Mbed OS Reference | sys.h Source File

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 /**
  * @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.
  * The mutex is allocated to the memory that 'mutex'
  * points to (which can be both a pointer or the actual OS structure).
  * If the mutex has been created, ERR_OK should be returned. Returning any
  * other error will provide a hint what went wrong, but except for assertions,
  * no real error handling is implemented.
  * 
  * @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
  * Blocks the thread until the mutex can be grabbed.
  * @param mutex the mutex to lock
  */
 void sys_mutex_lock(sys_mutex_t *mutex);
 /**
  * @ingroup sys_mutex
  * Releases the mutex previously locked through 'sys_mutex_lock()'.
  * @param mutex the mutex to unlock
  */
 void sys_mutex_unlock(sys_mutex_t *mutex);
 /**
  * @ingroup sys_mutex
  * Deallocates a mutex.
  * @param mutex the mutex to delete
  */
 void sys_mutex_free(sys_mutex_t *mutex);
 #ifndef sys_mutex_valid
 /**
  * @ingroup sys_mutex
  * Returns 1 if the mutes is valid, 0 if it is not valid.
  * When using pointers, a simple way is to check the pointer for != NULL.
  * When directly using OS structures, implementing this may be more complex.
  * This may also be a define, in which case the function is not prototyped.
  */
 int sys_mutex_valid(sys_mutex_t *mutex);
 #endif
 #ifndef sys_mutex_set_invalid
 /**
  * @ingroup sys_mutex
  * Invalidate a mutex so that sys_mutex_valid() returns 0.
  * ATTENTION: This does NOT mean that the mutex shall be deallocated:
  * sys_mutex_free() is always called before calling this function!
  * This may also be a define, in which case the function is not prototyped.
  */
 void sys_mutex_set_invalid(sys_mutex_t *mutex);
 #endif
 #endif /* LWIP_COMPAT_MUTEX */
 
