1 // Copyright 2014, VIXL authors
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are met:
6 //
7 // * Redistributions of source code must retain the above copyright notice,
8 // this list of conditions and the following disclaimer.
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
13 // used to endorse or promote products derived from this software without
14 // specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
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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
GenerateFactorial(MacroAssembler * masm)31 void 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
main(void)56 int 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.
main(void)79 int main(void) { return 0; }
80 #endif // VIXL_INCLUDE_SIMULATOR_AARCH64
81 #endif // TEST_EXAMPLES
82