awlsim/tests/tc999_projects/factorial.awl

ORGANIZATION_BLOCK OB 1
BEGIN
	
	CALL FC 1 (
		N	:= 0,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#1
	
	CALL FC 1 (
		N	:= 1,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#1
	
	CALL FC 1 (
		N	:= 2,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#2
	
	CALL FC 1 (
		N	:= 3,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#6
	
	CALL FC 1 (
		N	:= 4,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#24
	
	CALL FC 1 (
		N	:= 5,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#120
	
	CALL FC 1 (
		N	:= 6,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#720
	
	CALL FC 1 (
		N	:= 7,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#5040
	
	CALL FC 1 (
		N	:= 8,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#40320
	
	CALL FC 1 (
		N	:= 9,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#362880
	
	CALL FC 1 (
		N	:= 10,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#3628800
	
	CALL FC 1 (
		N	:= 11,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#39916800
	
	CALL FC 1 (
		N	:= 12,
		RET_VAL	:= MD 0,
	)
	__ASSERT==	MD 0, L#479001600
	
	
	CALL SFC 46 // STOP CPU
END_ORGANIZATION_BLOCK


FUNCTION FC 1 : DINT
	TITLE	= Calculate the factorial of #N
	
	VAR_INPUT
		N	: INT;
	END_VAR
	VAR_TEMP
		N_TMP	: INT;
		R_TMP	: DINT;
	END_VAR
BEGIN
	// If #N is 0 or 1, #RET_VAL is 1 and recursion ends.
	L	#N
	L	1
	T	#RET_VAL
	<=I
	BEB
	
	// Subtract 1 from #N
	-I
	T	#N_TMP
	
	// Recurse: Calculate (#N - 1)!
	CALL	FC 1 (
		N	:= #N_TMP,
		RET_VAL	:= #R_TMP,
	)
	
	// Multiply: (#N - 1)! * #N
	L	#R_TMP
	L	#N
	*D
	T	#RET_VAL
	BE
END_FUNCTION