static void apply_unsharp(      uint8_t *dst, int dst_stride,
                          const uint8_t *src, int src_stride,
                          int width, int height, FilterParam *fp)
{
    uint32_t **sc = fp->sc;
    uint32_t sr[(MAX_SIZE * MAX_SIZE) - 1], tmp1, tmp2;

    int32_t res;
    int x, y, z;
    const uint8_t *src2 = NULL;  //silence a warning

    if (!fp->amount) {
        if (dst_stride == src_stride)
            memcpy(dst, src, src_stride * height);
        else
            for (y = 0; y < height; y++, dst += dst_stride, src += src_stride)
                memcpy(dst, src, width);
        return;
    }

    for (y = 0; y < 2 * fp->steps_y; y++)
        memset(sc[y], 0, sizeof(sc[y][0]) * (width + 2 * fp->steps_x));

    for (y = -fp->steps_y; y < height + fp->steps_y; y++) {
        if (y < height)
            src2 = src;

        memset(sr, 0, sizeof(sr[0]) * (2 * fp->steps_x - 1));
        for (x = -fp->steps_x; x < width + fp->steps_x; x++) {
            tmp1 = x <= 0 ? src2[0] : x >= width ? src2[width-1] : src2[x];
            for (z = 0; z < fp->steps_x * 2; z += 2) {
                tmp2 = sr[z + 0] + tmp1; sr[z + 0] = tmp1;
                tmp1 = sr[z + 1] + tmp2; sr[z + 1] = tmp2;
            }
            for (z = 0; z < fp->steps_y * 2; z += 2) {
                tmp2 = sc[z + 0][x + fp->steps_x] + tmp1; sc[z + 0][x + fp->steps_x] = tmp1;
                tmp1 = sc[z + 1][x + fp->steps_x] + tmp2; sc[z + 1][x + fp->steps_x] = tmp2;
            }
            if (x >= fp->steps_x && y >= fp->steps_y) {
                const uint8_t *srx = src - fp->steps_y * src_stride + x - fp->steps_x;
                uint8_t       *dsx = dst - fp->steps_y * dst_stride + x - fp->steps_x;

                res = (int32_t)*srx + ((((int32_t) * srx - (int32_t)((tmp1 + fp->halfscale) >> fp->scalebits)) * fp->amount) >> 16);
                *dsx = av_clip_uint8(res);
            }
        }
        if (y >= 0) {
            dst += dst_stride;
            src += src_stride;
        }
    }
}