(* Aos, Copyright 2001, Pieter Muller, ETH Zurich *)

MODULE Streams; (** AUTHOR "pjm/be"; PURPOSE "I/O buffering and formatted writing and reading"; *)

IMPORT SYSTEM, RC := RealConversions;

CONST
	Ok* = 0; (** zero result code means no error occurred *)
	EOF* = 4201; (** error returned when Receive reads past end of file or stream *)

	EOT* = 1AX; (** EOT character *)

	StringFull = 4202;
	FormatError* = 4203; (** error returned when ReadInt fails *)

	DefaultWriterSize* = 4096;
	DefaultReaderSize* = 4096;

	Invalid* = -1; (** invalid stream position *)

CONST
	CR = 0DX; LF = 0AX; TAB = 9X; SP = 20X;

TYPE
	Size*	= SIZE; (* index type for array *)

TYPE
	Position* = HUGEINT; (* offset in the stream *)

	(** Any stream output procedure or method. *)
	Sender* = PROCEDURE { DELEGATE } ( CONST buf: ARRAY OF CHAR; ofs, len: SIZE; propagate: BOOLEAN; VAR res: WORD );

	(** Any stream input procedure or method. *)
	Receiver* = PROCEDURE { DELEGATE } ( VAR buf: ARRAY OF CHAR; ofs, size, min: SIZE; VAR len: SIZE; VAR res: WORD );

	Connection* = OBJECT

		PROCEDURE Send* ( CONST data: ARRAY OF CHAR; ofs, len: SIZE; propagate: BOOLEAN; VAR res: WORD );
		END Send;

		PROCEDURE Receive* ( VAR data: ARRAY OF CHAR; ofs, size, min: SIZE; VAR len: SIZE; VAR res: WORD );
		END Receive;

		PROCEDURE Close*;
		END Close;

	END Connection;

TYPE
	(** A writer buffers output before it is sent to a Sender.  Must not be shared between processes. *)
	Writer* = OBJECT
	VAR
		(* buf[ 0..tail-1 ] contains data to write. *)
		tail: SIZE;
		buf: POINTER TO ARRAY OF CHAR;

		res*: WORD; (** result of last output operation. *)

		send: Sender;
		sent*: UNSIGNED64; (** count of sent bytes *)

	(** -- Initialization -- *)
	
		PROCEDURE & InitWriter* ( send: Sender; size: SIZE );
		BEGIN
			ASSERT( send # NIL );
			IF ( buf = NIL ) OR ( LEN( buf ) # size ) THEN
				NEW( buf, size );
			END;
			SELF.send := send;
			Reset;
		END InitWriter;

		PROCEDURE Reset* ( );
		BEGIN
			tail := 0; res := Ok; sent := 0;
		END Reset;
		
	(* --  -- *)

		PROCEDURE CanSetPos* ( ): BOOLEAN;
		BEGIN
			RETURN FALSE;
		END CanSetPos;

		PROCEDURE SetPos* ( pos: Position );
		BEGIN
			HALT( 1234 )
		END SetPos;

		PROCEDURE Update* ( );
		BEGIN
			IF ( res = Ok ) THEN
				send( buf^, 0, tail, TRUE, res );
				IF res = Ok THEN INC( sent, tail ); tail := 0 END; (*! UInt64 *)
			END;
		END Update;

		(** Current write position. *)
		PROCEDURE Pos* ( ): Position;
		BEGIN
			RETURN sent + tail; (*! UInt64 *)
		END Pos;

	(** -- Write raw binary data -- *)

	(** Write one byte. *)
		PROCEDURE Char* ( x: CHAR );
		BEGIN
			IF ( tail = LEN( buf )) & ( res = Ok ) THEN
				send( buf^, 0, tail, FALSE, res );
				IF res = Ok THEN INC( sent, tail ); tail := 0 END; (*! UInt64 *)
			END;
			IF res = Ok THEN buf[ tail ] := x; INC( tail ) END;
		END Char;

	(** Write len bytes from x, starting at ofs. *)
		PROCEDURE Bytes* ( CONST x: ARRAY OF CHAR; ofs, len: SIZE );
		VAR n: SIZE;
		BEGIN
			LOOP
				n := LEN( buf ) - tail; (* space available in the internal buffer *)
				IF n = 0 THEN
					IF res = Ok THEN  (* send current buffer *)
						send( buf^, 0, tail, FALSE, res );
						IF res = Ok THEN INC( sent, tail ); tail := 0 ELSE EXIT END; (*! UInt64 *)
					ELSE
						EXIT  (* should not be writing on an erroneous rider *)
					END;
					n := LEN( buf );
				END;
				IF n > len THEN n := len END;
				ASSERT ( tail + n <= LEN( buf )); (* index check *)
				SYSTEM.MOVE( ADDRESSOF( x[ ofs ] ), ADDRESSOF( buf[ tail ] ), n ); INC( tail, n );
				IF len = n THEN EXIT END; (* done *)
				INC( ofs, n ); DEC( len, n );
			END
		END Bytes;

	(** Write a SHORTINT. *)
		PROCEDURE RawSInt* ( x: SHORTINT );
		BEGIN
			Char( SYSTEM.VAL( CHAR, x ));
		END RawSInt;

