CryptoAuthLib makefile for Linux I2C userspace

Makefile

.PHONY: all libcryptoauth libateccssl libpkcs11 dist install clean

OPTIONS := ATCAPRINTF ATCA_HAL_I2C ENGINE_DYNAMIC_SUPPORT USE_ECCX08 ECC_DEBUG

SYSTEM_INCLUDES := /usr/include

# Define helpful macros for interacting with the specific environment
BACK2SLASH = $(subst \,/,$(1))
SLASH2BACK = $(subst /,\,$(1))
FIND = $(shell find $(abspath $(1)) -name $(2))
MKDIR = $(shell mkdir -p $(1) 2>/dev/null)

CFLAGS += -g -O1 -m64 -Wall -fPIC $(addprefix -D,$(OPTIONS))
TARGET_ARCH := Linux

OUTDIR := $(abspath .build)

DEPFLAGS = -MT $@ -MMD -MP -MF $(OUTDIR)/$*.d
ARFLAGS = rcs


# Wildcard all the sources and headers
SOURCES := $(call FIND,lib,*.c)
INCLUDE := $(sort $(dir $(call FIND, lib, *.h)))

# Gather libcryptoauth objects
LIBCRYPTOAUTH_OBJECTS := $(filter-out $(abspath lib/hal)/%, $(SOURCES))
LIBCRYPTOAUTH_OBJECTS += atca_hal.c

# General Linux Support
LIBCRYPTOAUTH_OBJECTS += hal_linux_timer.c

# Native I2C hardware/driver
LIBCRYPTOAUTH_OBJECTS += hal_linux_i2c_userspace.c

LIBCRYPTOAUTH_OBJECTS := $(addprefix $(OUTDIR)/,$(notdir $(LIBCRYPTOAUTH_OBJECTS:.c=.o)))

CFLAGS += $(addprefix -I, $(INCLUDE) $(TEST_INCLUDE) $(SYSTEM_INCLUDES))

# Regardless of platform set the vpath correctly
vpath %.c $(call BACK2SLASH,$(sort $(dir $(SOURCES) $(TEST_SOURCES))))

$(OUTDIR):
	$(call MKDIR, $(OUTDIR))

$(OUTDIR)/%.o : %.c $(OUTDIR)/%.d | $(OUTDIR)
	$(CC) $(DEPFLAGS) $(CFLAGS) -c $< -o $@

$(OUTDIR)/%.d: ;
.PRECIOUS: $(OUTDIR)/%.d

$(OUTDIR)/libcryptoauth.a: $(LIBCRYPTOAUTH_OBJECTS) | $(OUTDIR)
	$(AR) $(ARFLAGS) $@ $(LIBCRYPTOAUTH_OBJECTS)
	
include $(wildcard $(patsubst %,$(OUTDIR)/%.d,$(basename $(SOURCES))))

libcryptoauth: $(OUTDIR)/libcryptoauth.a | $(OUTDIR)

all: $(LIBCRYPTOAUTH_OBJECTS) | $(OUTDIR)

clean:
	rm -r $(OUTDIR)