code: protected function readInt32( $pos = 0 ) {
  		static $lookups;
  
  		if ( !$lookups ) {
  			$lookups = [];
  			for ( $i = 1; $i < 256; $i++ ) {
  				$lookups[ chr( $i ) ] = $i;
  			}
  		}
  
  		$buf = $this->read( $pos, 4 );
  
  		$rv = 0;
  
  		if ( $buf[0] !== "\x0" ) {
  			$rv = $lookups[ $buf[0] ];
  		}
  		if ( $buf[1] !== "\x0" ) {
  			$rv |= ( $lookups[ $buf[1] ] << 8 );
  		}
  		if ( $buf[2] !== "\x0" ) {
  			$rv |= ( $lookups[ $buf[2] ] << 16 );
  		}
  		if ( $buf[3] !== "\x0" ) {
  			$rv |= ( $lookups[ $buf[3] ] << 24 );
  		}
  
  		return $rv;
  	}
docs: Unpack a 32-bit integer.
  
  @param int $pos
  @return int