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8bitworkshop/presets/vcs/6digit.inc

144 lines
3.5 KiB
PHP

seg.u Variables
; 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
; Adds value to 6-BCD-digit score.
; A = 1st BCD digit
; X = 2nd BCD digit
; Y = 3rd BCD digit
AddScore: subroutine
.temp equ Temp1
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 #$f0 ; isolate high nibble (* 16)
lsr ; shift right 1 bit (* 8)
sta Digit0,x ; store pointer lo byte
lda #>Digit6Font
sta Digit0+1,x ; store pointer hi byte
inx
inx ; next bitmap pointer
lda BCDScore,y ; get BCD value (again)
and #$f ; isolate low nibble
asl
asl
asl ; * 8
sta Digit0,x ; store pointer lo byte
lda #>Digit6Font
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.
; A = color of scoreboard
DrawDigits: subroutine
.temp equ Temp1
.count equ Temp2
; clear player bitmaps first
jsr ClearGRP
; set colors
sta COLUP0
sta COLUP1
; set horizontal position of player objects
sta WSYNC
; instead of SLEEP 26...
lda #THREE_COPIES
sta NUSIZ0
sta NUSIZ1
lda #1
sta VDELP0
sta VDELP1
lda #$10
sta HMP1
stx HMP0 ; x = 0
nop
; set player positions (26 cycles later)
stx RESP0
stx RESP1
stx REFP0
stx REFP1
; apply fine adjustment
sta WSYNC
sta HMOVE
sta HMCLR
lda #8
sta .count ; 8 scanlines
jsr ClearGRP ; just killing some time...
.bigloop
ldy .count ; 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
.storegrp
sta GRP1 ; B3 -> [GRP1]; B2 -> GRP0
stx GRP0 ; B4 -> [GRP0]; B3 -> GRP1
sty GRP1 ; B5 -> [GRP1]; B4 -> GRP0
sta GRP0 ; ?? -> [GRP0]; B5 -> GRP1
dec .count ; go to next line
bpl .bigloop ; repeat until < 0
ClearGRP
ldx #0 ; empty out player bitmaps
stx GRP0
stx GRP1
stx GRP0
stx GRP1
rts
; Font table for digits 0-9 (8x8 pixels)
align $100 ; make sure data doesn't cross page boundary
Digit6Font:
hex 003c6666766e663c007e181818381818
hex 007e60300c06663c003c66061c06663c
hex 0006067f661e0e06003c6606067c607e
hex 003c66667c60663c00181818180c667e
hex 003c66663c66663c003c66063e66663c
hex 00 ; so top of 9 is clean