text: /*
      ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                   2011,2012,2013,2014 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    chcore_v6m.h
   * @brief   ARMv6-M architecture port macros and structures.
   *
   * @addtogroup ARMCMx_V6M_CORE
   * @{
   */
  
  #ifndef _CHCORE_V6M_H_
  #define _CHCORE_V6M_H_
  
  /*===========================================================================*/
  /* Module constants.                                                         */
  /*===========================================================================*/
  
  /**
   * @name    Architecture and Compiler
   * @{
   */
  #if (CORTEX_MODEL == CORTEX_M0) || defined(__DOXYGEN__)
  /**
   * @brief   Macro defining the specific ARM architecture.
   */
  #define PORT_ARCHITECTURE_ARM_v6M
  
  /**
   * @brief   Name of the implemented architecture.
   */
  #define PORT_ARCHITECTURE_NAME          "ARMv6-M"
  
  /**
   * @brief   Name of the architecture variant.
   */
  #define PORT_CORE_VARIANT_NAME          "Cortex-M0"
  
  #elif (CORTEX_MODEL == CORTEX_M0PLUS)
  #define PORT_ARCHITECTURE_ARM_v6M
  #define PORT_ARCHITECTURE_NAME          "ARMv6-M"
  #define PORT_CORE_VARIANT_NAME          "Cortex-M0+"
  #endif
  
  /**
   * @brief   Port-specific information string.
   */
  #if !CORTEX_ALTERNATE_SWITCH || defined(__DOXYGEN__)
  #define PORT_INFO                       "Preemption through NMI"
  #else
  #define PORT_INFO                       "Preemption through PendSV"
  #endif
  /** @} */
  
  /**
   * @brief   This port does not support a realtime counter.
   */
  #define PORT_SUPPORTS_RT                FALSE
  
  /**
   * @brief   PendSV priority level.
   * @note    This priority is enforced to be equal to @p 0,
   *          this handler always has the highest priority that cannot preempt
   *          the kernel.
   */
  #define CORTEX_PRIORITY_PENDSV          0
  
  /*===========================================================================*/
  /* Module pre-compile time settings.                                         */
  /*===========================================================================*/
  
  /**
   * @brief   Stack size for the system idle thread.
   * @details This size depends on the idle thread implementation, usually
   *          the idle thread should take no more space than those reserved
   *          by @p PORT_INT_REQUIRED_STACK.
   * @note    In this port it is set to 16 because the idle thread does have
   *          a stack frame when compiling without optimizations. You may
   *          reduce this value to zero when compiling with optimizations.
   */
  #if !defined(PORT_IDLE_THREAD_STACK_SIZE)
  #define PORT_IDLE_THREAD_STACK_SIZE     16
  #endif
  
  /**
   * @brief   Per-thread stack overhead for interrupts servicing.
   * @details This constant is used in the calculation of the correct working
   *          area size.
   * @note    In this port this value is conservatively set to 64 because the
   *          function @p chSchDoReschedule() can have a stack frame, especially
   *          with compiler optimizations disabled. The value can be reduced
   *          when compiler optimizations are enabled.
   */
  #if !defined(PORT_INT_REQUIRED_STACK)
  #define PORT_INT_REQUIRED_STACK         64
  #endif
  
  /**
   * @brief   Enables the use of the WFI instruction in the idle thread loop.
   */
  #if !defined(CORTEX_ENABLE_WFI_IDLE)
  #define CORTEX_ENABLE_WFI_IDLE          FALSE
  #endif
  
  /**
   * @brief   Alternate preemption method.
   * @details Activating this option will make the Kernel use the PendSV
   *          handler for preemption instead of the NMI handler.
   */
  #ifndef CORTEX_ALTERNATE_SWITCH
  #define CORTEX_ALTERNATE_SWITCH         FALSE
  #endif
  
  /*===========================================================================*/
  /* Derived constants and error checks.                                       */
  /*===========================================================================*/
  
