crc32() and hash('crc32') Differ

Hi, I'm curious why I'm getting two different digests of the same message using crc32() and hash('crc32'). I've tried both hash('crc32') and hash('crc32b'), and neither match my crc32(). Some example code: <?php $message = "foo"; $crc32 = crc32($message); $hash_crc32 = hash('crc32', $message); $hash_crc32b = hash('crc32b', $message); $data = array ( array ( sprintf('%+011d', $crc32), // signed integer sprintf('%010u', $crc32), // unsigned integer

			dechex($crc32),            // hexadecimal

sprintf('%032b', $crc32) // binary ), array ( sprintf('%+011d', hexdec($hash_crc32)), sprintf('%010u', hexdec($hash_crc32)), $hash_crc32, sprintf('%032b', hexdec($hash_crc32)) ), array ( sprintf('%+011d', hexdec($hash_crc32b)), sprintf('%010u', hexdec($hash_crc32b)), $hash_crc32b, sprintf('%032b', hexdec($hash_crc32b)) ) ); echo join("\n", array_map(create_function('$vals', 'return join(" => ", $vals);'), array_values($data))); ?> Output: -1938594527 => 2356372769 => 8c736521 => 10001100011100110110010100100001 -1513816503 => 2781150793 => a5c4fe49 => 10100101110001001111111001001001 +0560296844 => 0560296844 => 2165738c => 00100001011001010111001110001100 Not only do none of these match, but when I try with a message that I intend to validate and am given a CRC32 to check against, the given CRC32 hash does not match any of these three. Granted, the message I'm trying to validate could in fact be invalid, but regardless there's still the discrepancy between crc32() and hash('crc32'). Is this expected behavior? Thanks, Morgan