/**
 ******************************************************************************
 * @file    stm32_seq.c
 * @author  MCD Application Team
 * @brief   Simple sequencer implementation
 ******************************************************************************
 * @attention
 *
 * <h2><center>&copy; Copyright (c) 2019 STMicroelectronics.
 * All rights reserved.</center></h2>
 *
 * This software is licensed under terms that can be found in the LICENSE file
 * in the root directory of this software component.
 * If no LICENSE file comes with this software, it is provided AS-IS.
 *
 ******************************************************************************
 */

/* Includes ------------------------------------------------------------------*/
#include "stm32_seq.h"
#include "utilities_conf.h"

/** @addtogroup SEQUENCER
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
/** @defgroup SEQUENCER_Private_type SEQUENCER private type
 *  @{
 */

/**
 * @brief structure used to manage task scheduling
 */
typedef struct
{
  uint32_t priority;    /*!<bit field of the enabled task.          */
  uint32_t round_robin; /*!<mask on the allowed task to be running. */
} UTIL_SEQ_Priority_t;

/**
 * @}
 */

/* Private defines -----------------------------------------------------------*/

/** @defgroup SEQUENCER_Private_define SEQUENCER private defines
 *  @{
 */

/**
 * @brief macro used to enter the critical section before calling the IDLE function
 * @note  in a basic configuration shall be identical to the macro
 *        UTIL_SEQ_ENTER_CRITICAL_SECTION. The redefinition of this macro will allow
 *        to perform specific operation

 */
#ifndef UTIL_SEQ_ENTER_CRITICAL_SECTION_IDLE
  #define UTIL_SEQ_ENTER_CRITICAL_SECTION_IDLE( )    UTIL_SEQ_ENTER_CRITICAL_SECTION( )
#endif

/**
 * @brief macro used to exit the critical section when exiting the IDLE function
 * @note  the behavior of the macro shall be symmetrical with the macro
 *        UTIL_SEQ_ENTER_CRITICAL_SECTION_IDLE
 */
#ifndef UTIL_SEQ_EXIT_CRITICAL_SECTION_IDLE
  #define UTIL_SEQ_EXIT_CRITICAL_SECTION_IDLE( )     UTIL_SEQ_EXIT_CRITICAL_SECTION( )
#endif

/**
 * @brief define to represent no task running
 */
#define UTIL_SEQ_NOTASKRUNNING       (0xFFFFFFFFU)

/**
 * @brief define to represent no bit set inside uint32_t mapping
 */
#define UTIL_SEQ_NO_BIT_SET     (0U)

/**
 * @brief define to represent all bits set inside uint32_t mapping
 */
#define UTIL_SEQ_ALL_BIT_SET    (~0U)

/**
 * @brief default number of task is default 32 (maximum), can be reduced by redefining in utilities_conf.h
 */
#ifndef UTIL_SEQ_CONF_TASK_NBR
	#define UTIL_SEQ_CONF_TASK_NBR  (32)
#endif

#if UTIL_SEQ_CONF_TASK_NBR > 32
#error "UTIL_SEQ_CONF_PRIO_NBR must be less of equal then 32"
#endif

/**
 * @brief default value of priority number.
 */
#ifndef UTIL_SEQ_CONF_PRIO_NBR
  #define UTIL_SEQ_CONF_PRIO_NBR  (2)
#endif

/**
 * @brief default memset function.
 */
#ifndef UTIL_SEQ_MEMSET8
#define UTIL_SEQ_MEMSET8( dest, value, size )   UTILS_MEMSET8( dest, value, size )
#endif

/**
 * @}
 */

/* Private variables ---------------------------------------------------------*/

/** @defgroup SEQUENCER_Private_varaible SEQUENCER private variables
 *  @{
 */

/**
 * @brief task set.
 */
static volatile UTIL_SEQ_bm_t TaskSet;

/**
 * @brief task mask.
 */
static volatile UTIL_SEQ_bm_t TaskMask = UTIL_SEQ_ALL_BIT_SET;

/**
 * @brief super mask.
 */
static UTIL_SEQ_bm_t SuperMask = UTIL_SEQ_ALL_BIT_SET;

/**
 * @brief evt set mask.
 */
static volatile UTIL_SEQ_bm_t EvtSet = UTIL_SEQ_NO_BIT_SET;

/**
 * @brief evt expected mask.
 */
static volatile UTIL_SEQ_bm_t EvtWaited = UTIL_SEQ_NO_BIT_SET;

/**
 * @brief current task id.
 */
static uint32_t CurrentTaskIdx = 0U;

