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/*
Copyright (C) 2016-2020, Dirk Krause
SPDX-License-Identifier: BSD-3-Clause
*/

/*
	WARNING: This file was generated by the dkct program (see
	http://dktools.sourceforge.net/ for details).
	Changes you make here will be lost if dkct is run again!
	You should modify the original source and run dkct on it.
	Original source: dk4lzwe.ctr
*/

#ifndef DK4LZWE_H_INCLUDED
/** Avoid multiple inclusions. */
#define DK4LZWE_H_INCLUDED 1


#line 8 "dk4lzwe.ctr"

/**	@file	dk4lzwe.h	LZW encoder to produce PS level 2 output.

- The unit length (input data length) is 8 bits.
- Code 256 is used for table cleanup, 257 is the end of data marker.
- EarlyChange is in use: the number of bits per code is increased after
  creating table entries for codes 511, 1023 and 2047.
- Table entries are created for codes up to 4093. Instead of generating
  an entry for 4094, the table is cleared.
*/


#ifndef	DK4CONF_H_INCLUDED
#if DK4_BUILDING_DKTOOLS4
#include "dk4conf.h"
#else
#include <dktools-4/dk4conf.h>
#endif
#endif

#ifndef DK4ERROR_H_INCLUDED
#if DK4_BUILDING_DKTOOLS4
#include "dk4error.h"
#else
#include <dktools-4/dk4error.h>
#endif
#endif

#ifndef	DK4BITSH_H_INCLUDED
#if DK4_BUILDING_DKTOOLS4
#include "dk4bitsh.h"
#else
#include <dktools-4/dk4bitsh.h>
#endif
#endif



/**	Table size.
	The table must be large enough to keep 4096 entries. Adding
	25 percent size significantly decreases the number of lookups.
	A prime number is required to ensure traversal of the entire
	table if necessary.
*/
enum {
	LZW_TABLE_SIZE = 5147	/**< Size of LZW compression table. */
};



/**	One table entry for LZW compression.
*/
typedef struct {
	unsigned short	os;		/**< Current (old) state or code. */
	unsigned short	ns;		/**< New state after applying input. */
	unsigned char	in;		/**< Input byte. */
} dk4_lzw_cell_t;



/**	LZW encoder structure.
*/
typedef struct {
	unsigned char	 ob[8];	/**< Output buffer. */
	dk4_bit_shift_t	 bs;	/**< Bit shifter. */
	dk4_lzw_cell_t	*p_tbl;	/**< Pointer to dynamically allocated table. */
	size_t			 obu;	/**< Used bytes in output buffer. */
	int				 mret;	/**< Flag: Must retrieve output data. */
	int				 hst;	/**< Flag: Have internal state. */
	unsigned short	 bits;	/**< Number of bits to use for output. */
	unsigned short	 cs;	/**< Current state. */
	unsigned short	 ns;	/**< Next state for new table entry. */
} dk4_lzwe_t;

#ifdef	__cplusplus
extern "C" {
#endif


/**	Initialize LZW encoder, allocate memory for resources.
	@param	lzwptr	Encoder to initialize.
	@param	erp		Error report, may be NULL.
	@return	1 on success, 0 on error.

	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if lzwptr is NULL,
	- DK4_E_MATH_OVERFLOW<br>
	  on numeric overflow when calculating the
	  product of elsize and nelem,
	- DK4_E_MEMORY_ALLOCATION_FAILED<br>
	  with mem.elsize and mem.nelem
	  set if there is not enough memory available,
	- DK4_E_BUG<br>
	  if the dk4bit_shift_add() call indicates an error
	  (should not happen as we provide a valid address to the function),
	- DK4_E_BUFFER_TOO_SMALL<br>
	  if the output buffer is already full. Typically this means
	  that output was not retrieved as expected by the library.
*/

int
dk4lzwe_init(
	dk4_lzwe_t	*lzwptr,
	dk4_er_t	*erp
);


/**	Add one byte to the encoder.
	@param	lzwptr	Encoder to use.
	@param	uc		Byte to add.
	@param	erp		Error report, may be NULL.
	@return	Operation result, one from:
	- DK4_EDSTM_ACCEPT<br>
	  if the input byte was successfully stored in the internal data
	  structures without completing a run. No further action
	  necessary.
	- DK4_EDSTM_FINISHED<br>
	  if output was created. Use dk4lzwe_output() to obtain the
	  output data.
	- DK4_EDSTM_ERROR<br>
	  if an error occured.
*/

int
dk4lzwe_add(
	dk4_lzwe_t		*lzwptr,
	unsigned char	 uc,
	dk4_er_t		*erp
);


/**	Finish encoded data stream, flush internal state and bits from
	the bit shifter to output buffer and release dynamic memory.
	@param	lzwptr	Encoder to use.
	@param	erp		Error report, may be NULL.
	@return	Operation result, one from:
	- DK4_EDSTM_ACCEPT<br>
	  if the input byte was successfully stored in the internal data
	  structures without completing a run. No further action
	  necessary.
	- DK4_EDSTM_FINISHED<br>
	  if output was created. Use dk4lzwe_output() to obtain the
	  output data.
	- DK4_EDSTM_ERROR<br>
	  if an error occured.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if lzwptr is NULL or lzwptr->s_tbl or lzwptr->i_tbl is NULL,
	- DK4_E_BUG<br>
	  if the dk4bit_shift_add() call indicates an error
	  (should not happen as we provide a valid address to the function),
	- DK4_E_BUFFER_TOO_SMALL<br>
	  if the output buffer is already full. Typically this means
	  that output was not retrieved as expected by the library.
*/

int
dk4lzwe_finish(
	dk4_lzwe_t		*lzwptr,
	dk4_er_t		*erp
);


/**	Retrieve output from encoder.
	@param	dptr	Address of result pointer.
	@param	szptr	Address of result size variable.
	@param	lzwptr	Encoder to use.
	@param	erp		Error report, may be NULL.
	@return	1 if data available, 0 otherwise.
*/

int
dk4lzwe_output(
	const unsigned char	**dptr,
	size_t				 *szptr,
	dk4_lzwe_t			 *lzwptr,
	dk4_er_t			 *erp
);


#ifdef	__cplusplus
}
#endif

/* vim: set ai sw=4 ts=4 : */

#endif