#include <stdlib.h>

#include <string.h>

#include "utf8.h"

/* Desc: convert UTF8 -> ASCII

 * 

 * In  : UTF8 string

 * Out : ASCII string

 *

 * Note: it is up to the caller to free the returned string

 */

char *utf8_decode(const char *src)

{

  unsigned char *ret, *aux;

  if (!src) return NULL;

  aux = ret = calloc(1, strlen(src) + 1);

  while (*src) {

    unsigned char lead = *src++;

    if ((lead & 0xe0) == 0xc0) {

      unsigned char ch2 = *src++;

      *aux = ((lead & 0x1f) << 6) | (ch2 & 0x3f);

    } else {

      *aux = lead;

    }

    aux++;

  }

  return (char*)ret;

}

/* Desc: convert ASCII -> UTF8

 * 

 * In  : ASCII string

 * Out : UTF8 string

 *

 * Note: it is up to the caller to free the returned string

 */

char *utf8_encode(const char *src)

{

  unsigned char *ret, *aux;

  if (!src) return NULL;

  aux = ret = calloc(1, (strlen(src) * 2) + 1);

  while (*src) {

    unsigned char ch = *src++;

    if (ch < 0x80U) {

      *aux++ = ch;

    } else {  /* if (ch < 0x800U) { */

      *aux++ = 0xc0 | (ch >> 6);

      *aux++ = 0x80 | (ch & 0x3f);

    }

  }

  return (char*)ret;

}