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:
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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
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12 // * Neither the name of ARM Limited nor the names of its contributors may be
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15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
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26
27 #include "examples.h"
28
29 using namespace vixl;
30 using namespace vixl::aarch64;
31
32 #define __ masm->
33
GenerateFactorialRec(MacroAssembler * masm)34 void GenerateFactorialRec(MacroAssembler* masm) {
35 // uint64_t factorial_rec(uint64_t n)
36 // Argument location:
37 // n -> x0
38
39 Label entry, input_is_zero;
40
41 __ Bind(&entry);
42 // Check for the stopping condition: the input number is null.
43 __ Cbz(x0, &input_is_zero);
44
45 __ Mov(x1, x0);
46 __ Sub(x0, x0, 1);
47 __ Push(x1, lr);
48 __ Bl(&entry); // Recursive call factorial_rec(n - 1).
49 __ Pop(lr, x1);
50 __ Mul(x0, x0, x1);
51 __ Ret();
52
53 __ Bind(&input_is_zero);
54 __ Mov(x0, 1);
55 __ Ret();
56 }
57
58
59 #ifndef TEST_EXAMPLES
60 #ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
main(void)61 int main(void) {
62 MacroAssembler masm;
63 Decoder decoder;
64 Simulator simulator(&decoder);
65
66 // Generate the code for the example function.
67 Label factorial_rec;
68 masm.Bind(&factorial_rec);
69 GenerateFactorialRec(&masm);
70 masm.FinalizeCode();
71
72 // Run the example function.
73 uint64_t input_val = 16;
74 simulator.WriteXRegister(0, input_val);
75 simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&factorial_rec));
76 printf("factorial(%" PRIu64 ") = %" PRId64 "\n",
77 input_val,
78 simulator.ReadXRegister(0));
79
80 return 0;
81 }
82 #else
83 // Without the simulator there is nothing to test.
main(void)84 int main(void) { return 0; }
85 #endif // VIXL_INCLUDE_SIMULATOR_AARCH64
86 #endif // TEST_EXAMPLES
87