171 lines
3.8 KiB
Plaintext
171 lines
3.8 KiB
Plaintext
processor 6502
|
|
include "vcs.h"
|
|
include "macro.h"
|
|
include "xmacro.h"
|
|
|
|
seg.u Variables
|
|
org $80
|
|
|
|
|
|
Temp .byte
|
|
LoopCount .byte ; counts scanline when drawing
|
|
|
|
; Pointers to bitmap for each digit
|
|
Digit0 .word
|
|
Digit1 .word
|
|
Digit2 .word
|
|
Digit3 .word
|
|
Digit4 .word
|
|
Digit5 .word
|
|
|
|
BCDScore hex 000000
|
|
|
|
THREE_COPIES equ %011 ; for NUSIZ registers
|
|
|
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
|
|
|
seg Code
|
|
org $f000
|
|
|
|
Start
|
|
CLEAN_START
|
|
|
|
NextFrame
|
|
VERTICAL_SYNC
|
|
|
|
TIMER_SETUP 37
|
|
lda #$18
|
|
sta COLUP0
|
|
lda #$28
|
|
sta COLUP1
|
|
lda #THREE_COPIES
|
|
sta NUSIZ0
|
|
sta NUSIZ1
|
|
; set horizontal position of player objects
|
|
sta WSYNC
|
|
SLEEP 26
|
|
sta RESP0
|
|
sta RESP1
|
|
lda #$10
|
|
sta HMP1
|
|
sta WSYNC
|
|
sta HMOVE
|
|
sta HMCLR
|
|
lda #1
|
|
sta VDELP0
|
|
sta VDELP1
|
|
TIMER_WAIT
|
|
|
|
TIMER_SETUP 192
|
|
|
|
jsr GetDigitPtrs ; get pointers
|
|
jsr DrawDigits ; draw digits
|
|
|
|
TIMER_WAIT
|
|
|
|
TIMER_SETUP 30
|
|
lda #1
|
|
ldx #0
|
|
ldy #0
|
|
jsr AddScore
|
|
TIMER_WAIT
|
|
jmp NextFrame
|
|
|
|
; Adds value to 6-BCD-digit score.
|
|
; A = 1st BCD digit
|
|
; X = 2nd BCD digit
|
|
; Y = 3rd BCD digit
|
|
AddScore subroutine
|
|
sed ; enter BCD mode
|
|
clc ; clear carry
|
|
sta Temp
|
|
lda BCDScore
|
|
adc Temp
|
|
sta BCDScore
|
|
stx Temp
|
|
lda BCDScore+1
|
|
adc Temp
|
|
sta BCDScore+1
|
|
sty Temp
|
|
lda BCDScore+2
|
|
adc Temp
|
|
sta BCDScore+2
|
|
cld ; exit BCD mode
|
|
rts
|
|
|
|
GetDigitPtrs subroutine
|
|
ldx #0 ; leftmost bitmap
|
|
ldy #2 ; start from most-sigificant BCD value
|
|
.Loop
|
|
lda BCDScore,y ; get BCD value
|
|
and #$f0 ; isolate high nibble (* 16)
|
|
lsr ; shift right 1 bit (* 8)
|
|
sta Digit0,x ; store pointer lo byte
|
|
lda #>FontTable
|
|
sta Digit0+1,x ; store pointer hi byte
|
|
inx
|
|
inx ; next bitmap pointer
|
|
lda BCDScore,y ; get BCD value (again)
|
|
and #$f ; isolate low nibble
|
|
asl
|
|
asl
|
|
asl ; * 8
|
|
sta Digit0,x ; store pointer lo byte
|
|
lda #>FontTable
|
|
sta Digit0+1,x ; store pointer hi byte
|
|
inx
|
|
inx ; next bitmap pointer
|
|
dey ; next BCD value
|
|
bpl .Loop ; repeat until < 0
|
|
rts
|
|
|
|
; Display the resulting 48x8 bitmap
|
|
; using the Digit0-5 pointers.
|
|
DrawDigits subroutine
|
|
sta WSYNC
|
|
SLEEP 40 ; start near end of scanline
|
|
lda #7
|
|
sta LoopCount
|
|
BigLoop
|
|
ldy LoopCount ; counts backwards
|
|
lda (Digit0),y ; load B0 (1st sprite byte)
|
|
sta GRP0 ; B0 -> [GRP0]
|
|
lda (Digit1),y ; load B1 -> A
|
|
sta GRP1 ; B1 -> [GRP1], B0 -> GRP0
|
|
sta WSYNC ; sync to next scanline
|
|
lda (Digit2),y ; load B2 -> A
|
|
sta GRP0 ; B2 -> [GRP0], B1 -> GRP1
|
|
lda (Digit5),y ; load B5 -> A
|
|
sta Temp ; B5 -> temp
|
|
lda (Digit4),y ; load B4
|
|
tax ; -> X
|
|
lda (Digit3),y ; load B3 -> A
|
|
ldy Temp ; load B5 -> Y
|
|
sta GRP1 ; B3 -> [GRP1]; B2 -> GRP0
|
|
stx GRP0 ; B4 -> [GRP0]; B3 -> GRP1
|
|
sty GRP1 ; B5 -> [GRP1]; B4 -> GRP0
|
|
sta GRP0 ; ?? -> [GRP0]; B5 -> GRP1
|
|
dec LoopCount ; go to next line
|
|
bpl BigLoop ; repeat until < 0
|
|
|
|
lda #0 ; clear the sprite registers
|
|
sta GRP0
|
|
sta GRP1
|
|
sta GRP0
|
|
sta GRP1
|
|
rts
|
|
|
|
; Font table for digits 0-9 (8x8 pixels)
|
|
align $100 ; make sure data doesn't cross page boundary
|
|
FontTable
|
|
hex 003c6666766e663c007e181818381818
|
|
hex 007e60300c06663c003c66061c06663c
|
|
hex 0006067f661e0e06003c6606067c607e
|
|
hex 003c66667c60663c00181818180c667e
|
|
hex 003c66663c66663c003c66063e66663c
|
|
|
|
; Epilogue
|
|
org $fffc
|
|
.word Start
|
|
.word Start
|