/**
 * @brief task function registered.
 */
static void (*TaskCb[UTIL_SEQ_CONF_TASK_NBR])( void );

/**
 * @brief task prio management.
 */
static volatile UTIL_SEQ_Priority_t TaskPrio[UTIL_SEQ_CONF_PRIO_NBR];

/**
 * @}
 */

/* Private function prototypes -----------------------------------------------*/
/** @defgroup SEQUENCER_Private_function SEQUENCER private functions
 *  @{
 */
uint8_t SEQ_BitPosition(uint32_t Value);

/**
 * @}
 */

/* Functions Definition ------------------------------------------------------*/

/** @addtogroup SEQUENCER_Exported_function SEQUENCER exported functions
 *  @{
 */
void UTIL_SEQ_Init( void )
{
  TaskSet = UTIL_SEQ_NO_BIT_SET;
  TaskMask = UTIL_SEQ_ALL_BIT_SET;
  SuperMask = UTIL_SEQ_ALL_BIT_SET;
  EvtSet = UTIL_SEQ_NO_BIT_SET;
  EvtWaited = UTIL_SEQ_NO_BIT_SET;
  CurrentTaskIdx = 0U;
  (void)UTIL_SEQ_MEMSET8((uint8_t *)TaskCb, 0, sizeof(TaskCb));
  for(uint32_t index = 0; index < UTIL_SEQ_CONF_PRIO_NBR; index++)
  {
      TaskPrio[index].priority = 0;
      TaskPrio[index].round_robin = 0;
  }
  UTIL_SEQ_INIT_CRITICAL_SECTION( );
}

void UTIL_SEQ_DeInit( void )
{
}

/**
 * This function can be nested.
 * That is the reason why many variables that are used only in that function are declared static.
 * Note: These variables could have been declared static in the function.
 *
 */
void UTIL_SEQ_Run( UTIL_SEQ_bm_t Mask_bm )
{
  uint32_t counter;
  UTIL_SEQ_bm_t current_task_set;
  UTIL_SEQ_bm_t super_mask_backup;
  UTIL_SEQ_bm_t local_taskset;
  UTIL_SEQ_bm_t local_evtset;
  UTIL_SEQ_bm_t local_taskmask;
  UTIL_SEQ_bm_t local_evtwaited;

  /*
   * When this function is nested, the mask to be applied cannot be larger than the first call
   * The mask is always getting smaller and smaller
   * A copy is made of the mask set by UTIL_SEQ_Run() in case it is called again in the task
   */
  super_mask_backup = SuperMask;
  SuperMask &= Mask_bm;

  /*
   * There are two independent mask to check:
   * TaskMask that comes from UTIL_SEQ_PauseTask() / UTIL_SEQ_ResumeTask
   * SuperMask that comes from UTIL_SEQ_Run
   * If the waited event is there, exit from  UTIL_SEQ_Run() to return to the
   * waiting task
   */
  local_taskset = TaskSet;
  local_evtset = EvtSet;
  local_taskmask = TaskMask;
  local_evtwaited =  EvtWaited;
  while(((local_taskset & local_taskmask & SuperMask) != 0U) && ((local_evtset & local_evtwaited)==0U))
  {
    counter = 0U;
    /*
     * When a flag is set, the associated bit is set in TaskPrio[counter].priority mask depending
     * on the priority parameter given from UTIL_SEQ_SetTask()
     * The while loop is looking for a flag set from the highest priority maskr to the lower
     */
    while((TaskPrio[counter].priority & local_taskmask & SuperMask)== 0U)
    {
      counter++;
    }

    current_task_set = TaskPrio[counter].priority & local_taskmask & SuperMask;

    /*
     * The round_robin register is a mask of allowed flags to be evaluated.
     * The concept is to make sure that on each round on UTIL_SEQ_Run(), if two same flags are always set,
     * the sequencer does not run always only the first one.
     * When a task has been executed, The flag is removed from the round_robin mask.
     * If on the next UTIL_SEQ_RUN(), the two same flags are set again, the round_robin mask will mask out the first flag
     * so that the second one can be executed.
     * Note that the first flag is not removed from the list of pending task but just masked by the round_robin mask
     *
     * In the check below, the round_robin mask is reinitialize in case all pending tasks haven been executed at least once
     */
    if ((TaskPrio[counter].round_robin & current_task_set) == 0U)
    {
      TaskPrio[counter].round_robin = UTIL_SEQ_ALL_BIT_SET;
    }

  /*
   * Read the flag index of the task to be executed
	 * Once the index is read, the associated task will be executed even though a higher priority stack is requested
	 * before task execution.
	 */
    CurrentTaskIdx = (SEQ_BitPosition(current_task_set & TaskPrio[counter].round_robin));

