Speed and size improvement in Print::printFloat()

[bblanchon]

Avoid using the overload of print() for signed integer since a negative value is not allowed here.
This results in a smaller (unless print(int) is used somewhere else in the program) and faster code because the overload for unsigned integer is simpler.

[bblanchon]

Please merge this PR 🙏
It just change two words in one file.
It'll take 2 seconds to review, literally.

[proppy]

friendly @cmaglie ping

[sandeepmistry]

I just tested this with the following test sketch on an Uno:

void setup() {
  Serial.begin(9600);
  while(!Serial);

  uint32_t start = millis();
  for (int i = 0; i < 100; i++) {
    Serial.println(PI);
  }
  uint32_t end = millis();

  Serial.println(end - start);
}
void loop() {
}

Here are some metrics:

• Without patch:
  • Sketch size 3,824 bytes
  • Execution time 556 ms
• With patch:
• Sketch size 3,644 bytes
• Execution time 556 ms

[sandeepmistry]

@bblanchon thanks!

I've also ported this change to the SAM (05be7ce) and SAMD (arduino/ArduinoCore-samd@94d6f56) cores.

More notes on size reduction for test sketch above:

• Due
  • Before: 25,212 bytes
  • After: 25,068 bytes
• MKR1000:
  • Before: 16,256 bytes
  • After: 16,088 bytes

Execution times were negligible.