[Snippet] RightShift

[Magtheridon96]

/************************************************
*
*   RightShift
*   v1.1.1.0
*   By Magtheridon96
*
*   - Used to perform the bitwise RIGHTSHIFT
*     operation for 8 bits. (1 byte)
*
*   API:
*   ----
*
*       function B_RIGHTSHIFT takes integer byte, integer n returns integer
*           - Returns (byte >> n)
*           - The arguments must be in the range [0x00 ... 0xff]
*           - The return value will be in the range [0x00 ... 0xff]
*
*       function B_RIGHTSHIFT_CARRY takes integer byte, integer n returns integer
*           - Returns the bits lost in (x) after (x >> n) is performed.
*           - B_RIGHTSHIFT_CARRY(0x5, 2) = 0x1
*           - B_RIGHTSHIFT_CARRY(0x5, 3) = 0x5
*
************************************************/
library RightShift
    
    function B_RIGHTSHIFT_CARRY takes integer byte, integer n returns integer
        return byte - byte / GetPowerOfTwo(n) * GetPowerOfTwo(n)
    endfunction
    
    function B_RIGHTSHIFT takes integer byte, integer n returns integer
        return byte / GetPowerOfTwo(n)
    endfunction
    
endlibrary

Yes, just another Bitwise operation snippet.
Nothing much to say really.

Feel free to comment, I guess..

 

[Nestharus]

Optimize this using the method we talked about in chat : )

 

[Magtheridon96]

function B_RIGHTSHIFT takes integer byte, integer n returns nothing
    return byte / powersOfTwo[n]
endfunction

Like that?

The carry would have to be handled by the user, meaning while writing the MD5 library, I'd have to find the carries myself.

This way, this resource does exactly what people would expect it to do:
Rightshift a byte and that's it.

edit
First, I'm going to make a repository for powersOfTwo.
Having that code repeated in many libraries is a terrible idea.

 

[Magtheridon96]

Updated.

 

[Nestharus]

For bytes, I would just do a lookup table

shiftLeft[0xff] = 0xf0
shiftRight[0xff] = 0x0f
shiftLeftCarry[0xff] = 0xf
shiftRightCarry[0x0ff] = 0xf

for integers, you want to use the math

 

[Magtheridon96]

Good idea.
I'll do that now.

 

[Magtheridon96]

Updated to fix an overflow problem.

 

[Nestharus]

lol..

        if output > 0xff then
            return output - output / 256 * 256
        endif

in right shift?? the number lowers in right shift
you don't need that

also, I'd drop the if statement and just do the mod, but only have mod in left shift