xref: /external/vixl/examples/sum-array.cc

// Copyright 2013, ARM Limited
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//
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#include "examples.h"

#define ARRAY_SIZE(Array) (sizeof(Array) / sizeof((Array)[0]))
#define BUF_SIZE (4096)
#define __ masm->

void GenerateSumArray(MacroAssembler* masm) {
  // uint32_t sum_array(uint8_t* array, uint32_t size)
  //  Argument locations:
  //    array (pointer) -> x0
  //    size            -> x1

  Label loop, end;

  __ Mov(x2, x0);
  __ Mov(w0, 0);

  // There's nothing to do if the array is empty.
  __ Cbz(w1, &end);

  // Go through the array and sum the elements.
  __ Bind(&loop);

  __ Ldrb(w3, MemOperand(x2, 1, PostIndex));  // w3 = *(x2++)
  __ Add(w0, w0, w3);

  __ Sub(w1, w1, 1);
  __ Cbnz(w1, &loop);

  __ Bind(&end);
  __ Ret();
}


#ifndef TEST_EXAMPLES
int main(void) {
  // Create and initialize the assembler and the simulator.
  byte assm_buf[BUF_SIZE];
  MacroAssembler masm(assm_buf, BUF_SIZE);
  Decoder decoder;
  Simulator simulator(&decoder);

  // Generate the code for the example function.
  Label sum_array;
  masm.Bind(&sum_array);
  GenerateSumArray(&masm);
  masm.FinalizeCode();

  // Run the example function.
  uint8_t data[] = { 2, 45, 63, 7, 245, 38 };
  uintptr_t data_addr = reinterpret_cast<uintptr_t>(data);
  simulator.set_xreg(0, data_addr);
  simulator.set_xreg(1, ARRAY_SIZE(data));
  simulator.RunFrom(sum_array.target());

  unsigned int i;
  for (i = 0; i < ARRAY_SIZE(data) - 1; ++i) {
    printf("%d + ", data[i]);
  }
  printf("%d = %d\n", data[i], simulator.wreg(0));

  return 0;
}
#endif