%%	options

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


%%	header

/**	@file
	String recoding from 32 bit to UTF-8.

	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 32 bit to UTF-8.
	@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_c32_to_utf8(
  char *dstb, size_t szdstb, const dk4_c32_t *src, dk4_er_t *erp
);

/**	Calculate required buffer size (including final 0x00 byte)
	for C32 to UTF-8 conversion.
	@param	src	C32 source string.
	@param	erp	Error report, may be NULL.
	@return	Positive buffer size on success, 0 on error.

	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if src or dstb is NULL or szdstb is 0,
	- DK4_E_SYNTAX<br>
	  with the number of successfully recoded characters in nelem if a
	  non-recodable character was found.
*/
size_t
dk4recode_size_c32_to_utf8(const dk4_c32_t *src, dk4_er_t *erp);

#ifdef __cplusplus
}
#endif

%%	module

#include "dk4rec18.h"
#include "dk4mem.h"
#include "dk4utf8.h"



$!trace-include



size_t
dk4recode_size_c32_to_utf8(const dk4_c32_t *src, dk4_er_t *erp)
{
  dk4_er_t		 er;
  unsigned char		 buf[8];
  size_t		 sz;
  size_t		 rd	= 0;
  size_t		 back	= 0;
  dk4_c32_t		 c32	= dkC32(0);

  if (NULL != src) {
    dk4error_init(&er);
    while (dkC32(0) != (c32 = *(src++))) {
      sz = sizeof(buf);
      if (0 != dk4utf8_encode(buf, &sz, c32, &er)) {
        if ((SIZE_MAX - sz) >= back) {
	  back += sz;
	  rd++;
	} else {
	  dk4error_set_simple_error_code(&er, DK4_E_MATH_OVERFLOW);
	}
      }
    }
    if (SIZE_MAX > back) {
      back++;
    } else {
      dk4error_set_simple_error_code(&er, DK4_E_MATH_OVERFLOW);
    }
    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_c32_to_utf8(
  char *dstb, size_t szdstb, const dk4_c32_t *src, dk4_er_t *erp
)
{
  unsigned char	 buf[8];
  size_t	 sz;
  size_t	 rd	=	0;
  size_t	 used	=	0;
  dk4_c32_t	 c32	=	dkC32(0);
  int		 back	=	0;

  if ((NULL != dstb) && (0 < szdstb) && (NULL != src)) {
    back = 1;
    while((dkC32(0) != *src) && (1 == back) && (used < szdstb)) {
      c32 = *(src++);
      sz = sizeof(buf);
      if (0 != dk4utf8_encode(buf, &sz, c32, erp)) {
        if ((szdstb - used) > sz) {
	  DK4_MEMCPY(&(dstb[used]),buf,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, 4, rd);
      }
      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);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}