Diffstat (limited to 'noncore/apps/opie-reader/Coder.h') (more/less context) (ignore whitespace changes)
| -rw-r--r-- | noncore/apps/opie-reader/Coder.h | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/noncore/apps/opie-reader/Coder.h b/noncore/apps/opie-reader/Coder.h new file mode 100644 index 0000000..64587cf --- a/dev/null +++ b/noncore/apps/opie-reader/Coder.h @@ -0,0 +1,113 @@ +#include "CSource.h" +/**************************************************************************** + * This file is part of PPMd project * + * Contents: 'Carryless rangecoder' by Dmitry Subbotin * + * Comments: this implementation is claimed to be a public domain * + ****************************************************************************/ +/********************** Original text ************************************* +//////// Carryless rangecoder (c) 1999 by Dmitry Subbotin //////// + +typedef unsigned int uint; +typedef unsigned char uc; + +#define DO(n) for (int _=0; _<n; _++) +#define TOP (1<<24) +#define BOT (1<<16) + + +class RangeCoder +{ + uint low, code, range, passed; + FILE *f; + + void OutByte (uc c) { passed++; fputc(c,f); } + uc InByte () { passed++; return fgetc(f); } + +public: + + uint GetPassed () { return passed; } + void StartEncode (FILE *F) { f=F; passed=low=0; range= (uint) -1; } + void FinishEncode () { DO(4) OutByte(low>>24), low<<=8; } + void StartDecode (FILE *F) { passed=low=code=0; range= (uint) -1; + f=F; DO(4) code= code<<8 | InByte(); + } + + void Encode (uint cumFreq, uint freq, uint totFreq) { + assert(cumFreq+freq<totFreq && freq && totFreq<=BOT); + low += cumFreq * (range/= totFreq); + range*= freq; + while ((low ^ low+range)<TOP || range<BOT && ((range= -low & BOT-1),1)) + OutByte(low>>24), range<<=8, low<<=8; + } + + uint GetFreq (uint totFreq) { + uint tmp= (code-low) / (range/= totFreq); + if (tmp >= totFreq) throw ("Input data corrupt"); // or force it to return + return tmp; // a valid value :) + } + + void Decode (uint cumFreq, uint freq, uint totFreq) { + assert(cumFreq+freq<totFreq && freq && totFreq<=BOT); + low += cumFreq*range; + range*= freq; + while ((low ^ low+range)<TOP || range<BOT && ((range= -low & BOT-1),1)) + code= code<<8 | InByte(), range<<=8, low<<=8; + } +}; +*****************************************************************************/ + +static struct SUBRANGE { + DWORD LowCount, HighCount, scale; +} SubRange; +enum { TOP=1 << 24, BOT=1 << 15 }; +static DWORD low, code, range; + +inline void ariInitEncoder() +{ + low=0; range=DWORD(-1); +} +#define ARI_ENC_NORMALIZE(stream) { \ + while ((low ^ (low+range)) < TOP || range < BOT && \ + ((range= -low & (BOT-1)),1)) { \ + _PPMD_E_PUTC(low >> 24,stream); \ + range <<= 8; low <<= 8; \ + } \ +} +inline void ariEncodeSymbol() +{ + low += SubRange.LowCount*(range /= SubRange.scale); + range *= SubRange.HighCount-SubRange.LowCount; +} +inline void ariShiftEncodeSymbol(UINT SHIFT) +{ + low += SubRange.LowCount*(range >>= SHIFT); + range *= SubRange.HighCount-SubRange.LowCount; +} +#define ARI_FLUSH_ENCODER(stream) { \ + for (UINT i=0;i < 4;i++) { \ + _PPMD_E_PUTC(low >> 24,stream); low <<= 8; \ + } \ +} +#define ARI_INIT_DECODER(stream) { \ + low=code=0; range=DWORD(-1); \ + for (UINT i=0;i < 4;i++) \ + code=(code << 8) | _PPMD_D_GETC(stream); \ +} +#define ARI_DEC_NORMALIZE(stream) { \ + while ((low ^ (low+range)) < TOP || range < BOT && \ + ((range= -low & (BOT-1)),1)) { \ + code=(code << 8) | _PPMD_D_GETC(stream); \ + range <<= 8; low <<= 8; \ + } \ +} +inline UINT ariGetCurrentCount() { + return (code-low)/(range /= SubRange.scale); +} +inline UINT ariGetCurrentShiftCount(UINT SHIFT) { + return (code-low)/(range >>= SHIFT); +} +inline void ariRemoveSubrange() +{ + low += range*SubRange.LowCount; + range *= SubRange.HighCount-SubRange.LowCount; +} |