| 1 | /**************************************************************************
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| 2 | *
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| 3 | * arithcode.h -- Arithmetic coding
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| 4 | * Copyright (C) 1994 Alistair Moffat
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or modify
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| 7 | * it under the terms of the GNU General Public License as published by
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| 8 | * the Free Software Foundation; either version 2 of the License, or
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| 9 | * (at your option) any later version.
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| 10 | *
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| 11 | * This program is distributed in the hope that it will be useful,
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details.
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| 15 | *
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| 16 | * You should have received a copy of the GNU General Public License
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| 17 | * along with this program; if not, write to the Free Software
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| 18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 19 | *
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| 20 | * $Id: arithcode.h 3745 2003-02-20 21:20:24Z mdewsnip $
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| 21 | *
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| 22 | **************************************************************************/
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| 23 |
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| 24 | #ifndef _arithcode_h
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| 25 | #define _arithcode_h
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| 26 |
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| 27 | extern FILE *arith_in, *arith_out;
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| 28 |
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| 29 | #define codevaluebits 16
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| 30 | #if (codevaluebits<16)
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| 31 | typedef unsigned short codevalue;
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| 32 | #else
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| 33 | typedef unsigned long codevalue;
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| 34 | #endif
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| 35 |
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| 36 | #define topvalue ((codevalue)((1<<codevaluebits)-1))
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| 37 | #define maxfrequency ((topvalue+1)/4 + 1)
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| 38 |
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| 39 | #define firstqtr (topvalue/4+1)
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| 40 | #define half (2*firstqtr)
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| 41 | #define thirdqtr (3*firstqtr)
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| 42 |
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| 43 | #define escape_event U->totalcnt-U->notfound, U->totalcnt, U->totalcnt
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| 44 |
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| 45 | void arithmetic_encode ();
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| 46 | codevalue arithmetic_decode_target ();
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| 47 |
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| 48 | #define arithmetic_decode_target(totl) \
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| 49 | ( ((S_value-S_low+1)*(totl)-1) / (S_high-S_low+1) )
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| 50 |
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| 51 | void arithmetic_decode ();
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| 52 |
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| 53 |
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| 54 | extern codevalue S_low, S_high, S_value;
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| 55 | extern long S_bitstofollow;
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| 56 | extern int S_buffer, S_bitstogo;
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| 57 |
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| 58 | extern long cmpbytes, rawbytes;
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| 59 |
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| 60 | extern long CountOfBitsOut;
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| 61 |
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| 62 | void EncodeGammaDist (int Off);
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| 63 | int DecodeGammaDist ();
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| 64 |
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| 65 | void EncodeGammaSigned (int snum, int *pos, int *neg);
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| 66 | int DecodeGammaSigned (int *pos, int *neg);
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| 67 |
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| 68 |
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| 69 | void InitArithEncoding (void);
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| 70 | void InitArithDecoding (void);
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| 71 |
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| 72 | void CloseDownArithEncoding (void);
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| 73 | void CloseDownArithDecoding (void);
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| 74 |
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| 75 | void EncodeChecksum ();
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| 76 | void DecodeChecksum (char str[]);
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| 77 |
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| 78 | #endif
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