c2iec

--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,11 @@
 C2IEC=c2iec
 TESTS=$(patsubst %.c, %.test, $(wildcard test/*.c))
 TEST_LOGS=$(patsubst %.c, %.test.log, $(wildcard test/*.c))
+
+# if parameter "DEBUG" is set, we set debug flags for lex/yacc
+ifneq (${DEBUG},)
+DEBUG_FLAGS += -d
+endif
 
 all: ${C2IEC}
 
@@ -8,10 +13,10 @@
 	gcc -o $@ $^
 
 lex.yy.c: ${C2IEC}.l
-	flex -d $^
+	flex ${DEBUG_FLAGS} $^
 
 y.tab.c: ${C2IEC}.y
-	yacc -d $^
+	yacc ${DEBUG_FLAGS} $^
 
 y.dot: ${C2IEC}.y
 	yacc -g $^
@@ -23,6 +28,8 @@
 clean:
 	rm -f ${C2IEC}
 	rm -f ${TEST_LOGS}
+	rm -f lex.yy.c
+	rm -f y.tab.c
 
 .PHONY: test
 test: ${TESTS}