codebase / stimlib

  #ifndef STIM_CUDA_UPDATE_DIR_BB_H
  #define STIM_CUDA_UPDATE_DIR_BB_H

  
  # include <iostream>
  # include <cuda.h>
  #include <stim/cuda/cudatools.h>
  #include <stim/cuda/sharedmem.cuh>

  #include <stim/visualization/aabb2.h>
  #include <stim/visualization/colormap.h>

  #include <math.h> 

  //#define RMAX_TEST	8

  
  namespace stim{
  	namespace cuda{

  		template<typename T>
  		__global__ void cuda_update_dir(T* gpuDir, T* gpuVote, T* gpuGrad, T* gpuTable, T phi, int rmax,  int x,  int y){

  			extern __shared__ T S[];
  			T* shared_atan = S;
  			size_t n_table = (rmax * 2 + 1) * (rmax * 2 + 1);
  			stim::cuda::threadedMemcpy((char*)shared_atan, (char*)gpuTable, sizeof(T) * n_table, threadIdx.x, blockDim.x);
  
  			//T* shared_vote = &S[n_table];
  			//size_t template_size_x = (blockDim.x + 2 * rmax);
  			//size_t template_size_y = (blockDim.y + 2 * rmax);
  			//stim::cuda::threadedMemcpy2D((char*)shared_vote, (char*)gpuVote, template_size_x, template_size_y, x,  threadIdx.y * blockDim.x + threadIdx.x, blockDim.x * blockDim.y);
  			
  			int xi = blockIdx.x * blockDim.x + threadIdx.x;				//calculate the 2D coordinates for this current thread.
  			int yi = blockIdx.y * blockDim.y + threadIdx.y;
  
  			if(xi >= x || yi >= y) return;								//if the index is outside of the image, terminate the kernel

  			int i = yi * x + xi;										//convert 2D coordinates to 1D
  			float theta = gpuGrad[2*i];									//calculate the voting direction based on the grtadient direction - global memory fetch

  			stim::aabb2<int> bb(xi, yi);								//initialize a bounding box at the current point
  			bb.insert(xi + ceil(rmax * cos(theta)),       ceil(yi + rmax * sin(theta)));
  			bb.insert(xi + ceil(rmax * cos(theta - phi)), yi + ceil(rmax * sin(theta - phi)));		//insert one corner of the triangle into the bounding box
  			bb.insert(xi + ceil(rmax * cos(theta + phi)), yi + ceil(rmax * sin(theta + phi)));		//insert the final corner into the bounding box
  
  			int x_table = 2*rmax +1;

  			T rmax_sq = rmax * rmax;

  
  			int lut_i;

  			T dx_sq, dy_sq;
  
  			bb.trim_low(0, 0);															//make sure the bounding box doesn't go outside the image
  			bb.trim_high(x-1, y-1);
  
  			int by, bx;
  			int dx, dy;													//coordinate relative to (xi, yi)

  			T v;
  			T max_v = 0;												//initialize the maximum vote value to zero
  			T alpha;

  			int max_dx = bb.low[0] - xi;
  			int max_dy = bb.low[1] - yi;

  			for(by = bb.low[1]; by <= bb.high[1]; by++){					//for each element in the bounding box
  				dy = by - yi;											//calculate the y coordinate of the current point relative to yi
  				dy_sq = dy * dy;
  				for(bx = bb.low[0]; bx <= bb.high[0]; bx++){
  					dx = bx - xi;
  					dx_sq = dx * dx;
  					lut_i = (rmax - dy) * x_table + rmax - dx;
  					alpha = shared_atan[lut_i];
  					if(dx_sq + dy_sq < rmax_sq && abs(alpha - theta) < phi){
  						v = gpuVote[by * x + bx];				// find the vote value for the current counter
  						if(v > max_v){
  							max_v = v;
  							max_dx = dx;
  							max_dy = dy;
  						}
  					}
  				}
  			}			
  			gpuDir[i] = atan2((T)max_dy, (T)max_dx);
  		}
  	

  
  		// this kernel updates the gradient direction by the calculated voting direction.
  		template<typename T>
  		__global__ void cuda_update_grad(T* gpuGrad, T* gpuDir, 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;

  
  			if(xi >= x || yi >= y) return;

  		
  			// convert 2D coordinates to 1D
  			int i = yi * x + xi;
  			
