/**
* @return int
*/
public function encodeModeStructure()
{
try {
$bs = new BitStream();
$bs->appendNum(4, 0x3);
$bs->appendNum(4, ord($this->data[1]) - 1);
$bs->appendNum(4, ord($this->data[0]) - 1);
$bs->appendNum(8, ord($this->data[2]));
$this->bStream = $bs;
} catch (\Exception $e) {
return -1;
}
return 0;
}
/**
* @param BitStream $bStream
*
* @return int
*/
public function appendPaddingBit(BitStream &$bStream)
{
$bits = $bStream->size();
$maxWords = Specifications::getDataLength($this->version, $this->level);
$maxBits = $maxWords * 8;
if ($maxBits == $bits) {
return 0;
}
if ($maxBits - $bits < 5) {
return $bStream->appendNum($maxBits - $bits, 0);
}
$bits += 4;
$words = (int) (($bits + 7) / 8);
$padding = new BitStream();
$ret = $padding->appendNum($words * 8 - $bits + 4, 0);
if ($ret < 0) {
return $ret;
}
$padLen = $maxWords - $words;
if ($padLen > 0) {
$padBuf = [];
for ($i = 0; $i < $padLen; $i++) {
$padBuf[$i] = $i & 1 ? 0x11 : 0xec;
}
$ret = $padding->appendBytes($padLen, $padBuf);
if ($ret < 0) {
return $ret;
}
}
$ret = $bStream->append($padding);
return $ret;
}