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 #define __ masm->
30
GenerateFactorialRec(MacroAssembler * masm)31 void GenerateFactorialRec(MacroAssembler* masm) {
32 // uint64_t factorial_rec(uint64_t n)
33 // Argument location:
34 // n -> x0
35
36 Label entry, input_is_zero;
37
38 __ Bind(&entry);
39 // Check for the stopping condition: the input number is null.
40 __ Cbz(x0, &input_is_zero);
41
42 __ Mov(x1, x0);
43 __ Sub(x0, x0, 1);
44 __ Push(x1, lr);
45 __ Bl(&entry); // Recursive call factorial_rec(n - 1).
46 __ Pop(lr, x1);
47 __ Mul(x0, x0, x1);
48 __ Ret();
49
50 __ Bind(&input_is_zero);
51 __ Mov(x0, 1);
52 __ Ret();
53 }
54
55
56 #ifndef TEST_EXAMPLES
57 #ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
main(void)58 int main(void) {
59 MacroAssembler masm;
60 Decoder decoder;
61 Simulator simulator(&decoder);
62
63 // Generate the code for the example function.
64 Label factorial_rec;
65 masm.Bind(&factorial_rec);
66 GenerateFactorialRec(&masm);
67 masm.FinalizeCode();
68
69 // Run the example function.
70 uint64_t input_val = 16;
71 simulator.WriteXRegister(0, input_val);
72 simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&factorial_rec));
73 printf("factorial(%" PRIu64 ") = %" PRId64 "\n",
74 input_val,
75 simulator.ReadXRegister(0));
76
77 return 0;
78 }
79 #else
80 // Without the simulator there is nothing to test.
main(void)81 int main(void) { return 0; }
82 #endif // VIXL_INCLUDE_SIMULATOR_AARCH64
83 #endif // TEST_EXAMPLES
84