src/include/lwip/sys.h - third_party/lwip - Git at Google

 /**
  * @file
  * OS abstraction layer
  */

 /*
  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
  *    this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright notice,
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  * OF SUCH DAMAGE.
  *
  * This file is part of the lwIP TCP/IP stack.
  *
  * Author: Adam Dunkels <adam@sics.se>
  */

 #ifndef LWIP_HDR_SYS_H
 #define LWIP_HDR_SYS_H

 #include "lwip/opt.h"

 #ifdef __cplusplus
 extern "C" {
 #endif

 #if NO_SYS

 /* For a totally minimal and standalone system, we provide null
    definitions of the sys_ functions. */
 typedef u8_t sys_sem_t;
 typedef u8_t sys_mutex_t;
 typedef u8_t sys_mbox_t;

 #define sys_sem_new(s, c) ERR_OK
 #define sys_sem_signal(s)
 #define sys_sem_wait(s)
 #define sys_arch_sem_wait(s,t)
 #define sys_sem_free(s)
 #define sys_sem_valid(s) 0
 #define sys_sem_valid_val(s) 0
 #define sys_sem_set_invalid(s)
 #define sys_sem_set_invalid_val(s)
 #define sys_mutex_new(mu) ERR_OK
 #define sys_mutex_lock(mu)
 #define sys_mutex_unlock(mu)
 #define sys_mutex_free(mu)
 #define sys_mutex_valid(mu) 0
 #define sys_mutex_set_invalid(mu)
 #define sys_mbox_new(m, s) ERR_OK
 #define sys_mbox_fetch(m,d)
 #define sys_mbox_tryfetch(m,d)
 #define sys_mbox_post(m,d)
 #define sys_mbox_trypost(m,d)
 #define sys_mbox_free(m)
 #define sys_mbox_valid(m)
 #define sys_mbox_valid_val(m)
 #define sys_mbox_set_invalid(m)
 #define sys_mbox_set_invalid_val(m)

 #define sys_thread_new(n,t,a,s,p)

 #define sys_msleep(t)

 #else /* NO_SYS */

 /** Return code for timeouts from sys_arch_mbox_fetch and sys_arch_sem_wait */
 #define SYS_ARCH_TIMEOUT 0xffffffffUL

 /** sys_mbox_tryfetch() returns SYS_MBOX_EMPTY if appropriate.
  * For now we use the same magic value, but we allow this to change in future.
  */
 #define SYS_MBOX_EMPTY SYS_ARCH_TIMEOUT

 #include "lwip/err.h"
 #include "arch/sys_arch.h"

 /** Function prototype for thread functions */
 typedef void (*lwip_thread_fn)(void *arg);

 /* Function prototypes for functions to be implemented by platform ports
    (in sys_arch.c) */

 /* Mutex functions: */

 /** Define LWIP_COMPAT_MUTEX if the port has no mutexes and binary semaphores
     should be used instead */
 #ifndef LWIP_COMPAT_MUTEX
 #define LWIP_COMPAT_MUTEX 0
 #endif

 #if LWIP_COMPAT_MUTEX
 /* for old ports that don't have mutexes: define them to binary semaphores */
 #define sys_mutex_t                   sys_sem_t
 #define sys_mutex_new(mutex)          sys_sem_new(mutex, 1)
 #define sys_mutex_lock(mutex)         sys_sem_wait(mutex)
 #define sys_mutex_unlock(mutex)       sys_sem_signal(mutex)
 #define sys_mutex_free(mutex)         sys_sem_free(mutex)
 #define sys_mutex_valid(mutex)        sys_sem_valid(mutex)
 #define sys_mutex_set_invalid(mutex)  sys_sem_set_invalid(mutex)

