Where could I find the "Serial.find()" source code?

Question

As written in the title, could you tell me where to find the source code of the function "Serial.find()"?

I haven' t installed the Arduino IDE, so I'm glad if you could me link a web resource, or if you directly copy the source code here .

Thanks for your time.

Answer 1

It is part of the Stream class which the Serial class inherits from.

• https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/cores/arduino/Stream.cpp#L93

It just calls findUntil() which is a little further down in the same file:

• https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/cores/arduino/Stream.cpp#L114

That itself calls findMulti() which is where all the magic happens:

• https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/cores/arduino/Stream.cpp#L256

---

int Stream::findMulti( struct Stream::MultiTarget *targets, int tCount) {
 // any zero length target string automatically matches and would make
 // a mess of the rest of the algorithm.
 for (struct MultiTarget *t = targets; t < targets+tCount; ++t) {
 if (t->len <= 0)
 return t - targets;
 }
 while (1) {
 int c = timedRead();
 if (c < 0)
 return -1;
 for (struct MultiTarget *t = targets; t < targets+tCount; ++t) {
 // the simple case is if we match, deal with that first.
 if (c == t->str[t->index]) {
 if (++t->index == t->len)
 return t - targets;
 else
 continue;
 }
 // if not we need to walk back and see if we could have matched further
 // down the stream (ie '1112' doesn't match the first position in '11112'
 // but it will match the second position so we can't just reset the current
 // index to 0 when we find a mismatch.
 if (t->index == 0)
 continue;
 int origIndex = t->index;
 do {
 --t->index;
 // first check if current char works against the new current index
 if (c != t->str[t->index])
 continue;
 // if it's the only char then we're good, nothing more to check
 if (t->index == 0) {
 t->index++;
 break;
 }
 // otherwise we need to check the rest of the found string
 int diff = origIndex - t->index;
 size_t i;
 for (i = 0; i < t->index; ++i) {
 if (t->str[i] != t->str[i + diff])
 break;
 }
 // if we successfully got through the previous loop then our current
 // index is good.
 if (i == t->index) {
 t->index++;
 break;
 }
 // otherwise we just try the next index
 } while (t->index);
 }
 }
 // unreachable
 return -1;
}