sys.c

00001 /**
00002  * @file
00003  * lwIP Operating System abstraction
00004  *
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved.
00010  *
00011  * Redistribution and use in source and binary forms, with or without modification,
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission.
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  *
00035  * Author: Adam Dunkels <adam@sics.se>
00036  *
00037  */
00038 
00039 #include "lwip/opt.h"
00040 
00041 #if (NO_SYS == 0) /* don't build if not configured for use in lwipopts.h */
00042 
00043 #include "lwip/sys.h"
00044 #include "lwip/def.h"
00045 #include "lwip/memp.h"
00046 #include "lwip/tcpip.h"
00047 
00048 /**
00049  * Struct used for sys_sem_wait_timeout() to tell wether the time
00050  * has run out or the semaphore has really become available.
00051  */
00052 struct sswt_cb
00053 {
00054   s16_t timeflag;
00055   sys_sem_t *psem;
00056 };
00057 
00058 /**
00059  * Wait (forever) for a message to arrive in an mbox.
00060  * While waiting, timeouts (for this thread) are processed.
00061  *
00062  * @param mbox the mbox to fetch the message from
00063  * @param msg the place to store the message
00064  */
00065 void
00066 sys_mbox_fetch(sys_mbox_t mbox, void **msg)
00067 {
00068   u32_t time_needed;
00069   struct sys_timeouts *timeouts;
00070   struct sys_timeo *tmptimeout;
00071   sys_timeout_handler h;
00072   void *arg;
00073 
00074  again:
00075   timeouts = sys_arch_timeouts();
00076 
00077   if (!timeouts || !timeouts->next) {
00078     UNLOCK_TCPIP_CORE();
00079     time_needed = sys_arch_mbox_fetch(mbox, msg, 0);
00080     LOCK_TCPIP_CORE();
00081   } else {
00082     if (timeouts->next->time > 0) {
00083       UNLOCK_TCPIP_CORE();
00084       time_needed = sys_arch_mbox_fetch(mbox, msg, timeouts->next->time);
00085       LOCK_TCPIP_CORE();
00086     } else {
00087       time_needed = SYS_ARCH_TIMEOUT;
00088     }
00089 
00090     if (time_needed == SYS_ARCH_TIMEOUT) {
00091       /* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
00092          could be fetched. We should now call the timeout handler and
00093          deallocate the memory allocated for the timeout. */
00094       tmptimeout = timeouts->next;
00095       timeouts->next = tmptimeout->next;
00096       h   = tmptimeout->h;
00097       arg = tmptimeout->arg;
00098       memp_free(MEMP_SYS_TIMEOUT, tmptimeout);
00099       if (h != NULL) {
00100         LWIP_DEBUGF(SYS_DEBUG, ("smf calling h=%p(%p)\n", (void*)&h, arg));
00101         h(arg);
00102       }
00103 
00104       /* We try again to fetch a message from the mbox. */
00105       goto again;
00106     } else {
00107       /* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
00108          occured. The time variable is set to the number of
00109          milliseconds we waited for the message. */
00110       if (time_needed < timeouts->next->time) {
00111         timeouts->next->time -= time_needed;
00112       } else {
00113         timeouts->next->time = 0;
00114       }
00115     }
00116   }
00117 }
00118 
00119 /**
00120  * Wait (forever) for a semaphore to become available.
00121  * While waiting, timeouts (for this thread) are processed.
00122  *
00123  * @param sem semaphore to wait for
00124  */
00125 void
00126 sys_sem_wait(sys_sem_t sem)
00127 {
00128   u32_t time_needed;
00129   struct sys_timeouts *timeouts;
00130   struct sys_timeo *tmptimeout;
00131   sys_timeout_handler h;
00132   void *arg;
00133 
00134  again:
00135 
00136   timeouts = sys_arch_timeouts();
00137 
00138   if (!timeouts || !timeouts->next) {
00139     sys_arch_sem_wait(sem, 0);
00140   } else {
00141     if (timeouts->next->time > 0) {
00142       time_needed = sys_arch_sem_wait(sem, timeouts->next->time);
00143     } else {
00144       time_needed = SYS_ARCH_TIMEOUT;
00145     }
00146 
00147     if (time_needed == SYS_ARCH_TIMEOUT) {
00148       /* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
00149         could be fetched. We should now call the timeout handler and
00150         deallocate the memory allocated for the timeout. */
00151       tmptimeout = timeouts->next;
00152       timeouts->next = tmptimeout->next;
00153       h = tmptimeout->h;
00154       arg = tmptimeout->arg;
00155       memp_free(MEMP_SYS_TIMEOUT, tmptimeout);
00156       if (h != NULL) {
00157         LWIP_DEBUGF(SYS_DEBUG, ("ssw h=%p(%p)\n", (void*)&h, (void *)arg));
00158         h(arg);
00159       }
00160 
00161       /* We try again to fetch a message from the mbox. */
00162       goto again;
00163     } else {
00164       /* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
00165          occured. The time variable is set to the number of
00166          milliseconds we waited for the message. */
00167       if (time_needed < timeouts->next->time) {
00168         timeouts->next->time -= time_needed;
00169       } else {
00170         timeouts->next->time = 0;
00171       }
00172     }
00173   }
00174 }
00175 
00176 /**
00177  * Create a one-shot timer (aka timeout). Timeouts are processed in the
00178  * following cases:
00179  * - while waiting for a message using sys_mbox_fetch()
00180  * - while waiting for a semaphore using sys_sem_wait() or sys_sem_wait_timeout()
00181  * - while sleeping using the inbuilt sys_msleep()
00182  *
00183  * @param msecs time in milliseconds after that the timer should expire
00184  * @param h callback function to call when msecs have elapsed
00185  * @param arg argument to pass to the callback function
00186  */
00187 void
00188 sys_timeout(u32_t msecs, sys_timeout_handler h, void *arg)
00189 {
00190   struct sys_timeouts *timeouts;
00191   struct sys_timeo *timeout, *t;
00192 
00193   timeout = memp_malloc(MEMP_SYS_TIMEOUT);
00194   if (timeout == NULL) {
00195     LWIP_ASSERT("sys_timeout: timeout != NULL", timeout != NULL);
00196     return;
00197   }
00198   timeout->next = NULL;
00199   timeout->h = h;
00200   timeout->arg = arg;
00201   timeout->time = msecs;
00202 
00203   timeouts = sys_arch_timeouts();
00204 
00205   LWIP_DEBUGF(SYS_DEBUG, ("sys_timeout: %p msecs=%"U32_F" h=%p arg=%p\n",
00206     (void *)timeout, msecs, (void*)&h, (void *)arg));
00207 
00208   if (timeouts == NULL) {
00209     LWIP_ASSERT("sys_timeout: timeouts != NULL", timeouts != NULL);
00210     return;
00211   }
00212 
00213   if (timeouts->next == NULL) {
00214     timeouts->next = timeout;
00215     return;
00216   }
00217 
00218   if (timeouts->next->time > msecs) {
00219     timeouts->next->time -= msecs;
00220     timeout->next = timeouts->next;
00221     timeouts->next = timeout;
00222   } else {
00223     for(t = timeouts->next; t != NULL; t = t->next) {
00224       timeout->time -= t->time;
00225       if (t->next == NULL || t->next->time > timeout->time) {
00226         if (t->next != NULL) {
00227           t->next->time -= timeout->time;
00228         }
00229         timeout->next = t->next;
00230         t->next = timeout;
00231         break;
00232       }
00233     }
00234   }
00235 }
00236 
00237 /**
00238  * Go through timeout list (for this task only) and remove the first matching
00239  * entry, even though the timeout has not triggered yet.
00240  *
00241  * @note This function only works as expected if there is only one timeout
00242  * calling 'h' in the list of timeouts.
00243  *
00244  * @param h callback function that would be called by the timeout
00245  * @param arg callback argument that would be passed to h
00246 */
00247 void
00248 sys_untimeout(sys_timeout_handler h, void *arg)
00249 {
00250   struct sys_timeouts *timeouts;
00251   struct sys_timeo *prev_t, *t;
00252 
00253   timeouts = sys_arch_timeouts();
00254 
00255   if (timeouts == NULL) {
00256     LWIP_ASSERT("sys_untimeout: timeouts != NULL", timeouts != NULL);
00257     return;
00258   }
00259   if (timeouts->next == NULL) {
00260     return;
00261   }
00262 
00263   for (t = timeouts->next, prev_t = NULL; t != NULL; prev_t = t, t = t->next) {
00264     if ((t->h == h) && (t->arg == arg)) {
00265       /* We have a match */
00266       /* Unlink from previous in list */
00267       if (prev_t == NULL)
00268         timeouts->next = t->next;
00269       else
00270         prev_t->next = t->next;
00271       /* If not the last one, add time of this one back to next */
00272       if (t->next != NULL)
00273         t->next->time += t->time;
00274       memp_free(MEMP_SYS_TIMEOUT, t);
00275       return;
00276     }
00277   }
00278   return;
00279 }
00280 
00281 /**
00282  * Timeout handler function for sys_sem_wait_timeout()
00283  *
00284  * @param arg struct sswt_cb* used to signal a semaphore and end waiting.
00285  */
00286 static void
00287 sswt_handler(void *arg)
00288 {
00289   struct sswt_cb *sswt_cb = (struct sswt_cb *) arg;
00290 
00291   /* Timeout. Set flag to TRUE and signal semaphore */
00292   sswt_cb->timeflag = 1;
00293   sys_sem_signal(*(sswt_cb->psem));
00294 }
00295 
00296 /**
00297  * Wait for a semaphore with timeout (specified in ms)
00298  *
00299  * @param sem semaphore to wait
00300  * @param timeout timeout in ms (0: wait forever)
00301  * @return 0 on timeout, 1 otherwise
00302  */
00303 int
00304 sys_sem_wait_timeout(sys_sem_t sem, u32_t timeout)
00305 {
00306   struct sswt_cb sswt_cb;
00307 
00308   sswt_cb.psem = &sem;
00309   sswt_cb.timeflag = 0;
00310 
00311   /* If timeout is zero, then just wait forever */
00312   if (timeout > 0) {
00313     /* Create a timer and pass it the address of our flag */
00314     sys_timeout(timeout, sswt_handler, &sswt_cb);
00315   }
00316   sys_sem_wait(sem);
00317   /* Was it a timeout? */
00318   if (sswt_cb.timeflag) {
00319     /* timeout */
00320     return 0;
00321   } else {
00322     /* Not a timeout. Remove timeout entry */
00323     sys_untimeout(sswt_handler, &sswt_cb);
00324     return 1;
00325   }
00326 }
00327 
00328 /**
00329  * Sleep for some ms. Timeouts are processed while sleeping.
00330  *
00331  * @param ms number of milliseconds to sleep
00332  */
00333 void
00334 sys_msleep(u32_t ms)
00335 {
00336   sys_sem_t delaysem = sys_sem_new(0);
00337 
00338   sys_sem_wait_timeout(delaysem, ms);
00339 
00340   sys_sem_free(delaysem);
00341 }
00342 
00343 
00344 #endif /* NO_SYS */