 #else /* LWIP_COMPAT_MUTEX */

 /**
  * @ingroup sys_mutex
  * Create a new mutex.
  * Note that mutexes are expected to not be taken recursively by the lwIP code,
  * so both implementation types (recursive or non-recursive) should work.
  * @param mutex pointer to the mutex to create
  * @return ERR_OK if successful, another err_t otherwise
  */
 err_t sys_mutex_new(sys_mutex_t *mutex);
 /**
  * @ingroup sys_mutex
  * Lock a mutex
  * @param mutex the mutex to lock
  */
 void sys_mutex_lock(sys_mutex_t *mutex);
 /**
  * @ingroup sys_mutex
  * Unlock a mutex
  * @param mutex the mutex to unlock
  */
 void sys_mutex_unlock(sys_mutex_t *mutex);
 /**
  * @ingroup sys_mutex
  * Delete a semaphore
  * @param mutex the mutex to delete
  */
 void sys_mutex_free(sys_mutex_t *mutex);
 #ifndef sys_mutex_valid
 /**
  * @ingroup sys_mutex
  * Check if a mutex is valid/allocated: return 1 for valid, 0 for invalid
  */
 int sys_mutex_valid(sys_mutex_t *mutex);
 #endif
 #ifndef sys_mutex_set_invalid
 /**
  * @ingroup sys_mutex
  * Set a mutex invalid so that sys_mutex_valid returns 0
  */
 void sys_mutex_set_invalid(sys_mutex_t *mutex);
 #endif
 #endif /* LWIP_COMPAT_MUTEX */

 /* Semaphore functions: */

 /**
  * @ingroup sys_sem
  * Create a new semaphore
  * @param sem pointer to the semaphore to create
  * @param count initial count of the semaphore
  * @return ERR_OK if successful, another err_t otherwise
  */
 err_t sys_sem_new(sys_sem_t *sem, u8_t count);
 /**
  * @ingroup sys_sem
  * Signals a semaphore
  * @param sem the semaphore to signal
  */
 void sys_sem_signal(sys_sem_t *sem);
 /**
  * @ingroup sys_sem
  * Wait for a semaphore for the specified timeout
  * @param sem the semaphore to wait for
  * @param timeout timeout in milliseconds to wait (0 = wait forever)
  * @return time (in milliseconds) waited for the semaphore
  *         or SYS_ARCH_TIMEOUT on timeout
  */
 u32_t sys_arch_sem_wait(sys_sem_t *sem, u32_t timeout);
 /**
  * @ingroup sys_sem
  * Delete a semaphore
  * @param sem semaphore to delete
  */
 void sys_sem_free(sys_sem_t *sem);
 /** Wait for a semaphore - forever/no timeout */
 #define sys_sem_wait(sem)                  sys_arch_sem_wait(sem, 0)
 #ifndef sys_sem_valid
 /**
  * @ingroup sys_sem
  * Check if a semaphore is valid/allocated: return 1 for valid, 0 for invalid
  */
 int sys_sem_valid(sys_sem_t *sem);
 #endif
 #ifndef sys_sem_set_invalid
 /**
  * @ingroup sys_sem
  * Set a semaphore invalid so that sys_sem_valid returns 0
  */
 void sys_sem_set_invalid(sys_sem_t *sem);
 #endif
 #ifndef sys_sem_valid_val
 /**
  * Same as sys_sem_valid() but taking a value, not a pointer
  */
 #define sys_sem_valid_val(sem)       sys_sem_valid(&(sem))
 #endif
 #ifndef sys_sem_set_invalid_val
 /**
  * Same as sys_sem_set_invalid() but taking a value, not a pointer
  */
 #define sys_sem_set_invalid_val(sem) sys_sem_set_invalid(&(sem))
 #endif

 #ifndef sys_msleep
 /**
  * @ingroup sys_misc
  * Sleep for specified number of ms
  */
 void sys_msleep(u32_t ms); /* only has a (close to) 1 ms resolution. */
 #endif

