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69 lines
1.2 KiB
ArmAsm
69 lines
1.2 KiB
ArmAsm
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; Ullrich von Bassewitz, 06.08.1998
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; char cgetc (void);
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;
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.export _cgetc
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.import cursor
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.include "pet.inc"
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_cgetc: lda KEY_COUNT ; Get number of characters
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bne L3 ; Jump if there are already chars waiting
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; Switch on the cursor if needed
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lda CURS_FLAG
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pha
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lda cursor
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jsr setcursor
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L1: lda KEY_COUNT
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beq L1
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ldx #0
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pla
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bne L2
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inx
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L2: txa
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jsr setcursor
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; Fetch the character from the keyboard buffer
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L3: sei
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ldy KEY_BUF
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ldx #$00
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L4: lda KEY_BUF+1,x
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sta KEY_BUF,x
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inx
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cpx KEY_COUNT
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bne L4
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dec KEY_COUNT
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cli
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ldx #$00 ; Clear high byte
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tya
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rts
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; Switch the cursor on or off
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setcursor:
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tax ; On or off?
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bne seton ; Go set it on
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lda CURS_FLAG ; Is the cursor currently off?
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bne crs9 ; Jump if yes
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lda #1
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sta CURS_FLAG ; Mark it as off
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lda CURS_STATE ; Cursor currently displayed?
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beq crs8 ; Jump if no
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ldy CURS_X ; Get the character column
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lda (SCREEN_PTR),y ; Get character
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eor #$80
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sta (SCREEN_PTR),y ; Store character back
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crs8: lda #0
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sta CURS_STATE ; Cursor not displayed
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crs9: rts
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seton: lda #0
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sta CURS_FLAG
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rts
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