GDSX (Extended General Device Support) Manual

Design and Development

Extended General Device Support (GDSX) Manual—529931-001

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Calling Restrictions

User code is compiled to produce an object file that is bound with TSCODE, so there

are restrictions to which user code must conform.

Multithreaded operation would not be possible within GDSX if user tasks called

Guardian I/O procedures in a waited manner. For example, if a DEVICE^HANDLER

task called a waited READ, the whole process, not just the one DEVICE^HANDLER

task, would come to a halt, and the other tasks could not be serviced during the

suspension.

Therefore, TSCODE provides you with a set of pseudo Guardian, Pathway/iTS, and

TMF procedure calls that, with some exceptions, have the same parameters, syntax,

meaning, and resultant capabilities as their Guardian, Pathway/iTS, and TMF

counterparts. These procedures comprise a layer of TSCODE software between

USCODE and Guardian systems that is virtually transparent to USCODE, while

allowing TSCODE to support multithreaded operation and keep track of each internal

I/O operation. Pseudo procedures determine whether an operation is to be handled

completely within GDSX or is to be handled outside GDSX.

Note that a number of Guardian procedures—NUMIN, NUMOUT, MYTERM, and

PROCESSHANDLE_DECOMPOSE_, for example—are resident system procedures

and do not cause the GDSX process to be suspended. Therefore, they can be called

by USCODE. As a rule, if a Guardian call would suspend not just a task but the whole

GDSX process, do not use it.

Following is a list of pseudo procedure calls supported by TSCODE. (Many TSCODE-

supported utility procedures do not have Guardian file-system counterparts, and are

not included here. See Section 8, “Service Routines,” for a description of all TSCODE-

supported procedures.) An X at the end of or in the middle of a procedure name

indicates that both local-memory and extended-memory procedures are available. For

example, ^AWAITIO[X] indicates that the ^AWAITIO and ^AWAITIOX procedures are

available.

Caution. The pseudo Guardian, Pathway/iTS, and TMF procedure calls must be used instead

of their counterparts.

** ^ABORTTRANSACTION ^READ[X]

^AWAITIO[X] ^READLOCK[X]

** ^BEGINTRANSACTION ^READUPDATE[X]

^CANCEL ^READUPDATELOCK[X]

^CANCELREQ ^RECEIVEINFO

^CANCELTIMEOUT ^REPLY[X]

** ^CLOSE ** ^RESUMETRANSACTION

^CONTROL ^SERVERCLASS_DIALOG_ABORT_