/*!
 * \file      systime.c
 *
 * \brief     System time functions implementation.
 *
 * \copyright Revised BSD License, see section \ref LICENSE.
 *
 * \code
 *                ______                              _
 *               / _____)             _              | |
 *              ( (____  _____ ____ _| |_ _____  ____| |__
 *               \____ \| ___ |    (_   _) ___ |/ ___)  _ \
 *               _____) ) ____| | | || |_| ____( (___| | | |
 *              (______/|_____)_|_|_| \__)_____)\____)_| |_|
 *              (C)2013-2018 Semtech - STMicroelectronics
 *
 * \endcode
 *
 * \author    Miguel Luis ( Semtech )
 *
 * \author    Gregory Cristian ( Semtech )
 *
 * \author    MCD Application Team ( STMicroelectronics International )
 */
/**
******************************************************************************
 * @file  stm32_systime.c
 * @author  MCD Application Team
 * @brief   System time functions implementation
 ******************************************************************************
 * @attention
 *
 * <h2><center>&copy; Copyright (c) 2019 STMicroelectronics. 
 * All rights reserved.</center></h2>
 *
 * This software component is licensed by ST under BSD 3-Clause license,
 * the "License"; You may not use this file except in compliance with the 
 * License. You may obtain a copy of the License at:
 *            opensource.org/licenses/BSD-3-Clause
 *
 ******************************************************************************
 */

/* Includes ------------------------------------------------------------------*/
#include <stdio.h>
#include "stm32_systime.h"

/** @addtogroup SYS_TIME
  * @{
  */

/* Private defines -----------------------------------------------------------*/
/**
 * @defgroup SYS_TIME_private_defines SYS_TIME private defines
 *  @{
 */
 
/**
  * @brief number of day in leap year up to the end of February
  *
  */
#define END_OF_FEBRUARY_LEAP             60 //31+29

/**
  * @brief number of day in leap year up to the end of july
  *
  */
#define END_OF_JULY_LEAP              213 //31+29+...

/**
  * @brief number of day in normal year up to the end of February
  *
  */
#define END_OF_FEBRUARY_NORM             59 //31+28

/**
  * @brief number of day in normal year up to the end of july
  *
  */
#define END_OF_JULY_NORM              212 //31+28+...

/**
  * @brief delta is referenced to Unix time
  * @note UNIX time 0 = starts at 01:00:00, 01/01/1970
  * but calculation is easier from Monday 1st January 1968 
  *
  */
#define CALC_REF_YEAR                  68 

/**
  * @brief delta is referenced to Unix time
  * @note UNIX time 0 = starts at 01:00:00, 01/01/1970
  * but calculation is easier from Monday 1st January 1968 
  *
  */
#define CALC_REF_YEAR_TO_UNIX_REF_YEAR_COMPENSATION_IN_SECONDS  ( ( TM_DAYS_IN_LEAP_YEAR + TM_DAYS_IN_YEAR ) * TM_SECONDS_IN_1DAY )

/**
  * @brief month correction table of a normal year. To calculate the day number within a year
  * @note error compensation is between 0 and 2 days. 2 bits per month
  *
  */
#define  DAYS_IN_MONTH_CORRECTION_NORM        ( (uint32_t )0x99AAA0 )

/**
  * @brief month correction table of a leap year. To calculate the day number within a year
  * @note error compensation is between 0 and 2 days. 2 bits per month
  *
  */
#define  DAYS_IN_MONTH_CORRECTION_LEAP        ( (uint32_t )0x445550 )

/**
  * @brief find  X/365.25
  *
  */
/* 365.25 = (366 + 365 + 365 + 365)/4 */
#define DIV_365_25( X )                 ( ( ( X ) * 91867 + 22750 ) >> 25 )

/**
  * @brief find the nearest quotient of X/86400 (8640 number of seconds in one week)
  *
  */
#define DIV_APPROX_86400( X )             ( ( ( X ) >> 18 ) + ( ( X ) >> 17 ) )

/**
  * @brief find the nearest quotient of X/1000
  *
  */
#define DIV_APPROX_1000( X )            ( ( ( X ) >> 10 ) +( ( X ) >> 16 ) + ( ( X ) >> 17 ) )

