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

> ## Name

> bitfieldExtract - return an extracted range of bits from a bitfield.

> ## Synopsis

>     int  bitfieldExtract(int  a, int b, int c)
>     int2 bitfieldExtract(int2 a, int b, int c)
>     int3 bitfieldExtract(int3 a, int b, int c)
>     int4 bitfieldExtract(int4 a, int b, int c)

>     uint  bitfieldExtract(uint  a, int b, int c)
>     uint2 bitfieldExtract(uint2 a, int b, int c)
>     uint3 bitfieldExtract(uint3 a, int b, int c)
>     uint4 bitfieldExtract(uint4 a, int b, int c)

> ## Parameters

> a
>   Bitfield to extract bits from.
> b
>   Bit offset number. Bit offsets start at 0.
> c
>   Number of bits to extract.

> ## Description

> Returns bits from offset b of length c in the bitfield a.

> ## Reference Implementation

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

>     int bitfieldExtract(int a, int b, int c)
>     {
>       int mask = ~(0xffffffff << c);
>       if (b > 0)
>         return (a >> (b - 1)) & mask;
>       else
>         return a & mask;
>     }

> ## Profile Support

> bitfieldExtract is supported in gp5 profiles.

> ## See Also

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

> bitfieldInsert, bitfieldReverse, bitCount, findLSB and findMSB