	(** Write an INTEGER. *)
		PROCEDURE RawInt* ( x: INTEGER );
		BEGIN
			Bytes( SYSTEM.VAL( Bytes2, x ), 0, 2 );
		END RawInt;

	(** Write a LONGINT. *)
		PROCEDURE RawLInt* ( x: LONGINT );
		BEGIN
			Bytes( SYSTEM.VAL( Bytes4, x ), 0, 4 );
		END RawLInt;

	(** Write a HUGEINT. *)
		PROCEDURE RawHInt* ( x: HUGEINT );
		BEGIN
			Bytes( SYSTEM.VAL( Bytes8, x ), 0, 8 );
		END RawHInt;

	(** Write a 64 bit value in network byte order ( most significant byte first ) *)
		PROCEDURE Net64* ( x: HUGEINT );
		BEGIN
			Net32( LONGINT( x DIV 100000000H MOD 100000000H ));
			Net32( LONGINT( x MOD 100000000H ));
		END Net64;

	(** Write a 32 bit value in network byte order ( most significant byte first ) *)
		PROCEDURE Net32* ( x: LONGINT );
		BEGIN
			Char( CHR( x DIV 1000000H MOD 100H )); Char( CHR( x DIV 10000H MOD 100H )); Char( CHR( x DIV 100H MOD 100H ));
			Char( CHR( x MOD 100H ));
		END Net32;

	(** Write a 16 bit value in network byte order ( most significant byte first ) *)
		PROCEDURE Net16* ( x: LONGINT );
		BEGIN
			Char( CHR( x DIV 100H MOD 100H )); Char( CHR( x MOD 100H ));
		END Net16;

	(** write unsigned byte *)
		PROCEDURE Net8* ( x: LONGINT );
		BEGIN
			Char( CHR( x MOD 100H ));
		END Net8;

	(** Write a SET. *)
		PROCEDURE RawSet* ( x: SET ); (*! 64 bits *)
		BEGIN
			Bytes( SYSTEM.VAL( Bytes4, x ), 0, 4 );
		END RawSet;

	(** Write a BOOLEAN. *)
		PROCEDURE RawBool* ( x: BOOLEAN );
		BEGIN
			IF x THEN Char( 1X ) ELSE Char( 0X ) END;
		END RawBool;

	(** Write a REAL. *)
		PROCEDURE RawReal* ( x: REAL );
		BEGIN
			Bytes( SYSTEM.VAL( Bytes4, x ), 0, 4 );
		END RawReal;

	(** Write a LONGREAL. *)
		PROCEDURE RawLReal* ( x: LONGREAL );
		BEGIN
			Bytes( SYSTEM.VAL( Bytes8, x ), 0, 8 );
		END RawLReal;

	(** Write a 0X-terminated string, including the 0X terminator. *)
		PROCEDURE RawString* ( CONST x: ARRAY OF CHAR );
		VAR i := 0: SIZE;
		BEGIN
			WHILE x[ i ] # 0X DO Char( x[ i ] ); INC( i ) END;
			Char( 0X );
		END RawString;

	(** Write a number in a compressed format. *)
		PROCEDURE RawNum* ( x: LONGINT );
		BEGIN
			WHILE ( x < -64 ) OR ( x > 63 ) DO Char( CHR( x MOD 128 + 128 )); x := x DIV 128 END;
			Char( CHR( x MOD 128 ));
		END RawNum;

	(** Write a size in a compressed format. *)
		PROCEDURE RawSize* ( x: SIZE );
		BEGIN
			WHILE ( x < -64 ) OR ( x > 63 ) DO Char( CHR( x MOD 128 + 128 )); x := x DIV 128 END;
			Char( CHR( x MOD 128 ));
		END RawSize;

		(** -- Write formatted data -- *)

	(** Write an ASCII end-of-line ( CR/LF ). *)
		PROCEDURE Ln*;
		BEGIN
			Char( CR ); Char( LF );
		END Ln;

	(** Write a 0X-terminated string, excluding the 0X terminator. *)
		PROCEDURE String* ( CONST x: ARRAY OF CHAR );
		VAR i := 0: SIZE;
		BEGIN
			WHILE x[ i ] # 0X DO Char( x[ i ] ); INC( i ) END;
		END String;

	(** Write an integer in decimal right-justified in a field of at least w characters. *)
		PROCEDURE Int* ( x: HUGEINT; w: SIZE );
		VAR i: SIZE; x0: HUGEINT;
			a: ARRAY 21 OF CHAR;
		BEGIN
			IF x < 0 THEN
				IF x = MIN( HUGEINT ) THEN
					DEC( w, 20 );
					WHILE w > 0 DO Char( " " ); DEC( w ) END;
					String( "-9223372036854775808" );
					RETURN;
				ELSE
					DEC( w ); x0 := -x;
				END;
			ELSE
				x0 := x;
			END;
			i := 0;
			REPEAT a[ i ] := CHR( x0 MOD 10 + 30H ); x0 := x0 DIV 10; INC( i ) UNTIL x0 = 0;
			WHILE w > i DO Char( " " ); DEC( w ) END;
			IF x < 0 THEN Char( "-" ) END;
			REPEAT DEC( i ); Char( a[ i ] ) UNTIL i = 0;
		END Int;

