/************************************************************************************
* arch/avr/src/avr32/up_switchcontext.S
*
* Copyright (C) 2010 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
************************************************************************************/
/************************************************************************************
* Included Files
************************************************************************************/
#include <nuttx/config.h>
#include <arch/irq.h>
#include <arch/avr32/avr32.h>
/************************************************************************************
* Pre-processor Definitions
************************************************************************************/
/************************************************************************************
* Global Symbols
************************************************************************************/
.file "up_switchcontext.S"
/************************************************************************************
* Macros
************************************************************************************/
/************************************************************************************
* Public Functions
************************************************************************************/
/************************************************************************************
* Name: up_switchcontext
*
* Description:
* Save the current thread context and restore the specified context. The full
* C function prototype is:
*
* void up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs);
*
* Return:
* up_switchcontext forces a context switch to the task "canned" in restoreregs.
* It does not 'return' in the normal sense, rather, it will context switch back
* to the function point. When it does 'return,' it is because the blocked
* task hat was "pickeled" in the saveregs "can" is again ready to run and has
* execution priority.
*
* Assumptions:
* global interrupts disabled by the caller.
*
************************************************************************************/
.text
.globl up_switchcontext
.type up_switchcontext, @function
up_switchcontext:
/* "Pickle" the current thread context in the saveregs "can." r12=saveregs. */
/* xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx */
/* ^r12 */
/* Sample SR and set r12 to just after the LR storage location. */
/* xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx */
/* ^r12 */
mfsr r10, AVR32_SR
sub r12, -4*(REG_LR+1)
/* Then "push" PC=LR, LR, SR, and SP as ther are on entry. */
/* xx xx xx xx xx xx xx xx SP SR PC LR xx xx xx xx xx */
/* ^r12 */
st.w --r12, lr
st.w --r12, lr
st.w --r12, r10
st.w --r12, sp
/* Save the preserved/static registers, r0-r7. There is no reason to save the */
/* scratch/volatile registers, r8-r12, in this context. */
/* 07 06 05 04 03 02 01 00 SP SR PC LR xx xx xx xx xx */
/* ^r12 */
stm --r12, r0-r7
/* Finally, let up_fullcontextrestore handling the re-instatement of the thread */
/* "canned" in restoregs. */
mov r12, r11
lddpc pc, .Lup_fullcontextrestore
.Lup_fullcontextrestore:
.word up_fullcontextrestore
.size up_switchcontext, .-up_switchcontext
.end
