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