	(** Write a SET in Oberon notation. *)
		PROCEDURE Set* ( s: SET ); (* from P. Saladin *)
		VAR i, last: LONGINT; dots: BOOLEAN;
		BEGIN
			Char( "{" ); last := MAX( LONGINT ); dots := FALSE;
			FOR i := MAX( SET ) TO 0 BY -1 DO
				IF i IN s THEN
					IF last = ( i + 1 ) THEN
						IF dots THEN String( ".." ); dots := FALSE END;
						IF ( i = 0 ) OR ~(( i - 1 ) IN s ) THEN Int( i, 1 ) END;
					ELSE
						IF last <= MAX( SET ) THEN String( ", " ) END;
						Int( i, 1 ); dots := TRUE;
					END;
					last := i;
				END;
			END;
			Char( "}" );
		END Set;

		(**
			Write an integer in hexadecimal right-justified in a field of at least ABS( w ) characters.
			If w < 0 THEN w least significant hex digits of x are written ( potentially including leading zeros )
		*)
		PROCEDURE Hex* ( x: HUGEINT; w: SIZE );
		VAR filler: CHAR; i, maxw: SIZE; y: HUGEINT; a: ARRAY 20 OF CHAR;
		BEGIN
			IF w < 0 THEN filler := '0'; w := -w; maxw := w ELSE filler := ' '; maxw := 16 END;
			i := 0;
			REPEAT
				y := x MOD 10H;
				IF y < 10 THEN a[ i ] := CHR( y + ORD( '0' )) ELSE a[ i ] := CHR( y-10+ORD( 'A' )) END;
				x := x DIV 10H;
				INC( i );
			UNTIL ( x=0 ) OR ( i=maxw );
			WHILE w > i DO Char( filler ); DEC( w ) END;
			REPEAT DEC( i ); Char( a[ i ] ) UNTIL i = 0;
		END Hex;

		(** Write "x" as a hexadecimal address. Do not use Hex because of arithmetic shift of the sign !*)
		PROCEDURE Address* ( x: ADDRESS );
		BEGIN
			Hex( x, -2*SIZEOF( ADDRESS ));
		END Address;

		PROCEDURE Pair( ch: CHAR; x: LONGINT );
		BEGIN
			IF ch # 0X THEN Char( ch ) END;
			Char( CHR( ORD( "0" ) + x DIV 10 MOD 10 )); Char( CHR( ORD( "0" ) + x MOD 10 ));
		END Pair;

	(** Write the date and time in ISO format ( yyyy-mm-dd hh: mm: ss ).  The t and d parameters are in Oberon time and date format.
			If all parameters are within range, the output string is exactly 19 characters wide.  The t or d parameter can be -1, in which
			case the time or date respectively are left out. *)
		PROCEDURE Date* ( t, d: LONGINT );
		VAR ch: CHAR;
		BEGIN
			IF d # -1 THEN
				Int( 1900 + d DIV 512, 4 ); (* year *)
				Pair( "-", d DIV 32 MOD 16 ); (* month *)
				Pair( "-", d MOD 32 ); (* day *)
				ch := " "; (* space between date and time *)
			ELSE
				ch := 0X; (* no space before time *)
			END;
			IF t # -1 THEN
				Pair( ch, t DIV 4096 MOD 32 ); (* hour *)
				Pair( ":", t DIV 64 MOD 64 ); (* min *)
				Pair( ":", t MOD 64 ); (* sec *)
			END;
		END Date;

	(** Write the date and time in RFC 822/1123 format without the optional day of the week ( dd mmm yyyy hh: mm: ss SZZZZ ) .
			The t and d parameters are in Oberon time and date format.  The tz parameter specifies the time zone offset in minutes
			( from -720 to 720 in steps of 30 ).  If all parameters are within range, the output string is exactly 26 characters wide.
			The t, d or tz parameter can be -1, in which case the time, date or timezone respectively are left out. *)
		PROCEDURE Date822* ( t, d, tz: LONGINT );
		VAR i, m: LONGINT; ch: CHAR;
		BEGIN
			IF d # -1 THEN
				Int( d MOD 32, 2 ); (* day *)
				m := ( d DIV 32 MOD 16 - 1 ) * 4; (* month *)
				FOR i := m TO m + 3 DO Char( months[ i ] ) END;
				Int( 1900 + d DIV 512, 5 ); (* year *)
				ch := " "; (* space *)
			ELSE
				ch := 0X; (* no space *)
			END;
			IF t # -1 THEN
				Pair( ch, t DIV 4096 MOD 32 ); (* hour *)
				Pair( ":", t DIV 64 MOD 64 ); (* min *)
				Pair( ":", t MOD 64 ); (* sec *)
				ch := " "; (* space *)
			ELSE
				(* leave ch as before *)
			END;
			IF tz # -1 THEN
				IF ch # 0X THEN Char( ch ) END;
				IF tz >= 0 THEN Pair( "+", tz DIV 60 ) ELSE Pair( "-", ( -tz ) DIV 60 ) END;
				Pair( 0X, ABS( tz ) MOD 60 );
			END;
		END Date822;


	(** Write LONGREAL x  using n character positions. *)
		PROCEDURE Float* ( x: LONGREAL; n: WORD );
		VAR buf: ARRAY 32 OF CHAR;
		BEGIN
			RC.RealToString( x, n, buf );
			String( buf );
		END Float;

