1ifeq ($(origin O), command line)
2	dummy := $(if $(shell test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
3	ABSOLUTE_O := $(shell cd $(O) ; pwd)
4	OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
5	COMMAND_O := O=$(ABSOLUTE_O)
6ifeq ($(objtree),)
7	objtree := $(O)
8endif
9endif
10
11ifneq ($(OUTPUT),)
12# check that the output directory actually exists
13OUTDIR := $(shell cd $(OUTPUT) && /bin/pwd)
14$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
15endif
16
17#
18# Include saner warnings here, which can catch bugs:
19#
20EXTRA_WARNINGS := -Wbad-function-cast
21EXTRA_WARNINGS += -Wdeclaration-after-statement
22EXTRA_WARNINGS += -Wformat-security
23EXTRA_WARNINGS += -Wformat-y2k
24EXTRA_WARNINGS += -Winit-self
25EXTRA_WARNINGS += -Wmissing-declarations
26EXTRA_WARNINGS += -Wmissing-prototypes
27EXTRA_WARNINGS += -Wnested-externs
28EXTRA_WARNINGS += -Wno-system-headers
29EXTRA_WARNINGS += -Wold-style-definition
30EXTRA_WARNINGS += -Wpacked
31EXTRA_WARNINGS += -Wredundant-decls
32EXTRA_WARNINGS += -Wshadow
33EXTRA_WARNINGS += -Wstrict-aliasing=3
34EXTRA_WARNINGS += -Wstrict-prototypes
35EXTRA_WARNINGS += -Wswitch-default
36EXTRA_WARNINGS += -Wswitch-enum
37EXTRA_WARNINGS += -Wundef
38EXTRA_WARNINGS += -Wwrite-strings
39EXTRA_WARNINGS += -Wformat
40
41ifneq ($(findstring $(MAKEFLAGS), w),w)
42PRINT_DIR = --no-print-directory
43else
44NO_SUBDIR = :
45endif
46
47#
48# Define a callable command for descending to a new directory
49#
50# Call by doing: $(call descend,directory[,target])
51#
52descend = \
53	+mkdir -p $(OUTPUT)$(1) && \
54	$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
55
56QUIET_SUBDIR0  = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
57QUIET_SUBDIR1  =
58
59ifneq ($(findstring $(MAKEFLAGS),s),s)
60ifndef V
61	QUIET_CC       = @echo '   ' CC $@;
62	QUIET_AR       = @echo '   ' AR $@;
63	QUIET_LINK     = @echo '   ' LINK $@;
64	QUIET_MKDIR    = @echo '   ' MKDIR $@;
65	QUIET_GEN      = @echo '   ' GEN $@;
66	QUIET_SUBDIR0  = +@subdir=
67	QUIET_SUBDIR1  = ;$(NO_SUBDIR) echo '   ' SUBDIR $$subdir; \
68			 $(MAKE) $(PRINT_DIR) -C $$subdir
69	QUIET_FLEX     = @echo '   ' FLEX $@;
70	QUIET_BISON    = @echo '   ' BISON $@;
71
72	descend = \
73		@echo '   ' DESCEND $(1); \
74		mkdir -p $(OUTPUT)$(1) && \
75		$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
76endif
77endif
78