dos33fsprogs/games/mist/handle_pages.s

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; FIXME: should be able to drop pages back where we picked them up
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;==============================
; Take Blue Page
;==============================
; A should be page to take (i.e. MECHE_PAGE or similar)
take_blue_page:
pha
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jsr drop_current_page
pla
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pha
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eor BLUE_PAGES_TAKEN ; toggle the taken flag
sta BLUE_PAGES_TAKEN
pla
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ora #HOLDING_BLUE_PAGE ; put it in hand
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sta HOLDING_PAGE
rts
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;==============================
; Take Red Page
;==============================
; A should be page to take (i.e. MECHE_PAGE or similar)
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take_red_page:
pha
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jsr drop_current_page
pla
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pha
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eor RED_PAGES_TAKEN
sta RED_PAGES_TAKEN
pla
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ora #HOLDING_RED_PAGE
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sta HOLDING_PAGE
rts
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;==============================
; Take White Page
;==============================
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take_white_page:
pha
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jsr drop_current_page
pla
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pha
lda #1
sta WHITE_PAGE_TAKEN
pla
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ora #HOLDING_WHITE_PAGE
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sta HOLDING_PAGE
rts
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;==============================
; Drop current page
;==============================
; clicked on a page while holding another
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drop_current_page:
lda HOLDING_PAGE
and #$c0
cmp #HOLDING_RED_PAGE
beq drop_red_page
cmp #HOLDING_BLUE_PAGE
beq drop_blue_page
cmp #HOLDING_WHITE_PAGE
beq drop_white_page
; there was no page?
rts
drop_white_page:
lda #0
sta WHITE_PAGE_TAKEN
rts
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drop_red_page:
lda HOLDING_PAGE
and #$3f
eor RED_PAGES_TAKEN
sta RED_PAGES_TAKEN
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rts
drop_blue_page:
lda HOLDING_PAGE
and #$3f
eor BLUE_PAGES_TAKEN
sta BLUE_PAGES_TAKEN
rts