bitCount
Keywords: bitCount, NVIDIA, NVIDIA Cg Toolkit, Cg Toolkit, Shader, Shader Programming, GPU Shader Programming, GPU Program

> ## Name

> bitCount - return the number of bits set in a bitfield.

> ## Synopsis

>     int  bitCount(int  x)
>     int2 bitCount(int2 x)
>     int3 bitCount(int3 x)
>     int4 bitCount(int4 x)

>     int  bitCount(uint  x)
>     int2 bitCount(uint2 x)
>     int3 bitCount(uint3 x)
>     int4 bitCount(uint4 x)

> ## Parameters

> x
>   Bitfield to count bits in.

> ## Description

> Returns the count of set bits (value of 1) in the bitfield x.

> ## Reference Implementation

> bitCount for an int bitfield can be implemented like this:

>     int bitCount(int x)
>     {
>       int i;
>       int res = 0;
>       for(i = 0; i < 32; i++) {
>         mask = 1 << i;
>         if (x & mask)
>           res ++;
>       }
>       return res;
>     }

> ## Profile Support

> bitCount is supported in gp5 profiles.

> ## See Also

>       http://www.opengl.org/registry/specs/ARB/gpu_shader5.txt

> bitfieldExtract, bitfieldInsert, bitfieldReverse, findLSB and findMSB