codebase / stimlib

  #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, float rotation){

  			// 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 + rotation;

  				a[i * 2 + 1] = r;

  		}
  
  
  		template<typename T>

  		void gpu_cart2polar(T* gpuGrad, unsigned int x, unsigned int y, float rotation = 0){

  			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, rotation);

  
  		}
  
  
  		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