coder.h

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/* ***** BEGIN LICENSE BLOCK ***** 
 * Version: RCSL 1.0/RPSL 1.0 
 *  
 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
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 * The contents of this file, and the files included with this file, are 
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 * 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 
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 * This file is part of the Helix DNA Technology. RealNetworks is the 
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 * ***** END LICENSE BLOCK ***** */ 

/**************************************************************************************
 * Fixed-point MP3 decoder
 * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com)
 * June 2003
 *
 * coder.h - private, implementation-specific header file
 **************************************************************************************/

#ifndef _CODER_H
#define _CODER_H

#include "mp3common.h"

#if defined(_WIN32) && defined(_M_IX86) && (defined (_DEBUG) || defined (REL_ENABLE_ASSERTS))
#define ASSERT(x) if (!(x)) __asm int 3;
#else
#define ASSERT(x) /* do nothing */
#endif

#ifndef MAX
#define MAX(a,b)        ((a) > (b) ? (a) : (b))
#endif

#ifndef MIN
#define MIN(a,b)        ((a) < (b) ? (a) : (b))
#endif

/* clip to range [-2^n, 2^n - 1] */
#define CLIP_2N(y, n) { \
        int sign = (y) >> 31;  \
        if (sign != (y) >> (n))  { \
                (y) = sign ^ ((1 << (n)) - 1); \
        } \
}

#define SIBYTES_MPEG1_MONO              17
#define SIBYTES_MPEG1_STEREO    32
#define SIBYTES_MPEG2_MONO               9
#define SIBYTES_MPEG2_STEREO    17

/* number of fraction bits for pow43Tab (see comments there) */
#define POW43_FRACBITS_LOW              22
#define POW43_FRACBITS_HIGH             12

#define DQ_FRACBITS_OUT                 25      /* number of fraction bits in output of dequant */
#define IMDCT_SCALE                             2       /* additional scaling (by sqrt(2)) for fast IMDCT36 */

#define HUFF_PAIRTABS                   32
#define BLOCK_SIZE                              18
#define NBANDS                                  32
#define MAX_REORDER_SAMPS               ((192-126)*3)           /* largest critical band for short blocks (see sfBandTable) */
#define VBUF_LENGTH                             (17 * 2 * NBANDS)       /* for double-sized vbuf FIFO */

/* additional external symbols to name-mangle for static linking */
#define SetBitstreamPointer     STATNAME(SetBitstreamPointer)
#define GetBits                         STATNAME(GetBits)
#define CalcBitsUsed            STATNAME(CalcBitsUsed)
#define DequantChannel          STATNAME(DequantChannel)
#define MidSideProc                     STATNAME(MidSideProc)
#define IntensityProcMPEG1      STATNAME(IntensityProcMPEG1)
#define IntensityProcMPEG2      STATNAME(IntensityProcMPEG2)
#define PolyphaseMono           STATNAME(PolyphaseMono)
#define PolyphaseStereo         STATNAME(PolyphaseStereo)
#define FDCT32                          STATNAME(FDCT32)

#define ISFMpeg1                        STATNAME(ISFMpeg1)
#define ISFMpeg2                        STATNAME(ISFMpeg2)
#define ISFIIP                          STATNAME(ISFIIP)
#define uniqueIDTab                     STATNAME(uniqueIDTab)
#define coef32                          STATNAME(coef32)
#define polyCoef                        STATNAME(polyCoef)
#define csa                                     STATNAME(csa)
#define imdctWin                        STATNAME(imdctWin)

#define huffTable                       STATNAME(huffTable)
#define huffTabOffset           STATNAME(huffTabOffset)
#define huffTabLookup           STATNAME(huffTabLookup)
#define quadTable                       STATNAME(quadTable)
#define quadTabOffset           STATNAME(quadTabOffset)
#define quadTabMaxBits          STATNAME(quadTabMaxBits)

