+ifndef srcdir-build
+src-depth = $(depth)
+else
+src-depth = $(configure-srcdir)
+endif
+
+top-src-dir := $(shell cd $(src-depth); pwd)
+
+ifndef srcdir-build
+src-dir = .
+else
+src-dir = $(top-src-dir)$(tree-dir)
+VPATH = $(src-dir)
+endif
+
+abs-src-dir = $(top-src-dir)$(tree-dir)
+
+.UNEXPORT: build-dir src-dir tree-dir
+
+src-wildcard = $(subst $(src-dir)/,,$(wildcard $(src-dir)/$(1)))
+