   *
   * Inputs:      valid BitStreamInfo struct, pointing to start of quadword codes
   *              pointer to vwxy buffer to received decoded values
   *              maximum number of codewords to decode
   *              index of quadword table (0 = table A, 1 = table B)
   *              number of bits remaining in bitstream
   *
   * Outputs:     quadruples of decoded coefficients in vwxy
   *              updated BitStreamInfo struct
   *
   * Return:      index of the first "zero_part" value (index of the first sample 
   *                of the quad word after which all samples are 0)
   * 
   * Notes:        si_huff.bit tests every vwxy output in both quad tables
   **************************************************************************************/
  static int DecodeHuffmanQuads(int *vwxy, int nVals, int tabIdx, int bitsLeft, unsigned char *buf, int bitOffset)
  {
  	int i, v, w, x, y;
  	int len, maxBits, cachedBits, padBits;
  	unsigned int cache;
  	unsigned char cw, *tBase;
  
  	if (bitsLeft <= 0)
  		return 0;
  
  	tBase = (unsigned char *)quadTable + quadTabOffset[tabIdx];
  	maxBits = quadTabMaxBits[tabIdx];
  
  	/* initially fill cache with any partial byte */
  	cache = 0;
  	cachedBits = (8 - bitOffset) & 0x07;
  	if (cachedBits)
  		cache = (unsigned int)(*buf++) << (32 - cachedBits);
  	bitsLeft -= cachedBits;
  
  	i = padBits = 0;
  	while (i < (nVals - 3)) {
  		/* refill cache - assumes cachedBits <= 16 */
  		if (bitsLeft >= 16) {
  			/* load 2 new bytes into left-justified cache */
  			cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  			cache |= (unsigned int)(*buf++) << (16 - cachedBits);
  			cachedBits += 16;
  			bitsLeft -= 16;
  		} else {
  			/* last time through, pad cache with zeros and drain cache */
  			if (cachedBits + bitsLeft <= 0) return i;
  			if (bitsLeft > 0)	cache |= (unsigned int)(*buf++) << (24 - cachedBits);
  			if (bitsLeft > 8)	cache |= (unsigned int)(*buf++) << (16 - cachedBits);
  			cachedBits += bitsLeft;
  			bitsLeft = 0;
  
  			cache &= (signed int)0x80000000 >> (cachedBits - 1);
  			padBits = 10;
  			cachedBits += padBits;	/* okay if this is > 32 (0's automatically shifted in from right) */
  		}
  
  		/* largest maxBits = 6, plus 4 for sign bits, so make sure cache has at least 10 bits */
  		while (i < (nVals - 3) && cachedBits >= 10 ) {
  			cw = tBase[cache >> (32 - maxBits)];
  			len = GetHLenQ(cw);
  			cachedBits -= len;
  			cache <<= len;
  
  			v = GetCWVQ(cw);	if(v) {ApplySign(v, cache); cache <<= 1; cachedBits--;}
  			w = GetCWWQ(cw);	if(w) {ApplySign(w, cache); cache <<= 1; cachedBits--;}
  			x = GetCWXQ(cw);	if(x) {ApplySign(x, cache); cache <<= 1; cachedBits--;}
  			y = GetCWYQ(cw);	if(y) {ApplySign(y, cache); cache <<= 1; cachedBits--;}
  
  			/* ran out of bits - okay (means we're done) */
  			if (cachedBits < padBits)
  				return i;
  
  			*vwxy++ = v;
  			*vwxy++ = w;
  			*vwxy++ = x;
  			*vwxy++ = y;
  			i += 4;
  		}
  	}
  
  	/* decoded max number of quad values */
  	return i;
  }
  
  /**************************************************************************************
   * 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 Huffman codes
   *              bitOffset also returned in parameter (0 = MSB, 7 = LSB of 
   *                byte located at buf + offset)
   *              -1 if null input pointers, huffBlockBits < 0, or decoder runs 
   *                out of bits prematurely (invalid bitstream)
   **************************************************************************************/
  int DecodeHuffman(MP3DecInfo *mp3DecInfo, unsigned char *buf, int *bitOffset, int huffBlockBits, int gr, int ch)
  {
  	int r1Start, r2Start, rEnd[4];	/* region boundaries */
  	int i, w, bitsUsed, bitsLeft;
  	unsigned char *startBuf = buf;
  
