IMPLEMENTATION MODULE Term ;

(* termios-based raw keyboard + ANSI screen output. *)

FROM Posix IMPORT read, write, tcgetattr, tcsetattr, cfmakeraw, poll ;
FROM SYSTEM IMPORT ADR, ADDRESS, BYTE ;

CONST
   TCSANOW = 0 ;
   STDIN   = 0 ;
   STDOUT  = 1 ;

VAR
   saved      : ARRAY [0..127] OF BYTE ;
   rawstate   : ARRAY [0..127] OF BYTE ;
   haveSaved  : BOOLEAN ;

PROCEDURE Out (s : ARRAY OF CHAR) ;
VAR i : CARDINAL ;
    n : LONGINT ;
BEGIN
   i := 0 ;
   WHILE (i <= HIGH (s)) AND (s [i] # 0C) DO
      n := write (STDOUT, ADR (s [i]), 1) ;
      INC (i)
   END
END Out ;

PROCEDURE Open ;
VAR r : INTEGER ;
BEGIN
   r := tcgetattr (STDIN, ADR (saved)) ;
   rawstate := saved ;
   cfmakeraw (ADR (rawstate)) ;
   r := tcsetattr (STDIN, TCSANOW, ADR (rawstate)) ;
   haveSaved := TRUE ;
   Out ("")          (* clear screen, home *)
END Open ;

PROCEDURE Close ;
VAR r : INTEGER ;
BEGIN
   IF haveSaved THEN
      r := tcsetattr (STDIN, TCSANOW, ADR (saved)) ;
      haveSaved := FALSE
   END ;
   Out ("")              (* normal attribute *)
END Close ;

PROCEDURE ClrScr ;
BEGIN
   Out ("")
END ClrScr ;

PROCEDURE GotoXY (row, col : CARDINAL) ;
BEGIN
   Out ("[") ;
   PutCard (row) ;
   Out (";") ;
   PutCard (col) ;
   Out ("H")
END GotoXY ;

PROCEDURE PutCh (ch : CHAR) ;
VAR n : LONGINT ;
BEGIN
   n := write (STDOUT, ADR (ch), 1)
END PutCh ;

PROCEDURE PutStr (s : ARRAY OF CHAR) ;
VAR i : CARDINAL ;
    n : LONGINT ;
BEGIN
   i := 0 ;
   WHILE (i <= HIGH (s)) AND (s [i] # 0C) DO
      n := write (STDOUT, ADR (s [i]), 1) ;
      INC (i)
   END
END PutStr ;

PROCEDURE PutCard (n : CARDINAL) ;
VAR dig : ARRAY [0..9] OF CHAR ;
    i   : CARDINAL ;
BEGIN
   IF n = 0 THEN
      PutCh ("0")
   ELSE
      i := 0 ;
      WHILE n > 0 DO
         dig [i] := CHR (ORD ("0") + (n MOD 10)) ;
         n := n DIV 10 ;
         INC (i)
      END ;
      WHILE i > 0 DO
         DEC (i) ;
         PutCh (dig [i])
      END
   END
END PutCard ;

PROCEDURE PutLongCard (n : LONGCARD) ;
VAR dig : ARRAY [0..19] OF CHAR ;
    i, m : CARDINAL ;
BEGIN
   IF n = 0 THEN
      PutCh ("0")
   ELSE
      i := 0 ;
      WHILE n > 0 DO
         m := n MOD 10 ;
         dig [i] := CHR (ORD ("0") + m) ;
         n := n DIV 10 ;
         INC (i)
      END ;
      WHILE i > 0 DO
         DEC (i) ;
         PutCh (dig [i])
      END
   END
END PutLongCard ;

PROCEDURE ScrnWide (n : CARDINAL) ;
VAR i : CARDINAL ;
BEGIN
   i := 0 ;
   WHILE i < n DO
      PutCh (" ") ;
      INC (i)
   END
END ScrnWide ;

PROCEDURE Marked ;
BEGIN
   Out ("")            (* bold + reverse video *);
END Marked ;

PROCEDURE Normal ;
BEGIN
   Out ("")
END Normal ;

PROCEDURE GetCh (VAR ch : CHAR) ;
VAR n : LONGINT ;
BEGIN
   n := read (STDIN, ADR (ch), 1) ;
   IF n # 1 THEN
      ch := 0C
   END
END GetCh ;

PROCEDURE Avail () : BOOLEAN ;
TYPE PollFd = RECORD
   fd      : CARDINAL ;
   events  : SHORTCARD ;
   revents : SHORTCARD ;
   END ;
VAR pfd : PollFd ;
    n   : INTEGER ;
BEGIN
   (* struct pollfd { int fd; short events; short revents; } *)
   pfd.fd := STDIN ;
   pfd.events := 1 ;             (* POLLIN *)
   pfd.revents := 0 ;
   n := poll (ADR (pfd), 1, 0) ;
   RETURN n > 0
END Avail ;

PROCEDURE GetKey (VAR ch : CHAR) ;
VAR n : LONGINT ;
BEGIN
   IF Avail () THEN
      n := read (STDIN, ADR (ch), 1) ;
      IF n # 1 THEN
         ch := 0C
      END
   ELSE
      ch := 0C
   END
END GetKey ;

PROCEDURE Beep ;
VAR n : LONGINT ;
    b  : CHAR ;
BEGIN
   b := CHR (7) ;
   n := write (STDOUT, ADR (b), 1)
END Beep ;

BEGIN
   haveSaved := FALSE
END Term.