qmk_firmware/tmk_core/protocol/midi/bytequeue/bytequeue.c

// this is a single reader [maybe multiple writer?] byte queue
// Copyright 2008 Alex Norman
// writen by Alex Norman
//
// This file is part of avr-bytequeue.
//
// avr-bytequeue is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
//(at your option) any later version.
//
// avr-bytequeue is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with avr-bytequeue.  If not, see <http://www.gnu.org/licenses/>.

#include "bytequeue.h"
#include "interrupt_setting.h"

void bytequeue_init(byteQueue_t* queue, uint8_t* dataArray, byteQueueIndex_t arrayLen) {
    queue->length = arrayLen;
    queue->data   = dataArray;
    queue->start = queue->end = 0;
}

bool bytequeue_enqueue(byteQueue_t* queue, uint8_t item) {
    interrupt_setting_t setting = store_and_clear_interrupt();
    // full
    if (((queue->end + 1) % queue->length) == queue->start) {
        restore_interrupt_setting(setting);
        return false;
    } else {
        queue->data[queue->end] = item;
        queue->end              = (queue->end + 1) % queue->length;
        restore_interrupt_setting(setting);
        return true;
    }
}

byteQueueIndex_t bytequeue_length(byteQueue_t* queue) {
    byteQueueIndex_t    len;
    interrupt_setting_t setting = store_and_clear_interrupt();
    if (queue->end >= queue->start)
        len = queue->end - queue->start;
    else
        len = (queue->length - queue->start) + queue->end;
    restore_interrupt_setting(setting);
    return len;
}

// we don't need to avoid interrupts if there is only one reader
uint8_t bytequeue_get(byteQueue_t* queue, byteQueueIndex_t index) {
    return queue->data[(queue->start + index) % queue->length];
}

// we just update the start index to remove elements
void bytequeue_remove(byteQueue_t* queue, byteQueueIndex_t numToRemove) {
    interrupt_setting_t setting = store_and_clear_interrupt();
    queue->start                = (queue->start + numToRemove) % queue->length;
    restore_interrupt_setting(setting);
}