%%	options

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


%%	header

/**	@file
	String recoding from UTF-8 to UTF-16.

	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-8 to UTF-16.
	@param	dstb	Destination buffer.
	@param	szdstb	Size of destination buffer (number of dk_c16-t).
	@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_utf8_to_utf16(
  dk4_c16_t *dstb, size_t szdstb, const char *src, dk4_er_t *erp
);

/**	Calculate required buffer size (including final 0x0000U word)
	to convert from UTF-8 to UTF-16.
	@param	src	UTF-8 encoded source string.
	@param	erp	Error report, may be NULL.
	@return	Positive required buffer size (number of dk4_c16_t) on success,
	0 on error.

	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if src is NULL,
	- DK4_E_MATH_OVERFLOW<br>
	  if the required size calculation results in mathematical overflow,
	- DK4_E_SYNTAX<br>
	  if there are errors while decoding the source string.
*/
size_t
dk4recode_size_utf8_to_utf16(const char *src, dk4_er_t *erp);

#ifdef __cplusplus
}
#endif

%%	module

#include "dk4rec11.h"
#include "dk4mem.h"
#include "dk4utf8.h"
#include "dk4utf16.h"


$!trace-include



size_t
dk4recode_size_utf8_to_utf16(const char *src, dk4_er_t *erp)
{
  dk4_er_t		 er;
  dk4_utf8_decoder_t	 dec;
  dk4_c16_t		 c16[4];
  size_t		 rdb	= 0;
  size_t		 back	= 0;
  size_t		 sz;
  dk4_c32_t		 c32;

  if (NULL != src) {
    /*	Initialize data structures.
    */
    dk4error_init(&er);
    dk4utf8_init(&dec);
    /*	Process source string.
    */
    while ('\0' != *src) {
      rdb++;
      switch(dk4utf8_add(&dec, (unsigned char)(*(src++)))) {
        case DK4_EDSTM_FINISHED: {
	  c32 = dk4utf8_get(&dec);
	  dk4utf8_init(&dec);
	  sz = DK4_SIZEOF(c16,dk4_c16_t);
	  if (0 != dk4utf16_encode(c16, &sz, c32, &er)) {
	    if ((SIZE_MAX - sz) >= back) {
	      back += sz;
	    } else {
	      dk4error_set_simple_error_code(&er, DK4_E_MATH_OVERFLOW);
	    }
	  } else {
	    dk4error_set_elsize_nelem(&er, DK4_E_SYNTAX, 1, rdb);
	  }
	} break;
	case DK4_EDSTM_ERROR: {
	  dk4error_set_elsize_nelem(&er, DK4_E_SYNTAX, 1, rdb);
	} break;
      }
    }
    if (0 == dk4utf8_is_empty(&dec)) {
      dk4error_set_elsize_nelem(&er, DK4_E_SYNTAX, 1, rdb);
    }
    /*	Add one for the finalizer.
    */
    if (SIZE_MAX == back) {
      dk4error_set_simple_error_code(&er, DK4_E_MATH_OVERFLOW);
    } else {
      back++;
    }
    /*	On error return 0 and pass error code.
    */
    if (DK4_E_NONE != er.ec) {
      back = 0;
      dk4error_copy(erp, &er);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}



int
dk4recode_utf8_to_utf16(
  dk4_c16_t *dstb, size_t szdstb, const char *src, dk4_er_t *erp
)
{
  dk4_c16_t		 buf[8];
  dk4_utf8_decoder_t	 dec;
  size_t		 sz;
  size_t		 used	=	0;
  size_t		 rdb	=	0;
  dk4_c32_t		 c32	=	dkC32(0);
  int			 back	=	0;

  if ((NULL != dstb) && (NULL != src) && (0 < szdstb)) {
    back = 1;
    dk4utf8_init(&dec);
    while(('\0' != *src) && (1 == back) && (used < szdstb)) {
      switch(dk4utf8_add(&dec, (unsigned char)(*(src++)))) {
        case DK4_EDSTM_FINISHED: {
	  c32 = dk4utf8_get(&dec);
	  dk4utf8_init(&dec);
	  sz = DK4_SIZEOF(buf,dk4_c16_t);
	  if (0 != dk4utf16_encode(buf, &sz, c32, erp)) {
	    if ((szdstb - used) > sz) {
	      DK4_MEMCPY(&(dstb[used]),buf,(2 * sz));
	      used += sz;
	    } else {
	      back = 0;
	      dk4error_set_simple_error_code(erp, DK4_E_BUFFER_TOO_SMALL);
	    }
	  } else {
	    back = 0;
	    dk4error_set_elsize_nelem(erp, DK4_E_SYNTAX, 1, rdb);
	  }
	} break;
	case DK4_EDSTM_ERROR: {
	  back = 0;
	  dk4error_set_elsize_nelem(erp, DK4_E_SYNTAX, 1, rdb);
	} break;
      }
      if(back) { rdb++; }
    }
    if (used < szdstb) {
      dstb[used] = (dk4_c16_t)0U;
    } else {
      dstb[szdstb - 1] = (dk4_c16_t)0U;
      back = 0;
      dk4error_set_simple_error_code(erp, DK4_E_BUFFER_TOO_SMALL);
    }
    if (0 == dk4utf8_is_empty(&dec)) {
      back = 0;
      dk4error_set_elsize_nelem(erp, DK4_E_SYNTAX, 1, rdb);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}