POSIX：如何在线程之间执行上下文切换？

Question

我想使用Xilkernel实现线程之间的上下文切换，但是没有原始的POSIX兼容允许停止然后恢复线程的执行。

有没有人可以帮助我？

Answer 1

我使用这个C代码为FPGA进行上下文切换。如果您发现它很有用并希望获得更多的周围代码，请问我。

/*
 * threadswitch - change thread
 * 
 * The thread stack-pointer is supplied as a parameter.
 * The old thread's stack-pointer value is saved to the array
 * thread_info_array, and a new thread is selected from the array.
 * The stack pointer of the new thread is returned.
 */
unsigned int * threadswitch( unsigned int * old_sp )
{
  unsigned int * new_sp;

  number_of_thread_switches += 1; /* Increase thread-switch counter. */

  /* Print line 1 of an informational message. */
  printf( "\nPerforming thread-switch number %d. The system has been running for %d ticks.\n",
          number_of_thread_switches,
          get_internal_globaltime() );

  /* Save the stack pointer of the old thread. */
  thread_info_array[ currently_running_thread ].thread_sp = old_sp;

  /* Print part 1 of a message saying which threads are involved this time. */
  printf( "Switching from thread-ID %d ",
          thread_info_array[ currently_running_thread ].thread_id );

  /* Perform the scheduling decision (round-robin). */
  currently_running_thread += 1;
  if( currently_running_thread >= current_thread_count )
  {
    currently_running_thread = 0;
  }

  /* Print part 2 of the informational message. */
  printf( "to thread-ID %d.\n",
          thread_info_array[ currently_running_thread ].thread_id );

  /* Get the stack pointer of the new thread. */
  new_sp = thread_info_array[ currently_running_thread ].thread_sp;

  /* Return. */
  return( new_sp );
}