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88 lines
2.2 KiB
ArmAsm
88 lines
2.2 KiB
ArmAsm
;
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; Mark Keates, Christian Groessler, Piotr Fusik
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;
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; void cputcxy (unsigned char x, unsigned char y, char c);
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; void cputc (char c);
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;
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.export _cputcxy, _cputc
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.export plot, cputdirect, putchar
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.import gotoxy, _mul40
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.importzp tmp4,ptr4
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.import _revflag,setcursor
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.include "atari.inc"
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_cputcxy:
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pha ; Save C
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jsr gotoxy ; Set cursor, drop x and y
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pla ; Restore C
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_cputc:
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cmp #$0D ; CR
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bne L4
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lda #0
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sta COLCRS
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beq plot ; return
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L4: cmp #$0A ; LF
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beq newline
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cmp #ATEOL ; Atari-EOL?
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beq newline
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asl a ; shift out the inverse bit
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adc #$c0 ; grab the inverse bit; convert ATASCII to screen code
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bpl codeok ; screen code ok?
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eor #$40 ; needs correction
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codeok: lsr a ; undo the shift
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bcc cputdirect
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eor #$80 ; restore the inverse bit
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cputdirect: ; accepts screen code
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jsr putchar
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; advance cursor
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inc COLCRS
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lda COLCRS
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cmp #40
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bcc plot
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lda #0
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sta COLCRS
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.export newline
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newline:
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inc ROWCRS
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lda ROWCRS
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cmp #24
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bne plot
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lda #0
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sta ROWCRS
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plot: jsr setcursor
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ldy COLCRS
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ldx ROWCRS
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rts
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; turn off cursor, update screen, turn on cursor
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putchar:
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pha ; save char
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ldy #0
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lda OLDCHR
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sta (OLDADR),y
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lda ROWCRS
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jsr _mul40 ; destroys tmp4, carry is cleared
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adc SAVMSC ; add start of screen memory
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sta ptr4
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txa
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adc SAVMSC+1
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sta ptr4+1
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pla ; get char again
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ora _revflag
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sta OLDCHR
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ldy COLCRS
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sta (ptr4),y
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jmp setcursor
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