Added BUILDDIR, a bit of script reworking

Now littlefs's Makefile can work with a custom build directory
for compilation output. Just set the BUILDDIR variable and the Makefile
will take care of the rest.

make BUILDDIR=build size

This makes it very easy to compare builds with different compile-time
configurations or different cross-compilers.

This meant most of code.py's build isolation is no longer needed,
so revisted the scripts and cleaned/tweaked a number of things.

Also bought code.py in line with coverage.py, fixing some of the
inconsistencies that were created while developing these scripts.

One change to note was removing the inline measuring logic, I realized
this feature is unnecessary thanks to GCC's -fkeep-static-functions and
-fno-inline flags.

Makefile

@@ -1,28 +1,43 @@
-TARGET = lfs.a
+ifdef BUILDDIR
+# make sure BUILDDIR ends with a slash
+override BUILDDIR := $(BUILDDIR)/
+# bit of a hack, but we want to make sure BUILDDIR directory structure
+# is correct before any commands
+$(if $(findstring n,$(MAKEFLAGS)),, $(shell mkdir -p \
+	$(BUILDDIR) \
+	$(BUILDDIR)bd \
+	$(BUILDDIR)tests))
+endif
+
+# overridable target/src/tools/flags/etc
 ifneq ($(wildcard test.c main.c),)
-override TARGET = lfs
+TARGET ?= $(BUILDDIR)lfs
+else
+TARGET ?= $(BUILDDIR)lfs.a
 endif
 
 CC ?= gcc
 AR ?= ar
 SIZE ?= size
+CTAGS ?= ctags
 NM ?= nm
-GCOV ?= gcov
 LCOV ?= lcov
 
-SRC += $(wildcard *.c bd/*.c)
-OBJ := $(SRC:.c=.o)
-DEP := $(SRC:.c=.d)
-ASM := $(SRC:.c=.s)
+SRC ?= $(wildcard *.c bd/*.c)
+OBJ := $(SRC:%.c=%.o)
+DEP := $(SRC:%.c=%.d)
+ASM := $(SRC:%.c=%.s)
+ifdef BUILDDIR
+override OBJ := $(addprefix $(BUILDDIR),$(OBJ))
+override DEP := $(addprefix $(BUILDDIR),$(DEP))
+override ASM := $(addprefix $(BUILDDIR),$(ASM))
+endif
 
 ifdef DEBUG
 override CFLAGS += -O0 -g3
 else
 override CFLAGS += -Os
 endif
-ifdef WORD
-override CFLAGS += -m$(WORD)
-endif
 ifdef TRACE
 override CFLAGS += -DLFS_YES_TRACE
 endif
@@ -31,13 +46,23 @@ override CFLAGS += -std=c99 -Wall -pedantic
 override CFLAGS += -Wextra -Wshadow -Wjump-misses-init -Wundef
 
 ifdef VERBOSE
-override SCRIPTFLAGS += -v
+override TESTFLAGS += -v
+override CODEFLAGS += -v
+override COVERAGEFLAGS += -v
 endif
 ifdef EXEC
-override TESTFLAGS += $(patsubst %,--exec=%,$(EXEC))
+override TESTFLAGS += --exec="$(EXEC)"
+endif
+ifdef BUILDDIR
+override TESTFLAGS += --build-dir="$(BUILDDIR:/=)"
+override CODEFLAGS += --build-dir="$(BUILDDIR:/=)"
+endif
+ifneq ($(NM),nm)
+override CODEFLAGS += --nm-tool="$(NM)"
 endif
 
 
+# commands
 .PHONY: all build
 all build: $(TARGET)
 
@@ -48,44 +73,46 @@ asm: $(ASM)
 size: $(OBJ)
 	$(SIZE) -t $^
 
+.PHONY: tags
+tags:
+	$(CTAGS) --totals --c-types=+p $(shell find -name '*.h') $(SRC)
+
 .PHONY: code
-code:
-	./scripts/code.py $(SCRIPTFLAGS)
+code: $(OBJ)
+	./scripts/code.py $^ $(CODEFLAGS)
 
 .PHONY: coverage
 coverage:
-	./scripts/coverage.py $(SCRIPTFLAGS)
+	./scripts/coverage.py $(BUILDDIR)tests/*.toml.info $(COVERAGEFLAGS)
 
 .PHONY: test
 test:
-	./scripts/test.py $(TESTFLAGS) $(SCRIPTFLAGS)
+	./scripts/test.py $(TESTFLAGS)
 .SECONDEXPANSION:
 test%: tests/test$$(firstword $$(subst \#, ,%)).toml
-	./scripts/test.py $@ $(TESTFLAGS) $(SCRIPTFLAGS)
+	./scripts/test.py $@ $(TESTFLAGS)
 
+# rules
 -include $(DEP)
+.SUFFIXES:
 
-lfs: $(OBJ)
+$(BUILDDIR)lfs: $(OBJ)
 	$(CC) $(CFLAGS) $^ $(LFLAGS) -o $@
 
-%.a: $(OBJ)
+$(BUILDDIR)%.a: $(OBJ)
 	$(AR) rcs $@ $^
 
-%.o: %.c
+$(BUILDDIR)%.o: %.c
 	$(CC) -c -MMD $(CFLAGS) $< -o $@
 
-%.s: %.c
+$(BUILDDIR)%.s: %.c
 	$(CC) -S $(CFLAGS) $< -o $@
 
-%.gcda.gcov: %.gcda
-	( cd $(dir $@) ; $(GCOV) -ri $(notdir $<) )
-
+# clean everything
 .PHONY: clean
 clean:
 	rm -f $(TARGET)
 	rm -f $(OBJ)
 	rm -f $(DEP)
 	rm -f $(ASM)
-	rm -f tests/*.toml.*
-	rm -f sizes/*
-	rm -f results/*
+	rm -f $(BUILDDIR)tests/*.toml.*