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| When technology complements business | Assembler Coding Examples |
| Copyright © 1987-2008 SimoTime Enterprises, LLC All Rights Reserved | http://www.simotime.com |
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This sample program descirbes some of the various techniques used to display a message or text string on the display. The program is written in IBM Mainframe Assembler, it will compile using Assembler/H or HLASM . This program provides examples of some of the coding techniques used to display a message on the user console. It will run as an MVS batch job on an IBM mainframe or as a project with Micro Focus Mainframe Express (MFE) running on a PC with Windows.
This program may serve as a tutorial for programmers that are new to 370 assembler or as a reference for experienced programmers.
This section provides examples of specific coding techniques that use the Write-To-Operator or WTO macro.
The simple and easy format of the WTO macro will display a text string that is embedded between a pair of apostrophes.
***********************************************************************
* WTO with text as a literal enclosed in single quotes
*
WTO 'ASMWTOA1 - Message Text, No Label...'
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
The following statement shows the use of the WTO macro with a label name specified in position 1.
WTOLABEL WTO 'ASMWTOA1 - Message Text, with Label...'
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
The preceding technique is commonly used to display a literal (or text string) to the terminal. Refer to the 370 assembler source member in the Assembler Source Code for WTO Examples section of this document.
This section describes the use of the WTO macro with the EXECUTE format to display a message from a list or table of messages. The WTO list of messages is created using the LIST format as per the following coding example.
*********************************************************************** * WTO using the LIST function. The WTO buffer created by the LIST * format may be used with a WTO using the EXECUTE format. * WTOLIST EQU * LISTMSG1 WTO 'ASMWTOA1 - List Message One from WTOLIST...',MF=L LISTMSG2 WTO 'ASMWTOA1 - List Message Two from WTOLIST...',MF=L
The following may be used to display a message from the list to the console. The first example shows how to use a label name to access and display a message from the list of messages.
***********************************************************************
* WTO using the EXECUTE format, WTO buffer created by the LIST format.
* The 1st WTO uses a label name, the 2nd WTO uses register notation.
*
WTO MF=(E,LISTMSG1)
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
The following example shows how to use register notation to access and display a message from the list of messages.
LA R8,LISTMSG2
WTO MF=(E,(R8))
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
This example shows how to create a common routine that may be executed with a Branch-and-Link with a return via register-3. This WTO example will display the text that is in the user defined buffer. Prior to doing the Branch-and-Link the user moves the text to be displayed into the buffer.
MVC WTOTEXT(76),WTOMSG1
BAL R3,DOMSG DISPLAY MESSAGE, RETURN VIA R3
MVC WTOTEXT(76),WTOMSG2
BAL R3,DOMSG DISPLAY MESSAGE, RETURN VIA R3
The common routine to display a user message is as follows.
***********************************************************************
* Common WTO routine to display WTOBLOCK...
*
DOMSG EQU *
WTO MF=(E,WTOBLOCK)
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
BR R3 Return via Register 3
The buffer used by the common routine is defined as follows.
***********************************************************************
* The following is an example of a user-coded WTO buffer.
*
DS 0H * INSURE HALF-WORD ALIGNMENT
WTOBLOCK EQU *
DC H'80' * For WTO, length of WTO buffer...
DC H'0' should be binary zeroes...
WTOTEXT DC CL76'ASMWTOA1 - WTO with user-coded buffer...'
*
WTOMSG1 DC CL76'ASMWTOA1 - User message number one...'
WTOMSG2 DC CL76'ASMWTOA1 - User message number two...'
The following is a list of the JCL member (ASMWTOJ1.JCL) for the WTO examples to run as a job on the mainframe. This will also run on the PC using Mainframe Express provided by Micro Focus.
//ASMWTOJ1 JOB SIMOTIME,ACCOUNT,CLASS=1,MSGCLASS=O,NOTIFY=LRSP1 //* ******************************************************************* //* This program is provided by: * //* SimoTime Enterprises, LLC * //* (C) Copyright 1987-2003 All Rights Reserved * //* * //* Web Site URL: http://www.simotime.com * //* e-mail: helpdesk@simotime.com * //* ******************************************************************* //* //* Text - 370 Assembler, Write-To-Operator or WTO macro //* Author - SimoTime Enterprises //* Date - January 01, 1997 //* //* This 370 Assembler program provides different techniques for //* using the Write-To-Operator (WTO) macro. //* //* This set of programs will run on a mainframe under MVS or on a //* Personal Computer with Windows and Micro Focus Mainframe Express. //* //* Micro Focus Mainframe Express, version 2.5 or later (MFE) with //* the Assembler Option should be used to Animate or visualize the //* execution of the sample program. //* //* The Animator or Debugger is an excellent tool for visualizing the //* execution of the individual instructions as they execute. //* //* This is a very effective way to become familiar with the 370 //* instruction set. //* //* ******************************************************************* //* Step 1 of 1 This is a single step job. //* //ASMWTOS1 EXEC PGM=ASMWTOA1 //STEPLIB DD DSN=SIMOTIME.DEMO.LOADLIB1,DISP=SHR //*
The following is a list of the source member (ASMWTOA1.MLC) for the WTO examples.