 /* Mailbox functions. */

 /**
  * @ingroup sys_mbox
  * Create a new mbox of specified size
  * @param mbox pointer to the mbox to create
  * @param size (minimum) number of messages in this mbox
  * @return ERR_OK if successful, another err_t otherwise
  */
 err_t sys_mbox_new(sys_mbox_t *mbox, int size);
 /**
  * @ingroup sys_mbox
  * Post a message to an mbox - may not fail
  * -> blocks if full, only used from tasks not from ISR
  * @param mbox mbox to posts the message
  * @param msg message to post (ATTENTION: can be NULL)
  */
 void sys_mbox_post(sys_mbox_t *mbox, void *msg);
 /**
  * @ingroup sys_mbox
  * Try to post a message to an mbox - may fail if full or ISR
  * @param mbox mbox to posts the message
  * @param msg message to post (ATTENTION: can be NULL)
  */
 err_t sys_mbox_trypost(sys_mbox_t *mbox, void *msg);
 /**
  * @ingroup sys_mbox
  * Wait for a new message to arrive in the mbox
  * @param mbox mbox to get a message from
  * @param msg pointer where the message is stored
  * @param timeout maximum time (in milliseconds) to wait for a message (0 = wait forever)
  * @return time (in milliseconds) waited for a message, may be 0 if not waited
            or SYS_ARCH_TIMEOUT on timeout
  *         The returned time has to be accurate to prevent timer jitter!
  */
 u32_t sys_arch_mbox_fetch(sys_mbox_t *mbox, void **msg, u32_t timeout);
 /* Allow port to override with a macro, e.g. special timeout for sys_arch_mbox_fetch() */
 #ifndef sys_arch_mbox_tryfetch
 /**
  * @ingroup sys_mbox
  * Wait for a new message to arrive in the mbox
  * @param mbox mbox to get a message from
  * @param msg pointer where the message is stored
  * @return 0 (milliseconds) if a message has been received
  *         or SYS_MBOX_EMPTY if the mailbox is empty
  */
 u32_t sys_arch_mbox_tryfetch(sys_mbox_t *mbox, void **msg);
 #endif
 /**
  * For now, we map straight to sys_arch implementation.
  */
 #define sys_mbox_tryfetch(mbox, msg) sys_arch_mbox_tryfetch(mbox, msg)
 /**
  * @ingroup sys_mbox
  * Delete an mbox
  * @param mbox mbox to delete
  */
 void sys_mbox_free(sys_mbox_t *mbox);
 #define sys_mbox_fetch(mbox, msg) sys_arch_mbox_fetch(mbox, msg, 0)
 #ifndef sys_mbox_valid
 /**
  * @ingroup sys_mbox
  * Check if an mbox is valid/allocated: return 1 for valid, 0 for invalid
  */
 int sys_mbox_valid(sys_mbox_t *mbox);
 #endif
 #ifndef sys_mbox_set_invalid
 /**
  * @ingroup sys_mbox
  * Set an mbox invalid so that sys_mbox_valid returns 0
  */
 void sys_mbox_set_invalid(sys_mbox_t *mbox);
 #endif
 #ifndef sys_mbox_valid_val
 /**
  * Same as sys_mbox_valid() but taking a value, not a pointer
  */
 #define sys_mbox_valid_val(mbox)       sys_mbox_valid(&(mbox))
 #endif
 #ifndef sys_mbox_set_invalid_val
 /**
  * Same as sys_mbox_set_invalid() but taking a value, not a pointer
  */
 #define sys_mbox_set_invalid_val(mbox) sys_mbox_set_invalid(&(mbox))
 #endif


 /**
  * @ingroup sys_misc
  * The only thread function:
  * Creates a new thread
  * ATTENTION: although this function returns a value, it MUST NOT FAIL (ports have to assert this!)
  * @param name human-readable name for the thread (used for debugging purposes)
  * @param thread thread-function
  * @param arg parameter passed to 'thread'
  * @param stacksize stack size in bytes for the new thread (may be ignored by ports)
  * @param prio priority of the new thread (may be ignored by ports) */
 sys_thread_t sys_thread_new(const char *name, lwip_thread_fn thread, void *arg, int stacksize, int prio);

 #endif /* NO_SYS */

 /* sys_init() must be called before anything else. */
 void sys_init(void);

 #ifndef sys_jiffies
 /**
  * Ticks/jiffies since power up.
  */
 u32_t sys_jiffies(void);
 #endif

 /**
  * @ingroup sys_time
  * Returns the current time in milliseconds,
  * may be the same as sys_jiffies or at least based on it.
  */
 u32_t sys_now(void);