	(** Write LONGREAL x in a fixed point notation. n is the overall minimal length for the output field, f the number of fraction digits following the decimal point, D the fixed exponent ( printed only when D # 0 ). *)
		PROCEDURE FloatFix* ( x: LONGREAL; n, f, D: WORD );
		VAR buf: ARRAY 64 OF CHAR;
		BEGIN
			RC.RealToStringFix( x, n, f, D, buf );
			String( buf );
		END FloatFix;

	END Writer;

	(** A special writer that buffers output to be fetched by GetString or GetRawString. *)
	StringWriter* = OBJECT ( Writer )

		PROCEDURE & InitStringWriter* ( size: SIZE );
		BEGIN
			InitWriter( Send, size )
		END InitStringWriter;

		PROCEDURE Send( CONST buf: ARRAY OF CHAR; ofs, len: SIZE; propagate: BOOLEAN; VAR res: WORD );
		BEGIN
			res := StringFull
		END Send;

		PROCEDURE CanSetPos* ( ): BOOLEAN;
		BEGIN
			RETURN TRUE;
		END CanSetPos;

	(* Set the position for the writer *)
		PROCEDURE SetPos* ( pos: Position );
		BEGIN
			IF pos > LEN( buf ) THEN pos := LEN( buf ) END;
			tail := SIZE( pos ); sent := 0; res := Ok;
		END SetPos;

		PROCEDURE Update*;
		(* nothing to do *)
		END Update;

	(** Return the contents of the string writer ( 0X-terminated ). *)
		PROCEDURE Get* ( VAR s: ARRAY OF CHAR );
		VAR i, m: SIZE;
		BEGIN
			m := LEN( s ) - 1; i := 0;
			WHILE ( i # tail ) & ( i < m ) DO s[ i ] := buf[ i ]; INC( i ) END;
			s[ i ] := 0X; tail := 0; res := Ok
		END Get;

	(** Return the contents of the string writer ( not 0X-terminated ).  The len parameters returns the string length. *)
		PROCEDURE GetRaw* ( VAR s: ARRAY OF CHAR; VAR len: SIZE );
		VAR i, m: SIZE;
		BEGIN
			m := LEN( s ); i := 0;
			WHILE ( i # tail ) & ( i < m ) DO s[ i ] := buf[ i ]; INC( i ) END;
			len := i; tail := 0; res := Ok
		END GetRaw;

	END StringWriter;

TYPE
	(** A reader buffers input received from a Receiver.  Must not be shared between processes. *)
	Reader* = OBJECT
	VAR
		head, tail: SIZE;
		buf: POINTER TO ARRAY OF CHAR;
		res*: WORD; (** result of last input operation. *)
		receive: Receiver;
		received*: UNSIGNED64; (** count of received bytes *)
		(* buf[ buf.head..buf.tail-1 ] contains data to read. *)

		PROCEDURE & InitReader* ( receive: Receiver; size: SIZE );
		BEGIN
			ASSERT ( receive # NIL );
			IF ( buf = NIL ) OR ( LEN( buf ) # size ) THEN
				NEW( buf, size );
			END;
			SELF.receive := receive; Reset;
		END InitReader;

	(** reset the reader by dropping the bytes in the buffer, resetting the result code and setting received to 0.
			This is used by seekable extensions of the reader *)
		PROCEDURE Reset*;
		BEGIN
			head := 0; tail := 0; res := Ok; received := 0
		END Reset;

		PROCEDURE CanSetPos* ( ): BOOLEAN;
		BEGIN
			RETURN FALSE
		END CanSetPos;

		PROCEDURE SetPos* ( pos: Position );
		BEGIN
			HALT( 1234 )
		END SetPos;

	(** Return bytes currently available in input buffer. *)
		PROCEDURE Available* ( ): SIZE;
		VAR n: SIZE;
		BEGIN
			IF ( res = Ok ) THEN
				IF ( head = tail ) THEN head := 0; receive( buf^, 0, LEN( buf ), 0, tail, res ); INC( received, tail );
				ELSIF ( tail # LEN( buf )) THEN
					receive( buf^, tail, LEN( buf ) - tail, 0, n, res ); (* poll *)
					INC( tail, n ); INC( received, n )
				END;
				IF res = EOF THEN res := Ok END  (* ignore EOF here *)
			END;
			RETURN tail - head
		END Available;

	(** Current read position. *)
		PROCEDURE Pos* ( ): Position;
		BEGIN
			RETURN Position( received - ( tail - head ))
		END Pos;

		(** -- Read raw binary data -- *)

	(** Read one byte. x=0X if no success ( e.g. file ended ) *)
		PROCEDURE Char* ( VAR x: CHAR );
		BEGIN
			IF ( head = tail ) & ( res = Ok ) THEN head := 0; receive( buf^, 0, LEN( buf ), 1, tail, res ); INC( received, tail ) END;
			IF res = Ok THEN x := buf[ head ]; INC( head ) ELSE x := 0X END
		END Char;

