lib/drivers/lwip/src/core/sys.c

   1 /**
   2  * @file
   3  * lwIP Operating System abstraction
   4  *
   5  */
   6
   7 /*
   8  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without modification,
  12  * are permitted provided that the following conditions are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright notice,
  15  *    this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright notice,
  17  *    this list of conditions and the following disclaimer in the documentation
  18  *    and/or other materials provided with the distribution.
  19  * 3. The name of the author may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  23  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  24  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  25  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  27  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  30  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  31  * OF SUCH DAMAGE.
  32  *
  33  * This file is part of the lwIP TCP/IP stack.
  34  *
  35  * Author: Adam Dunkels <adam@sics.se>
  36  *
  37  */
  38
  39 #include "lwip/opt.h"
  40
  41 #if (NO_SYS == 0) /* don't build if not configured for use in lwipopts.h */
  42
  43 #include "lwip/sys.h"
  44 #include "lwip/def.h"
  45 #include "lwip/memp.h"
  46 #include "lwip/tcpip.h"
  47
  48 /**
  49  * Struct used for sys_sem_wait_timeout() to tell wether the time
  50  * has run out or the semaphore has really become available.
  51  */
  52 struct sswt_cb
  53 {
  54   s16_t timeflag;
  55   sys_sem_t *psem;
  56 };
  57
  58 /**
  59  * Wait (forever) for a message to arrive in an mbox.
  60  * While waiting, timeouts (for this thread) are processed.
  61  *
  62  * @param mbox the mbox to fetch the message from
  63  * @param msg the place to store the message
  64  */
  65 void
  66 sys_mbox_fetch(sys_mbox_t mbox, void **msg)
  67 {
  68   u32_t time_needed;
  69   struct sys_timeouts *timeouts;
  70   struct sys_timeo *tmptimeout;
  71   sys_timeout_handler h;
  72   void *arg;
  73
  74  again:
  75   timeouts = sys_arch_timeouts();
  76
  77   if (!timeouts || !timeouts->next) {
  78     UNLOCK_TCPIP_CORE();
  79     time_needed = sys_arch_mbox_fetch(mbox, msg, 0);
  80     LOCK_TCPIP_CORE();
  81   } else {
  82     if (timeouts->next->time > 0) {
  83       UNLOCK_TCPIP_CORE();
  84       time_needed = sys_arch_mbox_fetch(mbox, msg, timeouts->next->time);
  85       LOCK_TCPIP_CORE();
  86     } else {
  87       time_needed = SYS_ARCH_TIMEOUT;
  88     }
  89
  90     if (time_needed == SYS_ARCH_TIMEOUT) {
  91       /* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
  92          could be fetched. We should now call the timeout handler and
  93          deallocate the memory allocated for the timeout. */
  94       tmptimeout = timeouts->next;
  95       timeouts->next = tmptimeout->next;
  96       h   = tmptimeout->h;
  97       arg = tmptimeout->arg;
  98       memp_free(MEMP_SYS_TIMEOUT, tmptimeout);
  99       if (h != NULL) {
 100         LWIP_DEBUGF(SYS_DEBUG, ("smf calling h=%p(%p)\n", *(void**)&h, arg));
 101         h(arg);
 102       }
 103
 104       /* We try again to fetch a message from the mbox. */
 105       goto again;
 106     } else {
 107       /* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
 108          occured. The time variable is set to the number of
 109          milliseconds we waited for the message. */
 110       if (time_needed < timeouts->next->time) {
 111         timeouts->next->time -= time_needed;
 112       } else {
 113         timeouts->next->time = 0;
 114       }
 115     }
 116   }
 117 }
 118
 119 /**
 120  * Wait (forever) for a semaphore to become available.
 121  * While waiting, timeouts (for this thread) are processed.
