kernel/microkernel/k_semaphore.c

/*
 * Copyright (c) 1997-2010, 2012-2015 Wind River Systems, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @file
 *
 * @brief Semaphore kernel services.
 */

#include <microkernel.h>
#include <toolchain.h>
#include <sections.h>

#include <micro_private.h>

/**
 *
 * @brief Update value of semaphore structure
 *
 * This routine updates the value of the semaphore by 0 or more units, then
 * gives the semaphore to any waiting tasks that can now be satisfied.
 *
 * @param n      Number of additional times semaphore has been given.
 * @param sema   Semaphore structure to update.
 *
 * @return N/A
 */
void _k_sem_struct_value_update(int n, struct _k_sem_struct *S)
{
	struct k_args *A, *X, *Y;

#ifdef CONFIG_OBJECT_MONITOR
	S->count += n;
#endif

	S->level += n;
	A = S->waiters;
	Y = NULL;
	while (A && S->level) {
		X = A->next;

#ifdef CONFIG_SYS_CLOCK_EXISTS
		if (A->Comm == _K_SVC_SEM_WAIT_REQUEST
		    || A->Comm == _K_SVC_SEM_WAIT_REPLY_TIMEOUT)
#else
		if (A->Comm == _K_SVC_SEM_WAIT_REQUEST)
#endif
		{
			S->level--;
			if (Y) {
				Y->next = X;
			} else {
				S->waiters = X;
			}
#ifdef CONFIG_SYS_CLOCK_EXISTS
			if (A->Time.timer) {
				_k_timeout_cancel(A);
				A->Comm = _K_SVC_SEM_WAIT_REPLY;
			} else {
#endif
				A->Time.rcode = RC_OK;
				_k_state_bit_reset(A->Ctxt.task, TF_SEMA);
#ifdef CONFIG_SYS_CLOCK_EXISTS
			}
#endif
		} else if (A->Comm == _K_SVC_SEM_GROUP_WAIT_REQUEST) {
			S->level--;
			A->Comm = _K_SVC_SEM_GROUP_WAIT_READY;
			GETARGS(Y);
			*Y = *A;
			SENDARGS(Y);
			Y = A;
		} else {
			Y = A;
		}
		A = X;
	}
}

void _k_sem_group_wait(struct k_args *R)
{
	struct k_args *A = R->Ctxt.args;

	FREEARGS(R);
	if (--(A->args.s1.nsem) == 0) {
		_k_state_bit_reset(A->Ctxt.task, TF_LIST);
	}
}

void _k_sem_group_wait_cancel(struct k_args *A)
{
	struct _k_sem_struct *S = (struct _k_sem_struct *)A->args.s1.sema;
	struct k_args *X = S->waiters;
	struct k_args *Y = NULL;

	while (X && (X->priority <= A->priority)) {
		if (X->Ctxt.args == A->Ctxt.args) {
			if (Y) {
				Y->next = X->next;
			} else {
				S->waiters = X->next;
			}
			if (X->Comm == _K_SVC_SEM_GROUP_WAIT_REQUEST
			    || X->Comm == _K_SVC_SEM_GROUP_WAIT_READY) {
				if (X->Comm == _K_SVC_SEM_GROUP_WAIT_READY) {
					/* obtain struct k_args of waiting task */

					struct k_args *waitTaskArgs = X->Ctxt.args;

/*
 * Determine if the wait cancellation request is being
 * processed after the state of the 'waiters' packet state
 * has been updated to _K_SVC_SEM_GROUP_WAIT_READY, but before
 * the _K_SVC_SEM_GROUP_WAIT_READY packet has been processed.
 * This will occur if a _K_SVC_SEM_GROUP_WAIT_TIMEOUT
 * timer expiry occurs between the update of the packet state
 * and the processing of the WAITMRDY packet.
 */
					if (unlikely(waitTaskArgs->args.s1.sema ==
						ENDLIST)) {
						waitTaskArgs->args.s1.sema = A->args.s1.sema;
					} else {
						_k_sem_struct_value_update(1, S);
					}
				}

				_k_sem_group_wait(X);
			} else {
				FREEARGS(X); /* ERROR */
			}
			FREEARGS(A);
			return;
		}

