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/*
Copyright (C) 2015-2020, 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: dk4bom.ctr
*/

#ifndef DK4BOM_H_INCLUDED
/** Avoid multiple inclusions. */
#define DK4BOM_H_INCLUDED 1


#line 10 "dk4bom.ctr"

/**	@file
	Detect BOM (byte order marker) at start
	of data stream, keep track of unprocessed characters.

	First, use dk4bom_detect_init() to initialize the state machine.

	Now use dk4bom_detect_add() to add the data streams contents
	byte by byte to the state machine as long as the dk4bom_detect_add()
	function returns DK4_EDSTM_ACCEPT.
	If the function returns DK4_EDSTM_ERROR, an error occured, you
	should stop processing.
	If the function returns DK4_EDSTM_FINISHED or
	DK4_EDSTM_FINISHED_WITH_UNUSED a BOM was found or definitely not
	found. Use dk4bom_detect_get_encoding() to obtain the decoding
	found and process the remaining data stream in that encoding.
	If the function returned DK4_EDSTM_FINISHED_WITH_UNUSED, use
	dk4bom_detect_num_unused_bytes() to find the number of unused
	bytes saved in the detector and dk4bom_detect_unused_byte()
	to retrieve and process the unused bytes before processing the
	remaining bytes from the data stream.
	
	For a very short data stream, the detection may not be finished
	at the end of the stream. Use dk4bom_detect_in_detection() to
	find out whether the detection was not yet finished.
	If the function returns 1, the detection is not finished and unused
	bytes are stored in the detector. Use dk4bom_detect_num_unused_bytes()
	and dk4bom_detect_unused_byte() to obtain the unused bytes.

	CRT on Windows: Not used.
*/


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

#ifndef DK4TYPES_H_INCLUDED
#if	DK4_BUILDING_DKTOOLS4
#include "dk4types.h"
#else
#include <dktools-4/dk4types.h>
#endif
#endif

#ifndef DK4EDSTM_H_INCLUDED
#if	DK4_BUILDING_DKTOOLS4
#include "dk4edstm.h"
#else
#include <dktools-4/dk4edstm.h>
#endif
#endif

#if DK4_HAVE_SYS_TYPES_H
#ifndef SYS_TYPES_H_INCLUDED
#include <sys/types.h>
#define SYS_TYPES_H_INCLUDED 1
#endif
#endif


/**	State machine to detect a BOM (byte order marker)
	at the beginning of a data stream.
*/
typedef struct {
  size_t	rjb;	/**< Number of unused bytes. */
  int		defenc;	/**< Default encoding, used if no BOM detected. */
  int		found;	/**< Encoding from the BOM found. */
  int		state;	/**< Current state of BOM detection. */
  unsigned char	c1;	/**< Rejected byte 1. */
  unsigned char c2;	/**< Rejected byte 2. */
  unsigned char	c3;	/**< Rejected byte 3. */
  unsigned char	c4;	/**< Rejected byte 4. */
} dk4_bom_detector_t;



#ifdef __cplusplus
extern "C" {
#endif

/**	Initialize the BOM detector.
	@param	ptr	BOM detector to initialize.
	@param	defenc	Encoding to use if not BOM at beginning of data.
*/
void
dk4bom_detect_init(dk4_bom_detector_t *ptr, int defenc);

/**	Add one byte to the BOM detector.
	@param	ptr	Detector to use.
	@param	byte	The data byte to add.
	@return	Operation result, one from:
	DK4_EDSTM_ACCEPT if you can continue feeding bytes into the
	detector,
	DK4_EDSTM_FINISHED if a BOM was detected (do not feed further
	bytes),
	DK4_EDSTM_FINISHED_WITH_UNUSED if BOM detection was finished and there
	are unused bytes stored in the detector), or
	DK4_EDSTM_ERROR if you attempt to add further bytes after the
	detection was finished.
	On DK4_EDSTM_FINISHED and DK4_EDSTM_FINISHED_WITH_UNUSED you can use
	dk4bom_detect_get_encoding() to retrieve the encoding.
	On DK4_EDSTM_FINISHED_WITH_UNUSED use dk4bom_detect_num_unused_bytes()
	and dk4bom_detect_unused_byte() to retrieve the unused
	bytes from the detector and process them before processing
	further data from the data stream.
*/
int
dk4bom_detect_add(dk4_bom_detector_t *ptr, unsigned char byte);

/**	Retrieve the encoding from the detector.
	@param	ptr	Detector to use.
	@return	A file encoding, one from: DK4_FILE_ENCODING_PLAIN,
	DK4_FILE_ENCODING_WIN1252, DK4_FILE_ENCODING_UTF8,
	DK4_FILE_ENCODING_UTF16_LE, DK4_FILE_ENCODING_UTF16_BE,
	DK4_FILE_ENCODING_32_LE, or DK4_FILE_ENCODING_32_BE.
*/
int
dk4bom_detect_get_encoding(dk4_bom_detector_t const *ptr);

/**	Retrieve the number of cted bytes stored in the detector.
	@param	ptr	Detector to use.
	@return	Number of unused bytes stored in the detector.
*/
size_t
dk4bom_detect_num_unused_bytes(dk4_bom_detector_t const *ptr);

/**	Retrieve one unused byte stored in the detector.
	@param	ptr	Detector to use.
	@param	num	Byte number.
	@return	The byte value.
*/
unsigned char
dk4bom_detect_unused_byte(dk4_bom_detector_t const *ptr, size_t num);

/**	Check if BOM detection is still in progress.
	@param	ptr	Detector to check.
	@return	1 if detection is in progress and bytes are
	stored in the detector, 0 otherwise.
*/
int
dk4bom_detect_in_detection(dk4_bom_detector_t const *ptr);

#ifdef __cplusplus
}
#endif




#endif