 122  *
 123  * @param sem semaphore to wait for
 124  */
 125 void
 126 sys_sem_wait(sys_sem_t sem)
 127 {
 128   u32_t time_needed;
 129   struct sys_timeouts *timeouts;
 130   struct sys_timeo *tmptimeout;
 131   sys_timeout_handler h;
 132   void *arg;
 133
 134  again:
 135
 136   timeouts = sys_arch_timeouts();
 137
 138   if (!timeouts || !timeouts->next) {
 139     sys_arch_sem_wait(sem, 0);
 140   } else {
 141     if (timeouts->next->time > 0) {
 142       time_needed = sys_arch_sem_wait(sem, timeouts->next->time);
 143     } else {
 144       time_needed = SYS_ARCH_TIMEOUT;
 145     }
 146
 147     if (time_needed == SYS_ARCH_TIMEOUT) {
 148       /* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
 149         could be fetched. We should now call the timeout handler and
 150         deallocate the memory allocated for the timeout. */
 151       tmptimeout = timeouts->next;
 152       timeouts->next = tmptimeout->next;
 153       h = tmptimeout->h;
 154       arg = tmptimeout->arg;
 155       memp_free(MEMP_SYS_TIMEOUT, tmptimeout);
 156       if (h != NULL) {
 157         LWIP_DEBUGF(SYS_DEBUG, ("ssw h=%p(%p)\n", *(void**)&h, (void *)arg));
 158         h(arg);
 159       }
 160
 161       /* We try again to fetch a message from the mbox. */
 162       goto again;
 163     } else {
 164       /* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
 165          occured. The time variable is set to the number of
 166          milliseconds we waited for the message. */
 167       if (time_needed < timeouts->next->time) {
 168         timeouts->next->time -= time_needed;
 169       } else {
 170         timeouts->next->time = 0;
 171       }
 172     }
 173   }
 174 }
 175
 176 /**
 177  * Create a one-shot timer (aka timeout). Timeouts are processed in the
 178  * following cases:
 179  * - while waiting for a message using sys_mbox_fetch()
 180  * - while waiting for a semaphore using sys_sem_wait() or sys_sem_wait_timeout()
 181  * - while sleeping using the inbuilt sys_msleep()
 182  *
 183  * @param msecs time in milliseconds after that the timer should expire
 184  * @param h callback function to call when msecs have elapsed
 185  * @param arg argument to pass to the callback function
 186  */
 187 void
 188 sys_timeout(u32_t msecs, sys_timeout_handler h, void *arg)
 189 {
 190   struct sys_timeouts *timeouts;
 191   struct sys_timeo *timeout, *t;
 192
 193   timeout = memp_malloc(MEMP_SYS_TIMEOUT);
 194   if (timeout == NULL) {
 195     LWIP_ASSERT("sys_timeout: timeout != NULL", timeout != NULL);
 196     return;
 197   }
 198   timeout->next = NULL;
 199   timeout->h = h;
 200   timeout->arg = arg;
 201   timeout->time = msecs;
 202
 203   timeouts = sys_arch_timeouts();
 204
 205   LWIP_DEBUGF(SYS_DEBUG, ("sys_timeout: %p msecs=%"U32_F" h=%p arg=%p\n",
 206     (void *)timeout, msecs, *(void**)&h, (void *)arg));
 207
 208   if (timeouts == NULL) {
 209     LWIP_ASSERT("sys_timeout: timeouts != NULL", timeouts != NULL);
 210     return;
 211   }
 212
 213   if (timeouts->next == NULL) {
 214     timeouts->next = timeout;
 215     return;
 216   }
 217
 218   if (timeouts->next->time > msecs) {
 219     timeouts->next->time -= msecs;
 220     timeout->next = timeouts->next;
 221     timeouts->next = timeout;
 222   } else {
 223     for(t = timeouts->next; t != NULL; t = t->next) {
 224       timeout->time -= t->time;
 225       if (t->next == NULL || t->next->time > timeout->time) {
 226         if (t->next != NULL) {
 227           t->next->time -= timeout->time;
 228         }
 229         timeout->next = t->next;
 230         t->next = timeout;
 231         break;
 232       }
 233     }
 234   }
 235 }
 236
 237 /**
 238  * Go through timeout list (for this task only) and remove the first matching
 239  * entry, even though the timeout has not triggered yet.
