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(* IOChan.mod implement the ISO IOChan specification.
Copyright (C) 2002-2023 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.
This file is part of GNU Modula-2.
GNU Modula-2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GNU Modula-2 is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. *)
IMPLEMENTATION MODULE IOChan ;
IMPORT FIO, EXCEPTIONS, M2EXCEPTION, RTio,
RTentity, errno, ErrnoCategory, IOLink, StdChans, M2RTS ;
FROM EXCEPTIONS IMPORT ExceptionSource, RAISE, AllocateSource,
IsCurrentSource, IsExceptionalExecution ;
FROM Storage IMPORT ALLOCATE ;
TYPE
ChanId = RTio.ChanId ;
VAR
iochan : ExceptionSource ;
invalid: ChanId ;
PROCEDURE InvalidChan () : ChanId ;
(* Returns the value identifying the invalid channel. *)
BEGIN
RETURN( invalid )
END InvalidChan ;
PROCEDURE CheckValid (cid: ChanId) ;
(* internal routine to check whether we have a valid channel *)
BEGIN
IF cid=InvalidChan()
THEN
RAISE(iochan, ORD(notAChannel), 'IOChan: ChanId specified is invalid')
END
END CheckValid ;
(* For each of the following operations, if the device supports the
operation on the channel, the behaviour of the procedure conforms
with the description below. The full behaviour is defined for
each device module. If the device does not support the operation
on the channel, the behaviour of the procedure is to raise the
exception notAvailable.
*)
(* Text operations - these perform any required translation
between the internal and external representation of text.
*)
PROCEDURE Look (cid: ChanId; VAR ch: CHAR; VAR res: IOConsts.ReadResults) ;
(* If there is a character as the next item in the input stream cid,
assigns its value to ch without removing it from the stream;
otherwise the value of ch is not defined.
res (and the stored read result) are set to the value
allRight, endOfLine, or endOfInput.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.Look: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF cid=StdChans.NullChan()
THEN
result := IOConsts.endOfInput
ELSIF (ChanConsts.readFlag IN flags) AND (ChanConsts.textFlag IN flags)
THEN
doLook(dtp, ch, res)
ELSE
res := IOConsts.wrongFormat
END ;
result := res
END
END
END Look ;
PROCEDURE Skip (cid: ChanId) ;
(* If the input stream cid has ended, the exception skipAtEnd is raised;
otherwise the next character or line mark in cid is removed,
and the stored read result is set to the value allRight.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.Skip: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF (cid=StdChans.NullChan()) OR (result=IOConsts.endOfInput)
THEN
RAISE(iochan, ORD(skipAtEnd),
'IOChan.Skip: attempt to skip data from a stream that has ended')
ELSIF (ChanConsts.readFlag IN flags) AND (ChanConsts.textFlag IN flags)
THEN
doSkip(dtp) ;
result := IOConsts.allRight
ELSE
RAISE(iochan, ORD(notAvailable),
'IOChan.Skip: attempt to skip data from a channel which is not configured as read and text')
END
END
END
END Skip ;
PROCEDURE SkipLook (cid: ChanId;
VAR ch: CHAR;
VAR res: IOConsts.ReadResults) ;
(* If the input stream cid has ended, the exception skipAtEnd is raised;
otherwise the next character or line mark in cid is removed.
If there is a character as the next item in cid stream,
assigns its value to ch without removing it from the stream.
Otherwise, the value of ch is not defined.
