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help.asm
98 lines (75 loc) · 2.13 KB
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help.asm
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helpScreenLineStart = screenRam + helpOffsetY * screenWidth
helpOffsetX = 13
helpOffsetY = 9
helpScreenWidth = 14
helpScreenHeight = 7
offset BYTE $0
;-------------------------------------------------------------------------------
showHelpScreen
jsr setupHelp
jsr drawHelp
@wait jsr GETIN
beq @wait
jsr setupHelp
jsr hideHelpWindow
sec
rts
;-------------------------------------------------------------------------------
;-------------------------------------------------------------------------------
setupHelp
lda #helpOffsetY
sta row
lda #>helpScreenLineStart
sta lineStart+1
lda #<helpScreenLineStart
sta lineStart
lda #$00
sta offset
rts
;-------------------------------------------------------------------------------
;-------------------------------------------------------------------------------
drawHelp
lda #helpOffsetX
sta col
ldx #helpScreenWidth
@loop
; save current byte
ldy col
lda (lineStart),y
ldy offset
sta savedScreen,y
; output help byte
lda helpScreen,y
jsr outputChar
inc offset
; check if finished line
dex
bne @loop
jsr moveToNextLine
; check if finished drawing window
lda offset
cmp #helpScreenWidth * helpScreenHeight
bne drawHelp
rts
;-------------------------------------------------------------------------------
;-------------------------------------------------------------------------------
hideHelpWindow
lda #helpOffsetX
sta col
ldx #helpScreenWidth
@loop
; output saved byte
ldy offset
lda savedScreen,y
jsr outputChar
inc offset
; check if finished line
dex
bne @loop
jsr moveToNextLine
; check if finished restoring screen
lda offset
cmp #helpScreenWidth * helpScreenHeight
bne hideHelpWindow
rts
;-------------------------------------------------------------------------------