  /**
   * @brief   Maximum usable priority for normal ISRs.
   */
  #if CORTEX_ALTERNATE_SWITCH || defined(__DOXYGEN__)
  #define CORTEX_MAX_KERNEL_PRIORITY      1
  #else
  #define CORTEX_MAX_KERNEL_PRIORITY      0
  #endif
  
  /*===========================================================================*/
  /* Module data structures and types.                                         */
  /*===========================================================================*/
  
  #if !defined(_FROM_ASM_)
  
   /* The documentation of the following declarations is in chconf.h in order
      to not have duplicated structure names into the documentation.*/
  #if !defined(__DOXYGEN__)
  struct port_extctx {
    regarm_t      r0;
    regarm_t      r1;
    regarm_t      r2;
    regarm_t      r3;
    regarm_t      r12;
    regarm_t      lr_thd;
    regarm_t      pc;
    regarm_t      xpsr;
  };
  
  struct port_intctx {
    regarm_t      r8;
    regarm_t      r9;
    regarm_t      r10;
    regarm_t      r11;
    regarm_t      r4;
    regarm_t      r5;
    regarm_t      r6;
    regarm_t      r7;
    regarm_t      lr;
  };
  #endif /* !defined(__DOXYGEN__) */
  
  /*===========================================================================*/
  /* Module macros.                                                            */
  /*===========================================================================*/
  
  /**
   * @brief   Platform dependent part of the @p chThdCreateI() API.
   * @details This code usually setup the context switching frame represented
   *          by an @p port_intctx structure.
   */
  #define PORT_SETUP_CONTEXT(tp, workspace, wsize, pf, arg) {                 \
    (tp)->p_ctx.r13 = (struct port_intctx *)((uint8_t *)(workspace) +         \
                                             (wsize) -                        \
                                             sizeof(struct port_intctx));     \
    (tp)->p_ctx.r13->r4 = (regarm_t)(pf);                                     \
    (tp)->p_ctx.r13->r5 = (regarm_t)(arg);                                    \
    (tp)->p_ctx.r13->lr = (regarm_t)(_port_thread_start);                     \
  }
  
  /**
   * @brief   Computes the thread working area global size.
   * @note    There is no need to perform alignments in this macro.
   */
  #define PORT_WA_SIZE(n) (sizeof(struct port_intctx) +                       \
                           sizeof(struct port_extctx) +                       \
                           (n) + (PORT_INT_REQUIRED_STACK))
  
  /**
   * @brief   IRQ prologue code.
   * @details This macro must be inserted at the start of all IRQ handlers
   *          enabled to invoke system APIs.
   */
  #if defined(__GNUC__) || defined(__DOXYGEN__)
  #define PORT_IRQ_PROLOGUE()                                                 \
    regarm_t _saved_lr = (regarm_t)__builtin_return_address(0)
  #elif defined(__ICCARM__)
  #define PORT_IRQ_PROLOGUE()                                                 \
    regarm_t _saved_lr = (regarm_t)__get_LR()
  #elif defined(__CC_ARM)
  #define PORT_IRQ_PROLOGUE()                                                 \
    regarm_t _saved_lr = (regarm_t)__return_address()
  #endif
  
  /**
   * @brief   IRQ epilogue code.
   * @details This macro must be inserted at the end of all IRQ handlers
   *          enabled to invoke system APIs.
   */
  #define PORT_IRQ_EPILOGUE() _port_irq_epilogue(_saved_lr)
  
  /**
   * @brief   IRQ handler function declaration.
   * @note    @p id can be a function name or a vector number depending on the
   *          port implementation.
   */
  #define PORT_IRQ_HANDLER(id) void id(void)
  
  /**
   * @brief   Fast IRQ handler function declaration.
   * @note    @p id can be a function name or a vector number depending on the
   *          port implementation.
   */
  #define PORT_FAST_IRQ_HANDLER(id) void id(void)
  
