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| 1 | +#include <array> |
| 2 | + |
| 3 | +// CUDA kernel. Each thread takes care of one element of c |
| 4 | +template<class T> |
| 5 | +__global__ void vecAdd(T *a, T *b, T *c, int n) |
| 6 | +{ |
| 7 | + // Get our global thread ID |
| 8 | + int id = blockIdx.x*blockDim.x+threadIdx.x; |
| 9 | + |
| 10 | + // Make sure we do not go out of bounds |
| 11 | + if (id < n) |
| 12 | + c[id] = a[id] + b[id]; |
| 13 | +} |
| 14 | + |
| 15 | +template <typename T, size_t N> |
| 16 | +void simple_vadd_cuda(const std::array<T, N>& VA, const std::array<T, N>& VB, |
| 17 | + std::array<T, N>& VC) { |
| 18 | + // Device input vectors |
| 19 | + T *d_a; |
| 20 | + T *d_b; |
| 21 | + //Device output vector |
| 22 | + T *d_c; |
| 23 | + |
| 24 | + // Size, in bytes, of each vector |
| 25 | + const size_t bytes = N*sizeof(T); |
| 26 | + |
| 27 | + // Allocate memory for each vector on GPU |
| 28 | + cudaMalloc(&d_a, bytes); |
| 29 | + cudaMalloc(&d_b, bytes); |
| 30 | + cudaMalloc(&d_c, bytes); |
| 31 | + |
| 32 | + // Copy host vectors to device |
| 33 | + cudaMemcpy( d_a, VA.data(), bytes, cudaMemcpyHostToDevice); |
| 34 | + cudaMemcpy( d_b, VB.data(), bytes, cudaMemcpyHostToDevice); |
| 35 | + |
| 36 | + int blockSize, gridSize; |
| 37 | + |
| 38 | + // Number of threads in each thread block |
| 39 | + blockSize = 1024; |
| 40 | + |
| 41 | + // Number of thread blocks in grid |
| 42 | + gridSize = (int)ceil((float)N/blockSize); |
| 43 | + |
| 44 | + // Execute the kernel |
| 45 | + vecAdd<<<gridSize, blockSize>>>(d_a, d_b, d_c, N); |
| 46 | + |
| 47 | + // Copy array back to host |
| 48 | + cudaMemcpy( VC.data(), d_c, bytes, cudaMemcpyDeviceToHost ); |
| 49 | + |
| 50 | + // Release device memory |
| 51 | + cudaFree(d_a); |
| 52 | + cudaFree(d_b); |
| 53 | + cudaFree(d_c); |
| 54 | + |
| 55 | +} |
| 56 | + |
| 57 | + |
| 58 | +template void simple_vadd_cuda<float, 4>(const std::array<float, 4>& VA, const std::array<float, 4>& VB, |
| 59 | + std::array<float, 4>& VC); |
| 60 | +template void simple_vadd_cuda<int, 4>(const std::array<int, 4>& VA, const std::array<int, 4>& VB, |
| 61 | + std::array<int, 4>& VC); |
| 62 | + |
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