\section{Initalization and Information}


\cvCppFunc{gpu::getCudaEnabledDeviceCount}
Returns number of CUDA-enabled devices installed. It is to be used before any other GPU funtions calls. If OpenCV is compiled without GPU support this function returns 0. 

\cvdefCpp{int getCudaEnabledDeviceCount();}


\cvCppFunc{gpu::setDevice}
Sets device and initializes it for current thread. If this call is omitted, default device will be initialized.

\cvdefCpp{void setDevice(int device);}
\begin{description}
\cvarg{device}{index of GPU device in system starting with 0.}
\end{description}


\cvCppFunc{gpu::getDevice}
Returns current device index, which was set by \cvCppCross{gpu::getDevice} of initialized by default.

\cvdefCpp{int getDevice();}


\cvCppFunc{gpu::getComputeCapability}
Returns compute capability version for given device.

\cvdefCpp{void getComputeCapability(int device, int\& major, int\& minor);}
\begin{description}
\cvarg{device}{GPU index. Can be obtained via \cvCppCross{gpu::getDevice}.}
\cvarg{major}{Major CC version.}
\cvarg{minor}{Minor CC version.}
\end{description}

\cvCppFunc{gpu::getNumberOfSMs}
Returns number of Streaming Multiprocessors for given device.

\cvdefCpp{int getNumberOfSMs(int device);}
\begin{description}
\cvarg{device}{GPU index. Can be obtained via \cvCppCross{gpu::getDevice}.}
\end{description}


\cvCppFunc{gpu::getGpuMemInfo}
Returns free and total memory for the current device.

\cvdefCpp{void getGpuMemInfo(size\_t\& free, size\_t\& total);}
\begin{description}
\cvarg{free}{Reference to free GPU memory counter.}
\cvarg{total}{Reference to total GPU memory counter.}
\end{description}


\cvCppFunc{gpu::hasNativeDoubleSupport}
Returns true, if the specified GPU has native double support, otherwise false.

\cvdefCpp{bool hasNativeDoubleSupport(int device);}
\begin{description}
\cvarg{device}{GPU index. Can be obtained via \cvCppCross{gpu::getDevice}.}
\end{description}


\cvCppFunc{gpu::hasAtomicsSupport}
Returns true, if the specified GPU has atomics support, otherwise false.

\cvdefCpp{bool hasAtomicsSupport(int device);}
\begin{description}
\cvarg{device}{GPU index. Can be obtained via \cvCppCross{gpu::getDevice}.}
\end{description} 


\cvCppFunc{gpu::ptxVersionIs}
Returns true, if the GPU module was built with PTX support of the given compute capability, otherwise false.

\cvdefCpp{bool ptxVersionIs(int major, int minor);}
\begin{description}
\cvarg{major}{Major compute capability version.}
\cvarg{minor}{Minor compute capability version.}
\end{description}


\cvCppFunc{gpu::ptxVersionIsLessOrEqual}
Returns true, if the GPU module was built with PTX support of the given compute capability or less, otherwise false.

\cvdefCpp{bool ptxVersionIsLessOrEqual(int major, int minor);}
\begin{description}
\cvarg{major}{Major compute capability version.}
\cvarg{minor}{Minor compute capability version.}
\end{description}


\cvCppFunc{gpu::ptxVersionIsGreaterOrEqual}
Returns true, if the GPU module was built with PTX support of the given compute capability or greater, otherwise false.

\cvdefCpp{bool ptxVersionIsGreaterOrEqual(int major, int minor);}
\begin{description}
\cvarg{major}{Major compute capability version.}
\cvarg{minor}{Minor compute capability version.}
\end{description}


\cvCppFunc{gpu::isCompatibleWith}
Returns true, if the GPU module is PTX compatible with the given NVIDIA GPU device, otherwise false.

\cvdefCpp{bool isCompatibleWith(int device);}
\begin{description}
\cvarg{device}{GPU index. Can be obtained via \cvCppCross{gpu::getDevice}.}
\end{description}

According to the CUDA C Programming Guide Version 3.2: "PTX code produced for some specific compute capability can always be compiled to binary code of greater or equal compute capability".