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https://github.com/sdesalas/arduino-queue.h
Generic C++ circular queue for Arduino embedded projects.
https://github.com/sdesalas/arduino-queue.h
arduino c-plus-plus cpp generic library queue
Last synced: 11 days ago
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Generic C++ circular queue for Arduino embedded projects.
- Host: GitHub
- URL: https://github.com/sdesalas/arduino-queue.h
- Owner: sdesalas
- Created: 2016-09-20T02:11:02.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2021-09-02T17:41:33.000Z (about 3 years ago)
- Last Synced: 2024-10-20T07:33:44.506Z (19 days ago)
- Topics: arduino, c-plus-plus, cpp, generic, library, queue
- Language: C++
- Size: 26.4 KB
- Stars: 71
- Watchers: 5
- Forks: 31
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
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README
[](https://app.travis-ci.com/sdesalas/Arduino-Queue.h)
# Queue.h
[Generic](https://en.wikipedia.org/wiki/Generic_programming) C++ circular queue for Arduino embedded projects.
## Why?
Because I need one, and I need it to be generic. I dabble with arduino [robotics](https://github.com/sdesalas/robotics) a bit and this is the cornerstone for getting the most out of the microcontroller [loop](https://www.arduino.cc/en/reference/loop) - ie dont delay, just stick stuff in a queue and process it when you can.
## Constructor
### `Queue queue = Queue(int maxlength = 256);`
Creates a queue of a generic type `T` with a maximum queue size. If `maxlength` is not defined it will default to 256.
NOTE: If the queue grows to `maxlength` items (and you dont take them out) any additional items added *will drop out of the queue*.
Please bear this in mind when defining maxlength so it is a reasonable balance between RAM usage and functional usefulness.
**Examples**
```cpp
Queue queue = Queue(1000); // Queue of max 1000 bytes
Queue queue = Queue(); // Queue of max 256 int
Queue queue = Queue(260); // Queue of max 260 chars
Queue queue = Queue(10); // Queue of max 10 'Point', where 'Point' is a struct
Queue queue = Queue(); // Queue of max 256 'String', where 'String' is a class
```
## Methods
### `queue.push(T item);`
Adds a generic item (of `T` type) at the back of the queue.
**Example**
```cpp
Queue queue = Queue();
byte a = 255;
byte b = 0;
queue.push(a);
queue.push(b);
```
### `T item = queue.pop();`
Gets a generic item (of `T` type) from the front of the queue.
### `T item = queue.peek();`
Same as .pop() but keeps the item in the queue.
**Example**
```cpp
Queue queue = Queue();
byte a = 255;
byte b = 0;
queue.push(a);
queue.push(b);
assert(a == queue.pop()); // true
assert(b == queue.peek()); // true
assert(b == queue.pop()); // true
```
### `int front = queue.front();`
Gets the current position in the front of the queue. Used for testing queue logic.
**Example**
```cpp
Queue queue = Queue();
byte a = 255;
byte b = 0;
queue.push(a);
assert(1 == queue.front()); // true
queue.push(b);
assert(2 == queue.front()); // true
```
### `int back = queue.back();`
Gets the current position at the back of the queue. Used for testing queue logic.
**Example**
```cpp
Queue queue = Queue();
byte a = 255;
byte b = 0;
queue.push(a);
assert(0 == queue.back()); // true
assert(1 == queue.front()); // true
queue.pop();
assert(1 == queue.back()); // true
assert(1 == queue.front()); // true
```
### `queue.clear();`
Removes all items from the queue.
**Example**
```cpp
Queue queue = Queue();
queue.push(1);
queue.push(2);
queue.clear();
queue.push(3);
assert(3 == queue.pop()); // true
```
## All Together now
The following example is testable using 'Serial Monitor' over USB connection from Arduino IDE.
Copy the file [`Queue.h`](./Queue.h) in the same folder as your `*.ino` code file.
Make sure you set the `baud rate` to 115200 and `No new line`.
```cpp
#include "Queue.h"
Queue queue = Queue(5); // Max 5 chars!
void setup() {
Serial.begin(115200);
}
void loop() {
while(Serial.available()) {
queue.push(Serial.read());
}
Serial.print(millis() / 1000);
Serial.print(": ");
int count = queue.count();
if (count > 0) {
Serial.print("Found ");
Serial.print(count);
Serial.print(" items.. '");
Serial.print(queue.pop());
Serial.print("' is the oldest. We are ");
Serial.print(queue.front());
Serial.print(" in front and ");
Serial.print(queue.back());
Serial.print(" in back. Next is.. '");
Serial.print(queue.peek());
Serial.println("'.");
} else {
Serial.println("Nothing to process...");
}
delay(2000);
}
```