Updated turboPmac version and added constructor for standard axis

README.md

@@ -44,7 +44,7 @@ Two additional PVs are provided in `db/seleneGuide.db`:
 ### Usage in IOC shell
 
 seleneGuide exports the following IOC shell functions:
-- `seleneGuideController`: Create a new controller object. This object is essentially a `turboPmacController` object from the standard [Turbo PMAC driver](https://git.psi.ch/sinq-epics-modules/turboPmac), but it supports the additional motor PVs for absolute position and normalization. This means that it can be used with "normal" `turboPmacAxis` as well.
+- `seleneGuideController`: Create a new controller object. This object is essentially a `turboPmacController` object from the standard [Turbo PMAC driver](https://git.psi.ch/sinq-epics-modules/turboPmac), but it supports the additional motor PVs for absolute position and normalization. This means that it can be used to control a "standard" TurboPMAC axis as well. To ensure compatibility between controller and axis, it is recommended to use the wrapper `seleneStandardAxis` instead of the `turboPmacAxis` provided by the basic TurboPMAC driver (because otherwise the versions of the `seleneGuide` and the `turboPmac` drivers are not independent from each other).
 - `seleneOffsetAxis`: Create a new offset axis object with the specified x- and z-offset from an arbitrary origin in mm.
 - `seleneVirtualAxes`: Create the virtual lift and the angle axes.
 
@@ -78,8 +78,9 @@ seleneOffsetAxis("$(NAME)",5, 5933.99477, 0.0);
 seleneOffsetAxis("$(NAME)",6, 7463.87259, 0.0);
 
 # These are two "normal" PMAC axes which work the same way they would with a turboPmacController.
-turboPmacAxis("$(NAME)",7);
-turboPmacAxis("$(NAME)",8);
+# Using the wrapper seleneStandardAxis ensures compatibility to the seleneGuideController.
+seleneStandardAxis("$(NAME)",7);
+seleneStandardAxis("$(NAME)",8);
 
 # This function call creates the lift and the angle axes.
 # The arguments on position 2 to 7 are the axis indices of the offset axes 

src/seleneGuide.dbd

@@ -1,3 +1,4 @@
 registrar(seleneVirtualAxesRegister) 
 registrar(seleneOffsetAxisRegister) 
+registrar(seleneStandardAxisRegister) 
 registrar(seleneGuideControllerRegister) 

src/seleneGuideController.cpp

@@ -161,4 +161,97 @@ static void seleneGuideControllerRegister(void) {
 }
 epicsExportRegistrar(seleneGuideControllerRegister);
 
+/*
+C wrapper for a "standard" TurboPMAC axis constructor. This function is
+identical to "turboPmacCreateAxis" in the standard TurboPMAC driver. However, it
+is recommended to use this constructor to make sure the version of the axis
+matches that of the controller. The controller is read from the portName.
+*/
+asynStatus seleneStandardCreateAxis(const char *portName, int axis) {
+
+    /*
+    findAsynPortDriver is a asyn library FFI function which uses the C ABI.
+    Therefore it returns a void pointer instead of e.g. a pointer to a
+    superclass of the controller such as asynPortDriver. Type-safe upcasting
+    via dynamic_cast is therefore not possible directly. However, we do know
+    that the void pointer is either a pointer to asynPortDriver (if a driver
+    with the specified name exists) or a nullptr. Therefore, we first do a
+    nullptr check, then a cast to asynPortDriver and lastly a (typesafe)
+    dynamic_upcast to Controller
+    https://stackoverflow.com/questions/70906749/is-there-a-safe-way-to-cast-void-to-class-pointer-in-c
+     */
+    void *ptr = findAsynPortDriver(portName);
+    if (ptr == nullptr) {
+        /*
+        We can't use asynPrint here since this macro would require us
+        to get an asynUser from a pointer to an asynPortDriver.
+        However, the given pointer is a nullptr and therefore doesn't
+        have an asynUser! printf is an EPICS alternative which
+        works w/o that, but doesn't offer the comfort provided
+        by the asynTrace-facility
+        */
+        errlogPrintf("Controller \"%s\" => %s, line %d\nPort not found.",
+                     portName, __PRETTY_FUNCTION__, __LINE__);
+        return asynError;
+    }
+    // Unsafe cast of the pointer to an asynPortDriver
+    asynPortDriver *apd = (asynPortDriver *)(ptr);
+
+    // Safe downcast
+    seleneGuideController *pC = dynamic_cast<seleneGuideController *>(apd);
+    if (pC == nullptr) {
+        errlogPrintf("Controller \"%s\" => %s, line %d\nController "
+                     "is not a seleneGuideController.",
+                     portName, __PRETTY_FUNCTION__, __LINE__);
+        return asynError;
+    }
+
+    // Prevent manipulation of the controller from other threads while we
+    // create the new axis.
+    pC->lock();
+
+    /*
+    We create a new instance of the axis, using the "new" keyword to
+    allocate it on the heap while avoiding RAII.
+    https://github.com/epics-modules/motor/blob/master/motorApp/MotorSrc/asynMotorController.cpp
+    https://github.com/epics-modules/asyn/blob/master/asyn/asynPortDriver/asynPortDriver.cpp
+
+    The created object is registered in EPICS in its constructor and can
+    safely be "leaked" here.
+    */
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+#pragma GCC diagnostic ignored "-Wunused-variable"
+    turboPmacAxis *pAxis = new turboPmacAxis(pC, axis);
+
+    // Allow manipulation of the controller again
+    pC->unlock();
+    return asynSuccess;
+}
+
+/*
+Same procedure as for the CreateController function, but for the axis
+itself.
+*/
+static const iocshArg CreateAxisArg0 = {"Controller name (e.g. mcu1)",
+                                        iocshArgString};
+static const iocshArg CreateAxisArg1 = {"Axis number", iocshArgInt};
+static const iocshArg *const CreateAxisArgs[] = {&CreateAxisArg0,
+                                                 &CreateAxisArg1};
+static const iocshFuncDef configSeleneStandardCreateAxis = {
+    "seleneStandardAxis", 2, CreateAxisArgs,
+    "Create an instance of a standard turboPmac axis for the selene "
+    "controller. The first argument is the controller this axis should be "
+    "attached to, the second argument is the axis number."};
+static void configSeleneStandardCreateAxisCallFunc(const iocshArgBuf *args) {
+    seleneStandardCreateAxis(args[0].sval, args[1].ival);
+}
+
+// This function is made known to EPICS in turboPmac.dbd and is called by
+// EPICS in order to register both functions in the IOC shell
+static void seleneStandardAxisRegister(void) {
+    iocshRegister(&configSeleneStandardCreateAxis,
+                  configSeleneStandardCreateAxisCallFunc);
+}
+epicsExportRegistrar(seleneStandardAxisRegister);
+
 } // extern "C"