utf8_to_unicode in PHP

想使用8:UCS2格式編碼下行簡訊的時候,需要把UTF8轉換成Unicode的十六進位編碼，但是PHP沒有內建Unicode的支援，怎麼辦呢?

/* *
* 從UTF8轉換成unicode beta1.0
* @param mixed $string要轉換的字串,
* @return unicode的十六進位編碼
*/
function utf8_to_unicode_hex( $string ){
$length = strlen ( $string );
$outstring = "" ;
for ( $i = 0 ; $i < $length ; $i ++ ) {
$asc_value = ord ( $string [ $i ]);
if ( $asc_value > 127 ) {
if ( $asc_value >= 192 && $asc_value <= 223 ){
$str_dec = ( ord ( $string [ $i ]) & 0x3f ) << 6 ;
$i ++ ;
$str_dec += ord ( $string [ $i ]) & 0x3f ;
$str_hex = dechex ( $str_dec );
$outstring .= str_pad ( $str_hex , 4 , " 0 " , STR_PAD_LEFT);
} elseif ( $asc_value >= 224 && $asc_value <= 239 ){
$str_dec = ( ord ( $string [ $i ]) & 0x1f ) << 12 ;
$i ++ ;
$str_dec += ( ord ( $string [ $i ]) & 0x3f ) << 6 ;
$i ++ ;
$str_dec += ord ( $string [ $i ]) & 0x3f ;
$outstring .= dechex ( $str_dec );
} elseif ( $asc_value >= 240 && $asc_value <= 247 ){
$str_dec = ( ord ( $string [ $i ]) & 0x0f ) << 18 ;
$i ++ ;
$str_dec += ( ord ( $string [ $i ]) & 0x3f ) << 12 ;
$i ++ ;
$str_dec += ( ord ( $string [ $i ]) & 0x3f ) << 6 ;
$i ++ ;
$str_dec += ord ( $string [ $i ]) & 0x3f ;
$outstring .= dechex ( $str_dec );
} else {
$str_hex = dechex ( ord ( $string [ $i ]));
$outstring .= str_pad ( $str_hex , 4 , " 0 " , STR_PAD_LEFT);
}
} else {
$str_hex = dechex ( ord ( $string [ $i ]));
$outstring .= str_pad ( $str_hex , 4 , " 0 " , STR_PAD_LEFT);
}
}
return $outstring ;
}

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