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Next Power Of 2
Submitted by |
Here is my little code of the day tip thing, its used to replace
all those large and bulky NextPow2 functions that people always
seem to use. Its simple and effective and it works, well on Intel
based systems anyways - I'm sure that it could be adapted to the
motorolla and other chips.
What it does is it uses intel's Bit Scan Reverse function to scan
the integer from the highiest bit to the lowest bit that is a '1'.
Then it puts the location of that bit into the ecx value, that is
increased by one so it will get the next highiest value, and finally
the return value is shifted by the ecx register to return the next
highiest power of two.
Dominik Grabiec
(a.k.a Dæmin)
sdgrab@eisa.net.au
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Download Associated File: nextpow2.cpp (305 bytes)
//Editor's note:
//COTD Entry: Next Power Of 2 by Dominik Grabiec [sdgrab@eisa.net.au]
__inline int NextPow2(int Number)
{
unsigned int RetVal = 1;
__asm
{
xor ecx, ecx
bsr ecx, Number
inc ecx
shl RetVal, cl
}
return(RetVal);
} |
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