compress.c File Reference

An adaptive order-2 PPM range coder. More...

#include <string.h>
#include "enet/enet.h"

Classes
struct	_ENetRangeCoder
struct	_ENetSymbol

Macros
#define	ENET_BUILDING_LIB   1
#define	ENET_CONTEXT_CREATE(context, escapes_, minimum)
#define	ENET_CONTEXT_DECODE(context, symbol_, code, value_, under_, count_, update, minimum, createRoot, visitNode, createRight, createLeft)
#define	ENET_CONTEXT_ENCODE(context, symbol_, value_, under_, count_, update, minimum)
#define	ENET_CONTEXT_NOT_EXCLUDED(value_, after, before)
#define	ENET_CONTEXT_RESCALE(context, minimum)
#define	ENET_CONTEXT_ROOT_DECODE(context, symbol_, code, value_, under_, count_, update, minimum, exclude)
#define	ENET_CONTEXT_TRY_DECODE(context, symbol_, code, value_, under_, count_, update, minimum, exclude)   ENET_CONTEXT_DECODE (context, symbol_, code, value_, under_, count_, update, minimum, return 0, exclude (node -> value, after, before), return 0, return 0)
#define	ENET_RANGE_CODER_DECODE(under, count, total)
#define	ENET_RANGE_CODER_ENCODE(under, count, total)
#define	ENET_RANGE_CODER_FLUSH
#define	ENET_RANGE_CODER_FREE_SYMBOLS
#define	ENET_RANGE_CODER_OUTPUT(value)
#define	ENET_RANGE_CODER_READ(total)   ((decodeCode - decodeLow) / (decodeRange /= (total)))
#define	ENET_RANGE_CODER_SEED
#define	ENET_SYMBOL_CREATE(symbol, value_, count_)

Typedefs
typedef struct _ENetRangeCoder	ENetRangeCoder
typedef struct _ENetSymbol	ENetSymbol

Enumerations
enum	{   ENET_RANGE_CODER_TOP = 1<<24, ENET_RANGE_CODER_BOTTOM = 1<<16, ENET_CONTEXT_SYMBOL_DELTA = 3, ENET_CONTEXT_SYMBOL_MINIMUM = 1,   ENET_CONTEXT_ESCAPE_MINIMUM = 1, ENET_SUBCONTEXT_ORDER = 2, ENET_SUBCONTEXT_SYMBOL_DELTA = 2, ENET_SUBCONTEXT_ESCAPE_DELTA = 5 }

Functions
int	enet_host_compress_with_range_coder (ENetHost *host)
	Sets the packet compressor the host should use to the default range coder. More...
size_t	enet_range_coder_compress (void *context, const ENetBuffer *inBuffers, size_t inBufferCount, size_t inLimit, enet_uint8 *outData, size_t outLimit)
void *	enet_range_coder_create (void)
size_t	enet_range_coder_decompress (void *context, const enet_uint8 *inData, size_t inLimit, enet_uint8 *outData, size_t outLimit)
void	enet_range_coder_destroy (void *context)
static enet_uint16	enet_symbol_rescale (ENetSymbol *symbol)

Detailed Description

An adaptive order-2 PPM range coder.

Macro Definition Documentation

#define ENET_BUILDING_LIB   1

#define ENET_CONTEXT_CREATE	(		context,
			escapes_,
			minimum
	)

Value:

{ \
    ENET_SYMBOL_CREATE (context, 0, 0); \
    (context) -> escapes = escapes_; \
    (context) -> total = escapes_ + 256*minimum; \
    (context) -> symbols = 0; \
}

#define ENET_CONTEXT_DECODE	(		context,
			symbol_,
			code,
			value_,
			under_,
			count_,
			update,
			minimum,
			createRoot,
			visitNode,
			createRight,
			createLeft
	)

#define ENET_CONTEXT_ENCODE	(		context,
			symbol_,
			value_,
			under_,
			count_,
			update,
			minimum
	)

#define ENET_CONTEXT_NOT_EXCLUDED	(		value_,
			after,
			before
	)

#define ENET_CONTEXT_RESCALE	(		context,
			minimum
	)

Value:

{ \
    (context) -> total = (context) -> symbols ? enet_symbol_rescale ((context) + (context) -> symbols) : 0; \
    (context) -> escapes -= (context) -> escapes >> 1; \
    (context) -> total += (context) -> escapes + 256*minimum; \
}

#define ENET_CONTEXT_ROOT_DECODE	(		context,
			symbol_,
			code,
			value_,
			under_,
			count_,
			update,
			minimum,
			exclude
	)

Value:

ENET_CONTEXT_DECODE (context, symbol_, code, value_, under_, count_, update, minimum, \
    { \
        value_ = code / minimum; \
        under_ = code - code%minimum; \
        ENET_SYMBOL_CREATE (symbol_, value_, update); \
        (context) -> symbols = symbol_ - (context); \
    }, \
    exclude (node -> value, after, before), \
    { \
        value_ = node->value + 1 + (code - after)/minimum; \
        under_ = code - (code - after)%minimum; \
        ENET_SYMBOL_CREATE (symbol_, value_, update); \
        node -> right = symbol_ - node; \
    }, \
    { \
        value_ = node->value - 1 - (after - before - code - 1)/minimum; \
        under_ = code - (after - before - code - 1)%minimum; \
        ENET_SYMBOL_CREATE (symbol_, value_, update); \
        node -> left = symbol_ - node; \
    }) \