  			//update the gradient image with the vote direction
  			gpuGrad[2*i] = gpuDir[i];
  		}
  		
  		template<typename T>
  		void gpu_update_dir(T* gpuVote, T* gpuGrad, T* gpuTable, T phi, unsigned int rmax, unsigned int x, unsigned int y){
  
  			//calculate the number of bytes in the array
  			unsigned int bytes = x * y * sizeof(T);

  			
  			// allocate space on the GPU for the updated vote direction
  			T* gpuDir;

  			HANDLE_ERROR( cudaMalloc(&gpuDir, bytes) );	
  
  			unsigned int max_threads = stim::maxThreadsPerBlock();

  			dim3 threads( sqrt(max_threads), sqrt(max_threads) );
  			dim3 blocks(x/threads.x + 1, y/threads.y + 1);
  
  			size_t table_bytes = sizeof(T) * (rmax * 2 + 1) * (rmax * 2 + 1);
  			//size_t curtain = 2 * rmax;
  			//size_t template_bytes = sizeof(T) * (threads.x + curtain) * (threads.y + curtain);
  			size_t shared_mem_req = table_bytes;// + template_bytes;
  			std::cout<<"Shared Memory required: "<<shared_mem_req<<std::endl;
  
  			size_t shared_mem = stim::sharedMemPerBlock();
  			if(shared_mem_req > shared_mem){
  				std::cout<<"Error: insufficient shared memory for this implementation of cuda_update_dir()."<<std::endl;
  				exit(1);
  			}

  
  			//call the kernel to calculate the new voting direction

  			cuda_update_dir <<< blocks, threads, shared_mem_req>>>(gpuDir, gpuVote, gpuGrad, gpuTable, phi, rmax, x , y);

  			//stim::gpu2image<T>(gpuDir, "dir_david.bmp", x, y, -pi, pi, stim::cmBrewer);

  
  			//exit(0);
  

  			//threads = dim3( sqrt(max_threads), sqrt(max_threads) );
  			//blocks = dim3(x/threads.x + 1, y/threads.y + 1);

  
  			//call the kernel to update the gradient direction
  			cuda_update_grad <<< blocks, threads >>>(gpuGrad, gpuDir, x , y);

  			//free allocated memory

  			HANDLE_ERROR( cudaFree(gpuDir) );

  
  		}
  		
  		template<typename T>
  		void cpu_update_dir(T* cpuVote, T* cpuGrad,T* cpuTable, T phi, unsigned int rmax, unsigned int x, unsigned int y){
  
  			//calculate the number of bytes in the array
  			unsigned int bytes = x * y * sizeof(T);
  
  			//calculate the number of bytes in the atan2 table
  			unsigned int bytes_table = (2*rmax+1) * (2*rmax+1) * sizeof(T);
  
  			//allocate space on the GPU for the Vote Image
  			T* gpuVote;
  			cudaMalloc(&gpuVote, bytes);
  
  			//copy the input vote image to the GPU
  			HANDLE_ERROR(cudaMemcpy(gpuVote, cpuVote, bytes, cudaMemcpyHostToDevice));	
  
  			//allocate space on the GPU for the input Gradient image
  			T* gpuGrad;
  			HANDLE_ERROR(cudaMalloc(&gpuGrad, bytes*2));
  
  			//copy the Gradient data to the GPU
  			HANDLE_ERROR(cudaMemcpy(gpuGrad, cpuGrad, bytes*2, cudaMemcpyHostToDevice));
  
  			//allocate space on the GPU for the atan2 table
  			T* gpuTable;
  			HANDLE_ERROR(cudaMalloc(&gpuTable, bytes_table));
  
  			//copy the atan2 values to the GPU
  			HANDLE_ERROR(cudaMemcpy(gpuTable, cpuTable, bytes_table, cudaMemcpyHostToDevice));
  						
  			//call the GPU version of the update direction function
  			gpu_update_dir<T>(gpuVote, gpuGrad, gpuTable, phi, rmax, x , y);
  							
  			//copy the new gradient image back to the CPU
  			cudaMemcpy(cpuGrad, gpuGrad, bytes*2, cudaMemcpyDeviceToHost) ;
  
  			//free allocated memory
  			cudaFree(gpuTable);
  			cudaFree(gpuVote);
  			cudaFree(gpuGrad);
  		}
  		
  	}
  }
  
  #endif