// Copyright 2014, VIXL authors
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//
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//
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#include "examples.h"

using namespace vixl;
using namespace vixl::aarch64;

#define __ masm->

void GenerateFactorialRec(MacroAssembler* masm) {
  // uint64_t factorial_rec(uint64_t n)
  // Argument location:
  //   n -> x0

  Label entry, input_is_zero;

  __ Bind(&entry);
  // Check for the stopping condition: the input number is null.
  __ Cbz(x0, &input_is_zero);

  __ Mov(x1, x0);
  __ Sub(x0, x0, 1);
  __ Push(x1, lr);
  __ Bl(&entry);  // Recursive call factorial_rec(n - 1).
  __ Pop(lr, x1);
  __ Mul(x0, x0, x1);
  __ Ret();

  __ Bind(&input_is_zero);
  __ Mov(x0, 1);
  __ Ret();
}


#ifndef TEST_EXAMPLES
#ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
int main(void) {
  MacroAssembler masm;
  Decoder decoder;
  Simulator simulator(&decoder);

  // Generate the code for the example function.
  Label factorial_rec;
  masm.Bind(&factorial_rec);
  GenerateFactorialRec(&masm);
  masm.FinalizeCode();

  // Run the example function.
  uint64_t input_val = 16;
  simulator.WriteXRegister(0, input_val);
  simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&factorial_rec));
  printf("factorial(%" PRIu64 ") = %" PRId64 "\n",
         input_val,
         simulator.ReadXRegister(0));

  return 0;
}
#else
// Without the simulator there is nothing to test.
int main(void) { return 0; }
#endif  // VIXL_INCLUDE_SIMULATOR_AARCH64
#endif  // TEST_EXAMPLES