mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-12-29 11:31:42 +00:00
144 lines
3.5 KiB
PHP
144 lines
3.5 KiB
PHP
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seg.u Variables
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; Pointers to bitmap for each digit
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Digit0 .word
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Digit1 .word
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Digit2 .word
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Digit3 .word
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Digit4 .word
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Digit5 .word
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BCDScore hex 000000
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THREE_COPIES equ %011 ; for NUSIZ registers
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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seg Code
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; Adds value to 6-BCD-digit score.
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; A = 1st BCD digit
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; X = 2nd BCD digit
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; Y = 3rd BCD digit
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AddScore: subroutine
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.temp equ Temp1
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sed ; enter BCD mode
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clc ; clear carry
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sta .temp
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lda BCDScore
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adc .temp
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sta BCDScore
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stx .temp
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lda BCDScore+1
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adc .temp
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sta BCDScore+1
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sty .temp
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lda BCDScore+2
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adc .temp
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sta BCDScore+2
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cld ; exit BCD mode
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rts
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GetDigitPtrs: subroutine
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ldx #0 ; leftmost bitmap
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ldy #2 ; start from most-sigificant BCD value
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.Loop
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lda BCDScore,y ; get BCD value
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and #$f0 ; isolate high nibble (* 16)
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lsr ; shift right 1 bit (* 8)
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sta Digit0,x ; store pointer lo byte
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lda #>Digit6Font
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sta Digit0+1,x ; store pointer hi byte
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inx
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inx ; next bitmap pointer
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lda BCDScore,y ; get BCD value (again)
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and #$f ; isolate low nibble
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asl
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asl
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asl ; * 8
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sta Digit0,x ; store pointer lo byte
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lda #>Digit6Font
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sta Digit0+1,x ; store pointer hi byte
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inx
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inx ; next bitmap pointer
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dey ; next BCD value
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bpl .Loop ; repeat until < 0
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rts
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; Display the resulting 48x8 bitmap
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; using the Digit0-5 pointers.
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; A = color of scoreboard
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DrawDigits: subroutine
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.temp equ Temp1
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.count equ Temp2
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; clear player bitmaps first
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jsr ClearGRP
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; set colors
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sta COLUP0
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sta COLUP1
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; set horizontal position of player objects
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sta WSYNC
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; instead of SLEEP 26...
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lda #THREE_COPIES
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sta NUSIZ0
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sta NUSIZ1
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lda #1
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sta VDELP0
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sta VDELP1
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lda #$10
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sta HMP1
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stx HMP0 ; x = 0
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nop
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; set player positions (26 cycles later)
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stx RESP0
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stx RESP1
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stx REFP0
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stx REFP1
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; apply fine adjustment
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sta WSYNC
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sta HMOVE
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sta HMCLR
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lda #8
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sta .count ; 8 scanlines
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jsr ClearGRP ; just killing some time...
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.bigloop
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ldy .count ; counts backwards
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lda (Digit0),y ; load B0 (1st sprite byte)
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sta GRP0 ; B0 -> [GRP0]
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lda (Digit1),y ; load B1 -> A
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sta GRP1 ; B1 -> [GRP1], B0 -> GRP0
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sta WSYNC ; sync to next scanline
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lda (Digit2),y ; load B2 -> A
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sta GRP0 ; B2 -> [GRP0], B1 -> GRP1
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lda (Digit5),y ; load B5 -> A
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sta .temp ; B5 -> temp
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lda (Digit4),y ; load B4
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tax ; -> X
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lda (Digit3),y ; load B3 -> A
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ldy .temp ; load B5 -> Y
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.storegrp
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sta GRP1 ; B3 -> [GRP1]; B2 -> GRP0
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stx GRP0 ; B4 -> [GRP0]; B3 -> GRP1
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sty GRP1 ; B5 -> [GRP1]; B4 -> GRP0
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sta GRP0 ; ?? -> [GRP0]; B5 -> GRP1
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dec .count ; go to next line
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bpl .bigloop ; repeat until < 0
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ClearGRP
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ldx #0 ; empty out player bitmaps
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stx GRP0
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stx GRP1
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stx GRP0
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stx GRP1
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rts
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; Font table for digits 0-9 (8x8 pixels)
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align $100 ; make sure data doesn't cross page boundary
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Digit6Font:
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hex 003c6666766e663c007e181818381818
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hex 007e60300c06663c003c66061c06663c
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hex 0006067f661e0e06003c6606067c607e
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hex 003c66667c60663c00181818180c667e
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hex 003c66663c66663c003c66063e66663c
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hex 00 ; so top of 9 is clean
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