Koffi Redux 2020 part 3

Entry posted by Cafeman October 11, 2020

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Updated 10/12/20 with the results, see bottom.

I'm running out of ROM memory with the new code I'm adding for the 2-player mode of the game. Koffi: Yellow Kopter was programmed in 32k back in 2002. It seemed like a huge amount of ROM at the time, so I didn't try much to keep things small. There ended up being huge graphics tables and repetitive code routines, just because that was easiest to do. Also, before I finished Koffi, I used up as much remaining memory as I could.

Over summer 2020, I went back and rewrote several routines, and I've ditched the original game's credits / names text and freed up 1k or 2k. I thought this would be enough to add some fun new stuff, but I'm once again running low on ROM space, so I am now rewriting the routines/data tables which are the biggest ROM wastes: those that create the image of the Trees.

Stage 1 Mountain Valley's Tree / leaves graphics take up 1,000 bytes originally. But most of the bytes are the value of $55. I am now trying to store a big rectangular block of $55's (no need to code these into the ROM now) programmatically, and then just have left-edge and right-edge tables to provide the more rounded tree details.

To illustrate, an original code section:


;************ Draw Leaves Layer2 ******************   ; RWL 2001
    lda #<leaves2
    sta Ptr1
    lda #>leaves2
    sta Ptr1+1                                                   
        lda     #$32                               ;row 4 starts at $3208
        sta     $81                                                                  
        lda     #$08
        sta     $80
    jsr CommonMVTreeDrawLoop    ;  rewritten as common routine RWL 072520, saved hundreds of bytes

Using data tables like this one:


leaves2 .byte $15,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55 ;line 7
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$50    ;                     ;                                                      
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55 ;line 8
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$50    ;                     ;                                                      
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55 ;line 9
        .byte $55,$55,$55,$55,$55,$55,$55,$54,$55,$50    ;                     ;                                                      
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55 ;line 10
        .byte $55,$55,$55,$55,$55,$55,$55,$51,$15,$54    ;                     ;                                                      
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55 ;line 11
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$54    ;                     ;                                                      
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55,$55 ;line 12
        .byte $55,$55,$55,$55,$55,$55,$55,$55,$55,$54    ;                     ;

See all those $55 values? A compression routine would also reduce ROM needs, I could compress these tables and expand them into screen RAM directly. But I'm not wanting to add a compress/decompress routine to this game this late in the game, which would take up some ROM itself anyway. So, I'm reducing these tables with my own custom draw routines.

10/12/2020 Monday night. Results: Success! I got the same basic tree image but at a cost of about 640 bytes less!