Assignment 8 Solution

This assignment deals with data about players in a game called On-Line

Bowling. You will write a program that will read the file. The data will

be processed a little and put in a table. You will then XDUMP the table.

After that, you should print out the table contents in a report. Next,

sort the table contents in descending order by High Score, and then

reprint the table.

The data is stored in a small number of bytes.

------------------------------------------------------------------------

*Input*

The input to the program will be a file with an unknown number of

records. Each record represents a single player and has the following

format:

columns description

------- -----------

1 - 8 User Name (characters)

9 - 10 not used (spaces)

11 - 19 ID Number (digits)

20 - 21 not used (spaces)

22 - 29 Date of High Score (8 digits: Year, Month, Day)

30 - 31 not used (spaces)

32 - 34 High Score (3 digits) (between 000 and 300)

35 - 80 not used (spaces)

Use the following JCL statement to specify the input file:

//FT05F001 DD DSN=KC02314.SPRING18.CSCI360.HW8DATA,DISP=SHR





------------------------------------------------------------------------

*Processing Requirements*

The main program will carry out the following steps:

1. Call subroutine BUILD to read the file and store the data in a table.

2. Use XDUMP to print the entire table in hex.

3. Call subroutine PRINT to print the contents of the table using

appropriate page and column headings.

4. Call subroutine SORT to sort the table entries in descending order

using High Score as the key.

5. Call subroutine PRINT again.

------------------------------------------------------------------------

*BUILD subroutine*

The parameters for BUILD are the address of the table and the address of

a fullword containing the address of the first unused entry.

We are going to store the ID numbers as 4-byte binary values. In the

table, these may or may not be on fullword boundaries. You may need to

use ICM and STCM.

We are going to store the High Score as a 2-byte packed decimal number.

We are going to store each date in 2 bytes (16 bits) in a compressed

format:

* We will store the year using the first 7 bits as an offset from the

year 1990. For instance we will store 2012 as the value 22,

expressed in 7 bits.

* We will store the number of the month (1-12) using the next 4 bits.

* We will store the number of the day (1-31) using the last 5 bits.

To work with dates, you will presumably have to use PACK and CVB,

followed by shift and bitwise instructions, and you may need to use STCM

to put the value in the table and ICM to read the value from it.

We will store the User Names in an encrypted form. Specifically, we will

use the "XOR encryption" technique. It works like this: suppose we have

a 4-byte binary number KEY and we want to encrypt a 4-byte variable

called PHRASE. Then:

(encrypted form of PHRASE) = PHRASE XOR KEY

We will do this using the ID number (as a 4-byte binary value) as the

key. Each User Name is up to 8 bytes long, so we need to encrypt the

first 4 bytes and then the last 4 bytes.

The structure of a table entry is as follows, in this order:

* User Name (8 bytes)

* High Score (2 bytes, packed decimal)

* Date (2 bytes binary)

* ID Number (4 bytes, binary)





------------------------------------------------------------------------

*PRINT subroutine*

The parameters for PRINT are the address of the table, the address of a

fullword containing the address of the first unused entry and the

address of a 38-byte caption to use in the page heading.

The first time we call PRINT, the caption should say "List of Players in

On-Line Bowling", and the second time, the caption should say "List of

Players In Order by High Score".

When we extract the data from the table to print it, we will need to

decrypt the password. This can be done by exactly the same method. If we

have PHRASE and KEY as above

(decrypted form of PHRASE) = (encrypted form of PHRASE) XOR KEY

When we need to recover the date from its compressed form, we can do the

following:

* use ICM to put the value in a register

* use SLL and SRL to get just one number (perhaps the month) in the

rightmost bits with the rest of the register full of 0 bits

* use CVD to get hold of the number in packed decimal form

* use MVC and ED to get the number in zoned decimal form

* move just the digits we want onto the print line

------------------------------------------------------------------------

*SORT subroutine*

The parameters for SORT are the address of the table and the address of

a fullword containing the address of the first unused entry.

Use the Selection Sort technique (which we previously used in Assignment

7). When you need to swap two entries, use the XOR technique instead of

a temporary variable.

------------------------------------------------------------------------

*Other Notes*

1. You may assume that the table needs to hold no more than 25 entries,

16 bytes each.

ORG PROG8+((*-PROG8+15)/16)*16

where PROG8 is the name of the CSECT. This will align the table on a

16-byte boundary and make the XDUMP easier to read.

2. You should use a DSECT to describe the table entries.

3. The JCL for this assignment is the same as the JCL used in the

Assignment 6 except for the line given above to provide the data.

4. When you print a date, print it in the format 04/07/2018, is,

DD/MM/YYYY.

-----------------------------------------------------------------------

*Output*

Aside from the XDUMP, there will be about two pages of output.

Each table listing should have a page heading, centered. You do not need

to have a page number. There should be column headings, triple-spaced

from the page header.

The lines of player information should be triple-spaced.