/* map these to the corresponding 2-bit values in the frame header */
typedef enum {
        Stereo = 0x00,  /* two independent channels, but L and R frames might have different # of bits */
        Joint = 0x01,   /* coupled channels - layer III: mix of M-S and intensity, Layers I/II: intensity and direct coding only */
        Dual = 0x02,    /* two independent channels, L and R always have exactly 1/2 the total bitrate */
        Mono = 0x03             /* one channel */
} StereoMode;

typedef struct _BitStreamInfo {
        unsigned char *bytePtr;
        unsigned int iCache;
        int cachedBits;
        int nBytes;
} BitStreamInfo;

typedef struct _FrameHeader {
    MPEGVersion ver;    /* version ID */
    int layer;                  /* layer index (1, 2, or 3) */
    int crc;                    /* CRC flag: 0 = disabled, 1 = enabled */
    int brIdx;                  /* bitrate index (0 - 15) */
    int srIdx;                  /* sample rate index (0 - 2) */
    int paddingBit;             /* padding flag: 0 = no padding, 1 = single pad byte */
    int privateBit;             /* unused */
    StereoMode sMode;   /* mono/stereo mode */
    int modeExt;                /* used to decipher joint stereo mode */
    int copyFlag;               /* copyright flag: 0 = no, 1 = yes */
    int origFlag;               /* original flag: 0 = copy, 1 = original */
    int emphasis;               /* deemphasis mode */
    int CRCWord;                /* CRC word (16 bits, 0 if crc not enabled) */

        const SFBandTable *sfBand;
} FrameHeader;

typedef struct _SideInfoSub {
    int part23Length;           /* number of bits in main data */ 
    int nBigvals;                       /* 2x this = first set of Huffman cw's (maximum amplitude can be > 1) */
    int globalGain;                     /* overall gain for dequantizer */
    int sfCompress;                     /* unpacked to figure out number of bits in scale factors */
    int winSwitchFlag;          /* window switching flag */
    int blockType;                      /* block type */
    int mixedBlock;                     /* 0 = regular block (all short or long), 1 = mixed block */
    int tableSelect[3];         /* index of Huffman tables for the big values regions */
    int subBlockGain[3];        /* subblock gain offset, relative to global gain */
    int region0Count;           /* 1+region0Count = num scale factor bands in first region of bigvals */
    int region1Count;           /* 1+region1Count = num scale factor bands in second region of bigvals */
    int preFlag;                        /* for optional high frequency boost */
    int sfactScale;                     /* scaling of the scalefactors */
    int count1TableSelect;      /* index of Huffman table for quad codewords */
} SideInfoSub;

typedef struct _SideInfo {
        int mainDataBegin;
        int privateBits;
        int scfsi[MAX_NCHAN][MAX_SCFBD];                                /* 4 scalefactor bands per channel */
        
        SideInfoSub     sis[MAX_NGRAN][MAX_NCHAN];
} SideInfo;

typedef struct {
    int cbType;         /* pure long = 0, pure short = 1, mixed = 2 */
    int cbEndS[3];      /* number nonzero short cb's, per subbblock */
        int cbEndSMax;  /* max of cbEndS[] */
    int cbEndL;         /* number nonzero long cb's  */
} CriticalBandInfo;

typedef struct _DequantInfo {
        int workBuf[MAX_REORDER_SAMPS];         /* workbuf for reordering short blocks */
        CriticalBandInfo cbi[MAX_NCHAN];        /* filled in dequantizer, used in joint stereo reconstruction */
} DequantInfo;

typedef struct _HuffmanInfo {
        int huffDecBuf[MAX_NCHAN][MAX_NSAMP];           /* used both for decoded Huffman values and dequantized coefficients */
        int nonZeroBound[MAX_NCHAN];                            /* number of coeffs in huffDecBuf[ch] which can be > 0 */
        int gb[MAX_NCHAN];                                                      /* minimum number of guard bits in huffDecBuf[ch] */
} HuffmanInfo;

typedef enum _HuffTabType {
        noBits,
        oneShot,
        loopNoLinbits,
        loopLinbits,
        quadA,
        quadB,
        invalidTab
} HuffTabType;

typedef struct _HuffTabLookup {
        int     linBits;
        HuffTabType tabType;
} HuffTabLookup;

typedef struct _IMDCTInfo {
        int outBuf[MAX_NCHAN][BLOCK_SIZE][NBANDS];      /* output of IMDCT */   
        int overBuf[MAX_NCHAN][MAX_NSAMP / 2];          /* overlap-add buffer (by symmetry, only need 1/2 size) */
        int numPrevIMDCT[MAX_NCHAN];                            /* how many IMDCT's calculated in this channel on prev. granule */
        int prevType[MAX_NCHAN];
        int prevWinSwitch[MAX_NCHAN];
        int gb[MAX_NCHAN];
} IMDCTInfo;

typedef struct _BlockCount {
        int nBlocksLong;
        int nBlocksTotal;
        int nBlocksPrev; 
        int prevType;
        int prevWinSwitch;
        int currWinSwitch;
        int gbIn;
        int gbOut;
} BlockCount;

