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65 lines
1.6 KiB
ArmAsm
65 lines
1.6 KiB
ArmAsm
;
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; Kevin Ruland
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;
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; char cgetc (void);
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;
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; If open_apple key is pressed then the high-bit of the key is set.
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;
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.export _cgetc
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.ifndef __APPLE2ENH__
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.import machinetype
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.endif
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.import cursor, putchardirect
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.include "zeropage.inc"
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.include "apple2.inc"
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_cgetc:
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; Cursor on ?
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lda cursor
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beq :+
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; Show caret.
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.ifndef __APPLE2ENH__
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lda #' ' | $40 ; Blank, flashing
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bit machinetype
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bpl put_caret
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.endif
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lda #$7F | $80 ; Checkerboard, screen code
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put_caret:
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jsr putchardirect ; Saves old character in tmp3
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; Wait for keyboard strobe.
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: inc RNDL ; Increment random counter low
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bne :+
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inc RNDH ; Increment random counter high
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: lda KBD
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bpl :-- ; If < 128, no key pressed
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; Cursor on ?
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ldy cursor
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beq :+
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; Restore old character.
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pha
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lda tmp3
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jsr putchardirect
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pla
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; At this time, the high bit of the key pressed is set.
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: bit KBDSTRB ; Clear keyboard strobe
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.ifndef __APPLE2ENH__
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bit machinetype ; Apple //e or more recent?
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bpl clear
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.endif
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bit BUTN0 ; Check if OpenApple is down
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bmi done
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clear: and #$7F ; If not down, then clear high bit
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done: ldx #>$0000
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rts
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