gaussian_blur_vert.cu

__device__ float4 ready(const unsigned short * in_half, int x, int y, int w)
{
    return make_float4(__half2float(in_half[4 * (x + y * w) + 0]),
                       __half2float(in_half[4 * (x + y * w) + 1]),
                       __half2float(in_half[4 * (x + y * w) + 2]),
                       __half2float(in_half[4 * (x + y * w) + 3]));
}

__device__ float weighty(int j, int y, float invdx2)
{
    return exp(-invdx2*((j-y)*(j-y)));
}

__global__ void
gaussian_blur_vert(const unsigned short * in_half,
                   unsigned short * out_half,
                   const int n,
                   const int width,
                   const int height)
{
    const int x = blockIdx.x * blockDim.x + threadIdx.x;
    const int y = blockIdx.y * blockDim.y + threadIdx.y;

    // array index
    const int idx = x + width * y;

    // inside image bounds check
    if (x >= width || y >= height) {
        return;
    }

    // kernel code
    float4 out = make_float4(0, 0, 0, 0);
    const float invdx2 = 1.0/(width*width);
    float totWeight = 0;
    float w;
    for(int j = y - n; j <= y + n; ++j)  {
            if (j>= 0 && j < height) {
                w = weighty(j, y, invdx2);
                out += w * ready(in_half, x, j, width);
                totWeight += w;
            }
    }
    out /= totWeight;

    // float to half conversion
    out_half[4 * idx + 0] = __float2half_rn(out.x);
    out_half[4 * idx + 1] = __float2half_rn(out.y);
    out_half[4 * idx + 2] = __float2half_rn(out.z);
    out_half[4 * idx + 3] = __float2half_rn(out.w);
}