mirror of
https://github.com/deater/dos33fsprogs.git
synced 2025-02-05 21:34:30 +00:00
153 lines
2.6 KiB
ArmAsm
153 lines
2.6 KiB
ArmAsm
;====================================
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; scrolls large font
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; right to left, at 168
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; scroll by half
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; even frames, like normal
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; odd frames, start with odd
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; X6543210 XDCBA987
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; 0123456 789ABCD X Y Z
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; lda X, sta Y lda X+1, sta Y+1
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; 2345678 9ABCDef X<<2 | Y<<2
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; lda X, sta Y lda X+1 and #$fc lda Y+1, and #$3 ora, sta Y+1
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; 456789A BCDefgh X<<4 | Y<<4
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; lda X, sta Y lda X+1 and #$fc lda Y+1, and #$3 ora, sta Y+1
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; 6789ABC Defghij X<<6 | Y<<6
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; 89ABCDe fghijkl Y<<1 | Z<<1
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; ABCDefg hijklmn Y<<3 | Z<<3
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; CDefghi jklmnop Y<<5 | Z<<6
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; efghijk lmnopqr Z
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do_scroll:
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lda #0
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sta SCROLL_START
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sta SCROLL_ODD
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do_scroll_again:
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ldy #0 ; Y is column on screen currently drawing
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lda SCROLL_START ; reset string offset to current start
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sta SCROLL_OFFSET
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lda SCROLL_ODD ; check if odd/even inside of char
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beq do_scroll_loop ; if even, normal scroll
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ldx SCROLL_OFFSET ; load offset into string
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lda scroll_text,X ; get the character
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sec
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sbc #'@' ; convert from ASCII
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asl
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tax
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inx ; point to second half of char
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jmp do_scroll_col_loop
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do_scroll_loop:
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ldx SCROLL_OFFSET ; load offset into string
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lda scroll_text,X ; get the character
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sec
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sbc #'@' ; convert from ASCII
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asl
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tax
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do_scroll_col_loop:
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; row1
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lda large_font_row0,X
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sta $22D0,Y
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; row2
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lda large_font_row1,X
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sta $26D0,Y
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; row3
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lda large_font_row2,X
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sta $2AD0,Y
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; row4
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lda large_font_row3,X
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sta $2ED0,Y
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; row5
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lda large_font_row4,X
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sta $32D0,Y
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; row6
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lda large_font_row5,X
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sta $36D0,Y
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; row7
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lda large_font_row6,X
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sta $3AD0,Y
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; row8
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lda large_font_row7,X
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sta $3ED0,Y
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; row9
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lda large_font_row8,X
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sta $2350,Y
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; row10
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lda large_font_row9,X
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sta $2750,Y
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; row11
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lda large_font_row10,X
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sta $2B50,Y
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; row12
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lda large_font_row11,X
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sta $2F50,Y
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; row13
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lda large_font_row12,X
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sta $3350,Y
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; row14
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lda large_font_row13,X
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sta $3750,Y
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; row15
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lda large_font_row14,X
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sta $3B50,Y
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; row16
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lda large_font_row15,X
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sta $3F50,Y
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skip_first_col:
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inx
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iny
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txa ; see if done char
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and #1
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bne do_scroll_col_loop ; if not, draw second half
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inc SCROLL_OFFSET ; point to next char
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cpy #40 ; see if Y edge of screen
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bcc do_scroll_loop
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;=====================
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; check keyboard
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lda KEYPRESS
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bmi do_scroll_done
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lda #200
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jsr wait
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lda #$1
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eor SCROLL_ODD
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sta SCROLL_ODD
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bne jmp_scroll_again ; skip if odd
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inc SCROLL_START
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lda SCROLL_START
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cmp #80
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beq do_scroll_done
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jmp_scroll_again:
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jmp do_scroll_again
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do_scroll_done:
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bit KEYRESET
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rts
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scroll_text: ;0123456789012345678901234567890123456789
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.byte "@@@@@@@@@@@@@@@@@@@@\]^_THE@QUICK@BROWN@"
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.byte "FOX@JUMPED@OVER@THE@LAZY@DOG@PACK@MY@BOX"
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.byte "@WITH@FIVE@DOZEN@LIQOUR@JUGS"
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