 /* Critical Region Protection */
 /* These functions must be implemented in the sys_arch.c file.
    In some implementations they can provide a more light-weight protection
    mechanism than using semaphores. Otherwise semaphores can be used for
    implementation */
 #ifndef SYS_ARCH_PROTECT
 /** SYS_LIGHTWEIGHT_PROT
  * define SYS_LIGHTWEIGHT_PROT in lwipopts.h if you want inter-task protection
  * for certain critical regions during buffer allocation, deallocation and memory
  * allocation and deallocation.
  */
 #if SYS_LIGHTWEIGHT_PROT

 /**
  * @ingroup sys_prot
  * SYS_ARCH_DECL_PROTECT
  * declare a protection variable. This macro will default to defining a variable of
  * type sys_prot_t. If a particular port needs a different implementation, then
  * this macro may be defined in sys_arch.h.
  */
 #define SYS_ARCH_DECL_PROTECT(lev) sys_prot_t lev
 /**
  * @ingroup sys_prot
  * SYS_ARCH_PROTECT
  * Perform a "fast" protect. This could be implemented by
  * disabling interrupts for an embedded system or by using a semaphore or
  * mutex. The implementation should allow calling SYS_ARCH_PROTECT when
  * already protected. The old protection level is returned in the variable
  * "lev". This macro will default to calling the sys_arch_protect() function
  * which should be implemented in sys_arch.c. If a particular port needs a
  * different implementation, then this macro may be defined in sys_arch.h
  */
 #define SYS_ARCH_PROTECT(lev) lev = sys_arch_protect()
 /**
  * @ingroup sys_prot
  * SYS_ARCH_UNPROTECT
  * Perform a "fast" set of the protection level to "lev". This could be
  * implemented by setting the interrupt level to "lev" within the MACRO or by
  * using a semaphore or mutex.  This macro will default to calling the
  * sys_arch_unprotect() function which should be implemented in
  * sys_arch.c. If a particular port needs a different implementation, then
  * this macro may be defined in sys_arch.h
  */
 #define SYS_ARCH_UNPROTECT(lev) sys_arch_unprotect(lev)
 sys_prot_t sys_arch_protect(void);
 void sys_arch_unprotect(sys_prot_t pval);

 #else

 #define SYS_ARCH_DECL_PROTECT(lev)
 #define SYS_ARCH_PROTECT(lev)
 #define SYS_ARCH_UNPROTECT(lev)

 #endif /* SYS_LIGHTWEIGHT_PROT */

 #endif /* SYS_ARCH_PROTECT */

 /*
  * Macros to set/get and increase/decrease variables in a thread-safe way.
  * Use these for accessing variable that are used from more than one thread.
  */

 #ifndef SYS_ARCH_INC
 #define SYS_ARCH_INC(var, val) do { \
                                 SYS_ARCH_DECL_PROTECT(old_level); \
                                 SYS_ARCH_PROTECT(old_level); \
                                 var += val; \
                                 SYS_ARCH_UNPROTECT(old_level); \
                               } while(0)
 #endif /* SYS_ARCH_INC */

 #ifndef SYS_ARCH_DEC
 #define SYS_ARCH_DEC(var, val) do { \
                                 SYS_ARCH_DECL_PROTECT(old_level); \
                                 SYS_ARCH_PROTECT(old_level); \
                                 var -= val; \
                                 SYS_ARCH_UNPROTECT(old_level); \
                               } while(0)
 #endif /* SYS_ARCH_DEC */

 #ifndef SYS_ARCH_GET
 #define SYS_ARCH_GET(var, ret) do { \
                                 SYS_ARCH_DECL_PROTECT(old_level); \
                                 SYS_ARCH_PROTECT(old_level); \
                                 ret = var; \
                                 SYS_ARCH_UNPROTECT(old_level); \
                               } while(0)
 #endif /* SYS_ARCH_GET */

 #ifndef SYS_ARCH_SET
 #define SYS_ARCH_SET(var, val) do { \
                                 SYS_ARCH_DECL_PROTECT(old_level); \
                                 SYS_ARCH_PROTECT(old_level); \
                                 var = val; \
                                 SYS_ARCH_UNPROTECT(old_level); \
                               } while(0)
 #endif /* SYS_ARCH_SET */


