Noob question on setting/testing bits in Golang

[Tom D]

Hi all,

As someone who came to Go from python (as opposed to C) I never really had used bit manipulation before. Now I find myself in need of it.

These are my questions:

1. How can I easily set a bit in a byte of a []byte?

2. How can I easily test a bit in a byte of a []byte?

3. How can I easily set a 16bit/24/32/anything []byte to be the value of a number? (for instance, if a spec says bytes 3-4 are an unsigned/signed int16/24/32/whatever)

I know I have to use the << (or is it >>) operator, but I don't quite understand.

Thanks for your help :),

Tom

[Eric Gavaletz]

This is the best collection I have come across.  The examples are given in C, but port easily to Go.

http://graphics.stanford.edu/~seander/bithacks.html

[Michael Jones]

Go bit operations echo C.

Tutorials:

http://www.cprogramming.com/tutorial/bitwise_operators.html

http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/BitOp/bitwise.html

http://en.wikipedia.org/wiki/Bitwise_operations_in_C

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[Rob Pike]

Go has the &^ bit clear operator, which C does not.

-rob

[Michael Jones]

...and neither have <<< and >>> (or some other) for rotations.

x = x <<< 17

is clearer than

c = (x << 17) | (x >> 47)

or

c = (x << 17) | (x >> 15)

as the case may be.

On Wed, Oct 2, 2013 at 10:56 PM, Rob Pike <r...@golang.org> wrote:

Go has the &^ bit clear operator, which C does not.

-rob