  	FrameHeader *fh;
  	SideInfo *si;
  	SideInfoSub *sis;
  	//ScaleFactorInfo *sfi;
  	HuffmanInfo *hi;
  
  	/* validate pointers */
  	if (!mp3DecInfo || !mp3DecInfo->FrameHeaderPS || !mp3DecInfo->SideInfoPS || !mp3DecInfo->ScaleFactorInfoPS || !mp3DecInfo->HuffmanInfoPS)
  		return -1;
  
  	fh = ((FrameHeader *)(mp3DecInfo->FrameHeaderPS));
  	si = ((SideInfo *)(mp3DecInfo->SideInfoPS));
  	sis = &si->sis[gr][ch];
  	//sfi = ((ScaleFactorInfo *)(mp3DecInfo->ScaleFactorInfoPS));
  	hi = (HuffmanInfo*)(mp3DecInfo->HuffmanInfoPS);
  
  	if (huffBlockBits < 0)
  		return -1;
  
  	/* figure out region boundaries (the first 2*bigVals coefficients divided into 3 regions) */
  	if (sis->winSwitchFlag && sis->blockType == 2) {
  		if (sis->mixedBlock == 0) {
  			r1Start = fh->sfBand->s[(sis->region0Count + 1)/3] * 3;
  		} else {
  			if (fh->ver == MPEG1) {
  				r1Start = fh->sfBand->l[sis->region0Count + 1];
  			} else {
  				/* see MPEG2 spec for explanation */
  				w = fh->sfBand->s[4] - fh->sfBand->s[3];
  				r1Start = fh->sfBand->l[6] + 2*w;
  			}
  		}
  		r2Start = MAX_NSAMP;	/* short blocks don't have region 2 */
  	} else {
  		r1Start = fh->sfBand->l[sis->region0Count + 1];
  		r2Start = fh->sfBand->l[sis->region0Count + 1 + sis->region1Count + 1];
  	}
  
  	/* offset rEnd index by 1 so first region = rEnd[1] - rEnd[0], etc. */
  	rEnd[3] = MIN(MAX_NSAMP, 2 * sis->nBigvals);
  	rEnd[2] = MIN(r2Start, rEnd[3]);
  	rEnd[1] = MIN(r1Start, rEnd[3]);
  	rEnd[0] = 0;
  
  	/* rounds up to first all-zero pair (we don't check last pair for (x,y) == (non-zero, zero)) */
  	hi->nonZeroBound[ch] = rEnd[3];
  
  	/* decode Huffman pairs (rEnd[i] are always even numbers) */
  	bitsLeft = huffBlockBits;
  	for (i = 0; i < 3; i++) {
  		bitsUsed = DecodeHuffmanPairs(hi->huffDecBuf[ch] + rEnd[i], rEnd[i+1] - rEnd[i], sis->tableSelect[i], bitsLeft, buf, *bitOffset);
  		if (bitsUsed < 0 || bitsUsed > bitsLeft)	/* error - overran end of bitstream */
  			return -1;
  
  		/* update bitstream position */
  		buf += (bitsUsed + *bitOffset) >> 3;
  		*bitOffset = (bitsUsed + *bitOffset) & 0x07;
  		bitsLeft -= bitsUsed;
  	}
  
  	/* decode Huffman quads (if any) */
  	hi->nonZeroBound[ch] += DecodeHuffmanQuads(hi->huffDecBuf[ch] + rEnd[3], MAX_NSAMP - rEnd[3], sis->count1TableSelect, bitsLeft, buf, *bitOffset);
  
  	ASSERT(hi->nonZeroBound[ch] <= MAX_NSAMP);
  	for (i = hi->nonZeroBound[ch]; i < MAX_NSAMP; i++) {
  		hi->huffDecBuf[ch][i] = 0;
  	}
  	
  	/* If bits used for 576 samples < huffBlockBits, then the extras are considered
  	 *  to be stuffing bits (throw away, but need to return correct bitstream position) 
  	 */
  	buf += (bitsLeft + *bitOffset) >> 3;
  	*bitOffset = (bitsLeft + *bitOffset) & 0x07;
  	
  	return (buf - startBuf);
  }
  
  