Make GENHDR build faster

Author: fornellas

Makefile

@@ -46,6 +46,10 @@ endif
 
 # Avoid the use of shell find, for windows compatibility
 IRQ_DEFN_FILES  := $(foreach TARGET,$(TARGETS),$(wildcard include/libopencm3/$(TARGET)/irq.json))
+NVIC_H := $(IRQ_DEFN_FILES:%/irq.json=%/nvic.h)
+VECTOR_NVIC_C := $(IRQ_DEFN_FILES:./include/libopencm3/%/irq.json=./lib/%/vector_nvic.c)
+IRQHANDLERS_H := $(IRQ_DEFN_FILES:./include/libopencm3/%/irq.json=./include/libopencmsis/%/irqhandlers.h)
+IRQ_GENERATED_FILES = $(NVIC_H) $(VECTOR_NVIC_C) $(IRQHANDLERS_H)
 STYLECHECKFILES := $(wildcard include/*/*.h include/*/*/*.h include/*/*/*/*.h)
 STYLECHECKFILES += $(wildcard lib/*/*.h lib/*/*/*.h lib/*/*/*/*.h)
 STYLECHECKFILES += $(wildcard lib/*/*.c lib/*/*/*.c lib/*/*/*/*.c)
@@ -54,16 +58,16 @@ all: build
 
 build: lib
 
-%.genhdr:
+include/libopencm3/%/nvic.h lib/%/vector_nvic.c include/libopencmsis/%/irqhandlers.h: include/libopencm3/%/irq.json ./scripts/irq2nvic_h
 	@printf "  GENHDR  $*\n";
-	$(Q)./scripts/irq2nvic_h ./$*;
+	$(Q)./scripts/irq2nvic_h ./$<;
 
 %.cleanhdr:
 	@printf "  CLNHDR  $*\n";
 	$(Q)./scripts/irq2nvic_h --remove ./$*
 
 LIB_DIRS:=$(wildcard $(addprefix lib/,$(TARGETS)))
-$(LIB_DIRS): $(IRQ_DEFN_FILES:=.genhdr)
+$(LIB_DIRS): $(IRQ_GENERATED_FILES)
 	$(Q)$(RM) .stamp_failure_$(subst /,_,$@)
 	@printf "  BUILD   $@\n";
 	$(Q)$(MAKE) --directory=$@ PREFIX="$(PREFIX)" || \