 #ifdef __cplusplus
 }
 #endif

 #endif /* LWIP_HDR_SYS_H */
	/**
	* @file
	* OS abstraction layer
	*/

	/*
	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without modification,
	* are permitted provided that the following conditions are met:
	*
	* 1. Redistributions of source code must retain the above copyright notice,
	* this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright notice,
	* this list of conditions and the following disclaimer in the documentation
	* and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
	* OF SUCH DAMAGE.
	*
	* This file is part of the lwIP TCP/IP stack.
	*
	* Author: Adam Dunkels <adam@sics.se>
	*/

	#ifndef LWIP_HDR_SYS_H
	#define LWIP_HDR_SYS_H

	#include "lwip/opt.h"

	#ifdef __cplusplus
	extern "C" {
	#endif

	#if NO_SYS

	/* For a totally minimal and standalone system, we provide null
	definitions of the sys_ functions. */
	typedef u8_t sys_sem_t;
	typedef u8_t sys_mutex_t;
	typedef u8_t sys_mbox_t;

	#define sys_sem_new(s, c) ERR_OK
	#define sys_sem_signal(s)
	#define sys_sem_wait(s)
	#define sys_arch_sem_wait(s,t)
	#define sys_sem_free(s)
	#define sys_sem_valid(s) 0
	#define sys_sem_valid_val(s) 0
	#define sys_sem_set_invalid(s)
	#define sys_sem_set_invalid_val(s)
	#define sys_mutex_new(mu) ERR_OK
	#define sys_mutex_lock(mu)
	#define sys_mutex_unlock(mu)
	#define sys_mutex_free(mu)
	#define sys_mutex_valid(mu) 0
	#define sys_mutex_set_invalid(mu)
	#define sys_mbox_new(m, s) ERR_OK
	#define sys_mbox_fetch(m,d)
	#define sys_mbox_tryfetch(m,d)
	#define sys_mbox_post(m,d)
	#define sys_mbox_trypost(m,d)
	#define sys_mbox_free(m)
	#define sys_mbox_valid(m)
	#define sys_mbox_valid_val(m)
	#define sys_mbox_set_invalid(m)
	#define sys_mbox_set_invalid_val(m)

	#define sys_thread_new(n,t,a,s,p)

	#define sys_msleep(t)

	#else /* NO_SYS */

	/** Return code for timeouts from sys_arch_mbox_fetch and sys_arch_sem_wait */
	#define SYS_ARCH_TIMEOUT 0xffffffffUL

	/** sys_mbox_tryfetch() returns SYS_MBOX_EMPTY if appropriate.
	* For now we use the same magic value, but we allow this to change in future.
	*/
	#define SYS_MBOX_EMPTY SYS_ARCH_TIMEOUT

	#include "lwip/err.h"
	#include "arch/sys_arch.h"

	/** Function prototype for thread functions */
	typedef void (lwip_thread_fn)(void arg);

	/* Function prototypes for functions to be implemented by platform ports
	(in sys_arch.c) */

	/* Mutex functions: */

	/** Define LWIP_COMPAT_MUTEX if the port has no mutexes and binary semaphores
	should be used instead */
	#ifndef LWIP_COMPAT_MUTEX
	#define LWIP_COMPAT_MUTEX 0
	#endif

	#if LWIP_COMPAT_MUTEX
	/* for old ports that don't have mutexes: define them to binary semaphores */
	#define sys_mutex_t sys_sem_t
	#define sys_mutex_new(mutex) sys_sem_new(mutex, 1)
	#define sys_mutex_lock(mutex) sys_sem_wait(mutex)
	#define sys_mutex_unlock(mutex) sys_sem_signal(mutex)
	#define sys_mutex_free(mutex) sys_sem_free(mutex)
	#define sys_mutex_valid(mutex) sys_sem_valid(mutex)
	#define sys_mutex_set_invalid(mutex) sys_sem_set_invalid(mutex)

