memcpy from Byte * to unsigned int Is Reversing Byte Order

Question

I have a CFBitVector that looks like '100000000000000' I pass the byte array to CFBitVectorGetBits, which then contains the values from this CFBitVector. After this call, bytes[2] looks like:

bytes[0] == '0x80'
bytes[1] == '0x00'

This is exactly what I would expect. However, when copying the contents of bytes[2] to unsigned int bytesValue, the value is 128 when it should be 32768. The decimal value 128 is represented by the hex value 0x0080. Essentially it seems that the byte order is reversed while performing memcpy. What is going on here? Is this just an issue with endianness?

Thanks

CFMutableBitVectorRef bitVector = CFBitVectorCreateMutable(kCFAllocatorDefault, 16);
CFBitVectorSetCount(bitVector, 16);

CFBitVectorSetBitAtIndex(bitVector, 0, 1);

CFRange range = CFRangeMake(0, 16);
Byte bytes[2] = {0,0};
unsigned int bytesValue = 0;

CFBitVectorGetBits(bitVector, range, bytes);
memcpy(&bytesValue, bytes, sizeof(bytes));

return bytesValue;

Answer 1

What is going on here? Is this just an issue with endianness?

Yes.

Your computer is little endian. The 16-bit value 32768 would be represented in-memory as:

00 80

On a little endian machine. You have:

80 00

Which is the opposite, representing 128 as you're seeing.