tick.h

   1 /*
   2  * Copyright (C) 2024 Mikulas Patocka
   3  *
   4  * This file is part of Ajla.
   5  *
   6  * Ajla is free software: you can redistribute it and/or modify it under the
   7  * terms of the GNU General Public License as published by the Free Software
   8  * Foundation, either version 3 of the License, or (at your option) any later
   9  * version.
  10  *
  11  * Ajla is distributed in the hope that it will be useful, but WITHOUT ANY
  12  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  13  * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * Ajla. If not, see <https://www.gnu.org/licenses/>.
  17  */
  18
  19 #ifndef AJLA_TICK_H
  20 #define AJLA_TICK_H
  21
  22 #if defined(HAVE_TIMER_CREATE) && defined(HAVE_STRUCT_SIGEVENT)
  23 #define USE_TIMER_CREATE
  24 #endif
  25
  26 /* Cygwin has bugs in signal-vs-thread interactions */
  27 #if defined(HAVE_SIGNAL_H) && defined(HAVE_SETITIMER) && defined(HAVE_SIGACTION) && defined(HAVE_SIGSET_T) && !defined(__CYGWIN__)
  28 #define USEABLE_SIGNAL
  29 #endif
  30
  31 /*
  32  * If we don't have timer_create, we use setitimer. Unfortunatelly, there is no
  33  * way to stop setitimer (because it is sometimes implemented incorrectly
  34  * per-thread, not per-process).
  35  *
  36  * So we'd better fallback to a timer thread (that is stoppable), to reduce CPU
  37  * consumption when we are idle.
  38  */
  39 #if defined(USEABLE_SIGNAL) && !defined(THREAD_NONE) && !defined(USE_TIMER_CREATE)
  40 #undef USEABLE_SIGNAL
  41 #endif
  42
  43 extern uint32_t tick_us;
  44 extern uint32_t thread_tick;
  45
  46 typedef unsigned tick_stamp_t;
  47 extern atomic_type tick_stamp_t *tick_stamp_ptr;
  48 #define tick_start(state)       (*(state) = load_relaxed(&tick_stamp))
  49 #define tick_elapsed(state)     (unlikely(*(state) != load_relaxed(&tick_stamp)))
  50
  51 void tick_suspend(void);
  52 void tick_resume(void);
  53
  54 void tick_init(void);
  55 void tick_done(void);
  56
  57 #endif