[make] add 'make tags'

Tries to generate a curated ctags file for the current project and
configuration.

engine.mk

@@ -355,7 +355,11 @@ list-arch:
 list-toolchain:
 	@echo TOOLCHAIN_PREFIX = ${TOOLCHAIN_PREFIX}
 
-.PHONY: all clean install list-arch list-toolchain
+tags: $(BUILDDIR)/srcfiles.txt $(BUILDDIR)/include_paths.txt
+	$(info generating tags)
+	@ctags -L $<
+
+.PHONY: all clean install list-arch list-toolchain tags
 
 # generate a config.h file with all of the GLOBAL_DEFINES laid out in #define format
 configheader:

make/build.mk

@@ -1,3 +1,5 @@
+# Rules for generating the final binary and any auxillary files generated as a result.
+
 # use linker garbage collection, if requested
 WITH_LINKER_GC ?= false
 ifeq (true,$(call TOBOOL,$(WITH_LINKER_GC)))
@@ -58,12 +60,20 @@ $(OUTELF).size: $(OUTELF)
 	$(NOECHO)$(NM) -S --size-sort $< | $(CPPFILT) > $@
 	$(NOECHO)echo "# vim: ts=8 nolist nowrap" >> $@
 
-# print some information about the build
-$(BUILDDIR)/srcfiles.txt: $(OUTELF)
+# generate a list of source files that potentially participate in this build.
+# header file detection is a bit sloppy: it simply searches for every .h file inside
+# the combined include paths. May pick up files that are not strictly speaking used.
+# Alternate strategy that may work: union all of the .d files together and collect all
+# of the used headers used there.
+$(BUILDDIR)/srcfiles.txt: $(OUTELF) $(BUILDDIR)/include_paths.txt
+	@$(MKDIR)
 	$(info generating $@)
 	$(NOECHO)echo $(sort $(ALLSRCS)) | tr ' ' '\n' > $@
+	@for i in `cat $(BUILDDIR)/include_paths.txt`; do if [ -d $$i ]; then find $$i -type f -name \*.h; fi; done >> $@
 
+# generate a list of all the include directories used in this project
 $(BUILDDIR)/include_paths.txt: $(OUTELF)
+	@$(MKDIR)
 	$(info generating $@)
 	$(NOECHO)echo $(subst -I,,$(sort $(GLOBAL_INCLUDES))) | tr ' ' '\n' > $@
 

make/help.mk

@@ -21,6 +21,7 @@ help:
 	@echo "make list: List of buildable projects"
 	@echo "make clean: cleans build of current project"
 	@echo "make spotless: removes all build directories"
+	@echo "make tags: run ctags on all of the source files for the current project"
 	@echo "make <project>: try to build project named <project>"
 	@echo ""
 	@echo "make list-arch: print the architecture of the current project"