mp3common.h

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/**************************************************************************************
 * Fixed-point MP3 decoder
 * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com)
 * June 2003
 *
 * mp3common.h - implementation-independent API's, datatypes, and definitions
 **************************************************************************************/
 
#ifndef _MP3COMMON_H
#define _MP3COMMON_H
 
#include "mp3dec.h"
#include "statname.h" /* do name-mangling for static linking */
 
#define MAX_SCFBD   4   /* max scalefactor bands per channel */
#define NGRANS_MPEG1  2
#define NGRANS_MPEG2  1
 
/* 11-bit syncword if MPEG 2.5 extensions are enabled */
/*
#define SYNCWORDH   0xff
#define SYNCWORDL   0xe0
*/
 
/* 12-bit syncword if MPEG 1,2 only are supported */
#define SYNCWORDH   0xff
#define SYNCWORDL   0xf0
 
typedef struct _MP3DecInfo {
  /* pointers to platform-specific data structures */
  void *FrameHeaderPS;
  void *SideInfoPS;
  void *ScaleFactorInfoPS;
  void *HuffmanInfoPS;
  void *DequantInfoPS;
  void *IMDCTInfoPS;
  void *SubbandInfoPS;
 
  /* buffer which must be large enough to hold largest possible main_data section */
  unsigned char mainBuf[MAINBUF_SIZE];
 
  /* special info for "free" bitrate files */
  int freeBitrateFlag;
  int freeBitrateSlots;
 
  /* user-accessible info */
  int bitrate;
  int nChans;
  int samprate;
  int nGrans;       /* granules per frame */
  int nGranSamps;     /* samples per granule */
  int nSlots;
  int layer;
  MPEGVersion version;
 
  int mainDataBegin;
  int mainDataBytes;
 
  int part23Length[MAX_NGRAN][MAX_NCHAN];
 
} MP3DecInfo;
 
typedef struct _SFBandTable {
  short l[23];
  short s[14];
} SFBandTable;
 
/* decoder functions which must be implemented for each platform */
MP3DecInfo *AllocateBuffers(void);
void FreeBuffers(MP3DecInfo *mp3DecInfo);
int CheckPadBit(MP3DecInfo *mp3DecInfo);
int UnpackFrameHeader(MP3DecInfo *mp3DecInfo, unsigned char *buf);
int UnpackSideInfo(MP3DecInfo *mp3DecInfo, unsigned char *buf);
int DecodeHuffman(MP3DecInfo *mp3DecInfo, unsigned char *buf, int *bitOffset, int huffBlockBits, int gr, int ch);
int Dequantize(MP3DecInfo *mp3DecInfo, int gr);
int IMDCT(MP3DecInfo *mp3DecInfo, int gr, int ch);
int UnpackScaleFactors(MP3DecInfo *mp3DecInfo, unsigned char *buf, int *bitOffset, int bitsAvail, int gr, int ch);
int Subband(MP3DecInfo *mp3DecInfo, short *pcmBuf);
 
/* mp3tabs.c - global ROM tables */
extern const int samplerateTab[3][3];
extern const short bitrateTab[3][3][15];
extern const short samplesPerFrameTab[3][3];
extern const short bitsPerSlotTab[3];
extern const short sideBytesTab[3][2];
extern const short slotTab[3][3][15];
extern const SFBandTable sfBandTable[3][3];
 
#endif  /* _MP3COMMON_H */