85 lines
1007 B
ArmAsm
85 lines
1007 B
ArmAsm
; draw inverse box on text screen
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; we could use HLIN/VLIN instead?
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; note Y should be in text coords (0..23) not GR (0..47)
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drawbox:
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lda drawbox_y1
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jsr text_hlin
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lda drawbox_y2
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jsr text_hlin
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jsr text_vlins
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rts
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;========================
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; text hlin
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;========================
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; draw from x1,A to x2,A
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text_hlin:
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asl
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tay
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lda gr_offsets,Y
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sta OUTL
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lda gr_offsets+1,Y
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clc
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adc DRAW_PAGE
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sta OUTH
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lda #' '
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ldy drawbox_x1
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drawbox_hlin_loop:
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sta (OUTL),Y
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iny
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cpy drawbox_x2
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bne drawbox_hlin_loop
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rts
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;========================
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; text vlin
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;========================
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; draw from A,y1 to A,y2
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text_vlins:
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ldx drawbox_y1
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text_vlins_loop:
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txa
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asl
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tay
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lda gr_offsets,Y
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sta OUTL
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lda gr_offsets+1,Y
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clc
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adc DRAW_PAGE
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sta OUTH
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lda #' '
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ldy drawbox_x1
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sta (OUTL),Y
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ldy drawbox_x2
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sta (OUTL),Y
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inx
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cpx drawbox_y2
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bcc text_vlins_loop
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beq text_vlins_loop ; ble
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rts
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drawbox_x1: .byte $00
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drawbox_x2: .byte $00
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drawbox_y1: .byte $00
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drawbox_y2: .byte $00
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