keon/awesome-bits

:computer: A curated list of awesome bitwise operations and tricks

awesome-bits's Issues

Color conversoin seems wrong

Fast color conversion from R5G5B5 to R8G8B8 pixel format using shifts

R8 = (R5 << 3) | (R5 >> 2)
G8 = (R5 << 3) | (R5 >> 2)
B8 = (R5 << 3) | (R5 >> 2)

This looks to assign the same value to R8, G8 and B8

Atan2

https://discourse.processing.org/t/fast-approximate-square-root/12074/9

Round doesn't handle .5-iota correctly

See this page for a correct implementation of round.

Test Code in C

I'll put a testing code in c for each of the tricks.

add restrictions & dependencies

Shifting by a negative value is undefined behaviour in C. Also you should make sure that the second operand is never higher than or equal to the bit-width of the left-hand type, since that is undefined as well.

m & (n - 1) doesn't seem to work as m % (pow(2, n))

I assume "Modulo 2ⁿ against m" means m % (pow(2, n)). In that case, for m=11 and n = 3, m & (n - 1) gives 2, but 11 % 8 gives 3. Perhaps you mean m & ((1 << n) - 1)?

xor swap should be discouraged

a ^= b;
b ^= a;
a ^= b;

this technique should be discouraged, at least notes should be added. as it is by no means better than the temp approach. looking from the execution instruction perspective.

A finished Chinese translation

Find this repo really helpful.
So I translated it into Chinese.
https://github.com/RangerCD/awesome-bits/tree/zh_cn
I was wondering if you could start a new branch or add a link somewhere.

LaTeX support for the Readme

Hey @KeonKim,

It looks like this repository would really benefit from having some LaTeX typesetting. I'd be happy to set up a natural-looking typesetting script if you would like; the downside is that contributors will need to have some prerequisites and will need to run a script on check-out. Let me know if you think this might be a good idea. For reference, the renderer is at https://github.com/leegao/readme2tex

"Whether a number is some factorial of 2"

I think that should say "power" of 2, not "factorial" =)