    /*
     * remove from the roun_robin mask the task that has been selected to be executed
     */
    TaskPrio[counter].round_robin &= ~(1U << CurrentTaskIdx);

    UTIL_SEQ_ENTER_CRITICAL_SECTION( );
    /* remove from the list or pending task the one that has been selected to be executed */
    TaskSet &= ~(1U << CurrentTaskIdx);
    /* remove from all priority mask the task that has been selected to be executed */
    for (counter = UTIL_SEQ_CONF_PRIO_NBR; counter != 0U; counter--)
    {
      TaskPrio[counter - 1U].priority &= ~(1U << CurrentTaskIdx);
    }
    UTIL_SEQ_EXIT_CRITICAL_SECTION( );

    /* Execute the task */
    TaskCb[CurrentTaskIdx]( );

    local_taskset = TaskSet;
    local_evtset = EvtSet;
    local_taskmask = TaskMask;
    local_evtwaited = EvtWaited;
  }

  /* the set of CurrentTaskIdx to no task running allows to call WaitEvt in the Pre/Post ilde context */
  CurrentTaskIdx = UTIL_SEQ_NOTASKRUNNING;
  UTIL_SEQ_PreIdle( );

  UTIL_SEQ_ENTER_CRITICAL_SECTION_IDLE( );
  local_taskset = TaskSet;
  local_evtset = EvtSet;
  local_taskmask = TaskMask;
  if ((local_taskset & local_taskmask & SuperMask) == 0U)
  {
    if ((local_evtset & EvtWaited)== 0U)
    {
      UTIL_SEQ_Idle( );
    }
  }
  UTIL_SEQ_EXIT_CRITICAL_SECTION_IDLE( );

  UTIL_SEQ_PostIdle( );

  /* restore the mask from UTIL_SEQ_Run() */
  SuperMask = super_mask_backup;

  return;
}

void UTIL_SEQ_RegTask(UTIL_SEQ_bm_t TaskId_bm, uint32_t Flags, void (*Task)( void ))
{
  (void)Flags;
  UTIL_SEQ_ENTER_CRITICAL_SECTION();

  TaskCb[SEQ_BitPosition(TaskId_bm)] = Task;

  UTIL_SEQ_EXIT_CRITICAL_SECTION();

  return;
}

void UTIL_SEQ_SetTask( UTIL_SEQ_bm_t TaskId_bm , uint32_t Task_Prio )
{
  UTIL_SEQ_ENTER_CRITICAL_SECTION( );

  TaskSet |= TaskId_bm;
  TaskPrio[Task_Prio].priority |= TaskId_bm;

  UTIL_SEQ_EXIT_CRITICAL_SECTION( );

  return;
}

uint32_t UTIL_SEQ_IsSchedulableTask( UTIL_SEQ_bm_t TaskId_bm)
{
  uint32_t _status;
  UTIL_SEQ_bm_t local_taskset;

  UTIL_SEQ_ENTER_CRITICAL_SECTION();

  local_taskset = TaskSet;
  _status = ((local_taskset & TaskMask & SuperMask & TaskId_bm) == TaskId_bm)? 1U: 0U;

  UTIL_SEQ_EXIT_CRITICAL_SECTION();
  return _status;
}

void UTIL_SEQ_PauseTask( UTIL_SEQ_bm_t TaskId_bm )
{
  UTIL_SEQ_ENTER_CRITICAL_SECTION( );

  TaskMask &= (~TaskId_bm);

  UTIL_SEQ_EXIT_CRITICAL_SECTION( );

  return;
}

uint32_t UTIL_SEQ_IsPauseTask( UTIL_SEQ_bm_t TaskId_bm )
{
  uint32_t _status;
  UTIL_SEQ_ENTER_CRITICAL_SECTION( );

  _status = ((TaskMask & TaskId_bm) == TaskId_bm) ? 0u:1u;

  UTIL_SEQ_EXIT_CRITICAL_SECTION( );
  return _status;
}

void UTIL_SEQ_ResumeTask( UTIL_SEQ_bm_t TaskId_bm )
{
  UTIL_SEQ_ENTER_CRITICAL_SECTION( );

  TaskMask |= TaskId_bm;

  UTIL_SEQ_EXIT_CRITICAL_SECTION( );

  return;
}

void UTIL_SEQ_SetEvt( UTIL_SEQ_bm_t EvtId_bm )
{
  UTIL_SEQ_ENTER_CRITICAL_SECTION( );

  EvtSet |= EvtId_bm;

