diff lab4/test/mutual.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/lab4/test/mutual.p	Thu Oct 05 08:04:15 2017 +0100
@@ -0,0 +1,159 @@
+(* Mutual recursion *)
+
+proc flip(i: integer): integer;
+  var r: integer;
+begin
+  if i = 0 then 
+    r := 1
+  else 
+    r := 2 * flop(i-1)
+  end;
+  print_string("flip("); print_num(i); 
+  print_string(") = "); print_num(r);
+  newline();
+  return r
+end;
+
+proc flop(i: integer): integer;
+  var r: integer;
+begin
+  if i = 0 then 
+    r := 1
+  else 
+    r := flip(i-1) + k
+  end;
+  print_string("flop("); print_num(i); 
+  print_string(") = "); print_num(r);
+  newline();
+  return r
+end;
+
+const k = 5;
+
+begin
+  print_num(flip(5));
+  newline()
+end.
+
+(*<<
+flop(0) = 1
+flip(1) = 2
+flop(2) = 7
+flip(3) = 14
+flop(4) = 19
+flip(5) = 38
+38
+>>*)
+
+(*[[
+@ picoPascal compiler output
+	.include "fixup.s"
+	.global pmain
+
+@ proc flip(i: integer): integer;
+	.text
+_flip:
+	mov ip, sp
+	stmfd sp!, {r0-r1}
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   if i = 0 then 
+	ldr r0, [fp, #40]
+	cmp r0, #0
+	bne .L7
+@     r := 1
+	mov r4, #1
+	b .L8
+.L7:
+@     r := 2 * flop(i-1)
+	ldr r0, [fp, #40]
+	sub r0, r0, #1
+	bl _flop
+	lsl r4, r0, #1
+.L8:
+@   print_string("flip("); print_num(i); 
+	mov r1, #5
+	set r0, g1
+	bl print_string
+	ldr r0, [fp, #40]
+	bl print_num
+@   print_string(") = "); print_num(r);
+	mov r1, #4
+	set r0, g2
+	bl print_string
+	mov r0, r4
+	bl print_num
+@   newline();
+	bl newline
+@   return r
+	mov r0, r4
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+@ proc flop(i: integer): integer;
+_flop:
+	mov ip, sp
+	stmfd sp!, {r0-r1}
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   if i = 0 then 
+	ldr r0, [fp, #40]
+	cmp r0, #0
+	bne .L11
+@     r := 1
+	mov r4, #1
+	b .L12
+.L11:
+@     r := flip(i-1) + k
+	ldr r0, [fp, #40]
+	sub r0, r0, #1
+	bl _flip
+	add r4, r0, #5
+.L12:
+@   print_string("flop("); print_num(i); 
+	mov r1, #5
+	set r0, g3
+	bl print_string
+	ldr r0, [fp, #40]
+	bl print_num
+@   print_string(") = "); print_num(r);
+	mov r1, #4
+	set r0, g4
+	bl print_string
+	mov r0, r4
+	bl print_num
+@   newline();
+	bl newline
+@   return r
+	mov r0, r4
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+pmain:
+	mov ip, sp
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   print_num(flip(5));
+	mov r0, #5
+	bl _flip
+	bl print_num
+@   newline()
+	bl newline
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+	.data
+g1:
+	.byte 102, 108, 105, 112, 40
+	.byte 0
+g2:
+	.byte 41, 32, 61, 32
+	.byte 0
+g3:
+	.byte 102, 108, 111, 112, 40
+	.byte 0
+g4:
+	.byte 41, 32, 61, 32
+	.byte 0
+@ End
+]]*)