A C user routine which is produced from a single source can be stored as an LLM in a library without the need for a link stage. When loading the user routine, EDT specifies a "resolve context" which contains the required runtime modules.
The precise mechanism depends on whether or not EDT was initialized by a C main program with an ILCS flag:
If this is the case then user routines are loaded in a separate load context EDT#USER and the two load contexts EDT#CRTS and LOCAL#DEFAULT (in this sequence) are specified as the resolve context. As a result, external references to the C globals in the user routine are first resolved against the entries in EDT#CRTS (EDT runtime environment) and then against the entries in LOCAL#DEFAULT (C main program).
Since a (dynamically loadable) user routine is always called in the EDT runtime environment, the correct C globals are made available to the user routine irrespectively of whether the C main program itself possesses visible entries for the C globals.
The user routine's own load context must be taken into account if additional modules are to be dynamically loaded from within the user routine using BIND.
If the C main program has initialized EDT without an ILCS flag then, for reasons of compatibility, the user routine is loaded into the load context LOCAL#DEFAULT and EDT#CRTS is specified as the resolve context. In this case, the C main program should not have any visible entries to the C globals as otherwise these override the corresponding entries in the EDT runtime environment and the user routine is not able to work correctly with the C library functions.
The procedure below compiles and links C user routines which are stored as ANWEND1.C, ANWEND2.C, ... in the library EDT.BEISPIELE.
The generated LLM, the compiler lists and the diagnostic output are also stored in this library.
/SET-PROCEDURE-OPTIONS INPUT-FORMAT=FREE-RECORD-LENGTH,/
DATA-ESCAPE-CHAR=STD
/BEGIN-PARAMETER-DECLARATION
/ DECLARE-PARAMETER NAME=NR
/ DECLARE-PARAMETER NAME=LIB,INITIAL-VALUE=C'EDT.BEISPIELE
/END-PARAMETER-DECLARATION
/START-CPLUS-COMPILER
//MODIFY-SOURCE-PROP LANGUAGE=*C
//MODIFY-RUNTIME-PROPERTIES PARAMETER-PROMPTING=*NO
//MODIFY-INCLUDE-LIBRARIES USER-INCLUDE-LIBRARY=//
$.SYSLIB.EDT.170 ------------------------------ (1)
//MODIFY-DIAGNOSTIC-PROPERTIES OUTPUT=*LIBRARY-ELEMENT(//
LIB=&LIB,ELEM=*STD-ELEMENT()),//
MIN-MSG-WEIGHT=*NOTE
//MODIFY-MODULE-PROPERTIES LOWER-CASE-NAMES=*YES,-
// SPECIAL-CHARACTERS=*KEEP ------------------------------ (2)
//MODIFY-LISTING-PROPERTIES OUTPUT=*LIBRARY-ELEMENT(//
LIB=&LIB,ELEM=*STD-ELEMENT()),SOURCE=*YES()
//COMPILE SOURCE=*LIB-ELEM(LIB=&LIB,ELEM=ANWEND&NR..C),-
// MODULE-OUTPUT=*LIB-ELEM(LIB=&LIB,ELEM=ANWEND&NR)
//END
/EXIT-PROCEDURE
Explanations
| (1) | It is assumed that SYSLIB.EDT.170 is installed under the default user ID. The C compiler needs this library in order to locate the IEDTGLE interface header files. |
| (2) | It should be possible to address the entries in the user routine under their original names. Consequently, lowercase characters must be accepted and special characters (such as "_") should not be changed. |