# Last modified on Wed Nov  4 17:46:34 PST 1992 by heydon
#
# This program reads integers from the standard input, and then writes out
# their factorials. The program exits when the user inputs a number <= 0.

# PROCEDURE y := Factorial(x) IS
#   IF x <= 1.0 -> y := 1.0
#    | y := x * Factorial(x - 1.0)
#   FI
# END
#
# cont, i ::
#   cont := 1.0
# ; DO Print("> ")
#    ; i := Atof(Readln())
#    ; Print(Unparse(i))
#    ; Print("! = ")
#    ; Print(Unparse(Factorial(i)))
#    ; Print("\n")
#   OD
#
# (The loop exits when Readln() is undefined).

# Currently, this program supplies bogus "undefined" offsets for the
# instructions that require them.

# Global variables
V0
0.0
V1
1.0
V2
"> "
V3
"! = "
V4
"\n"
V5
"<end-of-file>\n"

# Factorial()
C1

# x = fp[-1] (IN parameter)
# y = fp[-2] (OUT parameter)

# x <= 1.0?
.PUSHL
s-1
.PUSHG
c1
.AT-MOST
.TJUMP
s29

# y := x * Factorial(x - 1.0)
.PUSHL
s-1
.INCSP
b1
.PUSHL
s-1
.PUSHG
c1
.SUBTRACT
s0
.CALL
c1
.DECSP
b1
.MULTIPLY
s0
.JUMP
s5
.PUSHG
c1
.POPL
s-2
.RET

# Main Loop
C2

# i = fp[1]
# t = fp[2]
.INCSP
b2
.PUSHG
c2
.CALLEXT
c0
.DECSP
b1

# t := Readln()
.INCSP
b1
.CALLEXT
c1
.POPL
s2
.TJUMP
s13
.PUSHG
c5
.CALLEXT
c0
.DECSP
b1
.RET

# i := Atof(t)
.INCSP
b1
.PUSHL
s2
.CALLEXT
c3
.DECSP
b1
.POPL
s1

# Print(Unparse(i))
.INCSP
b1
.PUSHL
s1
.CALLEXT
c2
.DECSP
b1
.CALLEXT
c0
.DECSP
b1

# Print("! = ")
.PUSHG
c3
.CALLEXT
c0
# DECSP (remove space for IN)
# INCSP (make space for OUT)

# t : = Factorial(i)
.PUSHL
s1
.CALL
c1
.DECSP
b1
.POPL
s2

# t := Unparse(t)
.INCSP
b1
.PUSHL
s2
.CALLEXT
c2
.DECSP
b1
# POPL 2 (store result in t)
# PUSHL 2 (push IN argument)

# Print(t)
.CALLEXT
c0
.DECSP
b1

# Print("\n")
.PUSHG
c4
.CALLEXT
c0
.DECSP
b1

# Jump to top of loop
.JUMP
s-129

END
0
1
2
2.5
3
4
5
10
30
34
35
1000