res (and the stored read result) are set to the value allRight,
endOfLine, or endOfInput.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.SkipLook: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF (cid=StdChans.NullChan()) OR (result=IOConsts.endOfInput)
THEN
RAISE(iochan, ORD(skipAtEnd),
'IOChan.SkipLook: attempt to skip data from a stream that has ended')
ELSIF (ChanConsts.readFlag IN flags) AND (ChanConsts.textFlag IN flags)
THEN
doSkipLook(dtp, ch, result)
ELSE
RAISE(iochan, ORD(notAvailable),
'IOChan.SkipLook: attempt to skip data from a channel which is not configured as read and text')
END ;
res := result
END
END
END SkipLook ;
PROCEDURE WriteLn (cid: ChanId) ;
(* Writes a line mark over the channel cid. *)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.WriteLn: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF cid=StdChans.NullChan()
THEN
(* do nothing *)
ELSIF (ChanConsts.writeFlag IN flags) AND (ChanConsts.textFlag IN flags)
THEN
dtp^.doLnWrite(dtp)
ELSE
RAISE(iochan, ORD(notAvailable),
'IOChan.WriteLn: attempting to write to a channel which is not configured as write and text')
END
END
END
END WriteLn ;
PROCEDURE TextRead (cid: ChanId;
to: SYSTEM.ADDRESS;
maxChars: CARDINAL;
VAR charsRead: CARDINAL) ;
(* Reads at most maxChars characters from the current line in cid,
and assigns corresponding values to successive components of an
ARRAY OF CHAR variable for which the address of the first
component is to. The number of characters read is assigned
to charsRead. The stored read result is set to allRight,
endOfLine, or endOfInput.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.TextRead: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF (cid=StdChans.NullChan()) OR (result=IOConsts.endOfInput)
THEN
charsRead := 0 ;
result := IOConsts.endOfInput
ELSIF (ChanConsts.readFlag IN flags) AND (ChanConsts.textFlag IN flags)
THEN
doTextRead(dtp, to, maxChars, charsRead)
ELSE
RAISE(iochan, ORD(notAvailable),
'IOChan.TextRead: attempt to read data from a channel which is not configured as read and text')
END
END
END
END TextRead ;
PROCEDURE TextWrite (cid: ChanId;
from: SYSTEM.ADDRESS;
charsToWrite: CARDINAL) ;
(* Writes a number of characters given by the value of charsToWrite,
from successive components of an ARRAY OF CHAR variable for which
the address of the first component is from, to the channel cid.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.TextWrite: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF cid=StdChans.NullChan()
THEN
(* do nothing *)
ELSIF (ChanConsts.writeFlag IN flags) AND (ChanConsts.textFlag IN flags)
THEN
doTextWrite(dtp, from, charsToWrite)
ELSE
RAISE(iochan, ORD(notAvailable),
'IOChan.TextWrite: attempt to write data to a channel which is not configured as write and text')
END
END
END
END TextWrite ;
(* Direct raw operations - these do not effect translation between
the internal and external representation of data
*)
PROCEDURE RawRead (cid: ChanId;
to: SYSTEM.ADDRESS;
maxLocs: CARDINAL;
VAR locsRead: CARDINAL) ;
(* Reads at most maxLocs items from cid, and assigns corresponding
values to successive components of an ARRAY OF LOC variable for
which the address of the first component is to. The number of
characters read is assigned to locsRead. The stored read result
is set to the value allRight, or endOfInput.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.RawRead: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF (cid=StdChans.NullChan()) OR (result=IOConsts.endOfInput)
THEN
locsRead := 0 ;
result := IOConsts.endOfInput
ELSIF (ChanConsts.readFlag IN flags) AND (ChanConsts.rawFlag IN flags)
THEN
doRawRead(dtp, to, maxLocs, locsRead)
ELSE
RAISE(iochan, ORD(notAvailable),
'IOChan.RawRead: attempt to read data from a channel which is not configured as read and raw')
END
END
END
END RawRead ;
PROCEDURE RawWrite (cid: ChanId; from: SYSTEM.ADDRESS; locsToWrite: CARDINAL) ;
(* Writes a number of items given by the value of charsToWrite,
from successive components of an ARRAY OF LOC variable for
which the address of the first component is from, to the channel cid.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.RawWrite: device table ptr is NIL')
ELSE
WITH dtp^ DO
IF (cid=StdChans.NullChan()) OR (result=IOConsts.endOfInput)
THEN
result := IOConsts.endOfInput
ELSIF (ChanConsts.writeFlag IN flags) AND (ChanConsts.rawFlag IN flags)
THEN
doRawWrite(dtp, from, locsToWrite)
ELSE
RAISE(iochan, ORD(notAvailable),
'IOChan.RawWrite: attempt to write data to a channel which is not configured as write and raw')
END
END
END
END RawWrite ;
(* Common operations *)
PROCEDURE GetName (cid: ChanId; VAR s: ARRAY OF CHAR) ;
(* Copies to s a name associated with the channel cid, possibly truncated
(depending on the capacity of s).
