Two's complement conversion

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I need to convert bytes in two's complement format to positive integer bytes. The range -128 to 127 mapped to 0 to 255.

Examples: -128 (10000000) -> 0 , 127 (01111111) -> 255, etc.

EDIT To clear up the confusion, the input byte is (of course) an unsigned integer in the range 0 to 255. BUT it represents a signed integer in the range -128 to 127 using two's complement format. For example, the input byte value of 128 (binary 10000000) actually represents -128.

EXTRA EDIT Alrighty, lets say we have the following byte stream 0,255,254,1,127. In two's complement format this represents 0, -1, -2, 1, 127. This I need clamping to the 0 to 255 range. For more info check out this hard to find article: Two's complement

twos-complement c#
10 Answers

So the problem is that the OP's problem isn't really two's complement conversion. He's adding a bias to a set of values, to adjust the range from -128..127 to 0..255.

To actually do a two's complement conversion, you just typecast the signed value to the unsigned value, like this:

sbyte test1 = -1;
byte test2 = (byte)test1;

-1 becomes 255. -128 becomes 128. This doesn't sound like what the OP wants, though. He just wants to slide an array up so that the lowest signed value (-128) becomes the lowest unsigned value (0).

To add a bias, you just do integer addition:

newValue = signedValue+128;
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