don't be a snowflake

Author: Bitbreaker / Performers
Category: Christmas Challenge
System:   C64
Language: 6502 assembler
Len source code: 1883 bytes
Len exe file:    52 bytes
Len code only:   48 bytes
Instructions:
Start with for e.g. x64 size.d64 with vice
Description:
Rasterises bits in data table (1 = *) over 19 lines, right side is mirrored in same go. Mirror on the x-axis is done by inverting the loop that runs over the table when 10th line is reached. Solid vertical line is done by a forced initial set when new line begins. The horizontal line is handled by cpx #$09, which forces a set over the whole line, and initiates the inversion as mentioned before.

start with y = 9, always print first point, do until y < 0
<--------|-------->
         *         | entry, a = 0, x = 0, start with print
       * * *       |
  * *   ***   * *  |
   **    *    **   |
  ***  * * *  ***  |- inx
     *  ***  *     |
      *  *  *      |
 *  *  * * *  *  * |
  *  *  ***  *  *  |
*******************   <- cpx #$09, force print only and change inx to dex
  *  *  ***  *  *  |
 *  *  * * *  *  * |
      *  *  *      |
     *  ***  *     |
  ***  * * *  ***  |- dex
   **    *    **   |
  * *   ***   * *  |
       * * *       |
         *         |-> x < 0 -> end

Comments:
Load from .d64, autostart might fail due to wrong initialisation of regs/zp vals if injected into RAM