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transpose-cuda-full.cu
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transpose-cuda-full.cu
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/*
* transpose an array - using a cuda device, 1 thread/element
*/
#include <stdio.h>
#include <stdlib.h>
__global__ void cudaTransposeRow(float* out, float *in, int size);
void startClock(char*);
void stopClock(char*);
void printClock(char*);
#define DIM 1024
int main(int argc, char** argv) {
float *h_in;
float *h_out;
h_in = (float*) malloc(DIM*DIM*sizeof(float));
h_out =(float*) malloc(DIM*DIM*sizeof(float));
void *d_in;
void *d_out;
cudaMalloc(&d_in,DIM*DIM*sizeof(float));
cudaMalloc(&d_out,DIM*DIM*sizeof(float));
int value = 1;
for (int i = 0; i < DIM; i++) {
for (int j = 0; j < DIM; j++) {
h_in[i + j*DIM] = value++;
}
}
startClock("copy in");
cudaMemcpy(d_in,h_in,DIM*DIM*sizeof(float),cudaMemcpyHostToDevice);
stopClock("copy in");
startClock("compute");
cudaTransposeRow<<<1024,1024>>>((float*)d_out,(float*)d_in,DIM);
cudaThreadSynchronize();
stopClock("compute");
startClock("copy out");
cudaMemcpy(h_out,d_out,DIM*DIM*sizeof(float),cudaMemcpyDeviceToHost);
stopClock("copy out");
// sanity check
for (int i = 0; i < DIM; i++) {
for (int j = 0; j < DIM; j++) {
if (h_in[i + j*DIM] != h_out[i*DIM + j]) {
printf("ERROR");
exit(1);
}
}
}
free(h_in);
free(h_out);
cudaFree(d_in);
cudaFree(d_out);
printClock("copy in");
printClock("compute");
printClock("copy out");
}
__global__ void cudaTransposeRow(float* out, float* in, int size) {
int row = threadIdx.x;
int col = blockIdx.x;
out[col + row*size] = in[row + col*size];
}