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      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 //
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      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
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     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
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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 
     32 void 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
     58 #ifdef USE_SIMULATOR
     59 int main(void) {
     60   // Create and initialize the assembler and the simulator.
     61   byte assm_buf[BUF_SIZE];
     62   MacroAssembler masm(assm_buf, BUF_SIZE);
     63   Decoder decoder;
     64   Simulator simulator(&decoder);
     65 
     66   // Generate the code for the example function.
     67   Label factorial_rec;
     68   masm.Bind(&factorial_rec);
     69   GenerateFactorialRec(&masm);
     70   masm.FinalizeCode();
     71 
     72   // Run the example function.
     73   uint64_t input_val = 16;
     74   simulator.set_xreg(0, input_val);
     75   simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&factorial_rec));
     76   printf("factorial(%ld) = %ld\n", input_val, simulator.xreg(0));
     77 
     78   return 0;
     79 }
     80 #else
     81 // Without the simulator there is nothing to test.
     82 int main(void) { return 0; }
     83 #endif  // USE_SIMULATOR
     84 #endif  // TEST_EXAMPLES
     85