	#else /* LWIP_COMPAT_MUTEX */

	/**
	* @ingroup sys_mutex
	* Create a new mutex.
	* Note that mutexes are expected to not be taken recursively by the lwIP code,
	* so both implementation types (recursive or non-recursive) should work.
	* @param mutex pointer to the mutex to create
	* @return ERR_OK if successful, another err_t otherwise
	*/
	err_t sys_mutex_new(sys_mutex_t *mutex);
	/**
	* @ingroup sys_mutex
	* Lock a mutex
	* @param mutex the mutex to lock
	*/
	void sys_mutex_lock(sys_mutex_t *mutex);
	/**
	* @ingroup sys_mutex
	* Unlock a mutex
	* @param mutex the mutex to unlock
	*/
	void sys_mutex_unlock(sys_mutex_t *mutex);
	/**
	* @ingroup sys_mutex
	* Delete a semaphore
	* @param mutex the mutex to delete
	*/
	void sys_mutex_free(sys_mutex_t *mutex);
	#ifndef sys_mutex_valid
	/**
	* @ingroup sys_mutex
	* Check if a mutex is valid/allocated: return 1 for valid, 0 for invalid
	*/
	int sys_mutex_valid(sys_mutex_t *mutex);
	#endif
	#ifndef sys_mutex_set_invalid
	/**
	* @ingroup sys_mutex
	* Set a mutex invalid so that sys_mutex_valid returns 0
	*/
	void sys_mutex_set_invalid(sys_mutex_t *mutex);
	#endif
	#endif /* LWIP_COMPAT_MUTEX */

	/* Semaphore functions: */

	/**
	* @ingroup sys_sem
	* Create a new semaphore
	* @param sem pointer to the semaphore to create
	* @param count initial count of the semaphore
	* @return ERR_OK if successful, another err_t otherwise
	*/
	err_t sys_sem_new(sys_sem_t *sem, u8_t count);
	/**
	* @ingroup sys_sem
	* Signals a semaphore
	* @param sem the semaphore to signal
	*/
	void sys_sem_signal(sys_sem_t *sem);
	/**
	* @ingroup sys_sem
	* Wait for a semaphore for the specified timeout
	* @param sem the semaphore to wait for
	* @param timeout timeout in milliseconds to wait (0 = wait forever)
	* @return time (in milliseconds) waited for the semaphore
	* or SYS_ARCH_TIMEOUT on timeout
	*/
	u32_t sys_arch_sem_wait(sys_sem_t *sem, u32_t timeout);
	/**
	* @ingroup sys_sem
	* Delete a semaphore
	* @param sem semaphore to delete
	*/
	void sys_sem_free(sys_sem_t *sem);
	/** Wait for a semaphore - forever/no timeout */
	#define sys_sem_wait(sem) sys_arch_sem_wait(sem, 0)
	#ifndef sys_sem_valid
	/**
	* @ingroup sys_sem
	* Check if a semaphore is valid/allocated: return 1 for valid, 0 for invalid
	*/
	int sys_sem_valid(sys_sem_t *sem);
	#endif
	#ifndef sys_sem_set_invalid
	/**
	* @ingroup sys_sem
	* Set a semaphore invalid so that sys_sem_valid returns 0
	*/
	void sys_sem_set_invalid(sys_sem_t *sem);
	#endif
	#ifndef sys_sem_valid_val
	/**
	* Same as sys_sem_valid() but taking a value, not a pointer
	*/
	#define sys_sem_valid_val(sem) sys_sem_valid(&(sem))
	#endif
	#ifndef sys_sem_set_invalid_val
	/**
	* Same as sys_sem_set_invalid() but taking a value, not a pointer
	*/
	#define sys_sem_set_invalid_val(sem) sys_sem_set_invalid(&(sem))
	#endif

	#ifndef sys_msleep
	/**
	* @ingroup sys_misc
	* Sleep for specified number of ms
	*/
	void sys_msleep(u32_t ms); /* only has a (close to) 1 ms resolution. */
	#endif

