%%	options

copyright owner	=	Dirk Krause
copyright year	=	2015-xxxx
license		=	bsd


%%	header

/**	@file
	String recoding from UTF-16 to 32 bit.

	CRT on Windows: Not used.
*/

#ifndef DK4CONF_H_INCLUDED
#include "dk4conf.h"
#endif

#ifndef DK4TYPES_H_INCLUDED
#include "dk4types.h"
#endif

#ifndef DK4ERROR_H_INCLUDED
#include "dk4error.h"
#endif

#ifdef __cplusplus
extern "C" {
#endif

/**	Recode string from UTF-16 to 32 bit.
	@param	dstb	Destination buffer.
	@param	szdstb	Size of destination buffer (number of bytes).
	@param	src	Source string to convert.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if src or dstb is NULL or szdstb is 0,
	- DK4_E_BUFFER_TOO_SMALL<br>
	  if dstb is too small,
	- DK4_E_SYNTAX<br>
	  with the number of successfully recoded characters in nelem if a
	  non-recodable character was found.
*/
int
dk4recode_utf16_to_c32(
  dk4_c32_t *dstb, size_t szdstb, const dk4_c16_t *src, dk4_er_t *erp
);

#ifdef __cplusplus
}
#endif


%%	module

#include "dk4rec19.h"
#include "dk4utf16.h"



int
dk4recode_utf16_to_c32(
  dk4_c32_t *dstb, size_t szdstb, const dk4_c16_t *src, dk4_er_t *erp
)
{
  dk4_utf16_decoder_t	 dec;
  size_t		 used	=	0;
  size_t		 rd	=	0;
  dk4_c32_t		 c32	=	dkC32(0);
  int			 back	=	0;

  if ((NULL != dstb) && (NULL != src) && (0 < szdstb)) {
    back = 1;
    dk4utf16_init(&dec);
    while(((dk4_c16_t)0U != *src) && (1 == back) && (used < szdstb)) {
      switch(dk4utf16_add(&dec, *(src++))) {
        case DK4_EDSTM_FINISHED: {
	  c32 = dk4utf16_get(&dec);
	  dk4utf16_init(&dec);
	  dstb[used++] = c32;
	} break;
	case DK4_EDSTM_ERROR: {
	  back = 0;
	  dk4error_set_elsize_nelem(erp, DK4_E_SYNTAX, 2, rd);
	} break;
      }
      if (0 != back) { rd++; }
    }
    if (used < szdstb) {
      dstb[used] = '\0';
    } else {
      dstb[szdstb - 1] = '\0';
      back = 0;
      dk4error_set_simple_error_code(erp, DK4_E_BUFFER_TOO_SMALL);
    }
    if (0 == dk4utf16_is_empty(&dec)) {
      back = 0;
      dk4error_set_elsize_nelem(erp, DK4_E_SYNTAX, 2, rd);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}