#define ENET_CONTEXT_TRY_DECODE	(		context,
			symbol_,
			code,
			value_,
			under_,
			count_,
			update,
			minimum,
			exclude
	)		ENET_CONTEXT_DECODE (context, symbol_, code, value_, under_, count_, update, minimum, return 0, exclude (node -> value, after, before), return 0, return 0)

#define ENET_RANGE_CODER_DECODE	(		under,
			count,
			total
	)

Value:

{ \
    decodeLow += (under) * decodeRange; \
    decodeRange *= (count); \
    for (;;) \
    { \
        if((decodeLow ^ (decodeLow + decodeRange)) >= ENET_RANGE_CODER_TOP) \
        { \
            if(decodeRange >= ENET_RANGE_CODER_BOTTOM) break; \
            decodeRange = -decodeLow & (ENET_RANGE_CODER_BOTTOM - 1); \
        } \
        decodeCode <<= 8; \
        if (inData < inEnd) \
          decodeCode |= * inData ++; \
        decodeRange <<= 8; \
        decodeLow <<= 8; \
    } \
}

#define ENET_RANGE_CODER_ENCODE	(		under,
			count,
			total
	)

Value:

{ \
    encodeRange /= (total); \
    encodeLow += (under) * encodeRange; \
    encodeRange *= (count); \
    for (;;) \
    { \
        if((encodeLow ^ (encodeLow + encodeRange)) >= ENET_RANGE_CODER_TOP) \
        { \
            if(encodeRange >= ENET_RANGE_CODER_BOTTOM) break; \
            encodeRange = -encodeLow & (ENET_RANGE_CODER_BOTTOM - 1); \
        } \
        ENET_RANGE_CODER_OUTPUT (encodeLow >> 24); \
        encodeRange <<= 8; \
        encodeLow <<= 8; \
    } \
}

#define ENET_RANGE_CODER_FLUSH

Value:

{ \
    while (encodeLow) \
    { \
        ENET_RANGE_CODER_OUTPUT (encodeLow >> 24); \
        encodeLow <<= 8; \
    } \
}

#define ENET_RANGE_CODER_FREE_SYMBOLS

Value:

{ \
    if (nextSymbol >= sizeof (rangeCoder -> symbols) / sizeof (ENetSymbol) - ENET_SUBCONTEXT_ORDER ) \
    { \
        nextSymbol = 0; \
        ENET_CONTEXT_CREATE (root, ENET_CONTEXT_ESCAPE_MINIMUM, ENET_CONTEXT_SYMBOL_MINIMUM); \
        predicted = 0; \
        order = 0; \
    } \
}

#define ENET_RANGE_CODER_OUTPUT

(

value

)

Value:

{ \
    if (outData >= outEnd) \
      return 0; \
    * outData ++ = value; \
}

#define ENET_RANGE_CODER_READ

(

total

)

((decodeCode - decodeLow) / (decodeRange /= (total)))

#define ENET_RANGE_CODER_SEED

Value:

{ \
    if (inData < inEnd) decodeCode |= * inData ++ << 24; \
    if (inData < inEnd) decodeCode |= * inData ++ << 16; \
    if (inData < inEnd) decodeCode |= * inData ++ << 8; \
    if (inData < inEnd) decodeCode |= * inData ++; \
}

#define ENET_SYMBOL_CREATE	(		symbol,
			value_,
			count_
	)

Value:

{ \
    symbol = & rangeCoder -> symbols [nextSymbol ++]; \
    symbol -> value = value_; \
    symbol -> count = count_; \
    symbol -> under = count_; \
    symbol -> left = 0; \
    symbol -> right = 0; \
    symbol -> symbols = 0; \
    symbol -> escapes = 0; \
    symbol -> total = 0; \
    symbol -> parent = 0; \
}

Typedef Documentation

typedef struct _ENetRangeCoder ENetRangeCoder

typedef struct _ENetSymbol ENetSymbol

Enumeration Type Documentation

anonymous enum

Enumerator
ENET_RANGE_CODER_TOP
ENET_RANGE_CODER_BOTTOM
ENET_CONTEXT_SYMBOL_DELTA
ENET_CONTEXT_SYMBOL_MINIMUM
ENET_CONTEXT_ESCAPE_MINIMUM
ENET_SUBCONTEXT_ORDER
ENET_SUBCONTEXT_SYMBOL_DELTA
ENET_SUBCONTEXT_ESCAPE_DELTA

Function Documentation

size_t enet_range_coder_compress	(	void *	context,
		const ENetBuffer *	inBuffers,
		size_t	inBufferCount,
		size_t	inLimit,
		enet_uint8 *	outData,
		size_t	outLimit
	)

void* enet_range_coder_create

(

void

)

size_t enet_range_coder_decompress	(	void *	context,
		const enet_uint8 *	inData,
		size_t	inLimit,
		enet_uint8 *	outData,
		size_t	outLimit
	)

void enet_range_coder_destroy

(

void *

context

)

static enet_uint16 enet_symbol_rescale ( ENetSymbol *  symbol )

static