Adafruit mp3
coder.h
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35 
36 /**************************************************************************************
37  * Fixed-point MP3 decoder
38  * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com)
39  * June 2003
40  *
41  * coder.h - private, implementation-specific header file
42  **************************************************************************************/
43 
44 #ifndef _CODER_H
45 #define _CODER_H
46 
47 #include "mp3common.h"
48 
49 #if defined(ASSERT)
50 #undef ASSERT
51 #endif
52 #if defined(_WIN32) && defined(_M_IX86) && (defined (_DEBUG) || defined (REL_ENABLE_ASSERTS))
53 #define ASSERT(x) if (!(x)) __asm int 3;
54 #else
55 #define ASSERT(x) /* do nothing */
56 #endif
57 
58 #ifndef MAX
59 #define MAX(a,b) ((a) > (b) ? (a) : (b))
60 #endif
61 
62 #ifndef MIN
63 #define MIN(a,b) ((a) < (b) ? (a) : (b))
64 #endif
65 
66 /* clip to range [-2^n, 2^n - 1] */
67 #define CLIP_2N(y, n) { \
68  int sign = (y) >> 31; \
69  if (sign != (y) >> (n)) { \
70  (y) = sign ^ ((1 << (n)) - 1); \
71  } \
72 }
73 
74 #define SIBYTES_MPEG1_MONO 17
75 #define SIBYTES_MPEG1_STEREO 32
76 #define SIBYTES_MPEG2_MONO 9
77 #define SIBYTES_MPEG2_STEREO 17
78 
79 /* number of fraction bits for pow43Tab (see comments there) */
80 #define POW43_FRACBITS_LOW 22
81 #define POW43_FRACBITS_HIGH 12
82 
83 #define DQ_FRACBITS_OUT 25 /* number of fraction bits in output of dequant */
84 #define IMDCT_SCALE 2 /* additional scaling (by sqrt(2)) for fast IMDCT36 */
85 
86 #define HUFF_PAIRTABS 32
87 #define BLOCK_SIZE 18
88 #define NBANDS 32
89 #define MAX_REORDER_SAMPS ((192-126)*3) /* largest critical band for short blocks (see sfBandTable) */
90 #define VBUF_LENGTH (17 * 2 * NBANDS) /* for double-sized vbuf FIFO */
91 
92 /* additional external symbols to name-mangle for static linking */
93 #define SetBitstreamPointer STATNAME(SetBitstreamPointer)
94 #define GetBits STATNAME(GetBits)
95 #define CalcBitsUsed STATNAME(CalcBitsUsed)
96 #define DequantChannel STATNAME(DequantChannel)
97 #define MidSideProc STATNAME(MidSideProc)
98 #define IntensityProcMPEG1 STATNAME(IntensityProcMPEG1)
99 #define IntensityProcMPEG2 STATNAME(IntensityProcMPEG2)
100 #define PolyphaseMono STATNAME(PolyphaseMono)
101 #define PolyphaseStereo STATNAME(PolyphaseStereo)
102 #define FDCT32 STATNAME(FDCT32)
103 
104 #define ISFMpeg1 STATNAME(ISFMpeg1)
105 #define ISFMpeg2 STATNAME(ISFMpeg2)
106 #define ISFIIP STATNAME(ISFIIP)
107 #define uniqueIDTab STATNAME(uniqueIDTab)
108 #define coef32 STATNAME(coef32)
109 #define polyCoef STATNAME(polyCoef)
110 #define csa STATNAME(csa)
111 #define imdctWin STATNAME(imdctWin)
112 
113 #define huffTable STATNAME(huffTable)
114 #define huffTabOffset STATNAME(huffTabOffset)
115 #define huffTabLookup STATNAME(huffTabLookup)
116 #define quadTable STATNAME(quadTable)
117 #define quadTabOffset STATNAME(quadTabOffset)
118 #define quadTabMaxBits STATNAME(quadTabMaxBits)
119 
120 /* map these to the corresponding 2-bit values in the frame header */
121 typedef enum {
122  Stereo = 0x00, /* two independent channels, but L and R frames might have different # of bits */
123  Joint = 0x01, /* coupled channels - layer III: mix of M-S and intensity, Layers I/II: intensity and direct coding only */
124  Dual = 0x02, /* two independent channels, L and R always have exactly 1/2 the total bitrate */
125  Mono = 0x03 /* one channel */
126 } StereoMode;
127 
128 typedef struct _BitStreamInfo {
129  unsigned char *bytePtr;
130  unsigned int iCache;
