IBM SC34-6814-04 User Manual
Page 337
TITLE ’GUEXPI - GLOBAL USER EXIT PROGRAM WITH XPI’
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The first three instructions set up the global user exit
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environment, identify the user exit point, prepare for the use of
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the exit programming interface, and copy in the definitions that
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are to be used by the XPI function.
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DFHUEXIT TYPE=EP,ID=XFCREQ
PROVIDE DFHUEPAR PARAMETER
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LIST FOR XFCREQ IN THE FILE
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CONTROL PROGRAM AND LIST
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OF EXITID EQUATES
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DFHUEXIT TYPE=XPIENV
SET UP ENVIRONMENT FOR
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EXIT PROGRAMMING INTERFACE --
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MUST BE ISSUED BEFORE ANY
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XPI MACROS ARE ISSUED
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COPY
DFHSMMCY
DEFINE PARAMETER LIST FOR
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USE BY DFHSMMCX MACRO
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The following DSECT maps a storage area you can use to make the
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exit program reentrant by storing the address of the storage you
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acquire in the first four bytes of the 260-byte area provided by
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the user exit handler (DFHUEH) and addressed by UEPXSTOR.
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TRANSTOR DSECT
DSECT FOR STORAGE OBTAINED BY
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GETMAIN
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storage declarations
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The next seven instructions form the normal start of a global user
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exit program, setting the program addressing mode to 31-bit, saving
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the calling program’s registers, establishing base addressing, and
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establishing the addressing of the user exit parameter list.
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GXPI
CSECT
GXPI
AMODE 31
SET TO 31-BIT ADDRESSING
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SAVE (14,12)
SAVE CALLING PROGRAM’S REGISTERS
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LR
R11,R15
SET UP USER EXIT PROGRAM’S
USING GXPI,R11
BASE REGISTER
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LR
R2,R1
SET UP ADDRESSING FOR USER
USING DFHUEPAR,R2
EXIT PARAMETER LIST -- USE
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REGISTER 2 AS XPI CALLS USE
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REGISTER 1
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Figure 12. Global user exit program with XPI (part 1)
Chapter 3. The user exit programming interface (XPI)
315