	(** Like Read, but return result. Return 0X if no success ( e.g. file ended ) *)
		PROCEDURE Get* ( ): CHAR;
		BEGIN
			IF ( head = tail ) & ( res = Ok ) THEN head := 0; receive( buf^, 0, LEN( buf ), 1, tail, res ); INC( received, tail ) END;
			IF res = Ok THEN INC( head ); RETURN buf[ head - 1 ] ELSE RETURN 0X END
		END Get;

	(** Like Get, but leave the byte in the input buffer. *)
		PROCEDURE Peek* ( ): CHAR;
		BEGIN
			IF ( head = tail ) & ( res = Ok ) THEN
				head := 0; receive( buf^, 0, LEN( buf ), 1, tail, res ); INC( received, tail );
				IF res = EOF THEN  (* ignore EOF here *)
					res := Ok; tail := 0;
					RETURN 0X; (* Peek returns 0X at eof *)
				END
			END;
			IF res = Ok THEN RETURN buf[ head ] ELSE RETURN 0X END;
		END Peek;

	(** Read size bytes into x, starting at ofs.  The len parameter returns the number of bytes that were actually read. *)
		PROCEDURE Bytes* ( VAR x: ARRAY OF CHAR; ofs, size: SIZE; VAR len: SIZE );
		VAR n: SIZE;
		BEGIN
			len := 0;
			LOOP
				n := tail - head; (* bytes available *)
				IF n = 0 THEN  (* no data available *)
					head := 0;
					IF res = Ok THEN  (* fill buffer *)
						receive( buf^, 0, LEN( buf ), 1, tail, res ); INC( received, tail );
					END;
					IF res # Ok THEN  (* should not be reading from erroneous rider *)
						WHILE size # 0 DO x[ ofs ] := 0X; INC( ofs ); DEC( size ) END; (* clear rest of buffer *)
						IF ( res = EOF ) & ( len # 0 ) THEN res := Ok END; (* ignore EOF if some data being returned *)
						EXIT
					END;
					n := tail
				END;
				IF n > size THEN n := size END;
				ASSERT ( ofs + n <= LEN( x )); (* index check *)
				SYSTEM.MOVE( ADDRESSOF( buf[ head ] ), ADDRESSOF( x[ ofs ] ), n ); INC( head, n ); INC( len, n );
				IF size = n THEN EXIT END; (* done *)
				INC( ofs, n ); DEC( size, n )
			END
		END Bytes;

	(** Skip n bytes on the reader. *)
		PROCEDURE SkipBytes* ( n: Position );
		VAR ch: CHAR;
		BEGIN
			WHILE n > 0 DO ch := Get( ); DEC( n ) END
		END SkipBytes;

	(** Read a SHORTINT. *)
		PROCEDURE RawSInt* ( VAR x: SHORTINT );
		BEGIN
			x := SYSTEM.VAL( SHORTINT, Get( ))
		END RawSInt;

	(** Read an INTEGER. *)
		PROCEDURE RawInt* ( VAR x: INTEGER );
		VAR x0, x1: CHAR;
		BEGIN
			x0 := Get( ); x1 := Get( ); (* defined order *)
			x := ORD( x1 ) * 100H + ORD( x0 )
		END RawInt;

	(** Read a LONGINT. *)
		PROCEDURE RawLInt* ( VAR x: LONGINT );
		VAR ignore: SIZE;
		BEGIN
			Bytes( SYSTEM.VAL( Bytes4, x ), 0, 4, ignore )
		END RawLInt;

	(** Read a HUGEINT. *)
		PROCEDURE RawHInt* ( VAR x: HUGEINT );
		VAR ignore: SIZE;
		BEGIN
			Bytes( SYSTEM.VAL( Bytes8, x ), 0, 8, ignore )
		END RawHInt;

		(** Read a 64 bit value in network byte order ( most significant byte first ) *)
		PROCEDURE Net64* ( ): HUGEINT;
		BEGIN
			RETURN Net32( ) * 100000000H + Net32( )
		END Net64;

	(** Read a 32 bit value in network byte order ( most significant byte first ) *)
		PROCEDURE Net32* ( ): LONGINT;
		BEGIN
			RETURN LONG( ORD( Get( ))) * 1000000H + LONG( ORD( Get( ))) * 10000H + LONG( ORD( Get( ))) * 100H + LONG( ORD( Get( )))
		END Net32;

	(** Read an unsigned 16bit value in network byte order ( most significant byte first ) *)
		PROCEDURE Net16* ( ): LONGINT;
		BEGIN
			RETURN LONG( ORD( Get( ))) * 100H + LONG( ORD( Get( )))
		END Net16;

	(** Read an unsigned byte *)
		PROCEDURE Net8* ( ): LONGINT;
		BEGIN
			RETURN LONG( ORD( Get( )))
		END Net8;

	(** Read a SET. *)
		PROCEDURE RawSet* ( VAR x: SET );
		VAR ignore: SIZE;
		BEGIN
			Bytes( SYSTEM.VAL( Bytes4, x ), 0, 4, ignore )
		END RawSet;

	(** Read a BOOLEAN. *)
		PROCEDURE RawBool* ( VAR x: BOOLEAN );
		BEGIN
			x := ( Get( ) # 0X )
		END RawBool;

	(** Read a REAL. *)
		PROCEDURE RawReal* ( VAR x: REAL );
		VAR ignore: SIZE;
		BEGIN
			Bytes( SYSTEM.VAL( Bytes4, x ), 0, 4, ignore )
		END RawReal;

