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[TUT] Bits, Bit-fields, and Bit-wise Operators


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Bugsy
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Join Date: Feb 2005
Location: NJ, USA
Old 05-20-2014 , 11:57   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #71

claudiuhks: That post is over three years old.
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Last edited by Bugsy; 05-20-2014 at 11:59.
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vitorrossi
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Join Date: Apr 2012
Location: NY, USA
Old 05-13-2015 , 20:16   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #72

Stock that returns the number of SetBits in a bitfield, aka hamming weight or popcount:

PHP Code:
     NumberOfSetBits(iBitField)
    {
        
iBitField iBitField - ((iBitField >> 1) & 0x55555555);
        
iBitField = (iBitField 0x33333333) + ((iBitField >> 2) & 0x33333333);
        return (((
iBitField + (iBitField >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
    } 
Taken from here
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PartialCloning
Senior Member
Join Date: Dec 2015
Old 08-30-2016 , 03:00   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #73

If I have a variable equal to (1 << value) is it possible to get the value part of it?
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KliPPy
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Join Date: May 2013
Location: Serbia
Old 08-30-2016 , 07:03   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #74

I can't think of any efficient way, but what exactly are you trying to achieve? Having to find that value doesn't seem like a good thing to me.

EDIT:
This could work, but I don't like that it's a loop:
PHP Code:
getValue(variable) {
    for(new 
032i++) {
        if(
variable == (<< i)) {
            return 
i;
        }
    }
    
    
// Some invalid state I guess, variable has more than 1 bit set.
    
return -1;


Last edited by KliPPy; 08-30-2016 at 07:07.
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Emp`
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Join Date: Aug 2005
Location: Decapod 10
Old 08-30-2016 , 20:52   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #75

Alternative to KliPPy's:
PHP Code:
stock BitShiftCount)
{
    new 
i;
    while ( 
&& !( ) )
    {
        
>>= 1;
        
i++;
    }
    return 
i;


Last edited by Emp`; 08-31-2016 at 19:07. Reason: forgot this isn't the SourceMod section
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Old 08-30-2016, 23:31
Bugsy
This message has been deleted by Bugsy. Reason: nvm, misread
Bos93
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Join Date: Jul 2010
Old 08-31-2016 , 18:53   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #76

int i
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Depresie
Veteran Member
Join Date: Nov 2013
Old 10-02-2016 , 22:35   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #77

Now this, this is, this is a fucking bad ass tutorial, these little fuckers can be extremely useful
I tried to learn about bits some time ago, but i couldn't understand even the basic things from what i found on google, but this man is golden when it comes to tutorials
Thanks Bugs
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eyal282
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Join Date: Aug 2011
Old 06-06-2017 , 10:43   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #78

Can you do for example:

#define SetUserBool(%1,%2) ( %1 |= (1 << (%2 - 1)))

Because it will range from 0 to 31.

Last edited by eyal282; 06-06-2017 at 18:08.
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Bugsy
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Join Date: Feb 2005
Location: NJ, USA
Old 06-06-2017 , 10:52   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #79

SetUserBool(%1,%2) ( %1 |= (1 << (%2 - 1)))

You used |= instead of left shift and you should shift 1, not %1, but yea that will work as long as only 1 to 32 are inputted. Same logic as using ( %2 & 31 ).
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Last edited by Bugsy; 06-06-2017 at 10:53.
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eyal282
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Join Date: Aug 2011
Old 06-06-2017 , 18:07   Re: [TUT] Bits, Bit-fields, and Bit-wise Operators
Reply With Quote #80

Quote:
Originally Posted by Bugsy View Post
SetUserBool(%1,%2) ( %1 |= (1 << (%2 - 1)))

You used |= instead of left shift and you should shift 1, not %1, but yea that will work as long as only 1 to 32 are inputted. Same logic as using ( %2 & 31 ).
Yeah, mistake.
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