		Y = X;
		X = X->next;
	}
	A->next = X;
	if (Y) {
		Y->next = A;
	} else {
		S->waiters = A;
	}
}

void _k_sem_group_wait_accept(struct k_args *A)
{
	struct _k_sem_struct *S = (struct _k_sem_struct *)A->args.s1.sema;
	struct k_args *X = S->waiters;
	struct k_args *Y = NULL;

	while (X && (X->priority <= A->priority)) {
		if (X->Ctxt.args == A->Ctxt.args) {
			if (Y) {
				Y->next = X->next;
			} else {
				S->waiters = X->next;
			}
			if (X->Comm == _K_SVC_SEM_GROUP_WAIT_READY) {
				_k_sem_group_wait(X);
			} else {
				FREEARGS(X); /* ERROR */
			}
			FREEARGS(A);
			return;
		}

		Y = X;
		X = X->next;
	}
	/* ERROR */
}

void _k_sem_group_wait_timeout(struct k_args *A)
{
	ksem_t *L;

#ifdef CONFIG_SYS_CLOCK_EXISTS
	if (A->Time.timer) {
		FREETIMER(A->Time.timer);
	}
#endif

	L = A->args.s1.list;
	while (*L != ENDLIST) {
		struct k_args *R;

		GETARGS(R);
		R->priority = A->priority;
		R->Comm =
			((*L == A->args.s1.sema) ?
			    _K_SVC_SEM_GROUP_WAIT_ACCEPT : _K_SVC_SEM_GROUP_WAIT_CANCEL);
		R->Ctxt.args = A;
		R->args.s1.sema = *L++;
		SENDARGS(R);
	}
}

void _k_sem_group_ready(struct k_args *R)
{
	struct k_args *A = R->Ctxt.args;

	if (A->args.s1.sema == ENDLIST) {
		A->args.s1.sema = R->args.s1.sema;
		A->Comm = _K_SVC_SEM_GROUP_WAIT_TIMEOUT;
#ifdef CONFIG_SYS_CLOCK_EXISTS
		if (A->Time.timer) {
			_k_timeout_cancel(A);
		} else
#endif
			_k_sem_group_wait_timeout(A);
	}
	FREEARGS(R);
}

void _k_sem_wait_reply(struct k_args *A)
{
#ifdef CONFIG_SYS_CLOCK_EXISTS
	if (A->Time.timer) {
		FREETIMER(A->Time.timer);
	}
	if (A->Comm == _K_SVC_SEM_WAIT_REPLY_TIMEOUT) {
		REMOVE_ELM(A);
		A->Time.rcode = RC_TIME;
	} else
#endif
		A->Time.rcode = RC_OK;
	_k_state_bit_reset(A->Ctxt.task, TF_SEMA);
}

void _k_sem_wait_reply_timeout(struct k_args *A)
{
	_k_sem_wait_reply(A);
}

void _k_sem_group_wait_request(struct k_args *A)
{
	struct _k_sem_struct *S = (struct _k_sem_struct *)A->args.s1.sema;
	struct k_args *X = S->waiters;
	struct k_args *Y = NULL;

	while (X && (X->priority <= A->priority)) {
		if (X->Ctxt.args == A->Ctxt.args) {
			if (Y) {
				Y->next = X->next;
			} else {
				S->waiters = X->next;
			}
			if (X->Comm == _K_SVC_SEM_GROUP_WAIT_CANCEL) {
				_k_sem_group_wait(X);
			} else {
				FREEARGS(X); /* ERROR */
			}
			FREEARGS(A);
			return;
		}

		Y = X;
		X = X->next;
	}
	A->next = X;
	if (Y) {
		Y->next = A;
	} else {
		S->waiters = A;
	}
	_k_sem_struct_value_update(0, S);
}

void _k_sem_group_wait_any(struct k_args *A)
{
	ksem_t *L;

	L = A->args.s1.list;
	A->args.s1.sema = ENDLIST;
	A->args.s1.nsem = 0;

	if (*L == ENDLIST) {
		return;
	}

	while (*L != ENDLIST) {
		struct k_args *R;

		GETARGS(R);
		R->priority = _k_current_task->priority;
		R->Comm = _K_SVC_SEM_GROUP_WAIT_REQUEST;
		R->Ctxt.args = A;
		R->args.s1.sema = *L++;
		SENDARGS(R);
		(A->args.s1.nsem)++;
	}

	A->Ctxt.task = _k_current_task;
	_k_state_bit_set(_k_current_task, TF_LIST);