/**
  * @brief find the nearest quotient of X/60
  *
  */
#define DIV_APPROX_60( X )              ( ( ( X ) * 17476 ) >> 20 )

/**
  * @brief find the nearest quotient of X/61
  *
  */
#define DIV_APPROX_61( X )              ( ( ( X ) * 68759 ) >> 22 )

/**
  * @brief Calculates mod(x,7)
  *
  */
#define MODULO_7( X )                 ( ( X ) -( ( ( ( ( X ) + 1 ) * 299593 ) >> 21 ) * 7 ) )

/**
  * @brief Calculates ceiling( X / N )
  *
  */
#define DIVC( X, N )                ( ( ( X ) + ( N ) -1 ) / ( N ) )

/**
  * @brief Calculates ceiling( X / 4 )
  *
  */
#define DIVC_BY_4( X )                ( ( ( X ) + 3 ) >>2 )

/**
  * @brief Calculates ceiling( X / 2 )
  *
  */
#define DIVC_BY_2( X )                ( ( ( X ) + 1 ) >> 1 )
/**
  *  @}
  */

/* Private constants -----------------------------------------------------------*/
/**
 * @defgroup SYSTIME_private_variable SYSTIME private constants
 *  @{
 */
const char *WeekDayString[]={ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
/**
  *  @}
  */

/* Private function prototypes -----------------------------------------------*/

/**
 * @defgroup SYSTIME_private_function_prototypes SYSTIME private function prototypes
 *  @{
 */
static uint32_t CalendarGetMonth( uint32_t days, uint32_t year );
static void CalendarDiv86400( uint32_t in, uint32_t* out, uint32_t* remainder );
static uint32_t CalendarDiv61( uint32_t in );
static void CalendarDiv60( uint32_t in, uint32_t* out, uint32_t* remainder );
/**
  *  @}
  */

/* Functions Definition ------------------------------------------------------*/
/**
  * @addtogroup SYSTIME_exported_function
  *  @{
  */

SysTime_t SysTimeAdd( SysTime_t a, SysTime_t b )
{
  SysTime_t c =  { .Seconds = 0, .SubSeconds = 0 };

  c.Seconds = a.Seconds + b.Seconds;
  c.SubSeconds = a.SubSeconds + b.SubSeconds;
  if( c.SubSeconds >= 1000 )
  {
    c.Seconds++;
    c.SubSeconds -= 1000;
  }
  return c;
}

SysTime_t SysTimeSub( SysTime_t a, SysTime_t b )
{
  SysTime_t c = { .Seconds = 0, .SubSeconds = 0 };

  c.Seconds = a.Seconds - b.Seconds;
  c.SubSeconds = a.SubSeconds - b.SubSeconds;
  if( c.SubSeconds < 0 )
  {
    c.Seconds--;
    c.SubSeconds += 1000;
  }
  return c;
}

void SysTimeSet( SysTime_t sysTime )
{
  SysTime_t DeltaTime;
  
  SysTime_t calendarTime = { .Seconds = 0, .SubSeconds = 0 };

  calendarTime.Seconds = UTIL_SYSTIMDriver.GetCalendarTime( ( uint16_t* )&calendarTime.SubSeconds );

  // sysTime is UNIX epoch
  DeltaTime = SysTimeSub( sysTime, calendarTime );

  UTIL_SYSTIMDriver.BKUPWrite_Seconds( DeltaTime.Seconds );
  UTIL_SYSTIMDriver.BKUPWrite_SubSeconds( ( uint32_t ) DeltaTime.SubSeconds );
}

SysTime_t SysTimeGet( void )
{
  SysTime_t calendarTime = { .Seconds = 0, .SubSeconds = 0 };
  SysTime_t sysTime = { .Seconds = 0, .SubSeconds = 0 };
  SysTime_t DeltaTime;

  calendarTime.Seconds = UTIL_SYSTIMDriver.GetCalendarTime( ( uint16_t* )&calendarTime.SubSeconds );