  /**
   * @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.
   *
   * @param[in] ntp       the thread to be switched in
   * @param[in] otp       the thread to be switched out
   */
  #if !CH_DBG_ENABLE_STACK_CHECK || defined(__DOXYGEN__)
  #define port_switch(ntp, otp) _port_switch(ntp, otp)
  #else
  #define port_switch(ntp, otp) {                                             \
    struct port_intctx *r13 = (struct port_intctx *)__get_PSP();              \
    if ((stkalign_t *)(r13 - 1) < (otp)->p_stklimit)                          \
      chSysHalt("stack overflow");                                            \
    _port_switch(ntp, otp);                                                   \
  }
  #endif
  
  /*===========================================================================*/
  /* External declarations.                                                    */
  /*===========================================================================*/
  
  #ifdef __cplusplus
  extern "C" {
  #endif
    void _port_irq_epilogue(regarm_t lr);
    void _port_switch(thread_t *ntp, thread_t *otp);
    void _port_thread_start(void);
    void _port_switch_from_isr(void);
    void _port_exit_from_isr(void);
  #ifdef __cplusplus
  }
  #endif
  
  /*===========================================================================*/
  /* Module inline functions.                                                  */
  /*===========================================================================*/
  
  /**
   * @brief   Port-related initialization code.
   */
  static inline void port_init(void) {
  
    NVIC_SetPriority(PendSV_IRQn, CORTEX_PRIORITY_PENDSV);
  }
  
  /**
   * @brief   Returns a word encoding the current interrupts status.
   *
   * @return              The interrupts status.
   */
  static inline syssts_t port_get_irq_status(void) {
  
    return (syssts_t)__get_PRIMASK();
  }
  
  /**
   * @brief   Checks the interrupt status.
   *
   * @param[in] sts       the interrupt status word
   *
   * @return              The interrupt status.
   * @retvel false        the word specified a disabled interrupts status.
   * @retvel true         the word specified an enabled interrupts status.
   */
  static inline bool port_irq_enabled(syssts_t sts) {
  
    return (sts & 1) == 0;
  }
  
  /**
   * @brief   Determines the current execution context.
   *
   * @return              The execution context.
   * @retval false        not running in ISR mode.
   * @retval true         running in ISR mode.
   */
  static inline bool port_is_isr_context(void) {
  
    return (bool)((__get_IPSR() & 0x1FF) != 0);
  }
  
  /**
   * @brief   Kernel-lock action.
   * @details In this port this function disables interrupts globally.
   */
  static inline void port_lock(void) {
  
    __disable_irq();
  }
  
  /**
   * @brief   Kernel-unlock action.
   * @details In this port this function enables interrupts globally.
   */
  static inline void port_unlock(void) {
  
    __enable_irq();
  }
  
  /**
   * @brief   Kernel-lock action from an interrupt handler.
   * @details In this port this function disables interrupts globally.
   * @note    Same as @p port_lock() in this port.
   */
  static inline void port_lock_from_isr(void) {
  
    port_lock();
  }
  
  /**
   * @brief   Kernel-unlock action from an interrupt handler.
   * @details In this port this function enables interrupts globally.
   * @note    Same as @p port_lock() in this port.
   */
  static inline void port_unlock_from_isr(void) {
  
    port_unlock();
  }
  
  /**
   * @brief   Disables all the interrupt sources.
   */
  static inline void port_disable(void) {
  
    __disable_irq();
  }
  
  /**
   * @brief   Disables the interrupt sources below kernel-level priority.
   */
  static inline void port_suspend(void) {
  
    __disable_irq();
  }
  
  /**
   * @brief   Enables all the interrupt sources.
   */
  static inline void port_enable(void) {
  
    __enable_irq();
  }
  
  /**
   * @brief   Enters an architecture-dependent IRQ-waiting mode.
   * @details The function is meant to return when an interrupt becomes pending.
   *          The simplest implementation is an empty function or macro but this
   *          would not take advantage of architecture-specific power saving
   *          modes.
   * @note    Implemented as an inlined @p WFI instruction.
   */
  static inline void port_wait_for_interrupt(void) {
  
  #if CORTEX_ENABLE_WFI_IDLE
    __WFI();
  #endif
  }
  
  #endif /* _FROM_ASM_ */
  
  #endif /* _CHCORE_V6M_H_ */
  
  /** @} */
  