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|
;
; Ullrich von Bassewitz, 16.09.2001
;
; char cgetc (void);
;
.export _cgetc
.condes k_blncur, 2
.import cursor
.include "cbm510.inc"
.include "extzp.inc"
; ------------------------------------------------------------------------
.proc _cgetc
lda keyidx ; Characters waiting?
bne L3 ; Jump if so
; Switch on the cursor if needed
lda CURS_FLAG
pha
lda cursor
jsr setcursor
L1: lda keyidx
beq L1
ldx #0
pla
bne L2
inx
L2: txa
jsr setcursor
; Read the character from the keyboard buffer
L3: ldx #$00 ; Get index
ldy keybuf ; Get first character in the buffer
sei
L4: lda keybuf+1,x ; Move up the remaining chars
sta keybuf,x
inx
cpx keyidx
bne L4
dec keyidx
cli
ldx #$00 ; High byte
tya ; First char from buffer
rts
.endproc
; ------------------------------------------------------------------------
;
.proc setcursor
ldy #$00 ;
tax ; On or off?
bne @L9 ; Go set it on
lda CURS_FLAG ; Is the cursor currently off?
bne @L8 ; Jump if yes
lda #1
sta CURS_FLAG ; Mark it as off
lda CURS_STATE ; Cursor currently displayed?
sty CURS_STATE ; Cursor will be cleared later
beq @L8 ; Jump if no
; Switch to the system bank, load Y with the cursor X coordinate
lda #$0F
sta IndReg ; Access system bank
ldy CURS_X
; Reset the current cursor
lda CURS_COLOR
sta (CRAM_PTR),y ; Store cursor color
lda ExecReg
sta IndReg ; Switch to our segment
lda (SCREEN_PTR),y
eor #$80 ; Toggle reverse flag
sta (SCREEN_PTR),y
; Done
@L8: rts
@L9: sty CURS_FLAG ; Cursor on (Y = 0)
rts
.endproc
; ------------------------------------------------------------------------
; Blink the cursor in the interrupt. A blinking cursor is only available if
; we use the cgetc() function, so we will export this IRQ handler only in
; case the module is included into a program.
.proc k_blncur
lda CURS_FLAG ; Is the cursor on?
bne curend ; Jump if not
dec CURS_BLINK
bne curend
; Re-initialize the blink counter
lda #20 ; Initial value
sta CURS_BLINK
; Load Y with the cursor X coordinate
ldy CURS_X
; Check if the cursor state was on or off before
lda CURS_COLOR ; Load color behind cursor
lsr CURS_STATE ; Cursor currently displayed?
bcs curset ; Jump if yes
; Cursor was off before, switch it on
inc CURS_STATE ; Mark as displayed
lda (CRAM_PTR),y ; Get color behind cursor...
sta CURS_COLOR ; ...and remember it
lda CHARCOLOR ; Use character color
; Set the cursor with color in A
curset: sta (CRAM_PTR),y ; Store cursor color
lda ExecReg
sta IndReg ; Switch to our segment
lda (SCREEN_PTR),y
eor #$80 ; Toggle reverse flag
sta (SCREEN_PTR),y
; Switch back to the system bank
lda #$0F
sta IndReg
curend: rts
.endproc
|
