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|
;
; Default mouse callbacks for the Apple II
;
; Oliver Schmidt, 22.09.2005
;
; All functions in this module should be interrupt safe, because they may
; be called from an interrupt handler
;
.export _mouse_def_callbacks
.include "apple2.inc"
; ------------------------------------------------------------------------
.bss
backup: .res 1
visible:.res 1
; ------------------------------------------------------------------------
.rodata
; Callback structure
_mouse_def_callbacks:
.addr hide
.addr show
.addr prep
.addr draw
.addr movex
.addr movey
; ------------------------------------------------------------------------
.data
.ifdef __APPLE2ENH__
cursor = $42 ; Pointer MouseText character
.else
cursor = '+' | $40 ; Flashing crosshair
.endif
getcursor:
.ifdef __APPLE2ENH__
bit RD80VID ; In 80 column mode?
bpl column ; No, skip bank switching
switch: bit LOWSCR ; Patched at runtime
.endif
column: ldx #$00 ; Patched at runtime
getscr: lda $0400,x ; Patched at runtime
cmp #cursor
rts
setcursor:
lda #cursor
setscr: sta $0400,x ; Patched at runtime
.ifdef __APPLE2ENH__
bit LOWSCR ; Doesn't hurt in 40 column mode
.endif
rts
; ------------------------------------------------------------------------
.code
done:
.ifdef __APPLE2ENH__
bit LOWSCR ; Doesn't hurt in 40 column mode
.endif
return: rts
; Hide the mouse cursor.
hide:
dec visible
; Fall through
; Prepare to move the mouse cursor.
prep:
jsr getcursor ; Cursor visible at current position?
bne done ; No, we're done
lda backup ; Get character at cursor position
jmp setscr ; Draw character
; Show the mouse cursor.
show:
inc visible
; Fall through
; Draw the mouse cursor.
draw:
lda visible
beq return
jsr getcursor ; Cursor visible at current position?
beq done ; Yes, we're done
sta backup ; Save character at cursor position
jmp setcursor ; Draw cursor
; Move the mouse cursor x position to the value in A/X.
movex:
dex ; Is position [256..279]?
bmi :+ ; No, start with column 0
clc
adc #$0100 .MOD 7 ; Bias position
ldx #$0100 / 7 - 1 ; Bias column
: sec
: sbc #7 ; 280 positions / 40 columns
inx
bcs :-
stx column+1
.ifdef __APPLE2ENH__
adc #7 / 2 ; Left or right half of 40-col column?
ldx #<LOWSCR ; Columns 1,3,5..79
bcs :+
.assert LOWSCR + 1 = HISCR, error
inx ; Columns 0,2,4..78
: stx switch+1
.endif
rts
; Move the mouse cursor y position to the value in A/X.
movey:
tax ; ABCDExxx
lsr ; 0ABCDExx
lsr ; 00ABCDEx
lsr ; 000ABCDE
sta getscr+1
lsr ; 0000ABCD
and #%00000011 ; 000000CD
ora #>$0400 ; 000001CD
sta getscr+2
sta setscr+2
txa ; ABCDExxx
ror ; EABCDExx
and #%11100000 ; EAB00000
ora getscr+1 ; EABABCDE
and #%11111000 ; EABAB000
sta getscr+1
sta setscr+1
rts
|
