text: /* mbed Microcontroller Library
   * Copyright (c) 2013-2016 Realtek Semiconductor Corp.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include "objects.h"
  #include <stddef.h>
  #include "us_ticker_api.h"
  #include "PeripheralNames.h"
  
  #define TICK_READ_FROM_CPU  0   // 1: read tick from CPU, 0: read tick from G-Timer
  #define SYS_TIM_ID      1   // the G-Timer ID for System
  #define APP_TIM_ID      6   // the G-Timer ID for Application
  
  static int us_ticker_inited = 0;
  static TIMER_ADAPTER TimerAdapter;
  
  extern HAL_TIMER_OP HalTimerOp;
  extern HAL_TIMER_OP_EXT HalTimerOpExt;
  
  VOID _us_ticker_irq_handler(IN  VOID *Data)
  {
      us_ticker_irq_handler();
  }
  
  void us_ticker_init(void) 
  {
      
      if (us_ticker_inited) return;
      us_ticker_inited = 1;
      
  
      // Initial a G-Timer
      TimerAdapter.IrqDis = 0;    // Enable Irq @ initial
      TimerAdapter.IrqHandle.IrqFun = (IRQ_FUN) _us_ticker_irq_handler;
      TimerAdapter.IrqHandle.IrqNum = TIMER2_7_IRQ;
      TimerAdapter.IrqHandle.Priority = 10;
      TimerAdapter.IrqHandle.Data = (u32)NULL;
      TimerAdapter.TimerId = APP_TIM_ID;
      TimerAdapter.TimerIrqPriority = 0;
      TimerAdapter.TimerLoadValueUs = 0xFFFFFFFF;
      TimerAdapter.TimerMode = USER_DEFINED;
  
      HalTimerOp.HalTimerInit((VOID*) &TimerAdapter);
  
      DBG_TIMER_INFO("%s: Timer_Id=%d\n", __FUNCTION__, APP_TIM_ID);
  }
  
  uint32_t us_ticker_read() 
  {
      uint32_t tick_cnt;
      uint32_t ticks_125ms;
      uint32_t ticks_remain;
      uint64_t us_tick;
  
      tick_cnt = HalTimerOp.HalTimerReadCount(SYS_TIM_ID);
      tick_cnt = 0xffffffff - tick_cnt;   // it's a down counter
      ticks_125ms = tick_cnt/(GTIMER_CLK_HZ/8);  //use 125ms as a intermediate unit; 
      ticks_remain = tick_cnt - (ticks_125ms*(GTIMER_CLK_HZ/8));  //calculate the remainder
      us_tick = ticks_125ms * 125000;  //change unit to us, 125ms is 125000 us
      us_tick += (ticks_remain * 1000000)/GTIMER_CLK_HZ;  //also use us as unit
  
      return ((uint32_t)us_tick);  //return ticker value in micro-seconds (us)
  }
  
  void us_ticker_set_interrupt(timestamp_t timestamp) 
  {
      uint32_t cur_time_us;
      uint32_t time_def;
  
  
      cur_time_us = us_ticker_read();
      if ((uint32_t)timestamp >= cur_time_us) {
          time_def = (uint32_t)timestamp - cur_time_us;
      } else {
          time_def = 0xffffffff - cur_time_us + (uint32_t)timestamp;
      }    
  
      if (time_def < TIMER_TICK_US) {
          time_def = TIMER_TICK_US;       // at least 1 tick
      }
      HalTimerOp.HalTimerDis((u32)TimerAdapter.TimerId);
      HalTimerOpExt.HalTimerReLoad((u32)TimerAdapter.TimerId, time_def);
      HalTimerOpExt.HalTimerIrqEn((u32)TimerAdapter.TimerId);
      HalTimerOp.HalTimerEn((u32)TimerAdapter.TimerId);
  
  }
  
  void us_ticker_disable_interrupt(void) 
  {
      HalTimerOp.HalTimerDis((u32)TimerAdapter.TimerId);
  }
  
  void us_ticker_clear_interrupt(void) 
  {
      HalTimerOp.HalTimerIrqClear((u32)TimerAdapter.TimerId);
  }
  