context_switch.h

MANTIS是由科罗拉多大学开发的传感器网络嵌入式操作系统。 这是mantis的0.9.5版本的源码。

//  This file is part of MANTIS OS, Operating System for Nymph.
//  See http://mantis.cs.colorado.edu/
//
//  Copyright (C) 2003 University of Colorado, Boulder
//
//  This program is free software; you can redistribute it and/or
//  modify it under the terms of the GNU General Public License
//  as published by the Free Software Foundation; either version 2
//  of the License, or (at your option) any later version.
//

//  This program 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 General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  (See http://www.gnu.org/copyleft/gpl.html)
//  along with this program; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307,
//  USA, or send email to [e-mail].
/** @file context_switch.h
 * @brief Assembly routines required to preform a context switch.
 */
#ifndef __context_switch_h__
#define __context_switch_h__


/** @file avr/include/context_switch.h
 *  @brief save the necessary registers for a context switch
 * on the AVR architecture
 *
 * Save current stack pointer
 * Change stack pointer to process stack
 * Push address of start_thread function onto stack
 * Push zeroes for initial register vals and sreg
 * Save adjusted stack ptr to thread struct
 * Restore kernel stack ptr
 */
#define CONTEXT_SWITCH_PREAMBLE()			\
   {							\
      asm volatile(					\
	 "in %A0, __SP_L__\n\t"				\
	 "in %B0, __SP_H__\n\t"				\
	 : "=r" (_current_thread->sp) : );		\
							\
      asm volatile(					\
	 "out __SP_H__, %B0\n\t"			\
	 "out __SP_L__, %A0\n\t"			\
	 :: "r" (stack_addr) );				\
							\
      asm volatile(					\
	 "push %A0\n\t"					\
	 "push %B0\n\t"					\
	 :: "r" (start_wrapper) );			\
							\
      for(i = 0; i < 31; i++)				\
	asm volatile("push __zero_reg__\n\t" ::);	\
							\
      asm volatile(					\
	 "in %A0, __SP_L__\n\t"				\
	 "in %B0, __SP_H__\n\t"				\
	 : "=r" (threads[id].sp) : );			\
							\
      asm volatile(					\
	 "out __SP_H__, %B0\n\t"			\
	 "out __SP_L__, %A0\n\t"			\
	 :: "r" (_current_thread->sp) );		\
							\
   }

/** @brief save the current thread's context to the stack
 * Save all the registers
 * Save SREG
 * Push the stack pointer
 */
#define PUSH_THREAD_STACK()			\
   {						\
      asm volatile(				\
	 "push r24\n\t"				\
	 "in r24, __SREG__\n\t"			\
	 "cli\n\t"				\
	 "push r24\n\t"				\
	 );					\
      asm volatile(				\
	 "push r31\n\t"				\
	 "push r30\n\t"				\
	 "push r29\n\t"				\
	 "push r28\n\t"				\
	 "push r27\n\t"				\
	 "push r26\n\t"				\
	 "push r25\n\t"				\
	 "push r23\n\t"				\
	 "push r22\n\t"				\
	 "push r21\n\t"				\
	 "push r20\n\t"				\
	 "push r19\n\t"				\
	 "push r18\n\t"				\
	 "push r17\n\t"				\
	 "push r16\n\t"				\
	 "push r15\n\t"				\
	 "push r14\n\t"				\
	 "push r13\n\t"				\
	 "push r12\n\t"				\
	 "push r11\n\t"				\
	 "push r10\n\t"				\
	 "push r9\n\t"				\
	 "push r8\n\t"				\
	 "push r7\n\t"				\
	 "push r6\n\t"				\
	 "push r5\n\t"				\
	 "push r4\n\t"				\
	 "push r3\n\t"				\
	 "push r2\n\t"				\
	 /*"push r1\n\t"*/			\
	 /*"push r0\n\t"*/			\
	 );					\
      asm volatile(				\
	 "in %A0, __SP_L__\n\t"			\
	 "in %B0, __SP_H__\n\t"			\
	 : "=r" (_current_thread->sp) : );	\
   }

/** @brief retrieve a thread and context from the stack
 * Restore the stack pointer
 * Restore SREG
 * Restore the other registers
 */
#define POP_THREAD_STACK()			\
   {						\
      asm volatile(				\
	 "out __SP_H__, %B0\n\t"		\
	 "out __SP_L__, %A0\n\t"		\
	 :: "r" (_current_thread->sp));		\
      asm volatile(				\
	 /*"pop r0\n\t"*/			\
	 /*"pop r1\n\t"*/			\
	 "pop r2\n\t"				\
	 "pop r3\n\t"				\
	 "pop r4\n\t"				\
	 "pop r5\n\t"				\
	 "pop r6\n\t"				\
	 "pop r7\n\t"				\
	 "pop r8\n\t"				\
	 "pop r9\n\t"				\
	 "pop r10\n\t"				\
	 "pop r11\n\t"				\
	 "pop r12\n\t"				\
	 "pop r13\n\t"				\
	 "pop r14\n\t"				\
	 "pop r15\n\t"				\
	 "pop r16\n\t"				\
	 "pop r17\n\t"				\
	 "pop r18\n\t"				\
	 "pop r19\n\t"				\
	 "pop r20\n\t"				\
	 "pop r21\n\t"				\
	 "pop r22\n\t"				\
	 "pop r23\n\t"				\
	 "pop r25\n\t"				\
	 "pop r26\n\t"				\
	 "pop r27\n\t"				\
	 "pop r28\n\t"				\
	 "pop r29\n\t"				\
	 "pop r30\n\t"				\
	 "pop r31\n\t"				\
	 "pop r24\n\t"				\
	 "out __SREG__, r24\n\t"		\
	 "pop r24\n\t"				\
	 /*"sei\n\t"*/				\
	 );					\
   }


#endif