chcore.c
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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT 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 3 of the License, or
(at your option) any later version.
ChibiOS/RT 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, see <http://www.gnu.org/licenses/>.
---
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes ChibiOS/RT, without being obliged to provide
the source code for any proprietary components. See the file exception.txt
for full details of how and when the exception can be applied.
*/
/**
* @file AVR/chcore.c
* @brief AVR architecture port code.
*
* @addtogroup AVR_CORE
* @{
*/
#include "ch.h"
/**
* @brief Performs a context switch between two threads.
* @details This is the most critical code in any port, this function
* is responsible for the context switch between 2 threads.
* @note The implementation of this code affects <b>directly</b> the context
* switch performance so optimize here as much as you can.
* @note The function is declared as a weak symbol, it is possible to
* redefine it in your application code.
*
* @param[in] ntp the thread to be switched in
* @param[in] otp the thread to be switched out
*/
#if !defined(__DOXYGEN__)
__attribute__((naked, weak))
#endif
void port_switch(Thread *ntp, Thread *otp) {
asm volatile ("push r2");
asm volatile ("push r3");
asm volatile ("push r4");
asm volatile ("push r5");
asm volatile ("push r6");
asm volatile ("push r7");
asm volatile ("push r8");
asm volatile ("push r9");
asm volatile ("push r10");
asm volatile ("push r11");
asm volatile ("push r12");
asm volatile ("push r13");
asm volatile ("push r14");
asm volatile ("push r15");
asm volatile ("push r16");
asm volatile ("push r17");
asm volatile ("push r28");
asm volatile ("push r29");
asm volatile ("movw r30, r22");
asm volatile ("in r0, 0x3d");
asm volatile ("std Z+5, r0");
asm volatile ("in r0, 0x3e");
asm volatile ("std Z+6, r0");
asm volatile ("movw r30, r24");
asm volatile ("ldd r0, Z+5");
asm volatile ("out 0x3d, r0");
asm volatile ("ldd r0, Z+6");
asm volatile ("out 0x3e, r0");
asm volatile ("pop r29");
asm volatile ("pop r28");
asm volatile ("pop r17");
asm volatile ("pop r16");
asm volatile ("pop r15");
asm volatile ("pop r14");
asm volatile ("pop r13");
asm volatile ("pop r12");
asm volatile ("pop r11");
asm volatile ("pop r10");
asm volatile ("pop r9");
asm volatile ("pop r8");
asm volatile ("pop r7");
asm volatile ("pop r6");
asm volatile ("pop r5");
asm volatile ("pop r4");
asm volatile ("pop r3");
asm volatile ("pop r2");
asm volatile ("ret");
}
/**
* @brief Halts the system.
* @details This function is invoked by the operating system when an
* unrecoverable error is detected (for example because a programming
* error in the application code that triggers an assertion while in
* debug mode).
* @note The function is declared as a weak symbol, it is possible to
* redefine it in your application code.
*/
#if !defined(__DOXYGEN__)
__attribute__((weak))
#endif
void port_halt(void) {
port_disable();
while (TRUE) {
}
}
/**
* @brief Start a thread by invoking its work function.
* @details If the work function returns @p chThdExit() is automatically
* invoked.
*/
void _port_thread_start(void) {
chSysUnlock();
asm volatile ("movw r24, r4");
asm volatile ("movw r30, r2");
asm volatile ("icall");
asm volatile ("call chThdExit");
}
/** @} */