  DeltaTime.SubSeconds = (int16_t)UTIL_SYSTIMDriver.BKUPRead_SubSeconds();
  DeltaTime.Seconds = UTIL_SYSTIMDriver.BKUPRead_Seconds();

  sysTime = SysTimeAdd( DeltaTime, calendarTime );

  return sysTime;
}


SysTime_t SysTimeGetMcuTime( void )
{
  SysTime_t calendarTime = { .Seconds = 0, .SubSeconds = 0 };

  calendarTime.Seconds = UTIL_SYSTIMDriver.GetCalendarTime( ( uint16_t* )&calendarTime.SubSeconds );
  
  return calendarTime;
}

uint32_t SysTimeToMs( SysTime_t sysTime )
{
  SysTime_t DeltaTime;
  DeltaTime.SubSeconds = (int16_t)UTIL_SYSTIMDriver.BKUPRead_SubSeconds();
  DeltaTime.Seconds = UTIL_SYSTIMDriver.BKUPRead_Seconds();
  
  SysTime_t calendarTime = SysTimeSub( sysTime, DeltaTime );
  return calendarTime.Seconds * 1000 + calendarTime.SubSeconds;
}

SysTime_t SysTimeFromMs( uint32_t timeMs )
{
  uint32_t seconds = timeMs / 1000;
  SysTime_t sysTime = { .Seconds = seconds, .SubSeconds =  timeMs - seconds * 1000 };
  SysTime_t DeltaTime = { 0 };

  DeltaTime.SubSeconds = (int16_t)UTIL_SYSTIMDriver.BKUPRead_SubSeconds();
  DeltaTime.Seconds = UTIL_SYSTIMDriver.BKUPRead_Seconds();
  return SysTimeAdd( sysTime, DeltaTime );
}

uint32_t SysTimeMkTime( const struct tm* localtime )
{
  uint32_t nbdays;
  uint32_t nbsecs;
  uint32_t year = localtime->tm_year - CALC_REF_YEAR;
  uint32_t correctionMonth[4] =
  {
    DAYS_IN_MONTH_CORRECTION_LEAP,
    DAYS_IN_MONTH_CORRECTION_NORM,
    DAYS_IN_MONTH_CORRECTION_NORM,
    DAYS_IN_MONTH_CORRECTION_NORM
  };

  nbdays = DIVC( ( TM_DAYS_IN_YEAR * 3 + TM_DAYS_IN_LEAP_YEAR ) * year, 4 );

  nbdays += ( DIVC_BY_2( ( localtime->tm_mon ) * ( 30 + 31 ) ) -
        ( ( ( correctionMonth[year % 4] >> ( ( localtime->tm_mon ) * 2 ) ) & 0x03 ) ) );

  nbdays += ( localtime->tm_mday - 1 );

  // Convert from days to seconds
  nbsecs = nbdays * TM_SECONDS_IN_1DAY;

  nbsecs += ( ( uint32_t )localtime->tm_sec + 
        ( ( uint32_t )localtime->tm_min * TM_SECONDS_IN_1MINUTE ) +
        ( ( uint32_t )localtime->tm_hour * TM_SECONDS_IN_1HOUR ) );
  return nbsecs - CALC_REF_YEAR_TO_UNIX_REF_YEAR_COMPENSATION_IN_SECONDS;
}

void SysTimeLocalTime( const uint32_t timestamp, struct tm *localtime )
{
  uint32_t correctionMonth[4] =
  {
    DAYS_IN_MONTH_CORRECTION_LEAP,
    DAYS_IN_MONTH_CORRECTION_NORM,
    DAYS_IN_MONTH_CORRECTION_NORM,
    DAYS_IN_MONTH_CORRECTION_NORM
  };
  uint32_t weekDays = 1; // Monday 1st January 1968
  uint32_t seconds;
  uint32_t minutes;
  uint32_t days;
  uint32_t divOut;
  uint32_t divReminder;

  CalendarDiv86400( timestamp + CALC_REF_YEAR_TO_UNIX_REF_YEAR_COMPENSATION_IN_SECONDS, &days, &seconds );

  // Calculates seconds
  CalendarDiv60( seconds, &minutes, &divReminder );
  localtime->tm_sec = ( uint8_t )divReminder;

  // Calculates minutes and hours
  CalendarDiv60( minutes, &divOut, &divReminder);
  localtime->tm_min = ( uint8_t )divReminder;
  localtime->tm_hour = ( uint8_t )divOut;

