From: James A Simmons <jsimmons@acsu.buffalo.edu>
  To  : ggi-develop@eskimo.com
  Date: Thu, 9 Jul 1998 12:23:47 -0400 (EDT)

Re: Fast lines

> 	The fastest linedrawing/clipping routine possible uses the x and y
> coordinates of the two endpoints of the line and two corners of the
> clipping region as offsets into a sparse precalculated array of x,y pairs
> stored as offsets into a linear framebuffer + one extra entry at the
> beginning for the number of pixels in the line, making up all possible
> lines.  For a 320x200x8bpp framebuffer, this would require ~3.5 heptabytes
> of RAM, but the computational cost is: 
> 
> Setup:
> * One memory read + one register write to set the pixel color
> * three multiplies to get the array offset 
> * One menory read + one register write to set the pixel count
> 
> Pixel-setting loop:
> * One memory read + one register write to get the address of the next pixel
> * One register read + one memory write to set the pixel at that address 
>   with the value in the pixel color register
> * One decrement-and-branch-if-not zero instruction that tests the pixel 
> * count register
> 
> 	No compares, multiplies, or adds in the loop at all!  If your
> processor can do indirect writes with the offset coming from memory
> without additional cycle cost, that loop reduces to one indirected write
> and the conditional branch.  A good pipeline will reduce this loop to ONE
> CYCLE per pixel.  Beat *that*! |->
> 
> Jon
> 
> ---
> 'Cloning and the reprogramming of DNA is the first serious step in 
> becoming one with God.'
> 	- Scientist G. Richard Seed
> 
> 
> 

Where can I see such code