1// Copyright 2014, VIXL authors
2// All rights reserved.
3//
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5// modification, are permitted provided that the following conditions are met:
6//
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9//   * Redistributions in binary form must reproduce the above copyright notice,
10//     this list of conditions and the following disclaimer in the documentation
11//     and/or other materials provided with the distribution.
12//   * Neither the name of ARM Limited nor the names of its contributors may be
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15//
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25// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26
27#include "examples.h"
28
29#define __ masm->
30
31void GenerateFactorial(MacroAssembler* masm) {
32  // uint64_t factorial(uint64_t n)
33  // Argument location:
34  //   n -> x0
35
36  Label loop, end;
37
38  __ Mov(x1, x0);
39  __ Mov(x0, 1);  // Use x0 as the accumulator.
40
41  __ Cbz(x1, &end);  // Nothing to do if the input is null.
42
43  __ Bind(&loop);
44  __ Mul(x0, x0, x1);
45  __ Sub(x1, x1, 1);
46  __ Cbnz(x1, &loop);
47
48  __ Bind(&end);
49  // The return value is in x0.
50  __ Ret();
51}
52
53
54#ifndef TEST_EXAMPLES
55#ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
56int main(void) {
57  MacroAssembler masm;
58  Decoder decoder;
59  Simulator simulator(&decoder);
60
61  // Generate the code for the example function.
62  Label factorial;
63  masm.Bind(&factorial);
64  GenerateFactorial(&masm);
65  masm.FinalizeCode();
66
67  // Run the example function.
68  uint64_t input_val = 16;
69  simulator.WriteXRegister(0, input_val);
70  simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&factorial));
71  printf("factorial(%" PRIu64 ") = %" PRId64 "\n",
72         input_val,
73         simulator.ReadXRegister(0));
74
75  return 0;
76}
77#else
78// Without the simulator there is nothing to test.
79int main(void) { return 0; }
80#endif  // VIXL_INCLUDE_SIMULATOR_AARCH64
81#endif  // TEST_EXAMPLES
82