Home | History | Annotate | Download | only in examples 
      1 // Copyright 2014, ARM Limited
      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 BUF_SIZE (4096)
     30 #define __ masm->
     31 
     32 void 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
     56 #ifdef VIXL_INCLUDE_SIMULATOR
     57 int main(void) {
     58   // Create and initialize the assembler and the simulator.
     59   byte assm_buf[BUF_SIZE];
     60   MacroAssembler masm(assm_buf, BUF_SIZE);
     61   Decoder decoder;
     62   Simulator simulator(&decoder);
     63 
     64   // Generate the code for the example function.
     65   Label factorial;
     66   masm.Bind(&factorial);
     67   GenerateFactorial(&masm);
     68   masm.FinalizeCode();
     69 
     70   // Run the example function.
     71   uint64_t input_val = 16;
     72   simulator.set_xreg(0, input_val);
     73   simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&factorial));
     74   printf("factorial(%ld) = %ld\n", input_val, simulator.xreg(0));
     75 
     76   return 0;
     77 }
     78 #else
     79 // Without the simulator there is nothing to test.
     80 int main(void) { return 0; }
     81 #endif  // VIXL_INCLUDE_SIMULATOR
     82 #endif  // TEST_EXAMPLES
     83