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26
27#include "examples.h"
28
29#define BUF_SIZE (4096)
30#define __ masm->
31
32void GenerateFactorialRec(MacroAssembler* masm) {
33  // uint64_t factorial_rec(uint64_t n)
34  // Argument location:
35  //   n -> x0
36
37  Label entry, input_is_zero;
38
39  __ Bind(&entry);
40  // Check for the stopping condition: the input number is null.
41  __ Cbz(x0, &input_is_zero);
42
43  __ Mov(x1, x0);
44  __ Sub(x0, x0, 1);
45  __ Push(x1, lr);
46  __ Bl(&entry);    // Recursive call factorial_rec(n - 1).
47  __ Pop(lr, x1);
48  __ Mul(x0, x0, x1);
49  __ Ret();
50
51  __ Bind(&input_is_zero);
52  __ Mov(x0, 1);
53  __ Ret();
54}
55
56
57#ifndef TEST_EXAMPLES
58int main(void) {
59  // Create and initialize the assembler and the simulator.
60  byte assm_buf[BUF_SIZE];
61  MacroAssembler masm(assm_buf, BUF_SIZE);
62  Decoder decoder;
63  Simulator simulator(&decoder);
64
65  // Generate the code for the example function.
66  Label factorial_rec;
67  masm.Bind(&factorial_rec);
68  GenerateFactorialRec(&masm);
69  masm.FinalizeCode();
70
71  // Run the example function.
72  uint64_t input_val = 16;
73  simulator.set_xreg(0, input_val);
74  simulator.RunFrom(factorial_rec.target());
75  printf("factorial(%ld) = %ld\n", input_val, simulator.xreg(0));
76
77  return 0;
78}
79#endif
80