import STDLIB
    predef syscall, call, memset, getc, putc, puts, modaddr
    byte MACHID
end
//
// Handy constants.
//
const FALSE        = 0
const TRUE         = !FALSE
const FULLMODE     = 0
const MIXMODE      = 1
//
// Apple II hardware constants.
//
const speaker      = $C030
const showgraphics = $C050
const showtext     = $C051
const showfull     = $C052
const showmix      = $C053
const showpage1    = $C054
const showpage2    = $C055
const showlores    = $C056
const showhires    = $C057
const keyboard     = $C000
const keystrobe    = $C010
const hgr1         = $2000
const hgr2         = $4000
const page1        = 0
const page2        = 1
//
// Predefined functions.
//
predef a2reset,a2keypressed,a2home,a2gotoxy,a2viewport,a2texttype
predef a2textmode,a2writeint,a2writeln
predef a2grmode,grcolor,grplot
//
// String pool.
//
byte stdlib[]  = "STDLIB"
//
// Screen row address arrays.
//
word txt1scrn[]     = $0400,$0480,$0500,$0580,$0600,$0680,$0700,$0780
word                = $0428,$04A8,$0528,$05A8,$0628,$06A8,$0728,$07A8
word                = $0450,$04D0,$0550,$05D0,$0650,$06D0,$0750,$07D0
word txt2scrn[]     = $0800,$0880,$0900,$0980,$0A00,$0A80,$0B00,$0B80
word                = $0828,$08A8,$0928,$09A8,$0A28,$0AA8,$0B28,$0BA8
word                = $0850,$08D0,$0950,$09D0,$0A50,$0AD0,$0B50,$0BD0
//
// Text screen parameters.
//
byte textcols = 40
byte curshpos = 0
byte cursvpos = 0
//
// Apple 3 console codes.
//
byte textbwmode[]   = 2, 16, 0
byte textclrmode[]  = 2, 16, 1
byte grcharset[]    = 1, 0, $7F, $7F, $7F, $7F, $00, $00, $00, $00
byte devcons
//
// Exported function table.
//
export word conio[]
//
// Function pointers.
//
word = @a2reset
word = @a2keypressed
word = @a2home
word = @a2gotoxy
word = @a2viewport
word = @a2texttype
word = @a2textmode
word = @a2grmode
word = @grcolor
word = @grplot
//
// Native  routines.
//
asm equates
	!SOURCE	"vmsrc/plvmzp.inc"
end
//
// def grscrn(rowaddrs)
//
asm grscrn
GRSCRN	=	$26
GRSCRNL	=	GRSCRN
GRSCRNH	=	GRSCRNL+1
	LDA	ESTKL,X
	STA	GRSCRNL
	LDA	ESTKH,X
	STA	GRSCRNH
	RTS
end
//
// def grcolor(color)
//
asm grcolor
GRCLR	=	$30
	LDA	#$0F
	AND	ESTKL,X
	STA	GRCLR
	ASL
	ASL
	ASL
	ASL
	ORA	GRCLR
	STA	GRCLR
	RTS
end
//
// def grplot(x, y)
//
asm grplot
	STY	IPY
	LDA	ESTKL,X
	AND	#$FE
	CMP	ESTKL,X
	TAY
	LDA	(GRSCRN),Y
	STA	DSTL
	INY
	LDA	(GRSCRN),Y
	STA	DSTH
	LDA	#$FF
	ADC	#$00
	EOR	#$0F
	TAY
	AND	GRCLR
	STA	TMPL
	TYA
	EOR	#$FF
	LDY	ESTKL+1,X
	AND	(DST),Y
	ORA	TMPL
	STA	(DST),Y
	LDY	IPY
	INX
	RTS
end
//
// Apple 1 routines.
//
def a1keypressed
    return ^$D011 >= 128
end
def a1gotoxy(x, y)
    curshpos = x
    cursvpos = y
    putln
    while x
        putc(' ')
	x = x - 1
    loop
end
def a1viewport(left, top, width, height)
end
def a1texttype(type)
end
def a1textmode(columns)
end
def a1grmode(mix)
    return 0 // not supported
end
//
// Apple II routines.
//
def a2keypressed
    return ^keyboard >= 128
end
def a2home
    curshpos = 0
    cursypos = 0
    return call($FC58, 0, 0, 0, 0) // home()
end
def a2gotoxy(x, y)
    curshpos = x
    cursvpos = y
    ^$24 = x + ^$20
    return call($FB5B, y + ^$22, 0, 0, 0)
end
def a2viewport(left, top, width, height)
    if !width or !height
        left   = 0
	top    = 0
	width  = 40
	height = 24
    fin
    ^$20 = left
    ^$21 = width
    ^$22 = top
    ^$23 = height + top - 1
    return a2gotoxy(0, 0)
end
def a2texttype(type)
end
def a2writeln(string, start, fill)

