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106 lines
2.3 KiB
ArmAsm
106 lines
2.3 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 06.08.1998
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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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.import popa, _gotoxy
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.import PLOT
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.include "vic20.inc"
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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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bne L1
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lda #0
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sta CURS_X
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beq plot ; Recalculate pointers
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L1: cmp #$0D ; LF?
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beq newline ; Recalculate pointers
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; Printable char of some sort
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cmp #' '
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bcc cputdirect ; Other control char
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tay
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bmi L10
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cmp #$60
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bcc L2
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and #$DF
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bne cputdirect ; Branch always
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L2: and #$3F
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cputdirect:
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jsr putchar ; Write the character to the screen
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; Advance cursor position
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advance:
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iny
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cpy #XSIZE
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bne L3
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jsr newline ; new line
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ldy #0 ; + cr
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L3: sty CURS_X
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rts
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newline:
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clc
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lda #XSIZE
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adc SCREEN_PTR
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sta SCREEN_PTR
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bcc L4
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inc SCREEN_PTR+1
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clc
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L4: lda #XSIZE
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adc CRAM_PTR
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sta CRAM_PTR
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bcc L5
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inc CRAM_PTR+1
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L5: inc CURS_Y
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rts
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; Handle character if high bit set
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L10: and #$7F
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cmp #$7E ; PI?
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bne L11
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lda #$5E ; Load screen code for PI
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bne cputdirect
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L11: ora #$40
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bne cputdirect
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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:
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ora RVS ; Set revers bit
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ldy CURS_X
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sta (SCREEN_PTR),y ; Set char
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lda CHARCOLOR
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sta (CRAM_PTR),y ; Set color
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rts
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