 240  *
 241  * @note This function only works as expected if there is only one timeout
 242  * calling 'h' in the list of timeouts.
 243  *
 244  * @param h callback function that would be called by the timeout
 245  * @param arg callback argument that would be passed to h
 246 */
 247 void
 248 sys_untimeout(sys_timeout_handler h, void *arg)
 249 {
 250   struct sys_timeouts *timeouts;
 251   struct sys_timeo *prev_t, *t;
 252
 253   timeouts = sys_arch_timeouts();
 254
 255   if (timeouts == NULL) {
 256     LWIP_ASSERT("sys_untimeout: timeouts != NULL", timeouts != NULL);
 257     return;
 258   }
 259   if (timeouts->next == NULL) {
 260     return;
 261   }
 262
 263   for (t = timeouts->next, prev_t = NULL; t != NULL; prev_t = t, t = t->next) {
 264     if ((t->h == h) && (t->arg == arg)) {
 265       /* We have a match */
 266       /* Unlink from previous in list */
 267       if (prev_t == NULL) {
 268         timeouts->next = t->next;
 269       } else {
 270         prev_t->next = t->next;
 271       }
 272       /* If not the last one, add time of this one back to next */
 273       if (t->next != NULL) {
 274         t->next->time += t->time;
 275       }
 276       memp_free(MEMP_SYS_TIMEOUT, t);
 277       return;
 278     }
 279   }
 280   return;
 281 }
 282
 283 /**
 284  * Timeout handler function for sys_sem_wait_timeout()
 285  *
 286  * @param arg struct sswt_cb* used to signal a semaphore and end waiting.
 287  */
 288 static void
 289 sswt_handler(void *arg)
 290 {
 291   struct sswt_cb *sswt_cb = (struct sswt_cb *) arg;
 292
 293   /* Timeout. Set flag to TRUE and signal semaphore */
 294   sswt_cb->timeflag = 1;
 295   sys_sem_signal(*(sswt_cb->psem));
 296 }
 297
 298 /**
 299  * Wait for a semaphore with timeout (specified in ms)
 300  *
 301  * @param sem semaphore to wait
 302  * @param timeout timeout in ms (0: wait forever)
 303  * @return 0 on timeout, 1 otherwise
 304  */
 305 int
 306 sys_sem_wait_timeout(sys_sem_t sem, u32_t timeout)
 307 {
 308   struct sswt_cb sswt_cb;
 309
 310   sswt_cb.psem = &sem;
 311   sswt_cb.timeflag = 0;
 312
 313   /* If timeout is zero, then just wait forever */
 314   if (timeout > 0) {
 315     /* Create a timer and pass it the address of our flag */
 316     sys_timeout(timeout, sswt_handler, &sswt_cb);
 317   }
 318   sys_sem_wait(sem);
 319   /* Was it a timeout? */
 320   if (sswt_cb.timeflag) {
 321     /* timeout */
 322     return 0;
 323   } else {
 324     /* Not a timeout. Remove timeout entry */
 325     sys_untimeout(sswt_handler, &sswt_cb);
 326     return 1;
 327   }
 328 }
 329
 330 /**
 331  * Sleep for some ms. Timeouts are processed while sleeping.
 332  *
 333  * @param ms number of milliseconds to sleep
 334  */
 335 void
 336 sys_msleep(u32_t ms)
 337 {
 338   sys_sem_t delaysem = sys_sem_new(0);
 339
 340   sys_sem_wait_timeout(delaysem, ms);
 341
 342   sys_sem_free(delaysem);
 343 }
 344
 345
 346 #endif /* NO_SYS */