ASMWTOA1 CSECT
***********************************************************************
* This program is provided by: *
* SimoTime Enterprises, LLC *
* (C) Copyright 1987-2003 All Rights Reserved *
* *
* Web Site URL: http://www.simotime.com *
* e-mail: helpdesk@simotime.com *
***********************************************************************
* *
* Created: 1993/06/01, Simmons *
* Changed: 1993/06/01, Simmons, no changes to date... *
* *
***********************************************************************
* *
* This program will run an an IBM Mainframe using MVS or a PC using *
* Micro Focus Mainframe Express, version 2.5 or later (MFE) with *
* the Assembler Option. *
* *
* This program provides a sample of some of the coding techniques *
* used by assembler programmers. You can immediately see the results *
* of each instruction execution. This is a very effective way to *
* become familiar with how these techniques work. *
* *
* The purpose of this program is to test the various forms of the *
* WTO (Write-To-Operator) macro. *
* *
***********************************************************************
*
R0 EQU 0
R1 EQU 1
R2 EQU 2
R3 EQU 3
R4 EQU 4
R5 EQU 5
R6 EQU 6
R7 EQU 7
R8 EQU 8
R9 EQU 9
R10 EQU 10
R11 EQU 11
R12 EQU 12
R13 EQU 13
R14 EQU 14
R15 EQU 15
*
***********************************************************************
SAVE (14,12)
BALR 12,0
USING *,12
*
***********************************************************************
* WTO to display the copyright information
*
WTO '* ASMWTOA1 An Example of using the WTO macro v03.01.24-
http://www.simotime.com'
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
*
WTO '* ASMWTOA1 Copyright 1987-2003 SimoTime Enterprises, L-
LC All Rights Reserved'
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
***********************************************************************
* WTO with text as a literal enclosed in single quotes
*
WTO '* ASMWTOA1 is STARTING, Hello Mainframe World...'
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
*
WTO '* ASMWTOA1 Message Text, No Label...'
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
*
WTOLABEL WTO '* ASMWTOA1 Message Text, with Label...'
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
*
*
***********************************************************************
* WTO using the EXECUTE format, WTO buffer created by the LIST format.
* The 1st WTO uses a label name, the 2nd WTO uses register notation.
*
WTO MF=(E,LISTMSG1)
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
*
LA R8,LISTMSG2
WTO MF=(E,(R8))
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
*
*
***********************************************************************
* WTO using the EXECUTE format with user-coded WTO buffer. This
* routine illustrates the use of a single WTO to display different
* messages.
*
BAL R3,DOMSG DISPLAY MESSAGE, RETURN VIA R3
MVC WTOTEXT(76),WTOMSG1
BAL R3,DOMSG DISPLAY MESSAGE, RETURN VIA R3
MVC WTOTEXT(76),WTOMSG2
BAL R3,DOMSG DISPLAY MESSAGE, RETURN VIA R3
*
*
***********************************************************************
* WTO using the EXECUTE format with user-coded WTO buffer. This
* routine illustrates the use of a single WTO to display different
* messages. This will cause a length error with WTO execution.
*
WTO MF=(E,WTOCRASH)
LTR R15,R15 IS REG-15 = ZERO...
BZ ABEND4 THEN ABEND, SHOULD BE 4...
B EOJ
*
*
***********************************************************************
* Common WTO routine to display WTOBLOCK...
*
DOMSG EQU *
WTO MF=(E,WTOBLOCK)
LTR R15,R15 IS REG-15 = ZERO...
BNZ ABEND4 IF NOT, ABEND...
BR R3 Return via Register 3
***********************************************************************
* Return to caller
*
EOJ EQU *
WTO '* ASMWTOA1 is FINISHED...'
RETURN (14,12),RC=0
***********************************************************************
* Abnormal termination of program
*
ABEND4 EQU *
WTO '* ASMWTOA1 MLC, is ABENDING, RC=4...'
RETURN (14,12),RC=4
*
***********************************************************************
* WTO using the LIST function. The WTO buffer created by the LIST
* format may be used with a WTO using the EXECUTE format.
*
WTOLIST EQU *
LISTMSG1 WTO '* ASMWTOA1 List Message One from WTOLIST...',MF=L
LISTMSG2 WTO '* ASMWTOA1 List Message Two from WTOLIST...',MF=L
*
*
***********************************************************************
* The following is an example of a user-coded WTO buffer.
*
DS 0H * INSURE HALF-WORD ALIGNMENT
WTOBLOCK EQU *
DC H'80' * For WTO, length of WTO buffer...
DC H'0' should be binary zeroes...
WTOTEXT DC CL76'* ASMWTOA1 WTO with user-coded buffer...'
*
WTOMSG1 DC CL76'* ASMWTOA1 User message number one...'
WTOMSG2 DC CL76'* ASMWTOA1 User message number two...'
*
*
***********************************************************************
* The following is an example of a user-coded WTO buffer that will
* cause an error conditions, length of text exceeds 251 bytes.
DS 0H * INSURE HALF-WORD ALIGNMENT
WTOCRASH EQU *
DC H'512' * For WTO, length of WTO buffer...
DC H'0' should be binary zeroes...
WTOCTEXT DC CL76'* ASMWTOA1 WTO FOR CRASH TEST...'
*
DC 436CL1'X'
*
END
The purpose of this document is to assist as a tutorial for new assembler programmers or as a quick reference for experienced programmers. This example focuses on the various techniques used to display a message from the program to the user or system console. As always, it is the programmer's responsibility to thoroughly test all programs.
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You may download this example at http://www.simotime.com/sim4dzip.htm#AsmWTO as a Z-Pack. The Z-Packs provide individual programming examples, documentation and test data files in a single package. The Z-Packs are usually in zip format to reduce the amount of time to download.
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| Copyright © 1987-2008 SimoTime Enterprises, LLC All Rights Reserved |
| When technology complements business |
| http://www.simotime.com |