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26
27#include "examples.h"
28
29#define BUF_SIZE (4096)
30#define __ masm->
31
32void GenerateFactorial(MacroAssembler* masm) {
33  // uint64_t factorial(uint64_t n)
34  // Argument location:
35  //   n -> x0
36
37  Label loop, end;
38
39  __ Mov(x1, x0);
40  __ Mov(x0, 1);     // Use x0 as the accumulator.
41
42  __ Cbz(x1, &end);  // Nothing to do if the input is null.
43
44  __ Bind(&loop);
45  __ Mul(x0, x0, x1);
46  __ Sub(x1, x1, 1);
47  __ Cbnz(x1, &loop);
48
49  __ Bind(&end);
50  // The return value is in x0.
51  __ Ret();
52}
53
54
55#ifndef TEST_EXAMPLES
56int main(void) {
57  // Create and initialize the assembler and the simulator.
58  byte assm_buf[BUF_SIZE];
59  MacroAssembler masm(assm_buf, BUF_SIZE);
60  Decoder decoder;
61  Simulator simulator(&decoder);
62
63  // Generate the code for the example function.
64  Label factorial;
65  masm.Bind(&factorial);
66  GenerateFactorial(&masm);
67  masm.FinalizeCode();
68
69  // Run the example function.
70  uint64_t input_val = 16;
71  simulator.set_xreg(0, input_val);
72  simulator.RunFrom(factorial.target());
73  printf("factorial(%ld) = %ld\n", input_val, simulator.xreg(0));
74
75  return 0;
76}
77#endif
78