UTF-8.php

<?php
/**
 * $dec2char(65)       => A
 * $dec2char(15243674) => 虚 pack('C*',232,153,154)
 *
 *  @var char
 */
$dec2char = function ($hex)
{
	$z = array();
	$h = dechex($hex);
	while ($h !== '' && $h !== false) {
		$z[] = substr($h, -2, 2);
		$h = substr($h, 0, strlen($h) - 2);
	}
	foreach (array_reverse($z) as $n => $v) $z[$n] = hexdec($v);
	array_unshift($z, 'C*');
	return call_user_func_array('pack',$z);
};

/**
 * ucs code point convert char
 *
 * ucsBin('U+0x41')   => A
 * ucsBin('0x41')     => A
 * ucsBin('41')       => A
 * ucsBin('U+0x3042') => あ
 * ucsBin('0x3042')   => あ
 * ucsBin('3042')     => あ
 *
 * @param string $ucs 'U+0x???' or '0x???' or '???'
 *
 * @return string|false
 */
function ucsBin($ucs)
{
	$r = array();
	$ucs = str_replace('U+0x', '', $ucs);
	$dec = hexdec($ucs);
	$bin = decbin($dec);

	if ($dec <= 0x7F) { // ASCII 0???????
		$bin = sprintf('%07s', $bin);
		$r[] = bindec(substr($bin, 0, 7));
	} elseif ($dec <= 0x7FF) {
		// 2byte 110????? 10??????
		$bin = sprintf('%011s', $bin);
		$r[] = bindec(substr($bin, 0, 5)) + 128 + 64;
		$r[] = bindec(substr($bin, 5, 6)) + 128;
	} elseif ($dec <= 0xFFFF) {
		// 3byte 1110???? 10?????? 10??????
		$bin = sprintf('%016s', $bin);
		$r[] = bindec(substr($bin, 0, 4)) + 128 + 64 + 32;
		$r[] = bindec(substr($bin, 4, 6)) + 128;
		$r[] = bindec(substr($bin, 10, 6)) + 128;
	} elseif ($dec <= 0x1FFFFF) {
		// 4byte 11110??? 10?????? 10?????? 10??????
		$bin = sprintf('%021s', $bin);
		$r[] = bindec(substr($bin, 0, 3)) + 128 + 64 + 32 + 16;
		$r[] = bindec(substr($bin, 3, 6)) + 128;
		$r[] = bindec(substr($bin, 9, 6)) + 128;
		$r[] = bindec(substr($bin, 15, 6)) + 128;
	} elseif ($dec <= 0x3FFFFFF) {
		// 5byte 111110?? 10?????? 10?????? 10?????? 10??????
		$bin = sprintf('%026s', $bin);
		$r[] = bindec(substr($bin, 0, 2)) + 128 + 64 + 32 + 16 + 8;
		$r[] = bindec(substr($bin, 2, 6)) + 128;
		$r[] = bindec(substr($bin, 8, 6)) + 128;
		$r[] = bindec(substr($bin, 14, 6)) + 128;
		$r[] = bindec(substr($bin, 20, 6)) + 128;
	} elseif ($dec <= 0x7FFFFFFF) {
		// 6byte 1111110? 10?????? 10?????? 10?????? 10?????? 10??????
		$bin = sprintf('%031s', $bin);
		$r[] = bindec(substr($bin, 0, 1)) + 128 + 64 + 32 + 16 + 8 + 4;
		$r[] = bindec(substr($bin, 1, 6)) + 128;
		$r[] = bindec(substr($bin, 7, 6)) + 128;
		$r[] = bindec(substr($bin, 13, 6)) + 128;
		$r[] = bindec(substr($bin, 19, 6)) + 128;
		$r[] = bindec(substr($bin, 25, 6)) + 128;
	} else {
		return false;
	}

	array_unshift($r, 'C*');
	return call_user_func_array('pack',$r);
}