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
11 // and/or other materials provided with the distribution.
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
17 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26
27 #include "examples.h"
28
29 using namespace vixl;
30 using namespace vixl::aarch64;
31
32 #define __ masm->
33
GenerateFactorial(MacroAssembler * masm)34 void GenerateFactorial(MacroAssembler* masm) {
35 // uint64_t factorial(uint64_t n)
36 // Argument location:
37 // n -> x0
38
39 Label loop, end;
40
41 __ Mov(x1, x0);
42 __ Mov(x0, 1); // Use x0 as the accumulator.
43
44 __ Cbz(x1, &end); // Nothing to do if the input is null.
45
46 __ Bind(&loop);
47 __ Mul(x0, x0, x1);
48 __ Sub(x1, x1, 1);
49 __ Cbnz(x1, &loop);
50
51 __ Bind(&end);
52 // The return value is in x0.
53 __ Ret();
54 }
55
56
57 #ifndef TEST_EXAMPLES
58 #ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
main(void)59 int main(void) {
60 MacroAssembler masm;
61 Decoder decoder;
62 Simulator simulator(&decoder);
63
64 // Generate the code for the example function.
65 Label factorial;
66 masm.Bind(&factorial);
67 GenerateFactorial(&masm);
68 masm.FinalizeCode();
69
70 // Run the example function.
71 uint64_t input_val = 16;
72 simulator.WriteXRegister(0, input_val);
73 simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&factorial));
74 printf("factorial(%" PRIu64 ") = %" PRId64 "\n",
75 input_val,
76 simulator.ReadXRegister(0));
77
78 return 0;
79 }
80 #else
81 // Without the simulator there is nothing to test.
main(void)82 int main(void) { return 0; }
83 #endif // VIXL_INCLUDE_SIMULATOR_AARCH64
84 #endif // TEST_EXAMPLES
85