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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: dk4utf16.ctr
*/

#ifndef DK4UTF16_H_INCLUDED
/** Avoid multiple inclusions. */
#define DK4UTF16_H_INCLUDED 1


#line 10 "dk4utf16.ctr"

/**	@file
	Encode and decode 32 bit characters
	in UTF-16 encoding.

	CRT on Windows: Not used.

	The character to encode to UTF-16 must be in
	range U+00000000 to U+0010FFFF.
	(the hexadecimal numbers range defined by UNICODE).

	The character must not be in range U+0000D800 to U+0000DFFF which
	is reserved for surrogate pairs.

	Characters up to U+0000FFFF are converted to 16 bits and passed
	"as is".

	For characters above, we substract U+00010000 and split the result
	in two 10-bit blocks.
	We prepend bits 110110 to the higher 10 bits, this results in the
	"high surrogate".
	We prepend bits 110111 to the lower 10 bits, this results in the
	"low surrogate".

	When decoding we have to check for a byte order marker (BOM) at
	start of stream. The character U+0000FEFF as first character in the
	stream can be used to mark encoding and/or byte order.
	If we read an UTF-16 encoded stream and have 0xFEFF as first character
	we can leave byte order as is. If the first character is 0xFFFE we
	have to change byte order in each word.

*/

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

#ifndef DK4CONF_H_INCLUDED
#if DK4_BUILDING_DKTOOLS4
#include "dk4types.h"
#else
#include <dktools-4/dk4types.h>
#endif
#endif

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

#ifndef DK4DEC_H_INCLUDED
#if DK4_BUILDING_DKTOOLS4
#include "dk4edstm.h"
#else
#include <dktools-4/dk4edstm.h>
#endif
#endif

/**	Decode UTF-16 encoded data.
*/
typedef struct {
  dk4_c32_t	uc;	/**< Unicode character to produce. */
  int		state;	/**< Decoder state. */
} dk4_utf16_decoder_t;



/**	Decode UTF-16 encoded bytes.
*/
typedef struct {
  dk4_utf16_decoder_t	dec;	/**< Decoder UTF-16 to 32-bit char. */
  int			msb;	/**< Flag: Most significant byte comes first. */
  int			state;	/**< Decoder state. */
  dk4_c16_t		saved;	/**< Partial input character saved. */
} dk4_utf16_byte_decoder_t;



#ifdef __cplusplus
extern "C" {
#endif

/**	Initialize the UTF-16 decoder.
	@param	ptr	Decoder to initialize.
*/
void
dk4utf16_init(dk4_utf16_decoder_t *ptr);

/**	Add one word to the decoder.
	@param	ptr	Decoder to use.
	@param	word	Word to add.
	@return Operation result, one from:
	DK4_EDSTM_ACCEPT if the byte was added to the next output
	without completing output,
	DK4_EDSTM_FINISHED, if the byte was added to the next output
	completing the output, or
	DK4_EDSTM_ERROR on error.
*/
int
dk4utf16_add(dk4_utf16_decoder_t *ptr, dk4_c16_t word);

/**	Retrieve a completed Unicode character from the decoder.
	@param	ptr	Decoder to obtain character from.
*/
dk4_c32_t
dk4utf16_get(dk4_utf16_decoder_t const *ptr);

/**	Check whether the decoder is empty.
	@param	ptr	Decoder to check.
	@return	1 on success, 0 on error.
*/
int
dk4utf16_is_empty(dk4_utf16_decoder_t const *ptr);

/**	UTF-16 encode UNICODE character.
	@param	rb	Result buffer, should be at least 3 dk4_c16_t.
	@param	pszrb	Size of the result buffer, in: available, out: used.
	@param	c	Character to encode.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if rb or pszrb is NULL,
	- DK4_E_BUFFER_TOO_SMALL<br>
	  if the buffer size is less than 3,
	- DK4_E_SYNTAX<br>
	  if c is out of the encodable range.
*/
int
dk4utf16_encode(dk4_c16_t *rb, size_t *pszrb, dk4_c32_t c, dk4_er_t *erp);

/**	Initialize the UTF-16 decoder.
	@param	ptr	Decoder to initialize.
	@param	msb	Flag: Most significant byte comes first.
*/
void
dk4utf16_byte_init(dk4_utf16_byte_decoder_t *ptr, int msb);

/**	Add one byte to the decoder.
	@param	ptr	Decoder to use.
	@param	byte	Byte to add.
	@return Operation result, one from:
	DK4_EDSTM_ACCEPT if the byte was added to the next output
	without completing output,
	DK4_EDSTM_FINISHED, if the byte was added to the next output
	completing the output, or
	DK4_EDSTM_ERROR on error.
*/
int
dk4utf16_byte_add(dk4_utf16_byte_decoder_t *ptr, unsigned char byte);

/**	Retrieve a completed Unicode character from the decoder.
	@param	ptr	Decoder to obtain character from.
*/
dk4_c32_t
dk4utf16_byte_get(dk4_utf16_byte_decoder_t *ptr);

/**	Check whether a decoder is empty.
	@param	ptr	Decoder to check.
	@return	1 on success, 0 on error.
*/
int
dk4utf16_byte_is_empty(dk4_utf16_byte_decoder_t *ptr);

/**	UTF-16 encode UNICODE character, write to bytes.
	@param	rb	Result buffer, should be at least 5 bytes.
	@param	pszrb	Size of the result buffer (number of bytes),
			in: available, out: used.
	@param	c	Character to encode.
	@param	msb	Flag: Write most significant byte first.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if rb or pszrb is NULL,
	- DK4_E_BUFFER_TOO_SMALL<br>
	  if the buffer size is less than 3,
	- DK4_E_SYNTAX<br>
	  if c is out of the encodable range.
*/
int
dk4utf16_byte_encode(
  unsigned char *rb, size_t *pszrb, dk4_c32_t c, int msb, dk4_er_t *erp
);


#ifdef __cplusplus
}
#endif




#endif