  UTIL_SEQ_EXIT_CRITICAL_SECTION( );

  return;
}

void UTIL_SEQ_ClrEvt( UTIL_SEQ_bm_t EvtId_bm )
{
  UTIL_SEQ_ENTER_CRITICAL_SECTION( );

  EvtSet &= (~EvtId_bm);

  UTIL_SEQ_EXIT_CRITICAL_SECTION( );

  return;
}

void UTIL_SEQ_WaitEvt(UTIL_SEQ_bm_t EvtId_bm)
{
  UTIL_SEQ_bm_t event_waited_id_backup;
  UTIL_SEQ_bm_t current_task_idx;
  UTIL_SEQ_bm_t wait_task_idx;
  /*
   * store in local the current_task_id_bm as the global variable CurrentTaskIdx
   * may be overwritten in case there are nested call of UTIL_SEQ_Run()
   */
  current_task_idx = CurrentTaskIdx;
  if(UTIL_SEQ_NOTASKRUNNING == CurrentTaskIdx)
  {
    wait_task_idx = 0u;
  }
  else
  {
    wait_task_idx = (uint32_t)1u << CurrentTaskIdx;
  }

  /* backup the event id that was currently waited */
  event_waited_id_backup = EvtWaited;
  EvtWaited = EvtId_bm;
  /*
   * wait for the new event
   * note: that means that if the previous waited event occurs, it will not exit
   * the while loop below.
   * The system is waiting only for the last waited event.
   * When it will go out, it will wait again from the previous one.
   * It case it occurs while waiting for the second one, the while loop will exit immediately
   */

  while ((EvtSet & EvtId_bm) == 0U)
  {
    UTIL_SEQ_EvtIdle(wait_task_idx, EvtId_bm);
  }

  /*
   * Restore the CurrentTaskIdx that may have been modified by call of UTIL_SEQ_Run() from UTIL_SEQ_EvtIdle()
   * This is required so that a second call of UTIL_SEQ_WaitEvt() in the same process pass the correct current_task_id_bm
   * in the call of UTIL_SEQ_EvtIdle()
   */
  CurrentTaskIdx = current_task_idx;

  UTIL_SEQ_ENTER_CRITICAL_SECTION( );

  EvtSet &= (~EvtId_bm);

  UTIL_SEQ_EXIT_CRITICAL_SECTION( );

  EvtWaited = event_waited_id_backup;
  return;
}

UTIL_SEQ_bm_t UTIL_SEQ_IsEvtPend( void )
{
  UTIL_SEQ_bm_t local_evtwaited = EvtWaited;
  return (EvtSet & local_evtwaited);
}

__WEAK void UTIL_SEQ_EvtIdle( UTIL_SEQ_bm_t TaskId_bm, UTIL_SEQ_bm_t EvtWaited_bm )
{
  (void)EvtWaited_bm;
  UTIL_SEQ_Run(~TaskId_bm);
  return;
}

__WEAK void UTIL_SEQ_Idle( void )
{
  return;
}

__WEAK void UTIL_SEQ_PreIdle( void )
{
  /*
   * Unless specified by the application, there is nothing to be done
   */
  return;
}

__WEAK void UTIL_SEQ_PostIdle( void )
{
  /*
   * Unless specified by the application, there is nothing to be done
   */
  return;
}

/**
  * @}
  */

/** @addtogroup SEQUENCER_Private_function
 *  @{
 */

#if( __CORTEX_M == 0)
const uint8_t SEQ_clz_table_4bit[16U] = { 4U, 3U, 2U, 2U, 1U, 1U, 1U, 1U, 0U, 0U, 0U, 0U, 0U, 0U, 0U, 0U };
/**
 * @brief return the position of the first bit set to 1
 * @param Value 32 bit value
 * @retval bit position
 */
uint8_t SEQ_BitPosition(uint32_t Value)
{
uint8_t n = 0U;
uint32_t lvalue = Value;

  if ((lvalue & 0xFFFF0000U) == 0U)  { n  = 16U; lvalue <<= 16U;  }
  if ((lvalue & 0xFF000000U) == 0U)  { n +=  8U; lvalue <<=  8U;  }
  if ((lvalue & 0xF0000000U) == 0U)  { n +=  4U; lvalue <<=  4U;  }

  n += SEQ_clz_table_4bit[lvalue >> (32-4)];

  return (uint8_t)(31U-n);
}
#else
/**
 * @brief return the position of the first bit set to 1
 * @param Value 32 bit value
 * @retval bit position
 */
uint8_t SEQ_BitPosition(uint32_t Value)
{
  return (uint8_t)(31 -__CLZ( Value ));
}
#endif

/**
  * @}
  */

/**
  * @}
  */

