text: /*
   * 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 */
  #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 */
  
  /** Create a new mutex
   * @param mutex pointer to the mutex to create
   * @return a new mutex */
  err_t sys_mutex_new(sys_mutex_t *mutex);
  /** Lock a mutex
   * @param mutex the mutex to lock */
  void sys_mutex_lock(sys_mutex_t *mutex);
  /** Unlock a mutex
   * @param mutex the mutex to unlock */
  void sys_mutex_unlock(sys_mutex_t *mutex);
  /** Delete a semaphore
   * @param mutex the mutex to delete */
  void sys_mutex_free(sys_mutex_t *mutex);
  #ifndef sys_mutex_valid
  /** 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
  /** 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: */
  
  /** 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);
  /** Signals a semaphore
   * @param sem the semaphore to signal */
  void sys_sem_signal(sys_sem_t *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);
  /** 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
  /** 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
  /** 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
  
  /* Time functions. */
  #ifndef sys_msleep
  void sys_msleep(u32_t ms); /* only has a (close to) 1 ms resolution. */
  #endif
  
  /* Mailbox functions. */
  
  /** 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);
  /** 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);
  /** 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);
  /** 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
  /** 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)
  /** 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
  /** 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
  /** 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
  
  
  /** 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
  
  /** 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
  
  /** 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
  /** 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()
  /** 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 */
  
  