view lab4/test/queens3.p @ 1:b5139af1a420 tip basis

Fixed permissions on compile scripts
author Mike Spivey <mike@cs.ox.ac.uk>
date Fri, 13 Oct 2017 17:27:58 +0100
parents bfdcc3820b32
children
line wrap: on
line source
(* N queens with bitmap arrays *)

const N = 8;

var 
  choice: array N of integer;
  rank: array N of boolean;
  diagup, diagdown: array 2 * N - 1 of boolean;

proc queens(k: integer);
  var y, j, q: integer; ok: boolean;
begin
  if k = N then
    print()
  else
    y := 0;
    while y < N do
      if rank[y] and diagup[k+y] and diagdown[k+(N-1)-y] then
	rank[y] := false; diagup[k+y] := false; diagdown[k+(N-1)-y] := false;
	choice[k] := y; queens(k+1);
	rank[y] := true; diagup[k+y] := true; diagdown[k+(N-1)-y] := true;
      end;
      y := y+1
    end
  end
end;

proc print();
  var x: integer;
begin
  x := 0;
  while x < N do
    print_num(choice[x]+1);
    x := x+1
  end;
  newline()
end;

proc init();
  var i: integer;
begin
  i := 0; 
  while i < N do 
    rank[i] := true; 
    i := i+1 
  end;
  i := 0; 
  while i < 2*N-1 do 
    diagup[i] := true; diagdown[i] := true ;
    i := i+1
  end
end;

begin
  init();
  queens(0)
end.

(*<<
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>>*)

(*[[
@ picoPascal compiler output
	.include "fixup.s"
	.global pmain

@ proc queens(k: integer);
	.text
_queens:
	mov ip, sp
	stmfd sp!, {r0-r1}
	stmfd sp!, {r4-r10, fp, ip, lr}
	mov fp, sp
	sub sp, sp, #8
@   if k = N then
	ldr r0, [fp, #40]
	cmp r0, #8
	bne .L3
@     print()
	bl _print
	b .L1
.L3:
@     y := 0;
	mov r4, #0
.L5:
@     while y < N do
	cmp r4, #8
	bge .L1
@       if rank[y] and diagup[k+y] and diagdown[k+(N-1)-y] then
	set r0, _rank
	add r7, r0, r4
	ldrb r0, [r7]
	cmp r0, #0
	beq .L10
	ldr r8, [fp, #40]
	set r0, _diagup
	add r0, r0, r8
	add r9, r0, r4
	ldrb r0, [r9]
	cmp r0, #0
	beq .L10
	set r0, _diagdown
	add r1, r8, #7
	sub r1, r1, r4
	add r0, r0, r1
	ldrb r1, [r0]
	cmp r1, #0
	beq .L10
@ 	rank[y] := false; diagup[k+y] := false; diagdown[k+(N-1)-y] := false;
	mov r1, #0
	strb r1, [r7]
	mov r1, #0
	strb r1, [r9]
	mov r1, #0
	strb r1, [r0]
@ 	choice[k] := y; queens(k+1);
	set r0, _choice
	lsl r1, r8, #2
	add r0, r0, r1
	str r4, [r0]
	add r0, r8, #1
	bl _queens
@ 	rank[y] := true; diagup[k+y] := true; diagdown[k+(N-1)-y] := true;
	mov r0, #1
	set r1, _rank
	add r1, r1, r4
	strb r0, [r1]
	ldr r7, [fp, #40]
	mov r0, #1
	set r1, _diagup
	add r1, r1, r7
	add r1, r1, r4
	strb r0, [r1]
	mov r0, #1
	set r1, _diagdown
	add r2, r7, #7
	sub r2, r2, r4
	add r1, r1, r2
	strb r0, [r1]
.L10:
@       y := y+1
	add r4, r4, #1
	b .L5
.L1:
	ldmfd fp, {r4-r10, fp, sp, pc}
	.ltorg

@ proc print();
_print:
	mov ip, sp
	stmfd sp!, {r4-r10, fp, ip, lr}
	mov fp, sp
@   x := 0;
	mov r4, #0
.L14:
@   while x < N do
	cmp r4, #8
	bge .L16
@     print_num(choice[x]+1);
	set r0, _choice
	lsl r1, r4, #2
	add r0, r0, r1
	ldr r0, [r0]
	add r0, r0, #1
	bl print_num
@     x := x+1
	add r4, r4, #1
	b .L14
.L16:
@   newline()
	bl newline
	ldmfd fp, {r4-r10, fp, sp, pc}
	.ltorg

@ proc init();
_init:
	mov ip, sp
	stmfd sp!, {r4-r10, fp, ip, lr}
	mov fp, sp
@   i := 0; 
	mov r4, #0
.L18:
@   while i < N do 
	cmp r4, #8
	bge .L20
@     rank[i] := true; 
	mov r0, #1
	set r1, _rank
	add r1, r1, r4
	strb r0, [r1]
@     i := i+1 
	add r4, r4, #1
	b .L18
.L20:
@   i := 0; 
	mov r4, #0
.L21:
@   while i < 2*N-1 do 
	cmp r4, #15
	bge .L17
@     diagup[i] := true; diagdown[i] := true ;
	mov r0, #1
	set r1, _diagup
	add r1, r1, r4
	strb r0, [r1]
	mov r0, #1
	set r1, _diagdown
	add r1, r1, r4
	strb r0, [r1]
@     i := i+1
	add r4, r4, #1
	b .L21
.L17:
	ldmfd fp, {r4-r10, fp, sp, pc}
	.ltorg

pmain:
	mov ip, sp
	stmfd sp!, {r4-r10, fp, ip, lr}
	mov fp, sp
@   init();
	bl _init
@   queens(0)
	mov r0, #0
	bl _queens
	ldmfd fp, {r4-r10, fp, sp, pc}
	.ltorg

	.comm _choice, 32, 4
	.comm _rank, 8, 4
	.comm _diagup, 15, 4
	.comm _diagdown, 15, 4
@ End
]]*)