tinySA/ports/AVR/chcore.c

/*
    ChibiOS/RT - Copyright (C) 2006-2007 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/>.
*/

/**
 * @file ports/AVR/chcore.c
 * @brief AVR architecture port code.
 * @addtogroup AVR_CORE
 * @{
 */

#include <ch.h>

/**
 * Performs a context switch between two threads.
 * @param otp the thread to be switched out
 * @param ntp the thread to be switched in
 * @note The function is declared as a weak symbol, it is possible to redefine
 *       it in your application code.
 */
/** @cond never */
__attribute__((naked, weak))
/** @endcond */
void port_switch(Thread *otp, Thread *ntp) {

  asm volatile ("push    r2");
  asm volatile ("push    r3");
  asm volatile ("push    r4");
  asm volatile ("push    r5");
  asm volatile ("push    r6");
  asm volatile ("push    r7");
#ifndef CH_CURRP_REGISTER_CACHE
  asm volatile ("push    r8");
  asm volatile ("push    r9");
#endif
  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, r24");
  asm volatile ("in      r0, 0x3d");
  asm volatile ("std     Z+8, r0");
  asm volatile ("in      r0, 0x3e");
  asm volatile ("std     Z+9, r0");

  asm volatile ("movw    r30, r22");
  asm volatile ("ldd     r0, Z+8");
  asm volatile ("out     0x3d, r0");
  asm volatile ("ldd     r0, Z+9");
  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");
#ifndef CH_CURRP_REGISTER_CACHE
  asm volatile ("pop     r9");
  asm volatile ("pop     r8");
#endif
  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");
}

/**
 * Disables the interrupts and halts the system.
 * @note The function is declared as a weak symbol, it is possible to redefine
 *       it in your application code.
 */
/** @cond never */
__attribute__((weak))
/** @endcond */
void port_halt(void) {

  port_disable();
  while (TRUE) {
  }
}

/**
 * Start a thread by invoking its work function.
 * If the work function returns @p chThdExit() is automatically invoked.
 */
void threadstart(void) {

  asm volatile ("sei");
  asm volatile ("movw    r24, r4");
  asm volatile ("movw    r30, r2");
  asm volatile ("icall");
  asm volatile ("call    chThdExit");
}

/** @} */