1 files changed, 63 insertions, 0 deletions
diff --git a/include/subdir.mk b/include/subdir.mk
new file mode 100644
index 000000000..81a6f2a42
--- /dev/null
+++ b/include/subdir.mk
@@ -0,0 +1,63 @@
+# debug flags:
+#
+# d: show subdirectory tree
+# t: show added targets
+# l: show legacy targets
+
+ifeq ($(DEBUG),all)
+  build_debug:=dt
+else
+  build_debug:=$(DEBUG)
+endif
+
+define debug
+$$(findstring $(2),$$(if $$(DEBUG_DIR),$$(if $$(filter $$(DEBUG_DIR)%,$(1)),$(build_debug)),$(build_debug)))
+endef
+
+define warn
+$$(if $(call debug,$(1),$(2)),$$(warning $(3)))
+endef
+
+define warn_eval
+$(call warn,$(1),$(2),$(3)	$(4))
+$(4)
+endef
+
+dep/compile=$(1)/prepare
+dep/install=$(1)/compile
+SUBTARGETS:=clean download prepare compile install update refresh prereq
+
+# Parameters: <subdir>
+define subdir
+  $(call warn,$(1),d,D $(1))
+  $(foreach bd,$($(1)/builddirs),
+    $(call warn,$(1),d,BD $(1)/$(bd))
+    $(foreach target,$(SUBTARGETS),
+      $(call warn_eval,$(1)/$(bd),t,T,$(1)/$(bd)/$(target): $(call dep/$(target),$(1)/$(bd)) $($(1)/$(bd)/$(target)) $($(1)//$(target)))
+		@$$(MAKE) -j1 -C $(1)/$(bd) $(target)
+
+      # legacy targets
+      $(call warn_eval,$(1)/$(bd),l,T,$(1)/$(bd)-$(target): $(1)/$(bd)/$(target))
+	)
+  )
+  $(foreach target,$(SUBTARGETS),
+    $(call warn_eval,$(1),t,T,$(1)/$(target): $($(1)/) $(foreach bd,$($(1)/builddirs),$(1)/$(bd)/$(target)))
+  )
+endef
+
+# Parameters: <subdir> <name>
+define stampfile
+  $(1)/stamp:=$(STAGING_DIR)/stampfiles/.$(2)_installed
+  $(call rdep,$(1),$$($(1)/stamp))
+
+  $$($(1)/stamp):
+	@$(MAKE) $(1)/install
+	@mkdir -p $$$$(dirname $$($(1)/stamp))
+	@touch $$($(1)/stamp)
+  .PRECIOUS: $$($(1)/stamp) # work around a make bug
+
+  $(1)//clean:=$(1)/stamp/clean
+  $(1)/stamp/clean: FORCE
+	@rm -f $$($(1)/stamp)
+
+endef