#ifdef CONFIG_SYS_CLOCK_EXISTS
	if (A->Time.ticks != TICKS_NONE) {
		if (A->Time.ticks == TICKS_UNLIMITED) {
			A->Time.timer = NULL;
		} else {
			A->Comm = _K_SVC_SEM_GROUP_WAIT_TIMEOUT;
			_k_timeout_alloc(A);
		}
	}
#endif
}

void _k_sem_wait_request(struct k_args *A)
{
	struct _k_sem_struct *S;
	uint32_t Sid;

	Sid = A->args.s1.sema;
	S = (struct _k_sem_struct *)Sid;

	if (S->level) {
		S->level--;
		A->Time.rcode = RC_OK;
	} else if (A->Time.ticks != TICKS_NONE) {
		A->Ctxt.task = _k_current_task;
		A->priority = _k_current_task->priority;
		_k_state_bit_set(_k_current_task, TF_SEMA);
		INSERT_ELM(S->waiters, A);
#ifdef CONFIG_SYS_CLOCK_EXISTS
		if (A->Time.ticks == TICKS_UNLIMITED) {
			A->Time.timer = NULL;
		} else {
			A->Comm = _K_SVC_SEM_WAIT_REPLY_TIMEOUT;
			_k_timeout_alloc(A);
		}
#endif
		return;
	} else {
		A->Time.rcode = RC_FAIL;
	}
}

int task_sem_take(ksem_t sema, int32_t timeout)
{
	struct k_args A;

	A.Comm = _K_SVC_SEM_WAIT_REQUEST;
	A.Time.ticks = timeout;
	A.args.s1.sema = sema;
	KERNEL_ENTRY(&A);
	return A.Time.rcode;
}

ksem_t task_sem_group_take(ksemg_t group, int32_t timeout)
{
	struct k_args A;

	A.Comm = _K_SVC_SEM_GROUP_WAIT_ANY;
	A.priority = _k_current_task->priority;
	A.Time.ticks = timeout;
	A.args.s1.list = group;
	KERNEL_ENTRY(&A);
	return A.args.s1.sema;
}

void _k_sem_signal(struct k_args *A)
{
	uint32_t Sid = A->args.s1.sema;
	struct _k_sem_struct *S = (struct _k_sem_struct *)Sid;

	_k_sem_struct_value_update(1, S);
}

void _k_sem_group_signal(struct k_args *A)
{
	ksem_t *L = A->args.s1.list;

	while ((A->args.s1.sema = *L++) != ENDLIST) {
		_k_sem_signal(A);
	}
}

void task_sem_give(ksem_t sema)
{
	struct k_args A;

	A.Comm = _K_SVC_SEM_SIGNAL;
	A.args.s1.sema = sema;
	KERNEL_ENTRY(&A);
}

void task_sem_group_give(ksemg_t group)
{
	struct k_args A;

	A.Comm = _K_SVC_SEM_GROUP_SIGNAL;
	A.args.s1.list = group;
	KERNEL_ENTRY(&A);
}

FUNC_ALIAS(isr_sem_give, fiber_sem_give, void);

void isr_sem_give(ksem_t sema)
{
	nano_isr_stack_push(&_k_command_stack,
						(uint32_t)sema | KERNEL_CMD_SEMAPHORE_TYPE);
}

void _k_sem_reset(struct k_args *A)
{
	uint32_t Sid = A->args.s1.sema;
	struct _k_sem_struct *S = (struct _k_sem_struct *)Sid;

	S->level = 0;
}

void _k_sem_group_reset(struct k_args *A)
{
	ksem_t *L = A->args.s1.list;

	while ((A->args.s1.sema = *L++) != ENDLIST) {
		_k_sem_reset(A);
	}
}

void task_sem_reset(ksem_t sema)
{
	struct k_args A;

	A.Comm = _K_SVC_SEM_RESET;
	A.args.s1.sema = sema;
	KERNEL_ENTRY(&A);
}

void task_sem_group_reset(ksemg_t group)
{
	struct k_args A;

	A.Comm = _K_SVC_SEM_GROUP_RESET;
	A.args.s1.list = group;
	KERNEL_ENTRY(&A);
}

void _k_sem_inquiry(struct k_args *A)
{
	struct _k_sem_struct *S;
	uint32_t Sid;

	Sid = A->args.s1.sema;
	S = (struct _k_sem_struct *)Sid;
	A->Time.rcode = S->level;
}

int task_sem_count_get(ksem_t sema)
{
	struct k_args A;

	A.Comm = _K_SVC_SEM_INQUIRY;
	A.args.s1.sema = sema;
	KERNEL_ENTRY(&A);
	return A.Time.rcode;
}