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

debian/control.top.in

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

lib/python/hal.py

@@ -29,10 +29,28 @@
 
 import _hal
 from _hal import *
+from _hal import query
+import sys
 import warnings
 import lcnc_realtime
 
+# _hal exports the IntEnum tagging classes as 'type' and 'dir'. The
+# star import binds them here, but those names shadow the builtins used
+# inside this module, so unbind them and serve them lazily through
+# __getattr__ instead. hal.type.REAL, hal.dir.IN and the HALType/HALDir
+# class names (also consulted by pickle) all resolve to the shared
+# classes in _hal.
+globals().pop('type', None)
+globals().pop('dir', None)
+
+# _hal.query is a submodule, not a plain attribute. Registering it in
+# sys.modules under its dotted name makes 'import hal.query' and
+# 'from hal import query' work as they would for a real package.
+sys.modules['hal.query'] = query
+
 def __getattr__(name):
+    if name in ('type', 'dir', 'HALType', 'HALDir'):
+        return getattr(_hal, {'HALType': 'type', 'HALDir': 'dir'}.get(name, name))
     if name == 'is_rt':
         warnings.warn(f"{name} is deprecated, use lcnc_realtime.verify() instead", FutureWarning, stacklevel=2)
         return lcnc_realtime.verify()

src/Makefile

@@ -394,6 +394,8 @@ build-software: headers $(INFILES)
 #
 SRCHEADERS := \
     hal/hal.h \
+    hal/hal.hh \
+    hal/halenum.hh \
     hal/drivers/mesa-hostmot2/hostmot2-serial.h \
     emc/linuxcnc.h \
     emc/kinematics/kinematics.h \

src/hal/Submakefile

@@ -3,6 +3,14 @@
 ../include/hal.h: ./hal/hal.h
 	cp $^ $@
 
+# hal.hh is the C++ interface on top of the public C API
+../include/hal.hh: ./hal/hal.hh
+	cp $^ $@
+
+# halenum.hh builds the shared Python IntEnum tagging classes
+../include/halenum.hh: ./hal/halenum.hh
+	cp $^ $@
+
 HALLIBSRCS := hal/hal_lib.c hal/hal_lib_query.c hal/hal_lib_extra.c $(ULAPISRCS)
 $(call TOOBJSDEPS, $(HALLIBSRCS)): EXTRAFLAGS += -fPIC $(ULAPI_CFLAGS)
 USERSRCS += $(HALLIBSRCS)
@@ -28,5 +36,27 @@ $(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
+# pybind11 headers: python3-pybind11 (system include) or pip user site.
+# Without them the bindings are skipped, not failed: they are optional
+# until the build dependency is made mandatory.
+PYBIND11INCLUDES := $(shell $(PYTHON) -m pybind11 --includes 2>/dev/null)
+ifneq ($(PYBIND11INCLUDES),)
+HALPPSRCS := hal/halpybind.cc $(wildcard hal/utils/setps_util.c)
+PYSRCS += $(HALPPSRCS)
+
+$(call TOOBJS, $(HALPPSRCS)): EXTRAFLAGS += $(PYBIND11INCLUDES)
+
+HALPP := ../lib/python/halpp.so
+$(HALPP): $(call TOOBJS, $(HALPPSRCS)) $(HALLIB)
+	$(ECHO) Linking python module $(notdir $@)
+	$(Q)$(CXX) $(LDFLAGS) -shared -o $@ $^
+
+PYTARGETS += $(HALPP)
+else
+$(info NOTE: pybind11 headers not found, skipping the halpp bindings (install python3-pybind11))
+endif
+
 TARGETS += $(HALLIB) ../lib/liblinuxcnchal.so.0
 PYTARGETS += $(HALMODULE)