	(** Read a LONGREAL. *)
		PROCEDURE RawLReal* ( VAR x: LONGREAL );
		VAR ignore: SIZE;
		BEGIN
			Bytes( SYSTEM.VAL( Bytes8, x ), 0, 8, ignore )
		END RawLReal;

	(** Read a 0X-terminated string.  If the input string is larger than x, read the full string and assign the truncated 0X-terminated value to x. *)
		PROCEDURE RawString* ( VAR x: ARRAY OF CHAR );
		VAR i, m: SIZE; ch: CHAR;
		BEGIN
			i := 0; m := LEN( x ) - 1;
			LOOP
				ch := Get( ); (* also returns 0X on error *)
				IF ch = 0X THEN EXIT END;
				IF i < m THEN x[ i ] := ch; INC( i ) END
			END;
			x[ i ] := 0X
		END RawString;

	(** Read a number in a compressed format. *)
		PROCEDURE RawNum* ( VAR x: LONGINT );
		VAR ch: CHAR; n, y: LONGINT;
		BEGIN
			n := 0; y := 0; ch := Get( );
			WHILE ch >= 80X DO INC( y, LSH( LONGINT( ORD( ch )) - 128, n )); INC( n, 7 ); ch := Get( ) END;
			x := ASH( LSH( LONGINT( ORD( ch )), 25 ), n - 25 ) + y
		END RawNum;

	(** Read a size in a compressed format. *)
		PROCEDURE RawSize* ( VAR x: SIZE );
		VAR ch: CHAR; n, y: SIZE;
		BEGIN
			n := 0; y := 0; ch := Get( );
			WHILE ch >= 80X DO INC( y, LSH( SIZE( ORD( ch )) - 128, n )); INC( n, 7 ); ch := Get( ) END;
			x := ASH( LSH( SIZE( ORD( ch )), SIZE OF SIZE * 8 - 7 ), n - SIZE OF SIZE * 8 - 7 ) + y
		END RawSize;

		(** -- Read formatted data ( uses Peek for one character lookahead ) -- *)

	 (** Read an integer value in decimal or hexadecimal.  If hex = TRUE, recognize the "H" postfix for hexadecimal numbers. *)

		PROCEDURE Int* ( VAR x: LONGINT; hex: BOOLEAN );
		VAR vd, vh, sgn, d: LONGINT; ch: CHAR; ok: BOOLEAN;
		BEGIN
			vd := 0; vh := 0; sgn := 1; ok := FALSE;
			IF Peek( ) = "-" THEN sgn := -1; ch := Get( ) END;
			LOOP
				ch := Peek( );
				IF ( ch >= "0" ) & ( ch <= "9" ) THEN d := ORD( ch ) - ORD( "0" )
				ELSIF hex & ( CAP( ch ) >= "A" ) & ( CAP( ch ) <= "F" ) THEN d := ORD( CAP( ch )) - ORD( "A" ) + 10
				ELSE EXIT
				END;
				vd := 10 * vd + d; vh := 16 * vh + d; (* ignore overflow *)
				ch := Get( ); ok := TRUE
			END;
			IF hex & ( CAP( ch ) = "H" ) THEN  (* optional "H" present *)
				vd := vh; (* use the hex value *)
				ch := Get( )
			END;
			x := sgn * vd;
			IF ( res = 0 ) & ~ok THEN res := FormatError END
		END Int;


	(** Return TRUE iff at the end of a line ( or file ). *)
		PROCEDURE EOLN* ( ): BOOLEAN;
		VAR ch: CHAR;
		BEGIN
			ch := Peek( ); RETURN ( ch = CR ) OR ( ch = LF ) OR ( res # Ok )
		END EOLN;

	(** Read all characters until the end of the line ( inclusive ).  If the input string is larger than x, read the full string and assign
			the truncated 0X-terminated value to x. *)
		PROCEDURE Ln* ( VAR x: ARRAY OF CHAR );
		VAR i, m: SIZE; ch: CHAR;
		BEGIN
			i := 0; m := LEN( x ) - 1;
			LOOP
				ch := Peek( );
				IF ( ch = CR ) OR ( ch = LF ) OR ( res # Ok ) THEN EXIT END;
				IF i < m THEN x[ i ] := ch; INC( i ) END;
				ch := Get( );
			END;
			x[ i ] := 0X;
			IF ch = CR THEN ch := Get( ) END;
			IF Peek( ) = LF THEN ch := Get( ) END;
		END Ln;

	(** Read all characters until the end of the line ( inclusive ) or an <EOT> character.
			If the input string is larger than x, read the full string and assign the truncated 0X-terminated
			value to x. *)
		PROCEDURE LnEOT* ( VAR x: ARRAY OF CHAR );
		VAR i, m: SIZE; ch: CHAR;
		BEGIN
			i := 0; m := LEN( x ) - 1;
			LOOP
				ch := Peek( );
				IF ( ch = CR ) OR ( ch = LF ) OR ( ch = EOT ) OR ( res # Ok ) THEN EXIT END;
				IF i < m THEN x[ i ] := ch; INC( i ) END;
				ch := Get( )
			END;
			x[ i ] := 0X;
			IF ch = CR THEN ch := Get( ) END;
			IF Peek( ) = LF THEN ch := Get( ) END;
			IF ch = EOT THEN ch := Get( ) END
		END LnEOT;

