axi_dmac/tb: Add support for xsim

Add support for Vivado's simulator. By default the run script is using
the Icarus simulator.

If the user want to switch to another simulator, it can be explicitly
specify the required simulator tool in the SIMULATOR variable.
Currently, beside Icarus, Modelsim (SIMULATOR="modelsim") and Vivado's
xsim (SIMULATOR="xsim") is supported.

library/axi_dmac/tb/run_tb.sh

@@ -1,21 +1,24 @@
 NAME=`basename $0`
 
-if [[ ${SIMULATOR} != "modelsim" ]]; then
-
-  #Icarus flow
+case "$SIMULATOR" in
+	modelsim)
+  		# ModelSim flow
+  		vlib work
+  		vlog ${SOURCE} || exit 1
+  		vsim "dmac_"${NAME} -do "add log /* -r; run -a" -gui || exit 1
+		;;
+	xsim)
+  		# xsim flow
+  		xvlog -log ${NAME}_xvlog.log --sourcelibdir . ${SOURCE}
+  		xelab -log ${NAME}_xelab.log -debug all dmac_${NAME}
+  		xsim work.dmac_${NAME} -R
+		;;
+	*)
+  		#Icarus flow is the default
   		mkdir -p run
   		mkdir -p vcd
   		iverilog -o run/run_${NAME} -I.. ${SOURCE} $1 || exit 1
-
   		cd vcd
   		../run/run_${NAME}
-
-else
-
-  # ModelSim flow
-  vlib work
-
-  vlog ${SOURCE} || exit 1
-  vsim "dmac_"${NAME} -do "add log /* -r; run -a" -gui || exit 1
-
-fi
+		;;
+esac