全局用户出口 XPI 示例
本主题中提供了两个示例，一个示例显示了存储器的使用情况，另一个示例说明了以递增方式构建的参数列表。
显示使用存储器的示例
以下示例说明全局用户出口程序中 XPI 和存储器的使用情况。 不是完整的程序，而仅仅是任何全局用户出口程序的入口和出口代码的示例以及 XPI 函数使用示例。 示例中使用的 DFHSMMCX 宏的选项在 存储控制 XPI 函数中进行了描述。
此示例使用以下技术: 使用 XPI GETMAIN 调用为程序的此调用获取一些存储器，然后将此存储器的地址保存在 UEPXSTOR 寻址的 LIFO 存储器的前 4 个字节中。 在此示例中，将在单个宏中初始化参数列表 (使用 CLEAR 选项) ，构建参数列表和 GETMAIN 调用。 有关如何以递增方式构建参数列表以及如何分隔 CLEAR 和 GETMAIN 调用的详细信息，请参阅 显示如何以递增方式构建参数列表的示例。
TITLE 'GUEXPI - GLOBAL USER EXIT PROGRAM WITH XPI'
*************************************************************************
* The first three instructions set up the global user exit *
* environment, identify the user exit point, prepare for the use of *
* the exit programming interface, and copy in the definitions that *
* are to be used by the XPI function. *
*************************************************************************
*
DFHUEXIT TYPE=EP,ID=XFCREQ PROVIDE DFHUEPAR PARAMETER
* LIST FOR XFCREQ IN THE FILE
* CONTROL PROGRAM AND LIST
* OF EXITID EQUATES
*
DFHUEXIT TYPE=XPIENV SET UP ENVIRONMENT FOR
* EXIT PROGRAMMING INTERFACE --
* MUST BE ISSUED BEFORE ANY
* XPI MACROS ARE ISSUED
*
COPY DFHSMMCY DEFINE PARAMETER LIST FOR
* USE BY DFHSMMCX MACRO
*
*************************************************************************
* The following DSECT maps a storage area you can use to make the *
* exit program reentrant by storing the address of the storage you *
* acquire in the first four bytes of the 260-byte area provided by *
* the user exit handler (DFHUEH) and addressed by UEPXSTOR. *
*************************************************************************
*
TRANSTOR DSECT DSECT FOR STORAGE OBTAINED BY
* GETMAIN
.
.
.
storage declarations
.
.
.
*
*************************************************************************
* The next seven instructions form the normal start of a global user *
* exit program, setting the program addressing mode to 31-bit, saving *
* the calling program's registers, establishing base addressing, and *
* establishing the addressing of the user exit parameter list. *
*************************************************************************
*
GXPI CSECT
GXPI AMODE 31 SET TO 31-BIT ADDRESSING
*
SAVE (14,12) SAVE CALLING PROGRAM'S REGISTERS
*
LR R11,R15 SET UP USER EXIT PROGRAM'S
USING GXPI,R11 BASE REGISTER
*
LR R2,R1 SET UP ADDRESSING FOR USER
USING DFHUEPAR,R2 EXIT PARAMETER LIST -- USE
* REGISTER 2 AS XPI CALLS USE
* REGISTER 1
*
**************************************************************************
* Before issuing an XPI function call, set up addressing to XPI *
* parameter list. *
*************************************************************************
*
L R5,UEPXSTOR SET UP ADDRESSING FOR XPI
* PARAMETER LIST
*
USING DFHSMMC_ARG,R5 MAP PARAMETER LIST
*
*************************************************************************
* Before issuing an XPI function call, you must ensure that register *
* 13 addresses the kernel stack. *
*************************************************************************
*
L R13,UEPSTACK ADDRESS KERNEL STACK
*
*************************************************************************
* Issue the DFHSMMCX macro call, specifying: *
* *
* CALL -- the macro is to be called immediately *
* *
* CLEAR -- initialize the parameter list before inserting values. *
* *
* IN -- input values follow. *
* *
* FUNCTION(GETMAIN) -- acquire storage *
* GET_LENGTH(120) -- 120 bytes of it *
* SUSPEND(NO) -- don't suspend if storage not available *
* INITIAL_IMAGE(X'00') -- clear acquired storage *
* to hex zero throughout. *
* STORAGE_CLASS(USER) -- class of storage to be *
* acquired is user storage *
* above the 16MB line. *
* *
* OUT -- output values follow *
* *
* ADDRESS((R6)) -- put address of acquired storage in *
* register 6. *
* RESPONSE(*) -- put response at SMMC_RESPONSE in *
* macro parameter list. *
* REASON(*) -- put reason at SMMC_REASON in macro *
* parameter list. *
* *
*************************************************************************
*
DFHSMMCX CALL, *
CLEAR, *
IN, *
FUNCTION(GETMAIN), *
GET_LENGTH(120), *
SUSPEND(NO), *
INITIAL_IMAGE(X'00'), *
STORAGE_CLASS(USER), *
OUT, *
ADDRESS((R6)), *
RESPONSE(*), *
REASON(*)
* *
*************************************************************************
* Test SMMC_RESPONSE -- if OK, then branch round error handling. *
*************************************************************************
* *
CLI SMMC_RESPONSE,SMMC_OK CHECK RESPONSE AND...
