void ComputeFrame() {
            i = 0;
            x = 0;

            //lock the canvas, because i haven't delved into actual bitmap pointer drawing to the screen itself
            bmpData = canvas.LockBits(bmpRect, ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
            currPos = (uint*)bmpData.Scan0;

            fixed (byte* f = field) { //field contains the entire grid plus swap
                t = f + w3; //starting point of the current generation
                a = t; //starting point of the next generation

                //determine which is which
                if (altFrame)
                    t += outerL;
                else
                    a += outerL;

                while (i++ < l) {
                    //sum living neighbors
                    n = (uint)(*(t - 1) + *(t + 1) + *(t - w2) + *(t + w2) + *(t - w1) + *(t + w1) + *(t - wp1) + *(t + wp1));

                    if (*t == 1) { //current cell is alive
                        *a = (byte)((n >> 1) == 1 ? 1 : 0);
                        *currPos = 0xffffffff;
                    }
                    else { //he's dead, jim
                        *a = (byte)(n == 3 ? 1 : 0);
                        *currPos = 0xff000000;
                    }

                    currPos++;
                    if (++x == w) {
                        x = 0;
                        a += 3;
                        t += 3;
                    }
                    else {
                        a++;
                        t++;
                    }
                }
            }
            canvas.UnlockBits(bmpData);
        }
    }