131  int cachedBits;
132  int nBytes;
133 } BitStreamInfo;
134 
135 typedef struct _FrameHeader {
136  MPEGVersion ver; /* version ID */
137  int layer; /* layer index (1, 2, or 3) */
138  int crc; /* CRC flag: 0 = disabled, 1 = enabled */
139  int brIdx; /* bitrate index (0 - 15) */
140  int srIdx; /* sample rate index (0 - 2) */
141  int paddingBit; /* padding flag: 0 = no padding, 1 = single pad byte */
142  int privateBit; /* unused */
143  StereoMode sMode; /* mono/stereo mode */
144  int modeExt; /* used to decipher joint stereo mode */
145  int copyFlag; /* copyright flag: 0 = no, 1 = yes */
146  int origFlag; /* original flag: 0 = copy, 1 = original */
147  int emphasis; /* deemphasis mode */
148  int CRCWord; /* CRC word (16 bits, 0 if crc not enabled) */
149 
150  const SFBandTable *sfBand;
151 } FrameHeader;
152 
153 typedef struct _SideInfoSub {
154  int part23Length; /* number of bits in main data */
155  int nBigvals; /* 2x this = first set of Huffman cw's (maximum amplitude can be > 1) */
156  int globalGain; /* overall gain for dequantizer */
157  int sfCompress; /* unpacked to figure out number of bits in scale factors */
158  int winSwitchFlag; /* window switching flag */
159  int blockType; /* block type */
160  int mixedBlock; /* 0 = regular block (all short or long), 1 = mixed block */
161  int tableSelect[3]; /* index of Huffman tables for the big values regions */
162  int subBlockGain[3]; /* subblock gain offset, relative to global gain */
163  int region0Count; /* 1+region0Count = num scale factor bands in first region of bigvals */
164  int region1Count; /* 1+region1Count = num scale factor bands in second region of bigvals */
165  int preFlag; /* for optional high frequency boost */
166  int sfactScale; /* scaling of the scalefactors */
167  int count1TableSelect; /* index of Huffman table for quad codewords */
168 } SideInfoSub;
169 
170 typedef struct _SideInfo {
171  int mainDataBegin;
172  int privateBits;
173  int scfsi[MAX_NCHAN][MAX_SCFBD]; /* 4 scalefactor bands per channel */
174 
175  SideInfoSub sis[MAX_NGRAN][MAX_NCHAN];
176 } SideInfo;
177 
178 typedef struct {
179  int cbType; /* pure long = 0, pure short = 1, mixed = 2 */
180  int cbEndS[3]; /* number nonzero short cb's, per subbblock */
181  int cbEndSMax; /* max of cbEndS[] */
182  int cbEndL; /* number nonzero long cb's */
184 
185 typedef struct _DequantInfo {
186  int workBuf[MAX_REORDER_SAMPS]; /* workbuf for reordering short blocks */
187  CriticalBandInfo cbi[MAX_NCHAN]; /* filled in dequantizer, used in joint stereo reconstruction */
188 } DequantInfo;
189 
190 typedef struct _HuffmanInfo {
191  int huffDecBuf[MAX_NCHAN][MAX_NSAMP]; /* used both for decoded Huffman values and dequantized coefficients */
192  int nonZeroBound[MAX_NCHAN]; /* number of coeffs in huffDecBuf[ch] which can be > 0 */
193  int gb[MAX_NCHAN]; /* minimum number of guard bits in huffDecBuf[ch] */
194 } HuffmanInfo;
195 
196 typedef enum _HuffTabType {
197  noBits,
198  oneShot,
199  loopNoLinbits,
200  loopLinbits,
201  quadA,
202  quadB,
203  invalidTab
204 } HuffTabType;
205 
206 typedef struct _HuffTabLookup {
207  int linBits;
208  HuffTabType tabType;
209 } HuffTabLookup;
210 
211 typedef struct _IMDCTInfo {
212  int outBuf[MAX_NCHAN][BLOCK_SIZE][NBANDS]; /* output of IMDCT */
213  int overBuf[MAX_NCHAN][MAX_NSAMP / 2]; /* overlap-add buffer (by symmetry, only need 1/2 size) */
214  int numPrevIMDCT[MAX_NCHAN]; /* how many IMDCT's calculated in this channel on prev. granule */
215  int prevType[MAX_NCHAN];