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.GetName: device table ptr is NIL')
ELSE
dtp^.doGetName(dtp, s)
END
END GetName ;
PROCEDURE Reset (cid: ChanId) ;
(* Resets the channel cid to a state defined by the device module. *)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.Reset: device table ptr is NIL')
ELSE
dtp^.doReset(dtp)
END
END Reset ;
PROCEDURE Flush (cid: ChanId) ;
(* Flushes any data buffered by the device module out to the channel cid. *)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.Flush: device table ptr is NIL')
ELSE
dtp^.doFlush(dtp)
END
END Flush ;
(* Access to read results *)
PROCEDURE SetReadResult (cid: ChanId; res: IOConsts.ReadResults) ;
(* Sets the read result value for the channel cid to the value res. *)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.SetReadResult: device table ptr is NIL')
ELSE
dtp^.result := res
END
END SetReadResult ;
PROCEDURE ReadResult (cid: ChanId) : IOConsts.ReadResults ;
(* Returns the stored read result value for the channel cid.
(This is initially the value notKnown).
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.SetReadResult: device table ptr is NIL')
ELSE
RETURN( dtp^.result )
END
END ReadResult ;
(* Users can discover which flags actually apply to a channel *)
PROCEDURE CurrentFlags (cid: ChanId) : ChanConsts.FlagSet ;
(* Returns the set of flags that currently apply to the channel cid. *)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.SetReadResult: device table ptr is NIL')
ELSE
RETURN( dtp^.flags )
END
END CurrentFlags ;
(* The following exceptions are defined for this module and its clients *)
PROCEDURE IsChanException () : BOOLEAN ;
(* Returns TRUE if the current coroutine is in the exceptional
execution state because of the raising of an exception from
ChanExceptions; otherwise returns FALSE.
*)
BEGIN
RETURN( IsExceptionalExecution() AND IsCurrentSource(iochan) )
END IsChanException ;
PROCEDURE ChanException () : ChanExceptions ;
(* If the current coroutine is in the exceptional execution state
because of the raising of an exception from ChanExceptions,
returns the corresponding enumeration value, and otherwise
raises an exception.
*)
BEGIN
IF IsChanException()
THEN
RETURN( VAL(ChanExceptions, EXCEPTIONS.CurrentNumber(iochan)) )
ELSE
M2RTS.NoException (SYSTEM.ADR(__FILE__), __LINE__,
__COLUMN__, SYSTEM.ADR(__FUNCTION__),
SYSTEM.ADR ("not in the exceptional execution state"))
END
END ChanException ;
(* When a device procedure detects a device error, it raises the
exception softDeviceError or hardDeviceError. If these exceptions
are handled, the following facilities may be used to discover
an implementation-defined error number for the channel.
*)
PROCEDURE DeviceError (cid: ChanId) : DeviceErrNum ;
(* If a device error exception has been raised for the channel cid,
returns the error number stored by the device module.
*)
VAR
did: IOLink.DeviceId ;
dtp: IOLink.DeviceTablePtr ;
BEGIN
CheckValid(cid) ;
did := RTio.GetDeviceId(cid) ;
dtp := IOLink.DeviceTablePtrValue(cid, did) ;
IF dtp=NIL
THEN
RAISE(iochan, ORD(hardDeviceError),
'IOChan.DeviceError: device table ptr is NIL')
ELSE
RETURN( dtp^.errNum )
END
END DeviceError ;
BEGIN
AllocateSource(iochan) ;
invalid := ChanId(RTio.InitChanId())
END IOChan.
|