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matMul.cu
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matMul.cu
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#include <stdio.h>
#include <stdlib.h>
__global__ void matMul(float *d_A, float *d_B, float *d_C, int M, int N, int P) {
int row = blockIdx.y * blockDim.y + threadIdx.y;
int col = blockIdx.x * blockDim.x + threadIdx.x;
if(row < M && col < P) {
float sum = 0.0f;
// compute the dot product for each row of A and col of B
for(int i = 0; i < N; ++i) {
sum += d_A[row * N + i] * d_B[i * P + col];
}
d_C[row * P + col] = sum;
}
}
int main() {
// variable initialization
int M = 2;
int N = 3;
int P = 5;
float *h_A, *h_B, *h_C;
float *d_A, *d_B, *d_C;
// memory allocation
h_A = (float *)malloc(M * N * sizeof(float));
h_B = (float *)malloc(N * P * sizeof(float));
h_C = (float *)malloc(M * P * sizeof(float));
cudaMalloc((void**)&d_A, M * N * sizeof(float));
cudaMalloc((void**)&d_B, N * P * sizeof(float));
cudaMalloc((void**)&d_C, M * P * sizeof(float));
// initial data
for(int i = 0; i < M; ++i) {
for(int j = 0; j < N; ++j) {
h_A[i * N + j] = (float) (rand() % 10 + 1);
}
}
for(int i = 0; i < N; ++i) {
for(int j = 0; j < P; ++j) {
h_B[i * P + j] = (float) (rand() % 10 + 1);
}
}
// copy CPU data to GPU memory blocks
cudaMemcpy(d_A, h_A, M * N * sizeof(float), cudaMemcpyHostToDevice);
cudaMemcpy(d_B, h_B, N * P * sizeof(float), cudaMemcpyHostToDevice);
// set grid and block dimensions
dim3 blockDim(16, 16);
dim3 gridDim((P + blockDim.x - 1)/blockDim.x, (M + blockDim.y - 1)/blockDim.y);
// run matmul
matMul<<<gridDim, blockDim>>>(d_A, d_B, d_C, M, N, P);
// transfer data from device to host
cudaMemcpy(h_C, d_C, M * P * sizeof(float), cudaMemcpyDeviceToHost);
// print statements
printf("Matrix A:\n--------\n");
for(int i = 0; i < M; ++i) {
for(int j = 0; j < N; ++j) {
printf("%f ", h_A[i * N + j]);
}
printf("\n");
}
printf("--------\n");
printf("Matrix B:\n--------\n");
for(int i = 0; i < N; ++i) {
for(int j = 0; j < P; ++j) {
printf("%f ", h_B[i * P + j]);
}
printf("\n");
}
printf("--------\n");
printf("Matrix C:\n--------\n");
for(int i = 0; i < M; ++i) {
for(int j = 0; j < P; ++j) {
printf("%f ", h_C[i * P + j]);
}
printf("\n");
}
printf("--------\n");
// clean up device memory
cudaFree(d_A);
cudaFree(d_B);
cudaFree(d_C);
free(h_A);
free(h_B);
free(h_C);
return 0;
}