216  int prevWinSwitch[MAX_NCHAN];
217  int gb[MAX_NCHAN];
218 } IMDCTInfo;
219 
220 typedef struct _BlockCount {
221  int nBlocksLong;
222  int nBlocksTotal;
223  int nBlocksPrev;
224  int prevType;
225  int prevWinSwitch;
226  int currWinSwitch;
227  int gbIn;
228  int gbOut;
229 } BlockCount;
230 
231 /* max bits in scalefactors = 5, so use char's to save space */
232 typedef struct _ScaleFactorInfoSub {
233  char l[23]; /* [band] */
234  char s[13][3]; /* [band][window] */
236 
237 /* used in MPEG 2, 2.5 intensity (joint) stereo only */
238 typedef struct _ScaleFactorJS {
239  int intensityScale;
240  int slen[4];
241  int nr[4];
242 } ScaleFactorJS;
243 
244 typedef struct _ScaleFactorInfo {
245  ScaleFactorInfoSub sfis[MAX_NGRAN][MAX_NCHAN];
246  ScaleFactorJS sfjs;
248 
249 /* NOTE - could get by with smaller vbuf if memory is more important than speed
250  * (in Subband, instead of replicating each block in FDCT32 you would do a memmove on the
251  * last 15 blocks to shift them down one, a hardware style FIFO)
252  */
253 typedef struct _SubbandInfo {
254  int vbuf[MAX_NCHAN * VBUF_LENGTH]; /* vbuf for fast DCT-based synthesis PQMF - double size for speed (no modulo indexing) */
255  int vindex; /* internal index for tracking position in vbuf */
256 } SubbandInfo;
257 
258 /* bitstream.c */
259 void SetBitstreamPointer(BitStreamInfo *bsi, int nBytes, unsigned char *buf);
260 unsigned int GetBits(BitStreamInfo *bsi, int nBits);
261 int CalcBitsUsed(BitStreamInfo *bsi, unsigned char *startBuf, int startOffset);
262 
263 /* dequant.c, dqchan.c, stproc.c */
264 int DequantChannel(int *sampleBuf, int *workBuf, int *nonZeroBound, FrameHeader *fh, SideInfoSub *sis,
266 void MidSideProc(int x[MAX_NCHAN][MAX_NSAMP], int nSamps, int mOut[2]);
267 void IntensityProcMPEG1(int x[MAX_NCHAN][MAX_NSAMP], int nSamps, FrameHeader *fh, ScaleFactorInfoSub *sfis,
268  CriticalBandInfo *cbi, int midSideFlag, int mixFlag, int mOut[2]);
269 void IntensityProcMPEG2(int x[MAX_NCHAN][MAX_NSAMP], int nSamps, FrameHeader *fh, ScaleFactorInfoSub *sfis,
270  CriticalBandInfo *cbi, ScaleFactorJS *sfjs, int midSideFlag, int mixFlag, int mOut[2]);
271 
272 /* dct32.c */
273 // about 1 ms faster in RAM, but very large
274 void FDCT32(int *x, int *d, int offset, int oddBlock, int gb);// __attribute__ ((section (".data")));
275 
276 /* hufftabs.c */
277 extern const HuffTabLookup huffTabLookup[HUFF_PAIRTABS];
278 extern const int huffTabOffset[HUFF_PAIRTABS];
279 extern const unsigned short huffTable[];
280 extern const unsigned char quadTable[64+16];
281 extern const int quadTabOffset[2];
282 extern const int quadTabMaxBits[2];
283 
284 /* polyphase.c (or asmpoly.s)
285  * some platforms require a C++ compile of all source files,
286  * so if we're compiling C as C++ and using native assembly
287  * for these functions we need to prevent C++ name mangling.
288  */
289 #ifdef __cplusplus
290 extern "C" {
291 #endif
292 void PolyphaseMono(short *pcm, int *vbuf, const int *coefBase);
293 void PolyphaseStereo(short *pcm, int *vbuf, const int *coefBase);
294 #ifdef __cplusplus
295 }
296 #endif
297 
298 /* trigtabs.c */
299 extern const int imdctWin[4][36];
300 extern const int ISFMpeg1[2][7];
301 extern const int ISFMpeg2[2][2][16];
302 extern const int ISFIIP[2][2];
303 extern const int csa[8][2];
304 extern const int coef32[31];
305 extern const int polyCoef[264];
306 
307 #endif /* _CODER_H */
Definition: coder.h:185
Definition: mp3common.h:97
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