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      1 // Copyright 2013, ARM Limited
      2 // All rights reserved.
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      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 int 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