kernel/msg_q.c

/*
 * Copyright (c) 2016 Wind River Systems, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @file
 * @brief Message queues.
 */


#include <kernel.h>
#include <kernel_structs.h>
#include <debug/object_tracing_common.h>
#include <toolchain.h>
#include <sections.h>
#include <string.h>
#include <wait_q.h>
#include <misc/dlist.h>
#include <init.h>

extern struct k_msgq _k_msgq_list_start[];
extern struct k_msgq _k_msgq_list_end[];

#ifdef CONFIG_OBJECT_TRACING

struct k_msgq *_trace_list_k_msgq;

/*
 * Complete initialization of statically defined message queues.
 */
static int init_msgq_module(struct device *dev)
{
	ARG_UNUSED(dev);

	struct k_msgq *msgq;

	for (msgq = _k_msgq_list_start; msgq < _k_msgq_list_end; msgq++) {
		SYS_TRACING_OBJ_INIT(k_msgq, msgq);
	}
	return 0;
}

SYS_INIT(init_msgq_module, PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_OBJECTS);

#endif /* CONFIG_OBJECT_TRACING */

void k_msgq_init(struct k_msgq *q, char *buffer,
		 size_t msg_size, u32_t max_msgs)
{
	q->msg_size = msg_size;
	q->max_msgs = max_msgs;
	q->buffer_start = buffer;
	q->buffer_end = buffer + (max_msgs * msg_size);
	q->read_ptr = buffer;
	q->write_ptr = buffer;
	q->used_msgs = 0;
	sys_dlist_init(&q->wait_q);
	SYS_TRACING_OBJ_INIT(k_msgq, q);
}

int k_msgq_put(struct k_msgq *q, void *data, s32_t timeout)
{
	__ASSERT(!_is_in_isr() || timeout == K_NO_WAIT, "");

	unsigned int key = irq_lock();
	struct k_thread *pending_thread;
	int result;

	if (q->used_msgs < q->max_msgs) {
		/* message queue isn't full */
		pending_thread = _unpend_first_thread(&q->wait_q);
		if (pending_thread) {
			/* give message to waiting thread */
			memcpy(pending_thread->base.swap_data, data,
			       q->msg_size);
			/* wake up waiting thread */
			_set_thread_return_value(pending_thread, 0);
			_abort_thread_timeout(pending_thread);
			_ready_thread(pending_thread);
			if (!_is_in_isr() && _must_switch_threads()) {
				_Swap(key);
				return 0;
			}
		} else {
			/* put message in queue */
			memcpy(q->write_ptr, data, q->msg_size);
			q->write_ptr += q->msg_size;
			if (q->write_ptr == q->buffer_end) {
				q->write_ptr = q->buffer_start;
			}
			q->used_msgs++;
		}
		result = 0;
	} else if (timeout == K_NO_WAIT) {
		/* don't wait for message space to become available */
		result = -ENOMSG;
	} else {
		/* wait for put message success, failure, or timeout */
		_pend_current_thread(&q->wait_q, timeout);
		_current->base.swap_data = data;
		return _Swap(key);
	}

	irq_unlock(key);

	return result;
}

int k_msgq_get(struct k_msgq *q, void *data, s32_t timeout)
{
	__ASSERT(!_is_in_isr() || timeout == K_NO_WAIT, "");

	unsigned int key = irq_lock();
	struct k_thread *pending_thread;
	int result;

	if (q->used_msgs > 0) {
		/* take first available message from queue */
		memcpy(data, q->read_ptr, q->msg_size);
		q->read_ptr += q->msg_size;
		if (q->read_ptr == q->buffer_end) {
			q->read_ptr = q->buffer_start;
		}
		q->used_msgs--;

		/* handle first thread waiting to write (if any) */
		pending_thread = _unpend_first_thread(&q->wait_q);
		if (pending_thread) {
			/* add thread's message to queue */
			memcpy(q->write_ptr, pending_thread->base.swap_data,
			       q->msg_size);
			q->write_ptr += q->msg_size;
			if (q->write_ptr == q->buffer_end) {
				q->write_ptr = q->buffer_start;
			}
			q->used_msgs++;

			/* wake up waiting thread */
			_set_thread_return_value(pending_thread, 0);
			_abort_thread_timeout(pending_thread);
			_ready_thread(pending_thread);
			if (!_is_in_isr() && _must_switch_threads()) {
				_Swap(key);
				return 0;
			}
		}
		result = 0;
	} else if (timeout == K_NO_WAIT) {
		/* don't wait for a message to become available */
		result = -ENOMSG;
	} else {
		/* wait for get message success or timeout */
		_pend_current_thread(&q->wait_q, timeout);
		_current->base.swap_data = data;
		return _Swap(key);
	}

	irq_unlock(key);

	return result;
}

void k_msgq_purge(struct k_msgq *q)
{
	unsigned int key = irq_lock();
	struct k_thread *pending_thread;

	/* wake up any threads that are waiting to write */
	while ((pending_thread = _unpend_first_thread(&q->wait_q)) != NULL) {
		_set_thread_return_value(pending_thread, -ENOMSG);
		_abort_thread_timeout(pending_thread);
		_ready_thread(pending_thread);
	}

	q->used_msgs = 0;
	q->read_ptr = q->write_ptr;

	_reschedule_threads(key);
}