148 lines
1.8 KiB
ArmAsm
148 lines
1.8 KiB
ArmAsm
;===============================
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; draw desire letters, in order
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;===============================
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; X has color
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draw_logo:
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pha
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jsr HCOLOR1 ; set color to X
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ldx #5 ; draw 5 letters
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letter_time:
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lda letters_l,X ; get address
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sta INL
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lda #>letter_d ; assume on same page
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sta INH
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ldy letters_x,X ; get X offset
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txa ; save X
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pha
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jsr draw_letter
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pla
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tax
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dex
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bpl letter_time
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pla
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jmp draw_apple
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;========================
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; draw letter
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;========================
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; so inefficient
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; letter to draw in INL:INH
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; Y is X offset
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draw_letter:
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sty LETTER_X ; store X-coord
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lda LETTER_Y ; alternate up/down
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eor #$8
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sta LETTER_Y
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ldy #$FF ; iterator
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letter_loop:
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hplot:
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; setup X value
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iny ; skip the new-line indicator
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jsr get_x ; get adjusted x-coord in A
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tax ; put in X
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; setup Y value
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jsr get_y ; get adjusted y-coord in A
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ldy #0 ; set top of X value (FIXME)
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jsr HPLOT0 ; plot at (Y,X), (A)
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ldy SAVE_Y ; restore pointer
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iny
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hplot_to:
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; get X value
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jsr get_x ; get adjusted x-coord in A
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pha ; save for later
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lda #0 ; wrap if > 256
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adc #0
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tax
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; get Y value
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jsr get_y
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tay ; put into Y
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pla ; restore X value
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jsr HGLIN ; line to (X,A),(Y)
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ldy SAVE_Y
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iny
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; see if at end of line or of whole thing
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lda (INL),Y ; get next value
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bmi letter_done ; if negative, we are done
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cmp #$7F
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beq hplot
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bne hplot_to
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letter_done:
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rts
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;================
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; get next X co-ord
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; multipy by 2
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; increment y
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get_x:
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lda (INL),Y ; get X value
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asl ; need to multiply by 2
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clc
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adc LETTER_X
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iny
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rts
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;================
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; get next Y co-ord
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; increment y
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; save to SAVE_Y
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get_y:
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sty SAVE_Y ; save Y value on stack for later
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lda (INL),Y ; get Y value
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clc
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adc LETTER_Y
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rts
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