BE STOK ...IF OK, BYPASS ERROR ROUTINES
* *
.
.
.
error-handling routines
.
.
.
**************************************************************************
* The next section maps TRANSTOR on the acquired storage. *
**************************************************************************
STOK DS 0H
USING TRANSTOR,R6 MAP ACQUIRED STORAGE
ST R6,0(R5) SAVE STORAGE ADDRESS IN FIRST
* 4 BYTES OF STORAGE ADDRESSED
* BY UEPXSTOR
*
LA R5,4(R5) ADDRESS 4-BYTE OFFSET
DROP R5 REUSE REGISTER 5 TO BASE ALL
USING DFHxxyy_ARG,R5 FOLLOWING XPI PARAMETER LISTS
* AT 4-BYTE OFFSET INTO STORAGE
* ADDRESSED BY UEPXSTOR
.
.
.
rest of user exit program
.
.
.
*
*************************************************************************
* When the rest of the exit program is completed, free the storage
* and return.
*************************************************************************
*
DROP R5 REUSE REGISTER 5 TO MAP DFHSMMC
USING DFHSMMC_ARG,R5 XPI PARAMETER LIST
*
L R13,UEPSTACK ADDRESS KERNEL STACK
*
*************************************************************************
* Issue the DFHSMMCX macro call, specifying: *
* *
* CALL -- the macro is to be called immediately. *
* *
* CLEAR -- initialize the parameter list before inserting values. *
* *
* IN -- input values follow. *
* *
* FUNCTION(FREEMAIN) -- release storage *
* ADDRESS((R6)) -- address of storage is in register 6. *
* STORAGE_CLASS(USER) -- class of acquired storage was *
* 31-bit user storage. *
* *
* OUT -- output values follow *
* *
* RESPONSE(*) -- put response at SMMC_RESPONSE in *
* macro parameter list. *
* REASON(*) -- put reason at SMMC_REASON in macro *
* parameter list. *
* *
*************************************************************************
*
DFHSMMCX CALL, +
CLEAR, +
IN, +
FUNCTION(FREEMAIN), +
ADDRESS((R6)), +
STORAGE_CLASS(USER), +
OUT, +
RESPONSE(*), +
REASON(*)
* *
*************************************************************************
* Test SMMC_RESPONSE -- if OK, then branch round error handling. *
*************************************************************************
* *
CLI SMMC_RESPONSE,SMMC_OK CHECK RESPONSE AND...
BE STEND ...IF OK, BYPASS ERROR ROUTINES
* *
.
.
.
error-handling routines
.
.
.
*
*************************************************************************
* Restore registers, set return code, and return to user exit handler *
*************************************************************************
* *
STEND DS 0H
L R13,UEPEPSA
RETURN (14,12),RC=UERCNORM
LTORG
END GXPI
显示如何以递增方式构建参数列表的示例
此示例说明以递增方式构建的参数列表。 参数列表的初始化，使用 CLEAR 选项，参数列表的构建以及 GETMAIN 调用被分隔成离散的步骤。
重要信息: 必须 仅 使用 XPI 函数来设置参数。
DFHSMMCX CLEAR
⋮
DFHSMMCX GET_LENGTH(100)
⋮
DFHSMMCX CALL, *
IN, *
FUNCTION(GETMAIN), *
GET_LENGTH(*), *
SUSPEND(NO), *
INITIAL_IMAGE(X'00'), *
STORAGE_CLASS(USER), *
OUT, *
ADDRESS((R6)), *
RESPONSE(*), *
REASON(*)