C and Python code to Java help

Question

I'm trying to read in some bytes from a file in Java and then create bitmasks from some of the data and lengths and offsets from others.

I'm so close to getting my program working but I keep getting garbled data coming out the other end.

I'm 90% sure my problem is something to do with the way that Java is reading the bytes in.

There is some Python and C code that I'm basing my design on but I don't know how to convert this into Java. I've tried wrapping a byte[] in a byteBuffer but I'm still getting confusing results.

This is what I'm trying to get my head around:

bitmask:= copy inputBuffer[inputIndex] as 32-bit integer in little-endian format - needs to be four bytes

In C this is done as:

bitmask= (inputBuffer[inputIndex + 3] << 24) | (inputBuffer[inputIndex + 2] << 16) |
                        (inputBuffer[inputIndex + 1] <<  8) | inputBuffer[inputIndex];

In Python this is: bitmask= unpack("<L", inputBuffer[inputIndex:inputIndex + 4])[0]

Until I can get this working correctly my program is falling over.

Can anyone offer any information on the best way of implementing this?

Many thanks

Tony

I've put a bit of the code here mrthaggar.com/partialCode.txt Apologies for it being a bit messy, I hope you can understand what I'm trying to do from it!! — Tony
– Tony, Commented Jan 23, 2011 at 15:19
@user583240: Please add the Java code you're trying to use to this question. Please add the exact part that's supposed to match the Python and C parts. Please update the question. — S.Lott
– S.Lott, Commented Jan 23, 2011 at 18:08

bestsss · Accepted Answer · 2011-05-29 09:46:53Z

1

you can set ByteBuffer's byteOrder to littleEndian and just use getInt

edited May 29, 2011 at 9:46

answered Jan 23, 2011 at 13:55

bestsss

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