04
Mon, Nov
1 New Articles

TechTip: Extracting Decimal Elements from Command Lists in V5R3

CL
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

I am a big believer in creating commands to drive CL programs. Perhaps the greatest benefit of using commands is that the command processor converts parameter arguments to the proper data formats. But the command processor is not without its shortcomings. Anyone who has tried to pass a list of decimal numbers from a command to a CL program knows that CL has no way to extract decimal values from a list. Fortunately, this problem is easily overcome in V5R3.

Consider the following command, which accepts up to five department numbers:

CMD   PROMPT('Departmental Expense Report')
PARM  KWD(DEPT) TYPE(*DEC) LEN(5 0) MIN(0) MAX(5) +
         PROMPT('Departments')

Here is an example of the command in action:

MYCMD VALUE(11111 2222 333 44 5)

The command processor passes a 17-byte string to the command processing program (CPP). Here is that string in hexadecimal format:

. . . . + . . . . 1 . . . . + . .
000511111F02222F00333F00044F00005F

The first two bytes contain a binary integer that tells how many elements are in the list. In this case, there are five elements. Since an element is defined to be a five-digit packed decimal number, each element occupies three bytes.

The designers of the CL compiler did not provide a way to extract decimal numbers from a list, but V5R3 has a way to overcome that problem. i5/OS includes the Machine Interface (MI) _CPYBYTES instruction, which can copy a series of characters from one variable to another, regardless of the data types of those variables. _CPYBYTES requires three parameters: the variable to receive the data, the variable from which the data is copied, and the number of bytes to copy. The first two variables are passed by reference (i.e., their addresses in memory are passed to _CPYBYTES), but the third parameter must be passed by value. Since V5R3 allows parameters to be passed to procedures by value, V5R3 CL can bind to the _CPYBYTES command.

Here is a CPP for the command given above:

PGM        PARM(&DEPTLIST)

DCL        VAR(&DEPTLIST) TYPE(*CHAR) LEN(32)
DCL        VAR(&COUNTER)  TYPE(*INT)  LEN(4)
DCL        VAR(&ELEMENTS) TYPE(*INT)  LEN(4)
DCL        VAR(&SIZE)     TYPE(*INT)  LEN(4) VALUE(3)
DCL        VAR(&POS)      TYPE(*INT)  LEN(4) VALUE(3)
DCL        VAR(&CHARVAR)  TYPE(*CHAR) LEN(3)
DCL        VAR(&NUMDEPT)  TYPE(*DEC)  LEN(5)
DCL        VAR(&CHARDEPT) TYPE(*CHAR) LEN(5)

CHGVAR     VAR(&ELEMENTS) VALUE(%BIN(&DEPTLIST 1 2))

DOFOR      VAR(&COUNTER) FROM(1) TO(&ELEMENTS)
    CHGVAR     VAR(&CHARVAR) VALUE(%SST(&DEPTLIST &POS &SIZE))
    CALLPRC    PRC('_CPYBYTES') +
                 PARM((&NUMDEPT) (&CHARVAR) (&SIZE *BYVAL))
    CHGVAR     VAR(&CHARDEPT) VALUE(&NUMDEPT)

/* The next department number in the list has been extracted. */
/* The department number is in &NUMDEPT in numeric format and */
/* in &CHARDEPT in character format.                          */

    CHGVAR     VAR(&POS) VALUE(&POS + &SIZE)
ENDDO

The first CHGVAR command initializes the &ELEMENTS variable with the number of elements in the list in order to make the DOFOR loop run once for each value in the list. Within the loop, the three-byte substring that contains a decimal number is extracted into &CHARVAR, a working variable. &CHARVAR is fed to _CPYBYTES, which copies the department number into packed-decimal variable &DEPTNUM. The extraction has been successful! At this point, the program is able to use the extracted department number in decimal format or copy the department number to a character variable, as need dictates.

If you'd like to create these objects, you'll need the following commands. Replace xxx with the name of your library.

CRTCMD CMD(xxx/MYCMD) PGM(xxx/MYPGM) SRCFILE(xxx/QCMDSRC)

CRTCLMOD MODULE(xxx/MYPGM) SRCFILE(xxx/QCLSRC)

CRTPGM PGM(xxx/MYPGM) MODULE(xxx/MYPGM)

To learn more about creating commands, see Power CL by Ted Holt and Ernie Malaga. For up-to-date V5R3 CL features, refer to Complete CL, also by Ted Holt and Ernie Malaga .

Paul Amsden has worked in the information technology field for more than 10 years.












BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: