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(* Library module defined by the International Standard
Information technology - programming languages
BS ISO/IEC 10514-1:1996E Part 1: Modula-2, Base Language.
Copyright ISO/IEC (International Organization for Standardization
and International Electrotechnical Commission) 1996-2021.
It may be freely copied for the purpose of implementation (see page
707 of the Information technology - Programming languages Part 1:
Modula-2, Base Language. BS ISO/IEC 10514-1:1996). *)
DEFINITION MODULE ChanConsts;
(* Common types and values for channel open requests and results *)
TYPE
ChanFlags = (* Request flags possibly given when a channel is opened *)
( readFlag, (* input operations are requested/available *)
writeFlag, (* output operations are requested/available *)
oldFlag, (* a file may/must/did exist before the channel is opened *)
textFlag, (* text operations are requested/available *)
rawFlag, (* raw operations are requested/available *)
interactiveFlag, (* interactive use is requested/applies *)
echoFlag (* echoing by interactive device on removal of characters from input
stream requested/applies *)
);
FlagSet = SET OF ChanFlags;
(* Singleton values of FlagSet, to allow for example, read + write *)
CONST
read = FlagSet{readFlag}; (* input operations are requested/available *)
write = FlagSet{writeFlag}; (* output operations are requested/available *)
old = FlagSet{oldFlag}; (* a file may/must/did exist before the channel is opened *)
text = FlagSet{textFlag}; (* text operations are requested/available *)
raw = FlagSet{rawFlag}; (* raw operations are requested/available *)
interactive = FlagSet{interactiveFlag}; (* interactive use is requested/applies *)
echo = FlagSet{echoFlag}; (* echoing by interactive device on removal of characters from
input stream requested/applies *)
TYPE
OpenResults = (* Possible results of open requests *)
(opened, (* the open succeeded as requested *)
wrongNameFormat, (* given name is in the wrong format for the implementation *)
wrongFlags, (* given flags include a value that does not apply to the device *)
tooManyOpen, (* this device cannot support any more open channels *)
outOfChans, (* no more channels can be allocated *)
wrongPermissions, (* file or directory permissions do not allow request *)
noRoomOnDevice, (* storage limits on the device prevent the open *)
noSuchFile, (* a needed file does not exist *)
fileExists, (* a file of the given name already exists when a new one is required *)
wrongFileType, (* the file is of the wrong type to support the required operations *)
noTextOperations, (* text operations have been requested, but are not supported *)
noRawOperations, (* raw operations have been requested, but are not supported *)
noMixedOperations,(* text and raw operations have been requested, but they
are not supported in combination *)
alreadyOpen, (* the source/destination is already open for operations not supported
in combination with the requested operations *)
otherProblem (* open failed for some other reason *)
);
END ChanConsts.
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