159 lines
4.5 KiB
Modula-2
159 lines
4.5 KiB
Modula-2
(*$T-*)
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(*$R-*)
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(****************************************************************)
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(* *)
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(* MODULA-2/86 Library *)
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(* *)
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(* LOGITECH SA., CH-1143 Apples (Switzerland) *)
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(* *)
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(* Module: Keyboard *)
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(* Terminal driver for reading from the keyboard. *)
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(* The keyboard is read through MS-DOS. *)
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(* This module is private to the Terminal Sub-System and *)
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(* should not be used by application programs. *)
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(* *)
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(* Version 1.1 (Oct '84) *)
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(* *)
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(* (C) Copyright 1983, 1984 Logitech, All Rights Reserved *)
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(* *)
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(* Permission is hereby granted to registered users to use *)
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(* or abstract the following program in the implementation *)
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(* of customized versions. This permission does not *)
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(* include the right to redistribute the source code of *)
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(* this program. *)
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(****************************************************************)
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(*$T-*)
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(*$R-*)
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IMPLEMENTATION MODULE Keyboard; (* WS *)
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FROM SYSTEM IMPORT DOSCALL, SWI, RTSVECTOR,
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SETREG, GETREG, AX, BX, CX;
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(* FROM System IMPORT Status, Terminate; *)
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FROM ASCII IMPORT EOL;
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CONST
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CtrlC = 3C;
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KBDCR = 15C;
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BREAK = 1BH;
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PROCEDURE KeyPressed (): BOOLEAN;
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(* Returns TRUE, if a character has been entered,
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FALSE otherwise.
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*)
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VAR result: CARDINAL;
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BEGIN
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IF ti < tailc THEN
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RETURN TRUE
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END;
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DOSCALL (11, result);
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RETURN (result <> 0);
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END KeyPressed;
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PROCEDURE Read (VAR ch: CHAR);
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(* Waits until a character has been entered and returns it.
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If Ctrl-C is entered, the program is stopped.
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CR is transformed into ASCII.EOL.
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*)
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VAR ready: BOOLEAN;
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BEGIN
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IF ti < tailc THEN
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ch := tail[ti];
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INC(ti)
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ELSE
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REPEAT
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DOSCALL (6, 0FFH, ch, ready);
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UNTIL ready;
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END;
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IF ch = CtrlC THEN
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(* Terminate (warned); to ensure that module Break is called *)
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SWI(BREAK);
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END;
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IF ch = KBDCR THEN ch := EOL;
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(* ASCII-cr is transformed in Modula-2 EOL character *)
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END;
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END Read;
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PROCEDURE FNChar (ch: CHAR) : BOOLEAN;
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BEGIN
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CASE ch OF
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'A'..'Z', '0'..'9', 'a'..'z',
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'$', '&', '#', '@', '!', '%',
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"'", '`', '(', ')', '-', '_',
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'^', '~',
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'.', ':', '\' : RETURN (TRUE);
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ELSE RETURN (FALSE);
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END;
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END FNChar;
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TYPE PSP = RECORD
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stuff: ARRAY [1..128] OF CHAR;
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commTail: ARRAY [0..127] OF CHAR
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END;
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VAR PSPPtr: RECORD
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CASE BOOLEAN OF
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TRUE: addr: POINTER TO PSP;
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| FALSE: offset,base: CARDINAL;
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END;
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END;
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tail: ARRAY [0..127] OF CHAR;
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tailc,ti: [0..128];
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BEGIN
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(* DOS puts the command string in the Program Segment Prefix (PSP).
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This module Keyboard is reading and returning the command tail to
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the user. Therefore we get first the PSP address from RTS:
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*)
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SETREG(AX,0026H); (* RTS(38) - get Program Segment Prefix Pointer *)
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SWI(RTSVECTOR); (* rts call *)
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GETREG(BX,PSPPtr.offset);
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GETREG(CX,PSPPtr.base);
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(* Get length of command and copy it in the local variable 'tail':
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*)
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WITH PSPPtr.addr^ DO
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tailc := ORD(commTail[0]);
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FOR ti := 1 TO tailc DO
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tail[ti-1] := commTail[ti]
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END; (* FOR *)
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END; (* WITH *)
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(* we are going to skip the characters in PSP that have already
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been read by the RTS to load the Modula-2 program. We assume
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the following command structure:
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1: rtsname (not in PSP, read and skipped by DOS)
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2: parameters (for RTS, optional)
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3: separator (one or more spaces)
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4: M-2-program-name
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------- Keyboard swallows the above parts and
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------- returns the following parts
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5: parameters (for M-2 programs, optional)
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6: separator (optional)
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7: string (any sequence of characters, optional)
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*)
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ti := 0;
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WHILE (ti < tailc) AND (tail[ti] <> ' ') DO
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INC(ti) (* skip leading parameters *)
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END;
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WHILE (ti < tailc) AND (tail[ti] = ' ') DO
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INC(ti) (* skip leading blanks *)
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END;
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WHILE (ti < tailc) AND FNChar(tail[ti]) DO
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INC(ti) (* skip program name *)
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END;
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WHILE (ti < tailc) AND (tail[ti] = ' ') DO
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INC(ti) (* skip separator immediatly after progname *)
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END;
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IF ti < tailc THEN
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(* if there is a command tail, we return a CR at the end *)
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tail[tailc] := KBDCR;
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INC (tailc);
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END;
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END Keyboard.
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