Assignment 2: A program that reads in an unknown number of lines

Assignment 2

80 points


For this assignment you will write a program that reads in an unknown number of lines, each containing 4-digit numbers, 3 per line. For each line read, print out the numbers X, Y and Z, calculate the value of Y + Z - X and print the result.

Each line has the following format:

columns 1-3 first number X
columns 4-6 blank
columns 7-9 second number Y
columns 10-12 blank
columns 13-15 third number Z
columns 16-80 blank
When all processing is done, print the number of lines read and the sum of the result values from all of the lines.

Program incrementally! That means that you should begin by just reading one record and print out those numbers. When that works, put in a loop. If you get one part working before moving on to the next, your debugging will be much easier and less time-consuming.

Use a top driven loop:

Initialize the counter and the total
Top of the loop
Read a record
If end-of-file, branch to the end of the loop
Deal with the record just read using XDECI, arithmetic, XDECO and XPRNT
Add 1 to the counter
Calculate the value of Y + Z - X
Add the result (Y + Z - X) to the total
Branch to the top of the loop
End of the loop
Use XDECO and XPRNT to print the summary lines
You will need to put labels on two lines, one for the top of the loop and one for the bottom of the loop. You can actually put a label on any line of code, but many people put them on lines that don't do anything else, like this:

MYLABEL DS 0H
Here DS 0H takes up no space. (It declares 0 halfwords on a halfword boundary, and as each instruction is an even number of bytes, the location will already be on a halfword boundary.)

JCL for this assignment

Use the following JCL:

//KCnumberA JOB ,'Your Name',MSGCLASS=H
//STEP1 EXEC PGM=ASSIST
//STEPLIB DD DSN=KC02293.ASSIST.LOADLIB,DISP=SHR
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
************************************************************
*
* Program: ASSIGN2
* Programmer: Your Name
*
* Register usage:
*
************************************************************
/*
//FT05F001 DD *
8163 2529 2805
4536 1839 5741
0591 7843 9487
4190 3057 2775
2399 0667 4129
8118 3961 6535
4765 0498 1111
9056 2345 1110
0001 0002 0003
9999 9998 9997
8001 7999 3512
/*
//FT06F001 DD SYSOUT=*
//
As before, you will need to replace "Your Name" with your own name, and you will need to replace "KCnumber" with your own logon ID.

Your actual code should be after the comment box and before the /* line.

Data

Use the following data for the run you turn in. You may (and probably should) use your own data to test your program.

As indicated above, this should be in your source file between the FT05FT001 line and the following /* line.

8163 2529 2805
4536 1839 5741
0591 7843 9487
4190 3057 2775
2399 0667 4129
8118 3961 6535
4765 0498 1111
9056 2345 1110
0001 0002 0003
9999 9998 9997
8001 7999 3512
This is known as instream data. It is also possible to read from a specific disk file by name, and we will do so later.

Other requirements

In the JCL, at the very beginning of the program is a comment box. Notice the place that says "Register Usage". Make a list here of registers you used and how you made use of each one. For instance, you will be using register 15 as your base register, and register 1 is used by XDECI. Thus you might have:

*
* Register usage:
* 1 Used by XDECI
* 15 Base register
*
and probably several more such lines.

The comment box should also list your name and the number of the assignment (Assignment 2).

To use XREAD, you will need to have an 80-byte field to contain each line you read.

To produce the output, you will need to define a couple of output lines containing DC and DS statements (with labels on the DS statements).

Your program should include line documentation. At the end of each line (certainly for most lines) skip one or more spaces and insert a few words describing what that instruction does. Try to line these up so they start in the same column. For instance:

SR 4,4 Initialize counter.
SR 5,5 Initialize total.
If you wish, you may use register equates. These allow you to refer to register 3 as "R3" instead of just "3". To use these, include lines such as

R0 EQU 0
R1 EQU 1
.
.
.
R15 EQU 15
somewhere in your program file (such as at the end). You can read about EQU in our textbook, section 2.11, or on one of the web pages. This is not required.

Name your program file something like "ASSIGN2" or "ASSIGN2".