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153 lines
3.3 KiB
ArmAsm
153 lines
3.3 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 16.09.2001
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;
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; char cgetc (void);
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;
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.export _cgetc
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.condes k_blncur, 2
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.import cursor
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.include "cbm510.inc"
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.include "extzp.inc"
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; ------------------------------------------------------------------------
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.proc _cgetc
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lda keyidx ; Characters waiting?
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bne L3 ; Jump if so
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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 keyidx
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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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; Read the character from the keyboard buffer
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L3: ldx #$00 ; Get index
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ldy keybuf ; Get first character in the buffer
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sei
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L4: lda keybuf+1,x ; Move up the remaining chars
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sta keybuf,x
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inx
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cpx keyidx
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bne L4
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dec keyidx
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cli
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ldx #$00 ; High byte
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tya ; First char from buffer
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rts
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.endproc
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; ------------------------------------------------------------------------
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;
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.proc setcursor
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ldy #$00 ;
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tax ; On or off?
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bne @L9 ; Go set it on
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lda CURS_FLAG ; Is the cursor currently off?
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bne @L8 ; 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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sty CURS_STATE ; Cursor will be cleared later
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beq @L8 ; Jump if no
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; Switch to the system bank, load Y with the cursor X coordinate
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lda #$0F
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sta IndReg ; Access system bank
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ldy CURS_X
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; Reset the current cursor
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lda CURS_COLOR
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sta (CRAM_PTR),y ; Store cursor color
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lda ExecReg
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sta IndReg ; Switch to our segment
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lda (SCREEN_PTR),y
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eor #$80 ; Toggle reverse flag
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sta (SCREEN_PTR),y
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; Done
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@L8: rts
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@L9: sty CURS_FLAG ; Cursor on (Y = 0)
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rts
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.endproc
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; ------------------------------------------------------------------------
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; Blink the cursor in the interrupt. A blinking cursor is only available if
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; we use the cgetc() function, so we will export this IRQ handler only in
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; case the module is included into a program.
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.proc k_blncur
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lda CURS_FLAG ; Is the cursor on?
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bne curend ; Jump if not
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dec CURS_BLINK
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bne curend
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; Re-initialize the blink counter
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lda #20 ; Initial value
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sta CURS_BLINK
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; Load Y with the cursor X coordinate
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ldy CURS_X
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; Check if the cursor state was on or off before
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lda CURS_COLOR ; Load color behind cursor
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lsr CURS_STATE ; Cursor currently displayed?
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bcs curset ; Jump if yes
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; Cursor was off before, switch it on
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inc CURS_STATE ; Mark as displayed
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lda (CRAM_PTR),y ; Get color behind cursor...
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sta CURS_COLOR ; ...and remember it
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lda CHARCOLOR ; Use character color
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; Set the cursor with color in A
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curset: sta (CRAM_PTR),y ; Store cursor color
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lda ExecReg
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sta IndReg ; Switch to our segment
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lda (SCREEN_PTR),y
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eor #$80 ; Toggle reverse flag
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sta (SCREEN_PTR),y
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; Switch back to the system bank
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lda #$0F
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sta IndReg
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curend: rts
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.endproc
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