add shmem Python example

Former-commit-id: 905ff699

Source/Examples/shmem1.py

+#!/usr/bin/python3
+
+import dpsim
+
+comps = [dpsim.VoltSourceRes("v_s", 1, 0, 10000+0j, 1),
+    dpsim.Inductor("l_1", 1, 2, 1e-3)]
+evs = dpsim.ExternalVoltageSource("v_ext", 2, 0, 0+0j, 1)
+comps.append(evs)
+intf = dpsim.ShmemInterface("/dpsim12", "/dpsim21", samplelen=2)
+intf.register_source(evs, 0, 1)
+intf.export_current(evs, 0, 1)
+sim = dpsim.Simulation(comps, duration=1, llog="lvector-shmem1.csv")
+sim.add_interface(intf)
+sim.start()
+sim.wait()

Source/Examples/shmem2.py

+#!/usr/bin/python3
+
+import dpsim
+
+comps = [dpsim.LinearResistor("r_1", 1, 0, 1)]
+ecs = dpsim.ExternalCurrentSource("i_ext", 1, 0, 0+0j)
+comps.append(ecs)
+intf = dpsim.ShmemInterface("/dpsim21", "/dpsim12", samplelen=2)
+intf.register_source(ecs, 0, 1)
+intf.export_voltage(1, 0, 0, 1)
+sim = dpsim.Simulation(comps, duration=1, llog="lvector-shmem2.csv")
+sim.add_interface(intf)
+sim.start()
+sim.wait()

Source/ShmemInterface.cpp

@@ -13,7 +13,12 @@ using namespace DPsim;
 void ShmemInterface::init(const char* wname, const char* rname, struct shmem_conf* conf) {
 	/* using a static shmem_conf as a default argument for the constructor
 	 * doesn't seem to work, so use this as a workaround */
-	if (shmem_int_open(wname, rname, &this->mShmem, conf) < 0) {
+
+	// make local copies of the filenames, because shmem_int doesn't make copies
+	// and needs them for the close function
+	this->wname = std::string(wname);
+	this->rname = std::string(rname);
+	if (shmem_int_open(this->wname.c_str(), this->rname.c_str(), &this->mShmem, conf) < 0) {
 		std::perror("Failed to open/map shared memory object");
 		std::exit(1);
 	}

Source/ShmemInterface.h

@@ -22,6 +22,7 @@ namespace DPsim {
 		struct shmem_int mShmem;
 		struct sample *mLastSample;
 		int mSeq;
+		std::string rname, wname;
 
 		void init(const char *wname, const char *rname, struct shmem_conf *conf);