<?php 
function _to_unicode($str)
{
	$mState = 0; // cached expected number of octets after the current octet until the beginning of the next clsUTF8 character sequence
	$mUcs4  = 0; // cached Unicode character
	$mBytes = 1; // cached expected number of octets in the current sequence

	$out = array();

	$len = strlen($str);

	for ($i = 0; $i < $len; $i++)
	{
		$in = ord($str[$i]);

		if ($mState == 0)
		{
			// When mState is zero we expect either a US-ASCII character or a
			// multi-octet sequence.
			if (0 == (0x80 & $in))
			{
				// US-ASCII, pass straight through.
				$out[] = $in;
				$mBytes = 1;
			}
			elseif (0xC0 == (0xE0 & $in))
			{
				// First octet of 2 octet sequence
				$mUcs4 = $in;
				$mUcs4 = ($mUcs4 & 0x1F) << 6;
				$mState = 1;
				$mBytes = 2;
			}
			elseif (0xE0 == (0xF0 & $in))
			{
				// First octet of 3 octet sequence
				$mUcs4 = $in;
				$mUcs4 = ($mUcs4 & 0x0F) << 12;
				$mState = 2;
				$mBytes = 3;
			}
			elseif (0xF0 == (0xF8 & $in))
			{
				// First octet of 4 octet sequence
				$mUcs4 = $in;
				$mUcs4 = ($mUcs4 & 0x07) << 18;
				$mState = 3;
				$mBytes = 4;
			}
			elseif (0xF8 == (0xFC & $in))
			{
				// First octet of 5 octet sequence.
				//
				// This is illegal because the encoded codepoint must be either
				// (a) not the shortest form or
				// (b) outside the Unicode range of 0-0x10FFFF.
				// Rather than trying to resynchronize, we will carry on until the end
				// of the sequence and let the later error handling code catch it.
				$mUcs4 = $in;
				$mUcs4 = ($mUcs4 & 0x03) << 24;
				$mState = 4;
				$mBytes = 5;
			}
			elseif (0xFC == (0xFE & $in))
			{
				// First octet of 6 octet sequence, see comments for 5 octet sequence.
				$mUcs4 = $in;
				$mUcs4 = ($mUcs4 & 1) << 30;
				$mState = 5;
				$mBytes = 6;
			}
			else
			{
				// Current octet is neither in the US-ASCII range nor a legal first octet of a multi-octet sequence.
				trigger_error('clsUTF8::to_unicode: Illegal sequence identifier in UTF-8 at byte '.$i, E_USER_WARNING);
				return FALSE;
			}
		}
		else
		{
			// When mState is non-zero, we expect a continuation of the multi-octet sequence
			if (0x80 == (0xC0 & $in))
			{
				// Legal continuation
				$shift = ($mState - 1) * 6;
				$tmp = $in;
				$tmp = ($tmp & 0x0000003F) << $shift;
				$mUcs4 |= $tmp;

				// End of the multi-octet sequence. mUcs4 now contains the final Unicode codepoint to be output
				if (0 == --$mState)
				{
					// Check for illegal sequences and codepoints

					// From Unicode 3.1, non-shortest form is illegal
					if (((2 == $mBytes) AND ($mUcs4 < 0x0080)) OR
						((3 == $mBytes) AND ($mUcs4 < 0x0800)) OR
						((4 == $mBytes) AND ($mUcs4 < 0x10000)) OR
						(4 < $mBytes) OR
						// From Unicode 3.2, surrogate characters are illegal
						(($mUcs4 & 0xFFFFF800) == 0xD800) OR
						// Codepoints outside the Unicode range are illegal
						($mUcs4 > 0x10FFFF))
					{
						trigger_error('clsUTF8::to_unicode: Illegal sequence or codepoint in UTF-8 at byte '.$i, E_USER_WARNING);
						return FALSE;
					}

					if (0xFEFF != $mUcs4)
					{
						// BOM is legal but we don't want to output it
						$out[] = $mUcs4;
					}

					// Initialize UTF-8 cache
					$mState = 0;
					$mUcs4  = 0;
					$mBytes = 1;
				}
			}
			else
			{
				// ((0xC0 & (*in) != 0x80) AND (mState != 0))
				// Incomplete multi-octet sequence
				trigger_error('clsUTF8::to_unicode: Incomplete multi-octet sequence in UTF-8 at byte '.$i, E_USER_WARNING);
				return FALSE;
			}
		}
	}

	return $out;
}