	/* Mailbox functions. */

	/**
	* @ingroup sys_mbox
	* Create a new mbox of specified size
	* @param mbox pointer to the mbox to create
	* @param size (minimum) number of messages in this mbox
	* @return ERR_OK if successful, another err_t otherwise
	*/
	err_t sys_mbox_new(sys_mbox_t *mbox, int size);
	/**
	* @ingroup sys_mbox
	* Post a message to an mbox - may not fail
	* -> blocks if full, only used from tasks not from ISR
	* @param mbox mbox to posts the message
	* @param msg message to post (ATTENTION: can be NULL)
	*/
	void sys_mbox_post(sys_mbox_t mbox, void msg);
	/**
	* @ingroup sys_mbox
	* Try to post a message to an mbox - may fail if full or ISR
	* @param mbox mbox to posts the message
	* @param msg message to post (ATTENTION: can be NULL)
	*/
	err_t sys_mbox_trypost(sys_mbox_t mbox, void msg);
	/**
	* @ingroup sys_mbox
	* Wait for a new message to arrive in the mbox
	* @param mbox mbox to get a message from
	* @param msg pointer where the message is stored
	* @param timeout maximum time (in milliseconds) to wait for a message (0 = wait forever)
	* @return time (in milliseconds) waited for a message, may be 0 if not waited
	or SYS_ARCH_TIMEOUT on timeout
	* The returned time has to be accurate to prevent timer jitter!
	*/
	u32_t sys_arch_mbox_fetch(sys_mbox_t mbox, void *msg, u32_t timeout);
	/* Allow port to override with a macro, e.g. special timeout for sys_arch_mbox_fetch() */
	#ifndef sys_arch_mbox_tryfetch
	/**
	* @ingroup sys_mbox
	* Wait for a new message to arrive in the mbox
	* @param mbox mbox to get a message from
	* @param msg pointer where the message is stored
	* @return 0 (milliseconds) if a message has been received
	* or SYS_MBOX_EMPTY if the mailbox is empty
	*/
	u32_t sys_arch_mbox_tryfetch(sys_mbox_t mbox, void *msg);
	#endif
	/**
	* For now, we map straight to sys_arch implementation.
	*/
	#define sys_mbox_tryfetch(mbox, msg) sys_arch_mbox_tryfetch(mbox, msg)
	/**
	* @ingroup sys_mbox
	* Delete an mbox
	* @param mbox mbox to delete
	*/
	void sys_mbox_free(sys_mbox_t *mbox);
	#define sys_mbox_fetch(mbox, msg) sys_arch_mbox_fetch(mbox, msg, 0)
	#ifndef sys_mbox_valid
	/**
	* @ingroup sys_mbox
	* Check if an mbox is valid/allocated: return 1 for valid, 0 for invalid
	*/
	int sys_mbox_valid(sys_mbox_t *mbox);
	#endif
	#ifndef sys_mbox_set_invalid
	/**
	* @ingroup sys_mbox
	* Set an mbox invalid so that sys_mbox_valid returns 0
	*/
	void sys_mbox_set_invalid(sys_mbox_t *mbox);
	#endif
	#ifndef sys_mbox_valid_val
	/**
	* Same as sys_mbox_valid() but taking a value, not a pointer
	*/
	#define sys_mbox_valid_val(mbox) sys_mbox_valid(&(mbox))
	#endif
	#ifndef sys_mbox_set_invalid_val
	/**
	* Same as sys_mbox_set_invalid() but taking a value, not a pointer
	*/
	#define sys_mbox_set_invalid_val(mbox) sys_mbox_set_invalid(&(mbox))
	#endif


	/**
	* @ingroup sys_misc
	* The only thread function:
	* Creates a new thread
	* ATTENTION: although this function returns a value, it MUST NOT FAIL (ports have to assert this!)
	* @param name human-readable name for the thread (used for debugging purposes)
	* @param thread thread-function
	* @param arg parameter passed to 'thread'
	* @param stacksize stack size in bytes for the new thread (may be ignored by ports)
	* @param prio priority of the new thread (may be ignored by ports) */
	sys_thread_t sys_thread_new(const char name, lwip_thread_fn thread, void arg, int stacksize, int prio);

	#endif /* NO_SYS */

	/* sys_init() must be called before anything else. */
	void sys_init(void);

	#ifndef sys_jiffies
	/**
	* Ticks/jiffies since power up.
	*/
	u32_t sys_jiffies(void);
	#endif

	/**
	* @ingroup sys_time
	* Returns the current time in milliseconds,
	* may be the same as sys_jiffies or at least based on it.
	*/
	u32_t sys_now(void);

