/*************************************************************************
 * Copyright (C) 2010 Tavian Barnes <tavianator@gmail.com>               *
 *                                                                       *
 * This file is part of The Dimension Library.                           *
 *                                                                       *
 * The Dimension Library is free software; you can redistribute it and/  *
 * or modify it under the terms of the GNU Lesser General Public License *
 * as published by the Free Software Foundation; either version 3 of the *
 * License, or (at your option) any later version.                       *
 *                                                                       *
 * The Dimension Library is distributed in the hope that it will be      *
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty   *
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
 * Lesser General Public License for more details.                       *
 *                                                                       *
 * You should have received a copy of the GNU Lesser General Public      *
 * License along with this program.  If not, see                         *
 * <http://www.gnu.org/licenses/>.                                       *
 *************************************************************************/

#include "dimension-impl.h"
#if HAVE_UNISTD_H
  #include <unistd.h>
#endif
#if DMNSN_BACKTRACE
  #include <execinfo.h>    /* For backtrace() etc. */
#endif
#if DMNSN_GETTID
  #include <sys/syscall.h> /* For gettid() where supported */
#endif
#if DMNSN_SCHED_GETAFFINITY
  #include <sched.h>       /* For sched_getaffinity() */
#endif

void
dmnsn_backtrace(FILE *file)
{
#if DMNSN_BACKTRACE
  const size_t size = 128;
  void *buffer[size];

  int nptrs = backtrace(buffer, size);
  backtrace_symbols_fd(buffer, nptrs, fileno(file));
#endif
}

bool
dmnsn_is_main_thread()
{
#if DMNSN_GETTID
  return getpid() == syscall(SYS_gettid);
#else
  return true;
#endif
}

bool
dmnsn_is_little_endian()
{
  /* Undefined behaviour, but quite portable */
  union {
    unsigned int i;
    unsigned char c;
  } u = { .i = 1 };
  return u.c == 1;
}

size_t
dmnsn_ncpus()
{
#if DMNSN_SCHED_GETAFFINITY
  cpu_set_t cpuset;
  if (sched_getaffinity(0, sizeof(cpuset), &cpuset) == 0) {
    return CPU_COUNT(&cpuset);
  } else {
    dmnsn_error(DMNSN_SEVERITY_MEDIUM, "sched_getaffinity() failed.");
    return 1;
  }
#elif DMNSN_SC_NPROCESSORS_ONLN
  long nprocs = sysconf(_SC_NPROCESSORS_ONLN);
  if (nprocs > 0) {
    return nprocs;
  } else {
    dmnsn_error(DMNSN_SEVERITY_MEDIUM, "sysconf(_SC_NPROCESSORS_ONLN) failed.");
    return 1;
  }
#else
  return 1;
#endif
}