Oberon/V2/Input

MODULE Input; (*NW 5.10.86 / 15.11.90 Ceres-2*)
	IMPORT SYSTEM, Kernel;

	CONST N = 32;
		MOUSE = 0FFFFB000H; UART = 0FFFFC000H; ICU = 0FFFF9000H;

	VAR MW, MH: INTEGER; (*mouse limits*)
		T: LONGINT; (*time counter*)
		n, in, out: INTEGER;
		buf: ARRAY N OF CHAR;

	PROCEDURE Available*(): INTEGER;
	BEGIN RETURN n
	END Available;

	PROCEDURE Read*(VAR ch: CHAR);
	BEGIN
		REPEAT UNTIL n > 0;
		DEC(n); ch := buf[out]; out := (out+1) MOD N
	END Read;

	PROCEDURE Mouse*(VAR keys: SET; VAR x, y: INTEGER);
		VAR u: LONGINT;
	BEGIN SYSTEM.GET(MOUSE, u);
		keys := {0,1,2} - SYSTEM.VAL(SET, u DIV 1000H MOD 8);
		x := SHORT(u MOD 1000H) MOD MW;
		y := SHORT(u DIV 10000H) MOD 819;
		IF y >= MH THEN y := 0 END
	END Mouse;

	PROCEDURE SetMouseLimits*(w, h: INTEGER);
	BEGIN MW := w; MH := h
	END SetMouseLimits;

	PROCEDURE Time*(): LONGINT;
		VAR lo, lo1, hi: CHAR; t: LONGINT;
	BEGIN
		REPEAT SYSTEM.GET(UART+28, lo); SYSTEM.GET(UART+24, hi);
			t := T - LONG(ORD(hi))*256 - ORD(lo); SYSTEM.GET(UART+28, lo1)
		UNTIL lo1 = lo;
		RETURN t
	END Time;

	PROCEDURE+ KBINT;
		VAR ch: CHAR;
	BEGIN SYSTEM.GET(UART+12, ch); (*RHRA*)
		IF ch = 0FFX THEN HALT(24) END ;
		IF n < N THEN buf[in] := ch; in := (in+1) MOD N; INC(n) END
	END KBINT;

	PROCEDURE+ CTInt;
		VAR dmy: CHAR;
	BEGIN SYSTEM.GET(UART+60, dmy); (*stop timer*)
		INC(T, 0FFFFH); SYSTEM.GET(UART+56, dmy) (*restart timer*)
	END CTInt;
	
BEGIN MW := 1024; MH := 800;
	n := 0; in := 0; out := 0; T := 0FFFFH;
	Kernel.InstallIP(KBINT, 4); Kernel.InstallIP(CTInt, 0);
	SYSTEM.PUT(UART+16, 10X); (*ACR*)
	SYSTEM.PUT(UART+ 8, 15X); (*CRA enable*)
	SYSTEM.PUT(UART, 13X); (*MR1A, RxRdy -Int, no parity, 8 bits*)
	SYSTEM.PUT(UART, 7X); (*MR2A 1 stop bit*)
	SYSTEM.PUT(UART+ 4, 44X); (*CSRA, rate = 300 bps*)
	SYSTEM.PUT(UART+52, 14X); (*OPCR OP4 = KB and OP3 = C/T int*)
	SYSTEM.PUT(UART+28, 0FFX); (*CTLR*)
	SYSTEM.PUT(UART+24, 0FFX); (*CTUR*)
	SYSTEM.GET(UART+56, buf[0]); (*start timer*)
	SYSTEM.PUT(ICU + 4, 18X); (*clear ICU IMR and IRR bits 0*)
	SYSTEM.PUT(ICU + 4, 1CX); (*clear ICU IMR and IRR bits 4*)
END Input.