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92 lines
1.9 KiB
ArmAsm
92 lines
1.9 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 2000-08-06, 2002-12-21
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; Using lots of code from MagerValp, MagerValp@cling.gu.se
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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, cputdirect, putchar
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.export newline, plot
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.constructor initcputc
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.destructor donecputc
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.import popa, _gotoxy
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.import PLOT
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.include "c128.inc"
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cputdirect = PRINT
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newline = NEWLINE
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;--------------------------------------------------------------------------
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.code
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_cputcxy:
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pha ; Save C
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jsr popa ; Get Y
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jsr _gotoxy ; Set cursor, drop x
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pla ; Restore C
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; Plot a character - also used as internal function
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_cputc: cmp #$0A ; CR?
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beq cr ; Output a cr
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cmp #$0D ; LF?
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bne L2
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jmp NEWLINE ; Update cursor position
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; Printable char of some sort
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L2: cmp #' '
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bcc L4 ; Other control char
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tay
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bmi L5
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cmp #$60
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bcc L3
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and #$DF
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bne L4 ; Branch always
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L3: and #$3F
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L4: jmp PRINT ; Output character
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; Handle character if high bit set
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L5: and #$7F
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cmp #$7E ; PI?
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bne L6
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lda #$5E ; Load screen code for PI
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bne L4
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L6: ora #$40
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bne L4 ; Branch always
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; Carriage return
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cr: lda #0
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sta CURS_X
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; Set cursor position, calculate RAM pointers
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plot: ldy CURS_X
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ldx CURS_Y
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clc
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jmp PLOT ; Set the new cursor
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; Write one character to the screen without doing anything else, return X
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; position in Y
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putchar = $CC2F
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;--------------------------------------------------------------------------
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; Module constructor/destructor. Don't move the constructor into the INIT
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; segment, because it shares most of the code with the destructor.
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initcputc:
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lda #$C0
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.byte $2C
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donecputc:
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lda #$00
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sta SCROLL
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rts
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