dernc.c File Reference

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Detailed Description

RNC decompression support.

Purpose:

Compiled normally, this file is a well-behaved, re-entrant code module exporting only `rnc_ulen', `rnc_unpack' and `rnc_error'. Compiled with MAIN_DERNC defined, it's a standalone program which will decompress argv[1] into argv[2].

Comment:

in/out buffers should have 8 redundant "safe bytes" at end.

Author:

Jon Skeet

Date:

14 Oct 1997 - 22 Jul 2008

Copying and copyrights:

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Definition in file dernc.c.

#include "lbfileio.h"
#include "dernc.h"
#include "globals.h"

Go to the source code of this file.

Defines
#define	INTERNAL
#define	HUFTABLE_ENTRIES   32
Functions
void	bitread_init (bit_stream *bs, const unsigned char **p, const unsigned char *pend)
	Initialises a bit stream with the first two bytes of the packed data.
void	bitread_fix (bit_stream *bs, const unsigned char **p, const unsigned char *pend)
	Fixes up a bit stream after literals have been read out of the data stream.
unsigned long	bit_peek (bit_stream *bs, const unsigned long mask)
	Returns some bits, masked with given bit mask.
void	bit_advance (bit_stream *bs, int n, const unsigned char **p, const unsigned char *pend)
	Advances the bit stream.
char *	rnc_error (long errcode)
	Returns an error string corresponding to an error code.
long	rnc_ulen (void *packed)
	Return the uncompressed length of a packed data block.
long	rnc_plen (void *packed)
	Return the compressed length of a packed data block.
long	rnc_nocallback (long done, long total)
	Empty callback - for use if no callback is needed.
long	rnc_printcallback (long done, long total)
	Console print callback - for use in console tools.
long	rnc_unpack (const void *packed, void *unpacked, const unsigned int flags)
	Decompress a packed data block.
long	rnc_crc (const void *data, unsigned long len)
	Calculate a CRC, the RNC way.

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Define Documentation

#define HUFTABLE_ENTRIES   32

Definition at line 236 of file dernc.c.

#define INTERNAL

Definition at line 27 of file dernc.c.

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Function Documentation

void bit_advance	(	bit_stream *	bs,
		int	n,
		const unsigned char **	p,
		const unsigned char *	pend
	)			[inline]

Advances the bit stream.

Reads n bits from the bit_stream, then makes sure there are still at least 16 bits to read in next operation. The new bits are taken from buffer *p. Checks pend for proper buffer pointers range. The pend should point to the last readable byte in buffer.

Definition at line 653 of file dernc.c.

Referenced by rnc_unpack().

unsigned long bit_peek	(	bit_stream *	bs,
		unsigned long	mask
	)			[inline]

Returns some bits, masked with given bit mask.

Definition at line 641 of file dernc.c.

void bitread_fix	(	bit_stream *	bs,
		const unsigned char **	p,
		const unsigned char *	pend
	)			[inline]

Fixes up a bit stream after literals have been read out of the data stream.

Checks pend for proper buffer pointers range. The pend should point to the last readable byte in buffer.

Definition at line 619 of file dernc.c.

Referenced by rnc_unpack().

void bitread_init	(	bit_stream *	bs,
		const unsigned char **	p,
		const unsigned char *	pend
	)			[inline]

Initialises a bit stream with the first two bytes of the packed data.

Checks pend for proper buffer pointers range. The pend should point to the last readable byte in buffer. If buffer is exceeded, fills output (or part of output) with zeros.

Definition at line 598 of file dernc.c.

Referenced by rnc_unpack().

long rnc_crc	(	const void *	data,
		unsigned long	len
	)

Calculate a CRC, the RNC way.

Parameters:

	data	The data buffer.
	len	data Length of the data buffer.

Returns:

The CRC value for given data.

Definition at line 715 of file dernc.c.

Referenced by rnc_unpack().

char* rnc_error

(

long

errcode

)

Returns an error string corresponding to an error code.

Parameters:

errcode

Error code returned by a function.

Returns:

Error message string.

Definition at line 272 of file dernc.c.

Referenced by memfile_error().

long rnc_nocallback	(	long	done,
		long	total
	)

Empty callback - for use if no callback is needed.

Definition at line 327 of file dernc.c.

long rnc_plen

(

void *

packed

)

Return the compressed length of a packed data block.

The packed buffer must be longer than SIZEOF_RNC_HEADER.

Parameters:

packed

Packed buffer.

Returns:

Returns compressed length of the packed block, or a negative error code.

Definition at line 316 of file dernc.c.

Referenced by memfile_read().

long rnc_printcallback	(	long	done,
		long	total
	)

Console print callback - for use in console tools.

Definition at line 333 of file dernc.c.

long rnc_ulen

(

void *

packed

)

Return the uncompressed length of a packed data block.

The packed buffer must be longer than SIZEOF_RNC_HEADER.

Parameters:

packed

Packed buffer.

Returns:

Uncompressed length of the packed block, or a negative error code.

Definition at line 301 of file dernc.c.

Referenced by memfile_read().

long rnc_unpack	(	const void *	packed,
		void *	unpacked,
		const unsigned int	flags
	)

Decompress a packed data block.

Parameters:

	packed	Packed source data buffer.
	unpacked	Unpacked destination data buffer.
	flags	Option flags for the decompressor.

Returns:

Returns the unpacked length if successful, or negative error code if not. If COMPRESSOR is defined, it also returns the leeway number (which gets stored at offset 16 into the compressed-file header) in `*leeway', if `leeway' isn't NULL.

Definition at line 351 of file dernc.c.

Referenced by memfile_read().