	(** Skip over all characters until the end of the line ( inclusive ). *)
		PROCEDURE SkipLn*;
		VAR ch: CHAR;
		BEGIN
			LOOP
				ch := Peek( );
				IF ( ch = CR ) OR ( ch = LF ) OR ( res # Ok ) THEN EXIT END;
				ch := Get( )
			END;
			IF ch = CR THEN ch := Get( ) END;
			IF Peek( ) = LF THEN ch := Get( ) END
		END SkipLn;

	(** Skip over space and TAB characters. *)
		PROCEDURE SkipSpaces*;
		VAR ch: CHAR;
		BEGIN
			LOOP
				ch := Peek( );
				IF ( ch # TAB ) & ( ch # SP ) THEN EXIT END;
				ch := Get( )
			END
		END SkipSpaces;

	(** Skip over space, TAB and EOLN characters. *)
		PROCEDURE SkipWhitespace*;
		VAR ch: CHAR;
		BEGIN
			LOOP
				ch := Peek( );
				IF ( ch # SP ) & ( ch # CR ) & ( ch # LF ) & ( ch # TAB ) THEN EXIT END;
				ch := Get( )
			END
		END SkipWhitespace;

	(** Read a token, consisting of any string of characters terminated by space, TAB or EOLN. *)
		PROCEDURE Token* ( VAR token: ARRAY OF CHAR );
		VAR j, max: SIZE; ch: CHAR;
		BEGIN
			j := 0; max := LEN( token ) - 1;
			LOOP
				ch := Peek( );
				IF ( ch = SP ) OR ( ch = CR ) OR ( ch = LF ) OR ( ch = TAB ) OR ( res # Ok ) THEN EXIT END;
				IF j < max THEN token[ j ] := ch; INC( j ) END;
				ch := Get( )
			END;
			token[ j ] := 0X
		END Token;

	(** Read an optionally "" or '' enquoted string.  Will not read past the end of a line. *)
		PROCEDURE String* ( VAR string: ARRAY OF CHAR );
		VAR c, delimiter: CHAR; i, len: SIZE;
		BEGIN
			c := Peek( );
			IF ( c # "'" ) & ( c # '"' ) THEN Token( string )
			ELSE
				delimiter := Get( ); c := Peek( ); i := 0; len := LEN( string ) - 1;
				WHILE ( i < len ) & ( c # delimiter ) & ( c # CR ) & ( c # LF ) & ( res = Ok ) DO string[ i ] := Get( ); INC( i ); c := Peek( ) END;
				IF ( c = delimiter ) THEN c := Get( ) END;
				string[ i ] := 0X
			END
		END String;

		(** First skip whitespace, then read string *)
		PROCEDURE GetString* ( VAR string : ARRAY OF CHAR ): BOOLEAN;
		VAR c: CHAR;
		BEGIN
			SkipWhitespace;
			c := Peek( );
			String( string );
			RETURN ( string[ 0 ] # 0X ) OR ( c = "'" ) OR ( c = '"' );
		END GetString;

		(** First skip whitespace, then read integer *)
		PROCEDURE GetInteger* ( VAR integer : LONGINT; isHexadecimal : BOOLEAN ): BOOLEAN;
		BEGIN
			SkipWhitespace;
			Int( integer, isHexadecimal );
			RETURN res = Ok;
		END GetInteger;

		(** First skip whitespace, then read a real *)
		PROCEDURE GetReal* ( VAR real: LONGREAL ): BOOLEAN;
		BEGIN
			SkipWhitespace;
			real := RC.ScanReal( Get );
			RETURN res = Ok
		END GetReal;

		(** First skip whitespace, then read 1 byte character *)
		PROCEDURE GetChar* ( VAR ch : CHAR ): BOOLEAN;
		BEGIN
			SkipWhitespace;
			Char( ch );
			RETURN ch # 0X;
		END GetChar;

	END Reader;

TYPE
	(** A special reader that buffers input set by SetString or SetRawString. *)
	StringReader* = OBJECT ( Reader )

		PROCEDURE & InitStringReader* ( size: SIZE );
		BEGIN
			InitReader( Receive, size )
		END InitStringReader;

		PROCEDURE CanSetPos* ( ): BOOLEAN;
		BEGIN
			RETURN TRUE
		END CanSetPos;

	(** Set the reader position *)
		PROCEDURE SetPos* ( pos: Position );
		BEGIN
			IF pos > LEN( buf ) THEN pos := LEN( buf ) END;
			head := SIZE( pos ); tail := LEN( buf ); received := LEN( buf ); res := Ok;
		END SetPos;

		PROCEDURE Receive( VAR buf: ARRAY OF CHAR; ofs, size, min: SIZE; VAR len: SIZE; VAR res: WORD );
		BEGIN
			IF min = 0 THEN res := Ok ELSE res := EOF END;
			len := 0;
		END Receive;

