add iocsh helper

src/ioc/Makefile

@@ -7,6 +7,7 @@ pvAccessIOC_LIBS += pvAccess pvData
 pvAccessIOC_LIBS += $(EPICS_BASE_IOC_LIBS)
 
 INC += pv/syncChannelFind.h
+INC += pv/iocshelper.h
 
 DBD += PVAServerRegister.dbd
 DBD += PVAClientRegister.dbd

src/ioc/pv/iocshelper.h

@@ -0,0 +1,156 @@
+#ifndef IOCSHELPER_H
+#define IOCSHELPER_H
+/** Helper for exposing functions and variables in the IOC shell
+ *
+ * Limitations:
+ * - supports functions with up to 4 arguments
+ * - argument and variable types must be: int, double, char*, or const char*
+ *
+ @code
+ #include <pv/iocshelper.h>
+ void fn0() {}
+ void fn2(int a, const char *b) {}
+ int var;
+ void myRegistrar() {
+   epics::iocshRegister<&fn0>("fn0");
+   epics::iocshRegister<int, const char*, &fn2>("fn0", "a description", "b description");
+   epics::iocshVariable<int, &var>("var");
+ }
+ extern "C" {
+   epicsExportRegistrar(myRegistrar);
+ }
+ @endcode
+ */
+
+#include <string>
+
+#include <iocsh.h>
+
+namespace epics {
+namespace detail {
+
+template<typename T>
+struct getarg {};
+template<> struct getarg<int> {
+    static int op(const iocshArgBuf& a) { return a.ival; }
+    enum { argtype = iocshArgInt };
+};
+template<> struct getarg<double> {
+    static double op(const iocshArgBuf& a) { return a.dval; }
+    enum { argtype = iocshArgDouble };
+};
+template<> struct getarg<char*> {
+    static char* op(const iocshArgBuf& a) { return a.sval; }
+    enum { argtype = iocshArgString };
+};
+template<> struct getarg<const char*> {
+    static const char* op(const iocshArgBuf& a) { return a.sval; }
+    enum { argtype = iocshArgString };
+};
+
+
+template<int N>
+struct iocshFuncInfo{
+    iocshFuncDef def;
+    std::string name;
+    iocshArg *argarr[N];
+    iocshArg args[N];
+    std::string argnames[N];
+    iocshFuncInfo(const std::string& n) :name(n) {
+        def.name = name.c_str();
+        def.nargs = N;
+        def.arg = (iocshArg**)&argarr;
+        for(size_t i=0; i<N; i++)
+            argarr[i] = &args[i];
+    }
+    template<int n, typename T>
+    void set(const char *name) {
+        argnames[n] = name;
+        args[n].name = argnames[n].c_str();
+        args[n].type = (iocshArgType)detail::getarg<T>::argtype;
+    }
+};
+
+template<void (*fn)()>
+static void call0(const iocshArgBuf *args)
+{
+    fn();
+}
+
+template<typename A, void (*fn)(A)>
+static void call1(const iocshArgBuf *args)
+{
+    fn(getarg<A>::op(args[0]));
+}
+
+template<typename A, typename B, void (*fn)(A,B)>
+static void call2(const iocshArgBuf *args)
+{
+    fn(getarg<A>::op(args[0]),
+       getarg<B>::op(args[1]));
+}
+
+template<typename A, typename B, typename C, void (*fn)(A,B,C)>
+static void call3(const iocshArgBuf *args)
+{
+    fn(getarg<A>::op(args[0]),
+       getarg<B>::op(args[1]),
+       getarg<C>::op(args[2]));
+}
+
+} // namespace detail
+
+
+template<void (*fn)()>
+void iocshRegister(const char *name)
+{
+    static detail::iocshFuncInfo<0> info(name);
+    iocshRegister(&info.def, &detail::call0<fn>);
+}
+
+template<typename A, void (*fn)(A)>
+void iocshRegister(const char *name, const char *arg1name)
+{
+    static detail::iocshFuncInfo<1> info(name);
+    info.set<0,A>(arg1name);
+    iocshRegister(&info.def, &detail::call1<A, fn>);
+}
+
+template<typename A, typename B, void (*fn)(A,B)>
+void iocshRegister(const char *name,
+                   const char *arg1name,
+                   const char *arg2name)
+{
+    static detail::iocshFuncInfo<2> info(name);
+    info.set<0,A>(arg1name);
+    info.set<1,B>(arg2name);
+    iocshRegister(&info.def, &detail::call2<A, B, fn>);
+}
+
+template<typename A, typename B, typename C, void (*fn)(A,B,C)>
+void iocshRegister(const char *name,
+                   const char *arg1name,
+                   const char *arg2name,
+                   const char *arg3name)
+{
+    static detail::iocshFuncInfo<3> info(name);
+    info.set<0,A>(arg1name);
+    info.set<1,B>(arg2name);
+    info.set<2,C>(arg3name);
+    iocshRegister(&info.def, &detail::call3<A, B, C, fn>);
+}
+
+template<typename V, V* addr>
+void iocshVariable(const char *name)
+{
+    static iocshVarDef def[2];
+    def[0].name = name;
+    def[0].pval = (void*)addr;
+    def[0].type = (iocshArgType)detail::getarg<V>::argtype;
+    def[1].name = NULL;
+    iocshRegisterVariable(def);
+}
+
+} // namespace epics
+
+#endif // IOCSHELPER_H