  // Calculates year
  localtime->tm_year = DIV_365_25( days );
  days-= DIVC_BY_4( ( TM_DAYS_IN_YEAR * 3 + TM_DAYS_IN_LEAP_YEAR ) * localtime->tm_year );

  localtime->tm_yday = days;

  // Calculates month
  localtime->tm_mon = CalendarGetMonth( days, localtime->tm_year );

  // calculates weekdays
  weekDays += DIVC_BY_4( ( localtime->tm_year * 5 ) );
  weekDays += days;
  localtime->tm_wday = MODULO_7( weekDays );

  days -= ( DIVC_BY_2( ( localtime->tm_mon ) * ( 30 + 31 ) ) -
        ( ( ( correctionMonth[localtime->tm_year % 4] >> ( ( localtime->tm_mon ) * 2 ) ) & 0x03 ) ) );

  // Convert 0 to 1 indexed.
  localtime->tm_mday = days + 1;

  localtime->tm_year += CALC_REF_YEAR;

  localtime->tm_isdst = -1;
}

/**
  *  @}
  */
  
/**************************** Private functions *******************************/

/**
  *  @addtogroup SYSTIME_private_function
  *
  *  @{
  */
static uint32_t CalendarGetMonth( uint32_t days, uint32_t year )
{
  uint32_t month;
  if( ( year % 4 ) == 0 )
  {   /*leap year*/
    if( days < END_OF_FEBRUARY_LEAP )
    {   // January or February
      // month =  days * 2 / ( 30 + 31 );
      month = CalendarDiv61( days * 2 );
    }
    else if( days < END_OF_JULY_LEAP )
    {
      month = CalendarDiv61( ( days - END_OF_FEBRUARY_LEAP ) * 2 ) + 2;
    }
    else
    {
      month = CalendarDiv61( ( days - END_OF_JULY_LEAP ) * 2 ) + 7;
    }
  }
  else
  {
    if( days < END_OF_FEBRUARY_NORM )
    {   // January or February
      month = CalendarDiv61( days * 2 );
    }
    else if( days < END_OF_JULY_NORM )
    {
      month = CalendarDiv61( ( days - END_OF_FEBRUARY_NORM ) * 2 ) + 2;
    }
    else
    {
      month = CalendarDiv61( ( days - END_OF_JULY_NORM ) * 2 ) + 7;
    }
  }
  return month;
}

static void CalendarDiv86400( uint32_t in, uint32_t* out, uint32_t* remainder )
{
#if 0
  *remainder = in % SECONDS_IN_1DAY;
  *out     = in / SECONDS_IN_1DAY;
#else
  uint32_t outTemp = 0;
  uint32_t divResult = DIV_APPROX_86400( in );

  while( divResult >=1 )
  {
    outTemp += divResult;
    in -= divResult * 86400;
    divResult= DIV_APPROX_86400( in );
  }
  if( in >= 86400 )
  {
    outTemp += 1;
    in -= 86400;
  }

  *remainder = in;
  *out = outTemp;
#endif
}

static uint32_t CalendarDiv61( uint32_t in )
{
#if 0
  return( in / 61 );
#else
  uint32_t outTemp = 0;
  uint32_t divResult = DIV_APPROX_61( in );
  while( divResult >=1 )
  {
    outTemp += divResult;
    in -= divResult * 61;
    divResult = DIV_APPROX_61( in );
  }
  if( in >= 61 )
  {
    outTemp += 1;
    in -= 61;
  }
  return outTemp;
#endif
}

static void CalendarDiv60( uint32_t in, uint32_t* out, uint32_t* remainder )
{
#if 0
  *remainder = in % 60;
  *out     = in / 60;
#else
  uint32_t outTemp = 0;
  uint32_t divResult = DIV_APPROX_60( in );

  while( divResult >=1 )
  {
    outTemp += divResult;
    in -= divResult * 60;
    divResult = DIV_APPROX_60( in );
  }
  if( in >= 60 )
  {
    outTemp += 1;
    in -= 60;
  }
  *remainder = in;
  *out = outTemp;
#endif
}
/**
  *  @}
  */
  
/**
  *  @}
  */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