/* max bits in scalefactors = 5, so use char's to save space */
typedef struct _ScaleFactorInfoSub {
        char l[23];            /* [band] */
        char s[13][3];         /* [band][window] */
} ScaleFactorInfoSub;  

/* used in MPEG 2, 2.5 intensity (joint) stereo only */
typedef struct _ScaleFactorJS {
        int intensityScale;             
        int     slen[4];
        int     nr[4];
} ScaleFactorJS;

typedef struct _ScaleFactorInfo {
        ScaleFactorInfoSub sfis[MAX_NGRAN][MAX_NCHAN];
        ScaleFactorJS sfjs;
} ScaleFactorInfo;

/* NOTE - could get by with smaller vbuf if memory is more important than speed
 *  (in Subband, instead of replicating each block in FDCT32 you would do a memmove on the
 *   last 15 blocks to shift them down one, a hardware style FIFO)
 */ 
typedef struct _SubbandInfo {
        int vbuf[MAX_NCHAN * VBUF_LENGTH];              /* vbuf for fast DCT-based synthesis PQMF - double size for speed (no modulo indexing) */
        int vindex;                                                             /* internal index for tracking position in vbuf */
} SubbandInfo;

/* bitstream.c */
void SetBitstreamPointer(BitStreamInfo *bsi, int nBytes, unsigned char *buf);
unsigned int GetBits(BitStreamInfo *bsi, int nBits);
int CalcBitsUsed(BitStreamInfo *bsi, unsigned char *startBuf, int startOffset);

/* dequant.c, dqchan.c, stproc.c */
int DequantChannel(int *sampleBuf, int *workBuf, int *nonZeroBound, FrameHeader *fh, SideInfoSub *sis, 
                                        ScaleFactorInfoSub *sfis, CriticalBandInfo *cbi);
void MidSideProc(int x[MAX_NCHAN][MAX_NSAMP], int nSamps, int mOut[2]);
void IntensityProcMPEG1(int x[MAX_NCHAN][MAX_NSAMP], int nSamps, FrameHeader *fh, ScaleFactorInfoSub *sfis, 
                                                CriticalBandInfo *cbi, int midSideFlag, int mixFlag, int mOut[2]);
void IntensityProcMPEG2(int x[MAX_NCHAN][MAX_NSAMP], int nSamps, FrameHeader *fh, ScaleFactorInfoSub *sfis, 
                                                CriticalBandInfo *cbi, ScaleFactorJS *sfjs, int midSideFlag, int mixFlag, int mOut[2]);

/* dct32.c */
void FDCT32(int *x, int *d, int offset, int oddBlock, int gb);

/* hufftabs.c */
extern const HuffTabLookup huffTabLookup[HUFF_PAIRTABS];
extern const int huffTabOffset[HUFF_PAIRTABS];
extern const unsigned short huffTable[];
extern const unsigned char quadTable[64+16];
extern const int quadTabOffset[2];
extern const int quadTabMaxBits[2];

/* polyphase.c (or asmpoly.s)
 * some platforms require a C++ compile of all source files,
 * so if we're compiling C as C++ and using native assembly
 * for these functions we need to prevent C++ name mangling.
 */
#ifdef __cplusplus
extern "C" {
#endif
void PolyphaseMono(short *pcm, int *vbuf, const int *coefBase);
void PolyphaseStereo(short *pcm, int *vbuf, const int *coefBase);
#ifdef __cplusplus
}
#endif

/* trigtabs.c */
extern const int imdctWin[4][36];
extern const int ISFMpeg1[2][7];
extern const int ISFMpeg2[2][2][16];
extern const int ISFIIP[2][2];
extern const int csa[8][2];
extern const int coef32[31];
extern const int polyCoef[264];

#endif  /* _CODER_H */