end
def a2textmode(columns)
    call($FB39, 0, 0, 0, 0) // textmode()
    return a2home 
end
def a2grmode(mix)
    call($FB2F, 0, 0, 0, 0) // initmode()
    call($FB40, 0, 0, 0, 0) // grmode()
    if !mix
        ^showfull
    fin
    a2home
    return grscrn(@txt1scrn) // point to lo-res screen
end
//
// Apple III routines.
//
def dev_control(devnum, code, list)
    byte params[5]
    
    params.0 = 3
    params.1 = devnum
    params.2 = code
    params:3 = list
    return syscall($83, @params)
end
def dev_status(devnum, code, list)
    byte params[5]
    
    params.0 = 3
    params.1 = devnum
    params.2 = code
    params:3 = list
    return syscall($82, @params)
end
def a3keypressed
    byte count
    dev_status(devcons, 5, @count)
    return count
end
def a3home
    curshpos = 0
    cursvpos = 0
    return cout(28)
end
def a3gotoxy(x, y)
    curshpos = x
    cursvpos = y
    putc(24)
    putc(x)
    putc(25)
    return putc(y)
end
def a3viewport(left, top, width, height)
    if !width or !height
        //
	// Reset the full-screen viewport
	//
        left   = 0
	top    = 0
	width  = textwidth
	height = 24
    fin
    putc(1) // Reset viewport
    putc(26)
    putc(left)
    putc(top)
    putc(2)
    putc(26)
    putc(left + width  - 1)
    putc(top  + height - 1)
    putc(3)
    return a3gotoxy(0, 0)
end
def a3texttype(type)
end
def a3textmode(columns)
    puts(@textbwmode)
    if columns > 40
        a3viewport(0, 0, 80, 24)
    else
        a3viewport(0, 0, 40, 24)
    fin
    return putc(28)
end
def a3grmode(mix)
    byte i
    if mix
        mix = 19
    else
        mix = 23
    fin
    puts(@textclrmode)
    dev_control(devcons, 17, @grcharset)
    a3viewport(0, 20, 40, 4)
    for i = 0 to mix
        memset(txt1scrn[i], 40, $0000) // text  screen
        memset(txt2scrn[i], 40, $0000) // color screen
    next
    return grscrn(@txt2scrn) // point to color screen
end
//
// Machine specific initialization.
//
when MACHID & $C8
    is $08 // Apple 1
	conio:reset      = @a1reset
        conio:keypressed = @a1keypressed
	conio:home       = @a1home
	conio:gotoxy     = @a1gotoxy
	conio:viewport   = @a1viewport
	conio:texttype   = @a1texttype
	conio:textmode   = @a1textmode
	conio:grmixmode  = @a1grmixmode
    is $C0 // Apple ///
	conio:reset      = @a3reset
        conio:keypressed = @a3keypressed
	conio:home       = @a3home
	conio:gotoxy     = @a3gotoxy
	conio:viewport   = @a3viewport
	conio:texttype   = @a3texttype
	conio:textmode   = @a3textmode
	conio:grmixmode  = @a3grmixmode
	devcons = modaddr(@stdlib).5 // devcons variable from STDLIB
    otherwise // Apple ][
wend