Gugler Flake
Author: Sean Gugler
Category: Christmas Challenge
System: C64
Language: Assembler ca65
Len source code: 515
Len exe file: 102
Len code only: 88
Instructions: Install vice, drag and drop the prg file into it.
Description: The target image is a snowflake, consisting of cells that are either filled or not filled with a star character. A delta-compressed data table stores the number of screen positions needed to advance from one filled cell to the next, including wrap-around positions when traveling from the end of one row to the beginning of the next. Since the image is rotationally-symmetric, only half the data is stored, and the program plots cells simultaneously from the beginning forward and from the end backward, meeting in the middle.
Comments: No system calls into the kernal are used. This program writes directly to screen memory. The display looks nicer if you clear the screen after loading the program and before running it.