### view lab4/test/queens.p @ 4:9f5c8e19f204tipbasis

Oops: fix for lab0
author Mike Spivey Mon, 15 Oct 2018 21:58:03 +0100 5dd13b8deb54
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line source
```(* N queens in functional form *)

const N = 8;

proc queens(k: integer; proc choice(x: integer): integer);
var y, j, q: integer; ok: boolean;

proc choice1(x: integer): integer;
begin
if x = k then
return y
else
return choice(x)
end;
end;

begin
if k > N then
print(choice)
else
y := 1;
while y <= N do
j := 1; ok := true;
while ok and (j < k) do
q := choice(j);
ok := (q <> y) and (q+j <> y+k) and (q-j <> y-k);
j := j+1
end;
if ok then queens(k+1, choice1) end;
y := y+1
end
end
end;

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

proc choice0(x: integer): integer;
begin
return 0
end;

begin
queens(1, choice0)
end.

(*<<
15863724
16837425
17468253
17582463
24683175
25713864
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26831475
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35281746
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51863724
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57248136
57263148
57263184
57413862
58413627
58417263
61528374
62713584
62714853
63175824
63184275
63185247
63571428
63581427
63724815
63728514
63741825
64158273
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64718253
68241753
71386425
72418536
72631485
73168524
73825164
74258136
74286135
75316824
82417536
82531746
83162574
84136275
>>*)

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

@ proc queens(k: integer; proc choice(x: integer): integer);
.text
_queens:
mov ip, sp
stmfd sp!, {r0-r3}
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
ble .L3
@     print(choice)
ldr r1, [fp, #48]
ldr r0, [fp, #44]
bl _print
b .L1
.L3:
@     y := 1;
mov r0, #1
str r0, [fp, #-4]
.L5:
@     while y <= N do
ldr r0, [fp, #-4]
cmp r0, #8
bgt .L1
@       j := 1; ok := true;
mov r4, #1
mov r6, #1
.L8:
@       while ok and (j < k) do
cmp r6, #0
beq .L10
ldr r0, [fp, #40]
cmp r4, r0
bge .L10
@ 	q := choice(j);
mov r0, r4
ldr r10, [fp, #48]
ldr r1, [fp, #44]
blx r1
mov r5, r0
@ 	ok := (q <> y) and (q+j <> y+k) and (q-j <> y-k);
ldr r7, [fp, #-4]
ldr r8, [fp, #40]
cmp r5, r7
mov r0, #0
movne r0, #1
cmp r1, r2
mov r1, #0
movne r1, #1
and r0, r0, r1
sub r1, r5, r4
sub r2, r7, r8
cmp r1, r2
mov r1, #0
movne r1, #1
and r6, r0, r1
@         j := j+1
b .L8
.L10:
@       if ok then queens(k+1, choice1) end;
cmp r6, #0
beq .L14
mov r2, fp
set r1, _choice1
ldr r0, [fp, #40]
bl _queens
.L14:
@       y := y+1
ldr r0, [fp, #-4]
str r0, [fp, #-4]
b .L5
.L1:
ldmfd fp, {r4-r10, fp, sp, pc}
.ltorg

@   proc choice1(x: integer): integer;
_choice1:
mov ip, sp
stmfd sp!, {r0-r1}
stmfd sp!, {r4-r10, fp, ip, lr}
mov fp, sp
@     if x = k then
ldr r4, [fp, #24]
ldr r0, [fp, #40]
ldr r1, [r4, #40]
cmp r0, r1
bne .L17
@       return y
ldr r0, [r4, #-4]
b .L15
.L17:
@       return choice(x)
ldr r4, [fp, #24]
ldr r0, [fp, #40]
ldr r10, [r4, #48]
ldr r1, [r4, #44]
blx r1
.L15:
ldmfd fp, {r4-r10, fp, sp, pc}
.ltorg

@ proc print(proc choice(x: integer): integer);
_print:
mov ip, sp
stmfd sp!, {r0-r1}
stmfd sp!, {r4-r10, fp, ip, lr}
mov fp, sp
@   x := 1;
mov r4, #1
.L20:
@   while x <= N do
cmp r4, #8
bgt .L22
@     print_num(choice(x));
mov r0, r4
ldr r10, [fp, #44]
ldr r1, [fp, #40]
blx r1
bl print_num
@     x := x+1
b .L20
.L22:
@   newline()
bl newline
ldmfd fp, {r4-r10, fp, sp, pc}
.ltorg

@ proc choice0(x: integer): integer;
_choice0:
mov ip, sp
stmfd sp!, {r0-r1}
stmfd sp!, {r4-r10, fp, ip, lr}
mov fp, sp
@   return 0
mov r0, #0
ldmfd fp, {r4-r10, fp, sp, pc}
.ltorg

pmain:
mov ip, sp
stmfd sp!, {r4-r10, fp, ip, lr}
mov fp, sp
@   queens(1, choice0)
mov r2, #0
set r1, _choice0
mov r0, #1
bl _queens
ldmfd fp, {r4-r10, fp, sp, pc}
.ltorg

@ End
]]*)```