1// Copyright 2013, ARM Limited
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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 BUF_SIZE (4096)
30#define __ masm->
31
32void GenerateSwapInt32(MacroAssembler* masm) {
33  {
34    // In this scope the register x2 will be used by the macro-assembler
35    // as the stack pointer (via peek, poke, push, etc).
36    const Register old_stack_pointer = __ StackPointer();
37    __ Mov(x2, __ StackPointer());
38    __ SetStackPointer(x2);
39
40    // This call to Claim is not 16-byte aligned and would have failed
41    // if the current stack pointer was sp.
42    __ Claim(8);
43
44    __ Poke(w0, 0);
45    __ Poke(w1, 4);
46    __ Peek(w1, 0);
47    __ Peek(w0, 4);
48
49    __ Drop(8);
50
51    // Even if we didn't use the system stack pointer, sp might have been
52    // modified because the ABI forbids access to memory below the stack
53    // pointer.
54    __ Mov(old_stack_pointer, __ StackPointer());
55    __ SetStackPointer(old_stack_pointer);
56  }
57
58  // The stack pointer has now been switched back to sp.
59  __ Ret();
60}
61
62
63#ifndef TEST_EXAMPLES
64int main(void) {
65  // Create and initialize the assembler and the simulator.
66  byte assm_buf[BUF_SIZE];
67  MacroAssembler masm(assm_buf, BUF_SIZE);
68  Decoder decoder;
69  Simulator simulator(&decoder);
70
71  // Generate the code for the example function.
72  Label swap_int32;
73  masm.Bind(&swap_int32);
74  GenerateSwapInt32(&masm);
75  masm.FinalizeCode();
76
77  // Run the example function.
78  simulator.set_wreg(0, 0x11111111);
79  simulator.set_wreg(1, 0x22222222);
80
81  printf("Before swap_int32:\n"
82         "x0 = 0x%" PRIx32 "\n"
83         "x1 = 0x%" PRIx32 "\n",
84         simulator.wreg(0), simulator.wreg(1));
85
86  simulator.RunFrom(swap_int32.target());
87
88  printf("After swap_int32:\n"
89         "x0 = 0x%" PRIx32 "\n"
90         "x1 = 0x%" PRIx32 "\n",
91         simulator.wreg(0), simulator.wreg(1));
92
93  return 0;
94}
95#endif
96