small update to installation manual

also includes a bug fix for the backend, to handle VGA x and y arguments properly (the code did not allow the full range of these arguments)

Author: fpgacademy

backend/sim_task.cpp

@@ -98,6 +98,19 @@ static int CheckArgs(vpiHandle handle, PLI_INT32 type, int size) {
 	return 0;
 }
 
+/**
+ * Helper function for MyCompiletf specifically for VGA args, which have a legal range
+ * @return return 1 if the argument is not proper, o/w return 0
+ */
+static int CheckArgsRange(vpiHandle handle, PLI_INT32 type, int lsize, int hsize) {
+    int actual = vpi_get(vpiSize, handle);
+	if (handle == NULL || vpi_get(vpiType, handle) != type || (actual < lsize) || (actual > hsize)){
+		PrintUsageError(handle);
+		return 1;
+	}
+	return 0;
+}
+
 
 static void PrintUsageError(vpiHandle handle) {
 	vpi_printf_helper(USAGE "\n");
@@ -171,15 +184,14 @@ static int MyCompiletf(PLI_BYTE8 *user_data) {
 		return 0;
 	}
 
-
 	// Arguments for VGA
 	vpiHandle x_handle = vpi_scan(args);
-	if(CheckArgs(x_handle, vpiNet, 8)){
+	if(CheckArgsRange(x_handle, vpiNet, 8, 10)){
 		return 0;
 	}
 
 	vpiHandle y_handle = vpi_scan(args);
-	if(CheckArgs(y_handle, vpiNet, 7)){
+	if(CheckArgsRange(y_handle, vpiNet, 7, 9)){
 		return 0;
 	}
 

documentation/installation/DESim_install.tex

@@ -115,9 +115,14 @@ \section{Configuring the DESim Application}
 replace \texttt{<SimulatorPath>} with the actual location of the folder where you have
 installed your Simulator.
 
-In most cases you will not need to make any other changes to {\it DESim\_run.bat}, and you 
-should be ready to execute this batch script to start {\it DESim}. Complete instructions for
-using the {\it DESim} application are provided in the {\it docs} folder listed in 
+In most cases you will not need to make any other changes
+\footnote{If your {\it Questa} (or {\it ModelSim}) version requires a license, then you should
+make an \texttt{LM\_LICENSE\_FILE} environment variable that specifies the location of your
+{\it license file}. But if you cannot set this variable, then the {\it DESim\_run.bat} file 
+describes a command-line option that can be used to specify your license-file location.}
+to the {\it DESim\_run.bat} file, and you 
+should be ready to execute this batch script to start the {\it DESim} application. Complete
+instructions for using {\it DESim} are provided in the {\it docs} folder listed in 
 Figure~\ref{fig:install}, and also in the 
 \texttt{DESim} section of {\small \href{https://www.fpgacademy.org/tools.html}
 {FPGAcademy.org}}.