readme.md

A simple generic FIFO queue in C for microcontrollers

Originally based on Microcontrollers: Interrupt-safe ring buffers. However, I have since modified the code such that it is not safe for interrupts, but it is more portable without any assumptions.

features

• works with elements of any type
• overhead of 3 * sizeof(size_t)
• no dynamic allocation
• simple api init, push, pop

how to use

1. Include queue.h.
2. Create an instance of the queue type and functions by passing a name, type, and size to the macro QUEUE.
3. Create an instance of the type, struct queue_* where * is the name you passed to QUEUE.
4. Initialize the instance with queue_*_init.
5. Push and pop with queue_*_push and queue_*_pop.

example

#include "queue.h"

//define a queue called queue_example 
//with elements of type int and size 8
QUEUE(example, int, 8);

//create an instance of queue_example
volatile struct queue_example queue;

//analog to digital converter isr
void adc_isr(void) {
    int value = get_adc_value();
    if (queue_push(&queue, &value) == 0) {
        //push successful, no action required
    } else {
        //not enough room in queue, handle appropriately here
    }
}

int main(void) {
    //initialize the instance
    queue_example_init(&queue);
    while (1) {
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { //atomic section for atmel avr
            int value;
            if (queue_example_pop(&queue, &value) == 0) {
                //one element removed and stored in value
                printf("%d\r\n", value);
            } else {
                //queue empty
                continue;
            }
        }
    }
}