diff ppc/test/flip.p @ 0:bfdcc3820b32

Basis
author Mike Spivey <mike@cs.ox.ac.uk>
date Thu, 05 Oct 2017 08:04:15 +0100
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ppc/test/flip.p	Thu Oct 05 08:04:15 2017 +0100
@@ -0,0 +1,86 @@
+proc flip(x: integer): integer;
+  proc flop(y: integer): integer;
+  begin
+    if y = 0 then return 1 else return flip(y-1) + x end
+  end;
+begin
+  if x = 0 then return 1 else return 2 * flop(x-1) end
+end;
+
+begin
+  print_num(flip(5));
+  newline()
+end.
+
+(* flip(5) = 2 * flop(4) = 2 * (flip(3) + 5)
+    = 4 * flop(2) + 10 = 4 * (flip(1) + 3) + 10
+    = 8 * flop(0) + 22 = 30 *)
+
+(*<<
+30
+>>*)
+
+(*[[
+MODULE Main 0 0
+IMPORT Lib 0
+ENDHDR
+
+PROC _flip 0 0 0
+!   if x = 0 then return 1 else return 2 * flop(x-1) end
+LDLW 16
+JEQZ L1
+JUMP L2
+LABEL L1
+CONST 1
+RETURNW
+LABEL L2
+CONST 2
+LDLW 16
+CONST 1
+MINUS
+LOCAL 0
+GLOBAL _flop
+PCALLW 1
+TIMES
+RETURNW
+END
+
+PROC _flop 0 0 0
+!     if y = 0 then return 1 else return flip(y-1) + x end
+LDLW 16
+JEQZ L4
+JUMP L5
+LABEL L4
+CONST 1
+RETURNW
+LABEL L5
+LDLW 16
+CONST 1
+MINUS
+CONST 0
+GLOBAL _flip
+PCALLW 1
+LDLW 12
+LDNW 16
+PLUS
+RETURNW
+END
+
+PROC MAIN 0 0 0
+!   print_num(flip(5));
+CONST 5
+CONST 0
+GLOBAL _flip
+PCALLW 1
+CONST 0
+GLOBAL lib.print_num
+PCALL 1
+!   newline()
+CONST 0
+GLOBAL lib.newline
+PCALL 0
+RETURN
+END
+
+! End
+]]*)