	(** Set the contents of the string buffer.  The s parameter is a 0X-terminated string. *)
		PROCEDURE Set* ( CONST  s: ARRAY OF CHAR );
		VAR len: SIZE;
		BEGIN
			len := 0;
			WHILE s[ len ] # 0X DO INC( len ) END;
			IF len > LEN( buf ) THEN len := LEN( buf ) END;
			head := 0; tail := len; received := len; res := Ok;
			IF len > 0 THEN
				SYSTEM.MOVE( ADDRESSOF( s[ 0 ] ), ADDRESSOF( buf[ 0 ] ), len )
			END;
		END Set;

	(** Set the contents of the string buffer.  The len parameter specifies the size of the buffer s. *)
		PROCEDURE SetRaw* ( CONST s: ARRAY OF CHAR; ofs, len: SIZE );
		BEGIN
			IF len > LEN( buf ) THEN len := LEN( buf ) END;
			head := 0; tail := len; received := len; res := Ok;
			ASSERT (( len >= 0 ) & ( ofs + len <= LEN( s ))); (* index check *)
			IF len > 0 THEN
				SYSTEM.MOVE( ADDRESSOF( s[ ofs ] ), ADDRESSOF( buf[ 0 ] ), len )
			END;
		END SetRaw;

	END StringReader;

	Bytes2 = ARRAY 2 OF CHAR;
	Bytes4 = ARRAY 4 OF CHAR;
	Bytes8 = ARRAY 8 OF CHAR;

VAR
	months: ARRAY 12 * 4 + 1 OF CHAR;


	(** Open a writer to the specified stream sender.  Update must be called after writing to ensure the buffer is written to the stream. *)
	PROCEDURE OpenWriter* ( VAR b: Writer; send: Sender );
	BEGIN
		NEW( b, send, DefaultWriterSize )
	END OpenWriter;

(** Open a reader from the specified stream receiver. *)
	PROCEDURE OpenReader* ( VAR b: Reader; receive: Receiver );
	BEGIN
		NEW( b, receive, DefaultReaderSize )
	END OpenReader;

(** Copy the contents of a reader to a writer *)
	PROCEDURE Copy* ( r: Reader; w: Writer );
	VAR char: CHAR;
	BEGIN
		WHILE r.res = Ok DO
			r.Char ( char );
			IF r.res = Ok THEN w.Char ( char ) END
		END;
	END Copy;


BEGIN
	months := " Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec";
END Streams.

(**
Notes: 
o	Any single buffer instance must not be accessed by more than one process concurrently.
o 	The interface is blocking ( synchronous ).  If an output buffer is full, it is written with a synchronous write, which returns
	only when all the data has been written.   If an input buffer is empty, it is read with a synchronous read, which only returns
	once some data has been read.  The only exception is the Available( ) procedure, which "peeks" at the input stream
	and returns 0 if no data is currently available.
o 	All procedures set res to the error code reported by the lower-level I/O operation ( non-zero indicates error ).
	 E.g. closing an underlying TCP connection will result in the Read* procedures returning a non-zero error code.
o 	res is sticky.  Once it becomes non-zero, it remains non-zero.
o 	The only way to detect end of file is to attempt to read past the end of file, which returns a non-zero error code.
o 	All output written to an erroneous buffer is ignored.
o 	The value returned when reading from an erroneous buffer is undefined, except for the Read procedure, which returns 0X.
o 	ReadBytes sets the len parameter to the number of bytes that were actually read, e.g. if size = 10, and only 8 bytes are read, len is 8.
o 	Raw format is little-endian 2's complement integers, IEEE reals and 0X-terminated strings.
o 	Syntax for ReadInt with hex = FALSE: num = [ "-" ] digit { digit }. digit = "0".."9".
o 	Syntax for ReadInt with hex = TRUE: [ "-" ] hexdigit { hexdigit } [ "H"|"h" ]. hexdigit = digit | "A".."F" | "a".."f".
o 	ReadInt with hex = TRUE allows "A".."F" as digits, and looks for a "H" character after the number.
	If present, the number is interpreted as hexadecimal.  If hexadecimal digits are present, but no "H" flag, 
	the resulting decimal value is undefined.
o 	ReadInt ignores overflow.
o 	A Sender sends len bytes from buf at ofs to output and returns res non-zero on error.  It waits until all the data is written, 
	or an error occurs.
o 	A Receiver receives up to size bytes from input into buf at ofs and returns the number of bytes read in len.
	It returns res non-zero on error.  It waits until at least min bytes ( possibly zero ) are available, or an error occurs.
o 	EOLN and ReadLn recognize the following end-of-line characters: CR, LF and CR/LF.
o 	To read an unstructured file token-by-token: WHILE ( r.res = 0 ) DO SkipWhitespace; ReadToken END
o 	To read a line structured file token-by-token: WHILE r.res = 0 DO SkipSpaces; WHILE ~EOLN DO ReadToken; SkipSpaces END END
o 	A string writer is not flushed when it becomes full, but res is set to a non-zero value.
o 	Update has no effect on a string writer.
o 	GetString can be called on a string writer to return the buffer contents and reset it to empty.
o 	GetString always appends a 0X character to the buffer, but returns the true length ( excluding the added 0X ) in the len parameter, 
	so it can also be used for binary data that includes 0X characters.
o 	Receive procedure should set res to EOF when attempting to read past the end of file.
*)


(*
to do: 
o stream byte count
o read formatted data
o reads for all formatted writes
o write reals
o low-level version that can be used in kernel ( below KernelLog )
*)