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/*
* Copyright 2017 Mike Ryan
*
* This file is part of Project Ubertooth and is released under the
* terms of the GPL. Refer to COPYING for more information.
*/
#include "queue.h"
// queue implementation is based heavily on Koopman's "Better Embedded
// Systems Software" section 20.3.3.1 pg 209
void queue_init(queue_t *f) {
f->head = 0;
f->tail = 0;
}
// insert
int queue_insert(queue_t *f, void *x) {
unsigned newtail;
// access next free element
newtail = f->tail + 1;
// wrap around to beginning if needed
if (newtail >= FIFOSIZE) { newtail = 0; }
// if head and tail are equal, queue is full
if (newtail == f->head) { return 0; }
// write data before updating pointer
f->data[newtail] = x;
f->tail = newtail;
return 1;
}
// TODO remove
int queue_remove(queue_t *f, void **x) {
unsigned newhead;
if (f->head == f->tail) { return 0; }
newhead = f->head + 1;
if (newhead >= FIFOSIZE) { newhead = 0; }
*x = f->data[newhead];
f->head = newhead;
return 1;
}
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