Language Extensions for Gnosis

These are some facilities for extending PASCALVS to support the direct manipulation and invocation of keys. All actions that can be taken by a domain in Gnosis can be done by a PASCALVS program in a domain with these facilities.

To compile your program with these facilities, use the "LIB(PASGATES)" option of the "PASCALVS" command. This automaticly causes the compiler to use the maclib "PASGATES". This maclib may be found on GNOSIS 1A1. Include the statement "%INCLUDE GNOSIS;" in your program to copy in the following data:

CONST kt = minint;

TYPE SLOT = PACKED -32768 .. 32767;

STATIC dummy :SLOT; VALUE dummy := -2;

FUNCTION pasjmpc (CONST gate :SLOT;

CONST OrderCode :INTEGER;

CONST OutKey1,

OutKey2,

OutKey3 :SLOT;

CONST OutString :STRING;

VAR InKey1,

InKey2,

InKey3,

InKey4 :SLOT;

VAR InString :STRING)
:INTEGER { Return code from gate }; EXTERNAL;

PROCEDURE pasjmpf (CONST gate :SLOT;
CONST OrderCode :INTEGER;

CONST OutKey1,

OutKey2,

OutKey3,

OutKey4 :SLOT;

CONST OutString :STRING); EXTERNAL;

FUNCTION pasjmpr (CONST gate :SLOT;
CONST ReturnCode :INTEGER;

CONST OutKey1,

OutKey2,

OutKey3,

OutKey4 :SLOT;

CONST OutString :STRING;

VAR InKey1,

InKey2,

InKey3,

InKey4 :SLOT;

VAR DataByte :INTEGER;

VAR InString :STRING)

:INTEGER { Order code from next caller }; EXTERNAL;

Meanings of the Statements
The "pasjmpc", "pasjmpf" and "pasjmpr" routines respectively cause CALL, FORK, and RETURN jumps to be issued.

Meanings of the Fields
"OrderCode" is an integer expression whose value becomes the order code for "pasjmpc" and "pasjmpf"
Throughout this manual and especially in sections (p2,primary) and (p2,supp) we give mnemonics for these order codes. They are of the form "type__function" where "type" and "function" are PASCALVS style variables and "type" describes the kind of key being called and "function" describes what is being called for.

For "pasjmpc" the value of the function is the return code from the called gate.

For "pasjmpr" the value of the function is the value specified by the jumper the next time the domain is entered (the order code to the Pascal program).

"ReturnCode" is an integer expression whose value is passed to the gate with the "pasjmpr" function.

Values of type SLOT.

A slot designator is really an integer variable {(p3,pascalkeynames)} whose value normally changes just once. {The value is probably used to index into a supernode.}

The constant "dummy" as a slot designator provides the value DK(0) when used for "OutKey1", "OutKey2", "OutKey3", or "OutKey4".

The constant "dummy" when used for "InKey1", "InKey2", "InKey3", or "InKey4" causes the received key value to be discarded.

If a variable is used for "InKey1", "InKey2", "InKey3", or "InKey4" and the variable's value is -1 then an unused slot number will be assigned to that variable and that new value will be used. If the value of an expression for "OutKey1", "OutKey2", "OutKey3", or "OutKey4" is -1 then the key DK(0) will be provided.

We may provide a call to free a slot. "pasfree (sd);" where "sd" is a an integer variable that had occurred in "InKey1", "InKey2", "InKey3", or "InKey4" sd's value will be -1 after this call.

"InString" is a character string variable whose length and value become the value of the string argument. The maximum length that can be received through this mechanism is determined by the maximum length of the string variable "InString". Note that Gnosis does not support strings longer then 4096 characters. An error condition will occur when the offered string is longer than the maximum length of the string variable.

"OutString" is a character string expression.

"DataByte" receives the value of the databyte of the start key used to enter this domain.

"OrderCode" receives the order code.

The naming of keys:
In these calls keys are named with the aid of variables of type SLOT. Such a variable denotes a key slot. A reference to the variable is passed to the jump subroutine and if the value is -1 then a value is assigned to it that is different than the values assigned to other such variables in this domain. Thus the variable should be initialized to -1.

There is currently no method of reclaiming the space used to hold the keys. Thus if these variables are declared as AUTOMATIC, the storage used to hold the keys will not be reclaimed when the block where the variable is declared is exited. Thus such variables should usually be declared at the outermost nesting level or as STATIC or DEF/REF.

Initial key assignments - see (p2,osfactories).

Auxiliary functions and suggestions:

{ni}The function S is declared "FUNCTION s (CONST length, val :INTEGER) :STRING; EXTERNAL;" It returns a string whose length is the value of the first argument and whose bits are the binary value of the second argument form.
Where this manual might call for "((4,17),(2,45))" as the byte string argument you may write "(S(4,17)^^S(2,45))".

{ni}The entry PASCLEAN is declared "PROCEDURE pasclean(VAR slot :SLOT); :EXTERNAL;". Its effect is to save the expense of copying a value from the cache to the super-node when the value is not required. The result is that the key value may be replaced by an older value.
For example suppose that the last use has been made of the key in slot X. "pasclean(X)" at this point may make the program faster and cheaper but will not affect what the program does.

See (p3,kjumpa) for more information on the procedures that these statements call.