81 lines
1.2 KiB
ArmAsm
81 lines
1.2 KiB
ArmAsm
;================================
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; htab_vtab
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;================================
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; move to CH/CV
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htab_vtab:
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lda CV
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asl
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tay
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lda gr_offsets,Y ; lookup low-res memory address
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clc
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adc CH ; add in xpos
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sta BASL ; store out low byte of addy
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lda gr_offsets+1,Y ; look up high byte
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adc DRAW_PAGE ;
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sta BASH ; and store it out
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; BASH:BASL now points at right place
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rts
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;================================
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; move_and_print
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;================================
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; move to CH/CV
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move_and_print:
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jsr htab_vtab
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;================================
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; print_string
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;================================
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print_string:
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ldy #0
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print_string_loop:
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lda (OUTL),Y
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beq done_print_string
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ora #$80
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sta (BASL),Y
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iny
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bne print_string_loop
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done_print_string:
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; rts
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;====================
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; point_to_end_string
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;====================
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point_to_end_string:
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iny
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tya
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clc
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adc OUTL
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sta OUTL
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lda #0
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adc OUTH
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sta OUTH
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rts
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;================================
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; print_both_pages
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;================================
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print_both_pages:
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lda DRAW_PAGE
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pha
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lda #0
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sta DRAW_PAGE
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jsr move_and_print
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lda #4
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sta DRAW_PAGE
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jsr move_and_print
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pla
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sta DRAW_PAGE
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rts ; oops forgot this initially
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; explains the weird vertical stripes on the screen
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