	/* Critical Region Protection */
	/* These functions must be implemented in the sys_arch.c file.
	In some implementations they can provide a more light-weight protection
	mechanism than using semaphores. Otherwise semaphores can be used for
	implementation */
	#ifndef SYS_ARCH_PROTECT
	/** SYS_LIGHTWEIGHT_PROT
	* define SYS_LIGHTWEIGHT_PROT in lwipopts.h if you want inter-task protection
	* for certain critical regions during buffer allocation, deallocation and memory
	* allocation and deallocation.
	*/
	#if SYS_LIGHTWEIGHT_PROT

	/**
	* @ingroup sys_prot
	* SYS_ARCH_DECL_PROTECT
	* declare a protection variable. This macro will default to defining a variable of
	* type sys_prot_t. If a particular port needs a different implementation, then
	* this macro may be defined in sys_arch.h.
	*/
	#define SYS_ARCH_DECL_PROTECT(lev) sys_prot_t lev
	/**
	* @ingroup sys_prot
	* SYS_ARCH_PROTECT
	* Perform a "fast" protect. This could be implemented by
	* disabling interrupts for an embedded system or by using a semaphore or
	* mutex. The implementation should allow calling SYS_ARCH_PROTECT when
	* already protected. The old protection level is returned in the variable
	* "lev". This macro will default to calling the sys_arch_protect() function
	* which should be implemented in sys_arch.c. If a particular port needs a
	* different implementation, then this macro may be defined in sys_arch.h
	*/
	#define SYS_ARCH_PROTECT(lev) lev = sys_arch_protect()
	/**
	* @ingroup sys_prot
	* SYS_ARCH_UNPROTECT
	* Perform a "fast" set of the protection level to "lev". This could be
	* implemented by setting the interrupt level to "lev" within the MACRO or by
	* using a semaphore or mutex. This macro will default to calling the
	* sys_arch_unprotect() function which should be implemented in
	* sys_arch.c. If a particular port needs a different implementation, then
	* this macro may be defined in sys_arch.h
	*/
	#define SYS_ARCH_UNPROTECT(lev) sys_arch_unprotect(lev)
	sys_prot_t sys_arch_protect(void);
	void sys_arch_unprotect(sys_prot_t pval);

	#else

	#define SYS_ARCH_DECL_PROTECT(lev)
	#define SYS_ARCH_PROTECT(lev)
	#define SYS_ARCH_UNPROTECT(lev)

	#endif /* SYS_LIGHTWEIGHT_PROT */

	#endif /* SYS_ARCH_PROTECT */

	/*
	* Macros to set/get and increase/decrease variables in a thread-safe way.
	* Use these for accessing variable that are used from more than one thread.
	*/

	#ifndef SYS_ARCH_INC
	#define SYS_ARCH_INC(var, val) do { \
	SYS_ARCH_DECL_PROTECT(old_level); \
	SYS_ARCH_PROTECT(old_level); \
	var += val; \
	SYS_ARCH_UNPROTECT(old_level); \
	} while(0)
	#endif /* SYS_ARCH_INC */

	#ifndef SYS_ARCH_DEC
	#define SYS_ARCH_DEC(var, val) do { \
	SYS_ARCH_DECL_PROTECT(old_level); \
	SYS_ARCH_PROTECT(old_level); \
	var -= val; \
	SYS_ARCH_UNPROTECT(old_level); \
	} while(0)
	#endif /* SYS_ARCH_DEC */

	#ifndef SYS_ARCH_GET
	#define SYS_ARCH_GET(var, ret) do { \
	SYS_ARCH_DECL_PROTECT(old_level); \
	SYS_ARCH_PROTECT(old_level); \
	ret = var; \
	SYS_ARCH_UNPROTECT(old_level); \
	} while(0)
	#endif /* SYS_ARCH_GET */

	#ifndef SYS_ARCH_SET
	#define SYS_ARCH_SET(var, val) do { \
	SYS_ARCH_DECL_PROTECT(old_level); \
	SYS_ARCH_PROTECT(old_level); \
	var = val; \
	SYS_ARCH_UNPROTECT(old_level); \
	} while(0)
	#endif /* SYS_ARCH_SET */


	#ifdef __cplusplus
	}
	#endif

	#endif /* LWIP_HDR_SYS_H */