332 Exercises Plex-C 1 Programming: Data Sector Exercise 5 Consider the following declare sector...

DECLARE;
GLOBAL NSYMB DEVINDNUM (255);
NSYMB ZRINDNUM = 200;
VARIABLE CINDNUM 16 DS;
VARIABLE CBUFFER 8 BUFFER;
STRING VARIABLE CTEXT 15 DS;
RECORD DEVDATA;
SYMBOL VARIABLE STATE = (IDLE, BUSY) DS;
VARIABLE CATEGORY 16 DS;
END RECORD;
POINTER DEVDATAP (DEVDATA);
END DECLARE;
a)
Set the size of the file in the following ways:
− using a local number symbol (200 records)
− using a market-dependent global number symbol
b)
Set the variable STATE to idle for all the initiated records.
c)
Set the variable CATEGORY to 1 for the first 20 records.
d)
Allocate the stored variables consecutively to a base address starting with 1.
333
Plex-C 1
Plex-C 1 Programming: Block Interaction
Write the statements used to send and receive the following signals: Exercise 6.1
SIGMA1 with two signal data: ALPHA and BETA. The signal is single and unique.
Exercise 6.2
SIGMA2 with one signal data: DEVICEDATAP. The signal is single and multiple. The block reference of the receiving block is stored in the field variable CBLOCKREF.
Exercise 6.3
SIGMA3 with the data POINTER and ACTION. The signal is combined and unique. The answer is received in label L1 with the signal SIGMA3ACK which has only one signal data: RESULT.
Exercise 6.4
Consider the following segment of Plex-C code.
PROGRAM; PLEX;
....
CINDEX = 0;
SEND SIGMA WITH CINDEX, CINDEX;
CINDEX = 1;
EXIT;
ENTER SIGMA WITH CARRAY (CINDEX), CINDEX;
....
END PROGRAM;
Question ❶ : In the ENTER statement, which array element was modified to what value?
Question ❷ : What assumption did you make to answer Question ❶ ?
334
Exercises
Plex-C 1: Introduction to the Emulator
Exercise 7.1
In this exercise, you will use the EmuTool, an OpenWindows based version of the APZ 212 Emulator. To start the tool, you will need a directory containing an emudump and a PlexView file for the block emutest presented in this exercise.
See Chapter 12, Design Environment, for a quick introduction to testing with the emulator. For further information, please read the documents
"EMU - User’s Guide" and "EMUTOOL - User’s Guide" which you will find in your APStools docs directory.
To start the emulator, drag and drop the file emutest.emudump from the File Manager window to the EmuTool icon in your APStoolbox. The tool will pop up automatically. Click in the main window and press <ENTER> or <RETURN> to start up all existing blocks in the emulator.
Type "startpv" to start the Plex document browser PlexView. A large number of signals will be sent between blocks PCI and LARI. Finally, the PlexView window will pop up. In order to load block emutest to the existing PlexView database, open the pop-up menu in the PlexView main window and choose Properties. Under “Local update directory:” enter the name of the directory containing all your files for this exercise, i.e. the emudump and PlexView files etc. Then click on the Apply button.
At the top of the PlexView main window, at least one block called EMUT­
EST will appear. Double-click on this text line. You will see the document survey for block EMUTEST. To the right you will see several helpful buttons allowing you to access different parts of the block’s documentation.
Choose “Program Start” to get to the start of the SPI. Using display mode Plex, mixed or ASA, you may decide whether the program is displayed in source code, assembler code or both.
The EmuTool should now display the message "Correction System Started" in its main window. Use command ‘b’ to switch to the block discussed in the exercise, i.e., enter “b emutest”. Use ‘v’ to monitor variables and ‘s’ to send signals.
• Check the values of the variables CINDNUM, TCASE and STATE.
• Execute a program sequence by sending signal START with the data TCASE = 0, TVALUE = 42, INDP = 1.
• Check the values of the variables CINDNUM, TCASE and INDP.
335
Plex-C 1
• To look at temporary variables and pointers, the corresponding registers have to be checked directly. Set break points in the program code, to interrupt the execution before leaving the program.
• Use the mixed display mode in PlexView to look at both source and assembler code. Note that the code line addresses (hexadecimal) are shown too. Do not attempt at this stage to understand all the assembler code.
• To insert a breakpoint, open the PlexView pop-up menu and select
"Emulator...". Click on the Plex code line "CASE tcase IS" and choose
"Breakpoint: Set/Clear" from the pop-up menu. A breakpoint is inserted and indicated with the "STOP" symbol on the corresponding ASA code line.
• Execute a program sequence by sending signal START with the data TCASE = 1, TVALUE = 23, INDP = 3.
• At the breakpoint, inspect the value of the temporary and the pointer variables. Find out which registers contain these values.