116 lines
1.8 KiB
ArmAsm
116 lines
1.8 KiB
ArmAsm
;=====================================================================
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;= ROUTINES
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;=====================================================================
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clear_screens:
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;===================================
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; Clear top/bottom of page 0
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;===================================
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lda #$0
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sta DRAW_PAGE
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jsr clear_top
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jsr clear_bottom
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;===================================
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; Clear top/bottom of page 1
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;===================================
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lda #$4
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sta DRAW_PAGE
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jsr clear_top
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jsr clear_bottom
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rts
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clear_screens_notext:
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;===================================
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; Clear top/bottom of page 0
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;===================================
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lda #$0
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sta DRAW_PAGE
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jsr clear_top
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lda #$0
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jsr clear_bottom_a
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;===================================
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; Clear top/bottom of page 1
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;===================================
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lda #$4
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sta DRAW_PAGE
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jsr clear_top
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lda #$0
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jsr clear_bottom_a
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rts
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;=============================
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; clear_top
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;=============================
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; takes 2+10+ (24+703 )*20 +6
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; 14,558 cycles(?) 15ms, 70Hz
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clear_top:
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lda #$00 ; 2
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;=============================
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; clear_top_a
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;=============================
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clear_top_a:
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sta COLOR ; 3
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; HLIN Y, V2 AT A
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lda #39 ; 2
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sta V2 ; 3
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lda #0 ; 2
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clear_top_loop:
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ldy #0 ; 2
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pha ; 3
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jsr hlin_double ; 6+
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pla ; 4
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clc ; 2
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adc #$2 ; 2
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cmp #40 ; 2
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bne clear_top_loop ; 2nt/3
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rts ; 6
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;=============================
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; clear_bottom
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;=============================
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clear_bottom:
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lda #$a0 ; NORMAL space
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clear_bottom_a:
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sta COLOR
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lda #40
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sta V2
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clear_bottom_loop:
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ldy #0
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pha
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jsr hlin_double
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pla
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clc
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adc #$2
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cmp #48
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bne clear_bottom_loop
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rts
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