array_cart2polar.cuh
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#ifndef STIM_CUDA_ARRAY_CART2POLAR_H
#define STIM_CUDA_ARRAY_CART2POLAR_H
namespace stim{
namespace cuda{
template<typename T>
__global__ void cuda_cart2polar(T* a, int x, int y){
// calculate the 2D coordinates for this current thread.
int xi = blockIdx.x * blockDim.x + threadIdx.x;
int yi = blockIdx.y * blockDim.y + threadIdx.y;
// convert 2D coordinates to 1D
int i = yi * x + xi;
if(xi >= x|| yi >= y) return;
float xl = a[i * 2 + 0];
float yl = a[i * 2 + 1];
float theta = atan2( yl, xl ) ;
float r = sqrt(xl * xl + yl * yl);
a[i * 2 + 0] = theta;
a[i * 2 + 1] = r;
}
template<typename T>
void gpu_cart2polar(T* gpuGrad, unsigned int x, unsigned int y){
unsigned int max_threads = stim::maxThreadsPerBlock();
dim3 threads(max_threads, 1);
dim3 blocks(x/threads.x + (x %threads.x == 0 ? 0:1) , y);
//call the kernel to do the multiplication
cuda_cart2polar <<< blocks, threads >>>(gpuGrad, x, y);
}
template<typename T>
void cpu_cart2polar(T* a, unsigned int x, unsigned int y){
//calculate the number of bytes in the array
unsigned int N = x *y;
unsigned int bytes = N * sizeof(T) * 2;
//allocate memory on the GPU for the array
T* gpuA;
HANDLE_ERROR( cudaMalloc(&gpuA, bytes) );
//copy the array to the GPU
HANDLE_ERROR( cudaMemcpy(gpuA, a, bytes, cudaMemcpyHostToDevice) );
//call the GPU version of this function
gpu_cart2polar<T>(gpuA, x, y);
//copy the array back to the CPU
HANDLE_ERROR( cudaMemcpy(a, gpuA, bytes, cudaMemcpyDeviceToHost) );
//free allocated memory
cudaFree(gpuA);
}
}
}
#endif