Arduino - Optimising existing method for iterating through an array

Question

Is there a more efficient and cleaner way of doing what the following method is already doing?

void sendCode(prog_uint16_t inArray[], int nLimit) {

  unsigned int arr[nLimit];
  unsigned int c;
  int index = 0;

  while ((c = pgm_read_word(inArray++))) {
    arr[index] = c;
    index++;
  }

  for (int i = 0; i < nLimit; i=i+2) {
    delayMicroseconds(arr[i]);
    pulseIR(arr[i+1]);
  }

}

This is in reference to an existing question I had answered.

Arduino - Iterate through C array efficiently

Matthew Murdoch · Accepted Answer · 2012-01-24 16:53:43Z

2

There should be no need for the local arr array variable. If you do away with that you should both save temporary stack space and speed up execution by removing the need to copy data.

void sendCode(const prog_uint16_t inArray[]) {
  unsigned int c;

  for (int i = 0; c = pgm_read_word(inArray++); i++) {
    if (i % 2 == 0) { // Even array elements are delays
      delayMicroseconds(c);
    } else {          // Odd array elements are pulse lengths
      pulseIR(c);
    }
  }
}

This code assumes that the maximum integer stored in an int is greater than the maximum size of inArray (this seems reasonable as the original code essentially makes the same assumption by using an int for nLimit).

edited Jan 24, 2012 at 16:53

answered Jan 23, 2012 at 20:30

Matthew Murdoch

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1 Comment

gotnull Over a year ago

Thanks for that, looks like it's working fine. It saves space as I can remove the nLimit that's passed to each method. The only modification I had to make was that sendCode() should take const prog_uint16_t inArray[].

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