====== FIFO() ======

''FIFO()'' outputs the first stored 16-bit data first.

{{:en-us_commands:reference:fifo.svg?900|FIFO command operation flow}}

''bool FIFO(uint8_t fifo_id, bool IN, bool OUT, uint16_t input, uint16_t &output, uint8_t size, bool reset = false)''

===== Commands =====

^ Command ^ Arguments ^ Return Value ^ Operation ^
| ''FIFO(fifo_id, IN, OUT, input, output, size, reset)'' | ''uint8_t fifo_id'' — Buffer ID\\ ''bool IN'' — Store input on the rising edge\\ ''bool OUT'' — Output on the rising edge\\ ''uint16_t input'' — Word to store\\ ''uint16_t &output'' — Reference variable receiving the output\\ ''uint8_t size'' — Buffer size\\ ''bool reset = false'' — Reset the buffer | ''bool'' | Outputs the first stored 16-bit data first. |


===== Example =====

Send ''i'' twice from Serial Monitor to store 10 and 20. Send ''o'' twice to read 10 and then 20. Send ''r'' to empty the buffer.

<code cpp>
uint16_t nextValue = 10;
uint16_t removedValue = 0;

void setup() {
  Serial.begin(115200);
  Serial.println(F("i: store, o: take, r: reset"));
}

void loop() {
  if (!Serial.available()) return;
  const char key = Serial.read();
  const bool store = key == 'i';
  const bool take = key == 'o';
  const bool reset = key == 'r';
  if (!store && !take && !reset) return;

  const bool ok = FIFO(0, store, take, nextValue, removedValue, 4, reset);  // Store or retrieve a value on the rising edge of IN or OUT.
  FIFO(0, false, false, 0, removedValue, 4);  // Return IN and OUT to OFF so the next key creates a new rising edge.

  if (reset) {
    nextValue = 10;
    Serial.println(F("buffer cleared"));
  } else if (!ok) {
    Serial.println(F("buffer full or empty"));
  } else if (store) {
    Serial.print(F("stored: "));
    Serial.println(nextValue);
    nextValue += 10;
  } else {
    Serial.print(F("taken: "));
    Serial.println(removedValue);
  }
}
</code>

Pushing to a full buffer or popping from an empty one fails.

===== Precautions =====

''IN'', ''OUT'', ''CU'' and ''CD'' act on rising edges. Use a unique ''id'' for each counter or buffer, and keep ''size'' to the required minimum.

===== Built-in Commands in the Same Category =====

  * [[:en-us_commands:reference:filo|FILO() View detailed description]]

[[:en-us_commands:builtin|← Built-in Command List]]