cuda

// ***********************************************************************
//
// Demo program for education in subject
// Computer Architectures and Paralel Systems.
// Petr Olivka, dep. of Computer Science, FEI, VSB-TU Ostrava
// email:petr.olivka@vsb.cz
//
// Example of CUDA Technology Usage.
// Image transformation from RGB to BW schema.
//
// ***********************************************************************

#include <cuda_runtime.h>
#include <stdio.h>

// Demo kernel to tranfrom RGB color schema to BW schema
__global__ void kernel_grayscale( uchar4 *color_pic, uchar4* bw_pic, int sizex, int sizey )
{
    // X,Y coordinates and check image dimensions
    int y = blockDim.y * blockIdx.y + threadIdx.y;
    if ( y >= sizey ) return;
    int x = blockDim.x * blockIdx.x + threadIdx.x;
    if ( x >= sizex ) return;


    bw_pic[(sizex - x)* sizey + y] = color_pic[y * sizex + x ];

}

void run_grayscale( uchar4 *color_pic, uchar4* bw_pic, int sizex, int sizey )
{
    cudaError_t cerr;
    // Memory allocation in GPU device
    uchar4 *cudaColorPic;
    uchar4 *cudaBWPic;
    cerr = cudaMalloc( &cudaColorPic, sizex * sizey * sizeof( uchar4 ) );
    if ( cerr != cudaSuccess )
        printf( "CUDA Error [%d] - '%s'\n", __LINE__, cudaGetErrorString( cerr ) );

    cerr = cudaMalloc( &cudaBWPic, sizex * sizey * sizeof( uchar4 ) );
    if ( cerr != cudaSuccess )
        printf( "CUDA Error [%d] - '%s'\n", __LINE__, cudaGetErrorString( cerr ) );

    // Copy color image to GPU device
    cerr = cudaMemcpy( cudaColorPic, color_pic, sizex * sizey * sizeof( uchar4 ), cudaMemcpyHostToDevice );
    if ( cerr != cudaSuccess )
        printf( "CUDA Error [%d] - '%s'\n", __LINE__, cudaGetErrorString( cerr ) );

    int block = 16;
    dim3 blocks( ( sizex + block - 1 ) / block, ( sizey + block - 1 ) / block );
    dim3 threads( block, block );

    // Grid creation, size of grid must be greater than image
    kernel_grayscale<<< blocks, threads >>>( cudaColorPic, cudaBWPic, sizex, sizey );

    if ( ( cerr = cudaGetLastError() ) != cudaSuccess )
        printf( "CUDA Error [%d] - '%s'\n", __LINE__, cudaGetErrorString( cerr ) );

    // Copy new image from GPU device
    cerr = cudaMemcpy( bw_pic, cudaBWPic, sizex * sizey * sizeof( uchar4 ), cudaMemcpyDeviceToHost );
    if ( cerr != cudaSuccess )
        printf( "CUDA Error [%d] - '%s'\n", __LINE__, cudaGetErrorString( cerr ) );

    // Free memory
    cudaFree( cudaColorPic );
    cudaFree( cudaBWPic );
}