/*
  HardwareSerial.cpp - Hardware serial library for Wiring
*/

#include "HardwareSerial.h"
#include <uart_lib.h> 
#include "mik32_hal_irq.h"

// объект класса HardwareSerial для использования в arduino ide
HardwareSerial Serial;
void serialEvent() __attribute__((weak));
bool Serial0_available() __attribute__((weak));

void serialEventRun(void)
{
  if (Serial0_available && serialEvent && Serial0_available()) 
    serialEvent();
}


// Public Methods
void HardwareSerial::begin(unsigned long baud, uint8_t config)
{
  // find the frequency divider (F_CPU is in the preprocessor defines)
  uint32_t brr = (uint32_t)(F_CPU/baud); 
  if (brr < 16) // the driver says that the divisor must be at least 16
    brr = 16;

  // parse config
  uint32_t reg1config = UART_CONTROL1_RE_M | UART_CONTROL1_TE_M | UART_CONTROL1_RXNEIE_M;
  uint32_t reg2config = 0;
  uint32_t reg3config = 0;

  // first look at parity, because the parity bit is included in the data length
  bool useParity = true;                    
  if ((config >> 4) == 0)       // no - everything is zero, don't set anything in reg1config
    useParity = false;
  else if ((config >> 4) == 2)  // even
    reg1config |= UART_CONTROL1_PCE_M;
  else if ((config >> 4) == 3)  // odd
    reg1config |= (UART_CONTROL1_PCE_M | UART_CONTROL1_PS_M);

  // data length
  if (((config & 0x07) == 4) && (useParity == false))       // 7 bit + no parity
    // 7 bits without parity - configure 7 bits
    reg1config |= UART_CONTROL1_M_7BIT_M;
  else if (((config & 0x07) == 6) && (useParity == true))   // 8 bit + parity
    // 8 bits with parity - configure 9 bits
    reg1config |= UART_CONTROL1_M_9BIT_M;
  // if 7 bits with parity or 8 bits without parity - do not change anything, 
  // leaving the data length selected as 8 bits

  // stop bit                       // stop bit = 1 - everything is zero, don't set anything
  if  ((config >> 3) & (0x01 == 1)) // stop bit = 2
    reg2config |= UART_CONTROL2_STOP_1_M;

  // turn on the receiver and transmitter, apply the parsed config
  UART_Init(UART_0, brr, reg1config, reg2config, reg3config);
  // Enable level-based interrupts for the EPIC_UART_0 line, we have only receive interrupt enabled
  HAL_EPIC_MaskLevelSet(HAL_EPIC_UART_0_MASK);

  isInited = true;
}

void HardwareSerial::end()
{
  if (isInited)
  {
    // wait for the data to be sent if necessary
    flush();
    
    // disable clock
    __HAL_PCC_UART_0_CLK_DISABLE();
    HAL_EPIC_MaskLevelClear(HAL_EPIC_UART_0_MASK);

    // reconfigure pins to z state
    GPIO_InitTypeDef GPIO_InitStruct;
    memset(&GPIO_InitStruct, 0, sizeof(GPIO_InitStruct)); 
    GPIO_InitStruct.Pin = (HAL_PinsTypeDef)(GPIO_PIN_5 | GPIO_PIN_6);
    GPIO_InitStruct.Mode = HAL_GPIO_MODE_GPIO_INPUT;
    GPIO_InitStruct.Pull = HAL_GPIO_PULL_NONE;
    HAL_GPIO_Init(GPIO_0, &GPIO_InitStruct);
    // reset buffer indices
    _rx_buffer_head = _rx_buffer_tail = 0;

    isInited = false;
  }
}

int HardwareSerial::available(void)
{
  // free space in buffer
  return ((unsigned int)(SERIAL_RX_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail)) % SERIAL_RX_BUFFER_SIZE;
}

int HardwareSerial::availableForWrite(void)
{
  // don't use buffer
  return -1;
}

void HardwareSerial::rx_complete_irq(void)
{
  // find next index in buffer with upper limit
  uint8_t i = (uint8_t)(_rx_buffer_head + 1)%SERIAL_RX_BUFFER_SIZE;
  unsigned char c;
  // while there is something to receive, put the data into the buffer 
  // and edit the buffer index
  while (!UART_IsRxFifoEmpty(UART_0))
  {
    c = UART_ReadByte(UART_0);
    if (i != _rx_buffer_tail) 
    {
      // write if there is space in the buffer
      _rx_buffer[_rx_buffer_head] = c;
      _rx_buffer_head = i;
    }
  }
}

// wrapper for use in С-files
extern "C" void serial_handler_wrapper(void) 
{
    Serial.rx_complete_irq();
}

int HardwareSerial::peek(void)
{
  if (_rx_buffer_head == _rx_buffer_tail) // nothing to read
    return -1;
  else
    return _rx_buffer[_rx_buffer_tail];   // return first element 
}

int HardwareSerial::read(void)
{
  // if there is nothing to read, return -1
  if (_rx_buffer_head == _rx_buffer_tail)
    return -1;
  else 
  {
    // return first element and edit the buffer index
    unsigned char c = _rx_buffer[_rx_buffer_tail];
    _rx_buffer_tail = (uint8_t)(_rx_buffer_tail + 1)%SERIAL_RX_BUFFER_SIZE;
    return (int)c;
  }
}

// write byte
size_t HardwareSerial::write(uint8_t c)
{
  if (isInited)
  {
    UART_WriteByte(UART_0, c);
    UART_WaitTransmission(UART_0);
    return 1;
  }
  else
    return 0;
}

// write bytes buffer
size_t HardwareSerial::write(const uint8_t *buffer, size_t size)
{
  if (isInited)
  {
    size_t n = 0;
    while (size--) 
    {
      if (HardwareSerial::write(*buffer++))
        n++; 
      else 
        break;
    }
    return n;
  }
  else
    return 0;
}

void HardwareSerial::flush()
{
  // wait for the data transfer complete
  while((UART_0->FLAGS & UART_FLAGS_TC_M) == 0) 
    ;
}