### diff lab4/test/cpsfac.p @ 0:bfdcc3820b32

Basis
author Mike Spivey 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/cpsfac.p	Thu Oct 05 08:04:15 2017 +0100
@@ -0,0 +1,140 @@
+(* Compute factorials using CPS *)
+
+proc fac(n: integer; proc k(r: integer): integer): integer;
+  proc k1(r: integer): integer;
+    var r1: integer;
+  begin
+    r1 := n * r;
+    print_num(n); print_string(" * "); print_num(r);
+    print_string(" = "); print_num(r1); newline();
+    return k(r1)
+  end;
+begin
+  if n = 0 then return k(1) else return fac(n-1, k1) end
+end;
+
+proc id(r: integer): integer;
+begin
+  return r
+end;
+
+begin
+  print_num(fac(10, id));
+  newline()
+end.
+
+(*<<
+1 * 1 = 1
+2 * 1 = 2
+3 * 2 = 6
+4 * 6 = 24
+5 * 24 = 120
+6 * 120 = 720
+7 * 720 = 5040
+8 * 5040 = 40320
+9 * 40320 = 362880
+10 * 362880 = 3628800
+3628800
+>>*)
+
+(*[[
+@ picoPascal compiler output
+	.include "fixup.s"
+	.global pmain
+
+@ proc fac(n: integer; proc k(r: integer): integer): integer;
+	.text
+_fac:
+	mov ip, sp
+	stmfd sp!, {r0-r3}
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   if n = 0 then return k(1) else return fac(n-1, k1) end
+	ldr r0, [fp, #40]
+	cmp r0, #0
+	bne .L5
+	mov r0, #1
+	ldr r10, [fp, #48]
+	ldr r1, [fp, #44]
+	blx r1
+	b .L3
+.L5:
+	mov r2, fp
+	set r1, _k1
+	ldr r0, [fp, #40]
+	sub r0, r0, #1
+	bl _fac
+.L3:
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+@   proc k1(r: integer): integer;
+_k1:
+	mov ip, sp
+	stmfd sp!, {r0-r1}
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@     r1 := n * r;
+	ldr r0, [fp, #24]
+	ldr r5, [r0, #40]
+	ldr r0, [fp, #40]
+	mul r4, r5, r0
+@     print_num(n); print_string(" * "); print_num(r);
+	mov r0, r5
+	bl print_num
+	mov r1, #3
+	set r0, g1
+	bl print_string
+	ldr r0, [fp, #40]
+	bl print_num
+@     print_string(" = "); print_num(r1); newline();
+	mov r1, #3
+	set r0, g2
+	bl print_string
+	mov r0, r4
+	bl print_num
+	bl newline
+@     return k(r1)
+	ldr r5, [fp, #24]
+	mov r0, r4
+	ldr r10, [r5, #48]
+	ldr r1, [r5, #44]
+	blx r1
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+@ proc id(r: integer): integer;
+_id:
+	mov ip, sp
+	stmfd sp!, {r0-r1}
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   return r
+	ldr r0, [fp, #40]
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+pmain:
+	mov ip, sp
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   print_num(fac(10, id));
+	mov r2, #0
+	set r1, _id
+	mov r0, #10
+	bl _fac
+	bl print_num
+@   newline()
+	bl newline
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+	.data
+g1:
+	.byte 32, 42, 32
+	.byte 0
+g2:
+	.byte 32, 61, 32
+	.byte 0
+@ End
+]]*)```