DEFINITION MODULE ChanConsts; (* Common types and values for device open requests and results *) (* Device modules may allow combinations of the following flags to be given when a channel is opened. An open procedure may not accept or honor all combinations. *) TYPE ChanFlags = ( readFlag, (* input operations are requested/available *) writeFlag, (* output operations are requested/available *) oldFlag, (* a file may/must/did exist before channel was opened *) textFlag, (* text operations are requested/available *) rawFlag, (* raw operations are requested/available *) interactiveFlag, (* interactive use is requested/available *) 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}; write = FlagSet{writeFlag}; old = FlagSet{oldFlag}; text = FlagSet{textFlag}; raw = FlagSet{rawFlag}; interactive = FlagSet{interactiveFlag}; echo = FlagSet{echoFlag}; 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 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, (* file of given name already exists, a new one is required *) wrongFileType, (* file is of the wrong type to support 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 binary 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.