 /* Semaphore functions: */
 
 /**
  * @ingroup sys_sem
  * Create a new semaphore
  * Creates a new semaphore. The semaphore is allocated to the memory that 'sem'
  * points to (which can be both a pointer or the actual OS structure).
  * The "count" argument specifies the initial state of the semaphore (which is
  * either 0 or 1).
  * If the semaphore has been created, ERR_OK should be returned. Returning any
  * other error will provide a hint what went wrong, but except for assertions,
  * no real error handling is implemented.
  *
  * @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
  *  Blocks the thread while waiting for the semaphore to be signaled. If the
  * "timeout" argument is non-zero, the thread should only be blocked for the
  * specified time (measured in milliseconds). If the "timeout" argument is zero,
  * the thread should be blocked until the semaphore is signalled.
  * 
  * The return value is SYS_ARCH_TIMEOUT if the semaphore wasn't signaled within
  * the specified time or any other value if it was signaled (with or without
  * waiting).
  * Notice that lwIP implements a function with a similar name,
  * sys_sem_wait(), that uses the sys_arch_sem_wait() function.
  * 
  * @param sem the semaphore to wait for
  * @param timeout timeout in milliseconds to wait (0 = wait forever)
  * @return SYS_ARCH_TIMEOUT on timeout, any other value on success
  */
 u32_t sys_arch_sem_wait(sys_sem_t *sem, u32_t timeout);
 /**
  * @ingroup sys_sem
  * Deallocates 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
  * Returns 1 if the semaphore is valid, 0 if it is not valid.
  * When using pointers, a simple way is to check the pointer for != NULL.
  * When directly using OS structures, implementing this may be more complex.
  * This may also be a define, in which case the function is not prototyped.
  */
 int sys_sem_valid(sys_sem_t *sem);
 #endif
 #ifndef sys_sem_set_invalid
 /**
  * @ingroup sys_sem
  * Invalidate a semaphore so that sys_sem_valid() returns 0.
  * ATTENTION: This does NOT mean that the semaphore shall be deallocated:
  * sys_sem_free() is always called before calling this function!
  * This may also be a define, in which case the function is not prototyped.
  */
 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
  * Creates an empty mailbox for maximum "size" elements. Elements stored
  * in mailboxes are pointers. You have to define macros "_MBOX_SIZE"
  * in your lwipopts.h, or ignore this parameter in your implementation
  * and use a default size.
  * If the mailbox has been created, ERR_OK should be returned. Returning any
  * other error will provide a hint what went wrong, but except for assertions,
  * no real error handling is implemented.
  * 
  * @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 to be 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.
  * Can be used from ISR (if the sys arch layer allows this).
  * Returns ERR_MEM if it is full, else, ERR_OK if the "msg" is posted.
  * 
  * @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
  * Try to post a message to an mbox - may fail if full.
  * To be be used from ISR.
  * Returns ERR_MEM if it is full, else, ERR_OK if the "msg" is posted.
  * 
  * @param mbox mbox to posts the message
  * @param msg message to post (ATTENTION: can be NULL)
  */
 err_t sys_mbox_trypost_fromisr(sys_mbox_t *mbox, void *msg);
 /**
  * @ingroup sys_mbox
  * Blocks the thread until a message arrives in the mailbox, but does
  * not block the thread longer than "timeout" milliseconds (similar to
  * the sys_arch_sem_wait() function). If "timeout" is 0, the thread should
  * be blocked until a message arrives. The "msg" argument is a result
  * parameter that is set by the function (i.e., by doing "*msg =
  * ptr"). The "msg" parameter maybe NULL to indicate that the message
  * should be dropped.
  * The return values are the same as for the sys_arch_sem_wait() function:
  * SYS_ARCH_TIMEOUT if there was a timeout, any other value if a messages
  * is received.
  * 
  * Note that a function with a similar name, sys_mbox_fetch(), is
  * implemented by lwIP. 
  * 
  * @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 SYS_ARCH_TIMEOUT on timeout, any other value if a message has been received
  */
 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
  * This is similar to sys_arch_mbox_fetch, however if a message is not
  * present in the mailbox, it immediately returns with the code
  * SYS_MBOX_EMPTY. On success 0 is returned.
  * To allow for efficient implementations, this can be defined as a
  * function-like macro in sys_arch.h instead of a normal function. For
  * example, a naive implementation could be:
  * \#define sys_arch_mbox_tryfetch(mbox,msg) sys_arch_mbox_fetch(mbox,msg,1)
  * although this would introduce unnecessary delays.
  * 
  * @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
  * Deallocates a mailbox. If there are messages still present in the
  * mailbox when the mailbox is deallocated, it is an indication of a
  * programming error in lwIP and the developer should be notified.
  * 
  * @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
  * Returns 1 if the mailbox is valid, 0 if it is not valid.
  * When using pointers, a simple way is to check the pointer for != NULL.
  * When directly using OS structures, implementing this may be more complex.
  * This may also be a define, in which case the function is not prototyped.
  */
 int sys_mbox_valid(sys_mbox_t *mbox);
 #endif
 #ifndef sys_mbox_set_invalid
 /**
  * @ingroup sys_mbox
  * Invalidate a mailbox so that sys_mbox_valid() returns 0.
  * ATTENTION: This does NOT mean that the mailbox shall be deallocated:
  * sys_mbox_free() is always called before calling this function!
  * This may also be a define, in which case the function is not prototyped.
  */
 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:
  * Starts a new thread named "name" with priority "prio" that will begin its
  * execution in the function "thread()". The "arg" argument will be passed as an
  * argument to the thread() function. The stack size to used for this thread is
  * the "stacksize" parameter. The id of the new thread is returned. Both the id
  * and the priority are system dependent.
  * 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 */
 
 /**
  * @ingroup sys_misc
  * sys_init() must be called before anything else.
  * Initialize the sys_arch layer.
  */
 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.
  * Don't care for wraparound, this is only used for time diffs.
  * Not implementing this function means you cannot use some modules (e.g. TCP
  * timestamps, internal timeouts for NO_SYS==1).
  */
 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 */
 
 #ifndef SYS_ARCH_LOCKED
 #define SYS_ARCH_LOCKED(code) do { \
                                 SYS_ARCH_DECL_PROTECT(old_level); \
                                 SYS_ARCH_PROTECT(old_level); \
                                 code; \
                                 SYS_ARCH_UNPROTECT(old_level); \
                               } while(0)
 #endif /* SYS_ARCH_LOCKED */
 
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* LWIP_HDR_SYS_H */
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