private static byte[] calculateCRC32(PNGChunk chunk) {
		CRC32 checksum = new CRC32();
		checksum.update(ByteBuffer.allocate(4 + chunk.getLength()).putInt(chunk.getChunkID()).put(
			chunk.getData()).array());
		long result = checksum.getValue();
		return ByteBuffer.allocate(4).putInt((int) result).array();

	}
Calculates the crc32 based on info gathered from a given PNGChunk
@param chunk the chunk to calculate crc32 from
@return The crc32 result
Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ios/png/CrushedPNGUtil.java