hal: C++ API (hal.hh) and pybind11 bindings on the new HAL API

Reintroduce a C++ interface for HAL, built strictly on the public C
API and the user-land query API: no hal_priv.h, no direct shared
memory access, no re-implemented library internals.

- hal.hh: type-safe, header-only C++ layer in linuxcnc::hal. Typed
  pin/param handles via traits<T> over the rtapi_ types (compile-time
  accessor selection), runtime-typed pin_t variant and anypin for
  name-based access, component class with add_pin for the
  struct-member idiom, and ULAPI by-name query/set functions when the
  query API is present.

  Handles re-read the shmem slot on every access so hal_link() slot
  rewrites stay visible (C pointer-variable semantics). Handles are
  move-only; HAL objects are unique. Query callback paths are
  exception-free; errors are reported after the library releases the
  HAL mutex.

- halpybind.cc: pybind11 module (halpp.so) exposing component, Pin,
  enums and the by-name functions. Built alongside _hal/hal.py,
  replacing nothing. Library init/exit at import; string set values
  delegate to setps_common_cb for halcmd-consistent parsing.

- taskclass converted to the new API (it was the only hal.hh user).

- HAL_PORT intentionally exempted until the API break: the port
  handle type and creation semantics are still in flux.

- tests/halpp: Python and native C++ smoke suites.

Based on the pybind11 branch by rene-dev, re-based on the new HAL API.

Author: grandixximo

debian/control.top.in

@@ -40,6 +40,7 @@ Build-Depends:
     psmisc,
     python3,
     python3-dev,
+    python3-pybind11,
     python3-tk,
     python3-xlib,
     tcl,

src/emc/task/taskclass.cc

@@ -40,23 +40,26 @@ using namespace linuxcnc;
 ********************************************************************/
 int Task::iocontrol_hal_init(void)
 {
-    iocontrol.add_pin("user-enable-out", hal_dir::OUT, iocontrol_data.user_enable_out);
-    iocontrol.add_pin("emc-enable-in", hal_dir::IN, iocontrol_data.emc_enable_in);
-    iocontrol.add_pin("user-request-enable", hal_dir::OUT, iocontrol_data.user_request_enable);
-    iocontrol.add_pin("coolant-mist", hal_dir::OUT, iocontrol_data.coolant_mist);
-    iocontrol.add_pin("coolant-flood", hal_dir::OUT, iocontrol_data.coolant_flood);
-    iocontrol.add_pin("tool-prep-pocket", hal_dir::OUT, iocontrol_data.tool_prep_pocket);
-    iocontrol.add_pin("tool-from-pocket", hal_dir::OUT, iocontrol_data.tool_from_pocket);
-    iocontrol.add_pin("tool-prep-index", hal_dir::OUT, iocontrol_data.tool_prep_index);
-    iocontrol.add_pin("tool-prep-number", hal_dir::OUT, iocontrol_data.tool_prep_number);
-    iocontrol.add_pin("tool-number", hal_dir::OUT, iocontrol_data.tool_number);
-    iocontrol.add_pin("tool-prepare", hal_dir::OUT, iocontrol_data.tool_prepare);
-    iocontrol.add_pin("tool-prepared", hal_dir::IN, iocontrol_data.tool_prepared);
-    iocontrol.add_pin("tool-change", hal_dir::OUT, iocontrol_data.tool_change);
-    iocontrol.add_pin("tool-changed", hal_dir::IN, iocontrol_data.tool_changed);
-    iocontrol.ready();
-    if (iocontrol.error < 0)
+    try {
+        iocontrol.add_pin("user-enable-out", hal_dir::OUT, iocontrol_data.user_enable_out);
+        iocontrol.add_pin("emc-enable-in", hal_dir::IN, iocontrol_data.emc_enable_in);
+        iocontrol.add_pin("user-request-enable", hal_dir::OUT, iocontrol_data.user_request_enable);
+        iocontrol.add_pin("coolant-mist", hal_dir::OUT, iocontrol_data.coolant_mist);
+        iocontrol.add_pin("coolant-flood", hal_dir::OUT, iocontrol_data.coolant_flood);
+        iocontrol.add_pin("tool-prep-pocket", hal_dir::OUT, iocontrol_data.tool_prep_pocket);
+        iocontrol.add_pin("tool-from-pocket", hal_dir::OUT, iocontrol_data.tool_from_pocket);
+        iocontrol.add_pin("tool-prep-index", hal_dir::OUT, iocontrol_data.tool_prep_index);
+        iocontrol.add_pin("tool-prep-number", hal_dir::OUT, iocontrol_data.tool_prep_number);
+        iocontrol.add_pin("tool-number", hal_dir::OUT, iocontrol_data.tool_number);
+        iocontrol.add_pin("tool-prepare", hal_dir::OUT, iocontrol_data.tool_prepare);
+        iocontrol.add_pin("tool-prepared", hal_dir::IN, iocontrol_data.tool_prepared);
+        iocontrol.add_pin("tool-change", hal_dir::OUT, iocontrol_data.tool_change);
+        iocontrol.add_pin("tool-changed", hal_dir::IN, iocontrol_data.tool_changed);
+        iocontrol.ready();
+    } catch(const std::exception &e) {
+        fprintf(stderr, "iocontrol_hal_init: %s\n", e.what());
         return -1;
+    }
     return 0;
 }
 

src/hal/Submakefile

@@ -28,5 +28,19 @@ $(HALMODULE): $(call TOOBJS, $(HALMODULESRCS)) $(HALLIB)
 	$(ECHO) Linking python module $(notdir $@)
 	$(Q)$(CXX) $(LDFLAGS) -shared -o $@ $^
 
+# pybind11 C++ bindings (hal.hh based)
+# setps_util.c only exists in the tree with the HAL query API
+HALPPSRCS := hal/halpybind.cc $(wildcard hal/utils/setps_util.c)
+PYSRCS += $(HALPPSRCS)
+
+# pybind11 headers: python3-pybind11 (system include) or pip user site
+$(call TOOBJS, $(HALPPSRCS)): EXTRAFLAGS += $(shell python3 -m pybind11 --includes 2>/dev/null)
+
+HALPP := ../lib/python/halpp.so
+$(HALPP): $(call TOOBJS, $(HALPPSRCS)) $(HALLIB)
+	$(ECHO) Linking python module $(notdir $@)
+	$(Q)$(CXX) $(LDFLAGS) -shared -o $@ $^
+
 TARGETS += $(HALLIB) ../lib/liblinuxcnchal.so.0
 PYTARGETS += $(HALMODULE)
+PYTARGETS += $(HALPP)