Npp functions (gammaCorrection): where to find source code

Hi guys,

I found the function nppiGammaFwd_8u_C3R (NVIDIA 2D Image And Signal Performance Primitives (NPP): Color Gamma Correction) which performs gammaCorrection. But there is no GammaValue to specify, that is why I want to look up in the source code what this function is excactly doing.
Where can I find the source code?

Thank you for your help!