// MP1
include	<wb.h>

__global__ void vecAdd(float * in1, float * in2, float * out, int len) {
    //@@ Insert code to implement vector addition here
    int i = threadIdx.x + blockDim.x * blockIdx.x;
    if (i<len) out[i] = in1[i] + in2[i];
}

int main(int argc, char ** argv) {
    wbArg_t args;
    int inputLength;
    float * hostInput1;
    float * hostInput2;
    float * hostOutput;
    float * deviceInput1;
    float * deviceInput2;
    float * deviceOutput;

    args = wbArg_read(argc, argv);

    wbTime_start(Generic, "Importing data and creating memory on host");
    hostInput1 = (float *) wbImport(wbArg_getInputFile(args, 0), &inputLength);
    hostInput2 = (float *) wbImport(wbArg_getInputFile(args, 1), &inputLength);
    hostOutput = (float *) malloc(inputLength * sizeof(float));
    wbTime_stop(Generic, "Importing data and creating memory on host");

    wbLog(TRACE, "The input length is ", inputLength);

	wbTime_start(GPU, "Allocating GPU memory.");
    //@@ Allocate GPU memory here
    
    int n = inputLength * sizeof(float);
    //cudaMalloc((void **) &deviceInput1, inputLength);
    //cudaMalloc((void **) &deviceInput2, inputLength);
    //cudaMalloc((void **) &deviceOutput, inputLength);
    cudaMalloc((void **) &deviceInput1, n);
    cudaMalloc((void **) &deviceInput2, n);
    cudaMalloc((void **) &deviceOutput, n);

  
  
    wbTime_stop(GPU, "Allocating GPU memory.");

    wbTime_start(GPU, "Copying input memory to the GPU.");
    //@@ Copy memory to the GPU here
    //cudaMemcpy(deviceInput1, hostInput1, inputLength, cudaMemcpyHostToDevice);
    //cudaMemcpy(deviceInput2, hostInput2, inputLength, cudaMemcpyHostToDevice);
    cudaMemcpy(deviceInput1, hostInput1, n, cudaMemcpyHostToDevice);
    cudaMemcpy(deviceInput2, hostInput2, n, cudaMemcpyHostToDevice);


    wbTime_stop(GPU, "Copying input memory to the GPU.");
    
    //@@ Initialize the grid and block dimensions here
    //dim3 DimGrid((inputLength-1)/256 + 1, 1, 1);
    dim3 DimGrid((inputLength-1)/256 + 1, 1, 1);
    dim3 DimBlock(256, 1, 1);

    
    wbTime_start(Compute, "Performing CUDA computation");
    //@@ Launch the GPU Kernel here
    //vecAdd<<<DimGrid,DimBlock>>>(deviceInput1, deviceInput2, deviceOutput, inputLength);
    vecAdd<<<DimGrid,DimBlock>>>(deviceInput1, deviceInput2, deviceOutput, n);

    cudaThreadSynchronize();
    wbTime_stop(Compute, "Performing CUDA computation");
    
    wbTime_start(Copy, "Copying output memory to the CPU");
    //@@ Copy the GPU memory back to the CPU here
    //cudaMemcpy(hostOutput, deviceOutput, inputLength, cudaMemcpyDeviceToHost);
    cudaMemcpy(hostOutput, deviceOutput, n, cudaMemcpyDeviceToHost);

    wbTime_stop(Copy, "Copying output memory to the CPU");

    wbTime_start(GPU, "Freeing GPU Memory");
    //@@ Free the GPU memory here
    cudaFree(deviceInput1); cudaFree(deviceInput2); cudaFree(deviceOutput);

    wbTime_stop(GPU, "Freeing GPU Memory");

    wbSolution(args, hostOutput, inputLength);

    free(hostInput1);
    free(hostInput2);
    free(hostOutput);

    return 0;
}