MicroAPRS/bertos/emul/switch_ppc.S

57 lines
2.0 KiB
ArmAsm

/**
* \file
* <!--
* This file is part of BeRTOS.
*
* Bertos 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
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* As a special exception, you may use this file as part of a free software
* library without restriction. Specifically, if other files instantiate
* templates or use macros or inline functions from this file, or you compile
* this file and link it with other files to produce an executable, this
* file does not by itself cause the resulting executable to be covered by
* the GNU General Public License. This exception does not however
* invalidate any other reasons why the executable file might be covered by
* the GNU General Public License.
*
* Copyright 2008 Bernie Innocenti <bernie@codewiz.org>
* -->
*
* \author Bernie Innocenti <bernie@codewiz.org>
*
* \brief PowerPC context switch
*/
#ifdef __APPLE__
//This workaround is necessary to compile under OS X assembler.
#define SWITCH_CONTEXT _asm_switch_context
#else
#define SWITCH_CONTEXT asm_switch_context
#endif
.balign 4
/* void asm_switch_context(void ** new_sp, void ** save_sp) */
/* r3 r4 */
.globl SWITCH_CONTEXT
SWITCH_CONTEXT:
mflr 0 /* r0 = lr */
stw 0,8(1) /* store lr at *(sp+8) */
stw 1,0(4) /* *save_sp = sp */
lwz 1,0(3) /* sp = *new_sp */
lwz 0,8(1) /* retrieve lr from *(sp+8) */
mtlr 0 /* lr = r0 */
blr /* return */