/*
 Software Uart For Stm32
 By Liyanboy74
 https://github.com/liyanboy74
*/

#include "softuart.h"

// Some internal define
#if (SoftUart_PARITY)
#define SoftUart_IDEF_LEN_C1 (SoftUart_DATA_LEN + 2)
#else
#define SoftUart_IDEF_LEN_C1 (SoftUart_DATA_LEN + 1)
#endif
#define SoftUart_IDEF_LEN_C2 (SoftUart_IDEF_LEN_C1 + SoftUart_STOP_Bit)

// All Soft Uart Config and State
SoftUart_S SUart;

// TX RX Data Buffer
SoftUartBuffer_S SUBuffer;

// For timing division
uint8_t SU_Timer = 0;

// Parity var
static uint8_t DV, PCount;

// Initial Soft Uart
SoftUart_S *SoftUartInit() {
  SUart.TxNComplated = 0;

  SUart.RxBitCounter = 0;
  SUart.RxBitShift = 0;
  SUart.RxIndex = 0;

  SUart.TxEnable = 0;
  SUart.RxEnable = 0;

  SUart.TxBitCounter = 0;
  SUart.TxBitShift = 0;
  SUart.TxIndex = 0;

  SUart.TxSize = 0;

  SUart.Buffer = &SUBuffer;

  SUart.RxTimingFlag = 0;
  SUart.RxBitOffset = 0;

  return &SUart;
}

// Send one bit to TX pin
void SoftUartTransmitBit(SoftUart_S *SU, uint8_t Bit0_1) {
  SU->TxPinValue = Bit0_1;
}

// Enable Soft Uart Receiving
SoftUartState_E SoftUartEnableRx() {
  SUart.RxEnable = 1;
  return SoftUart_OK;
}

// Disable Soft Uart Receiving
SoftUartState_E SoftUartDisableRx() {
  SUart.RxEnable = 0;
  return SoftUart_OK;
}

// Read Size of Received Data in buffer
uint8_t SoftUartRxAlavailable() { return SUart.RxIndex; }

// Move Received Data to Another Buffer
SoftUartState_E SoftUartReadRxBuffer(uint8_t *Buffer, uint8_t Len) {
  int i;
  for (i = 0; i < Len; i++) {
    Buffer[i] = SUart.Buffer->Rx[i];
  }
  for (i = 0; i < SUart.RxIndex; i++) {
    SUart.Buffer->Rx[i] = SUart.Buffer->Rx[i + Len];
  }
  SUart.RxIndex -= Len;
  return SoftUart_OK;
}

// Soft Uart Transmit Data Process
void SoftUartTxProcess(SoftUart_S *SU) {
  if (SU->TxEnable) {
    // Start
    if (SU->TxBitCounter == 0) {
      SU->TxNComplated = 1;
      SU->TxBitShift = 0;
      SoftUartTransmitBit(SU, 0);
      SU->TxBitCounter++;
      PCount = 0;
    }
    // Data
    else if (SU->TxBitCounter < (SoftUart_DATA_LEN + 1)) {
      DV = ((SU->Buffer->Tx[SU->TxIndex]) >> (SU->TxBitShift)) & 0x01;
      SoftUartTransmitBit(SU, DV);
      SU->TxBitCounter++;
      SU->TxBitShift++;

      if (DV) PCount++;
    }
    // Parity
    else if (SU->TxBitCounter < SoftUart_IDEF_LEN_C1) {
      // Check Even or Odd
      DV = PCount % 2;

      // if Odd Parity
      if (SoftUart_PARITY == 1) DV = !DV;

      SoftUartTransmitBit(SU, DV);
      SU->TxBitCounter++;
    }
    // Stop
    else if (SU->TxBitCounter < SoftUart_IDEF_LEN_C2) {
      SoftUartTransmitBit(SU, 1);
      SU->TxBitCounter++;
    }
    // Complete
    else if (SU->TxBitCounter == SoftUart_IDEF_LEN_C2) {
      // Reset Bit Counter
      SU->TxBitCounter = 0;

      // Ready To Send Another Data
      SU->TxIndex++;

      // Check Size of Data
      if (SU->TxSize > SU->TxIndex) {
        // Continue Sending
        SU->TxNComplated = 1;
        SU->TxEnable = 1;
      } else {
        // Finish
        SU->TxNComplated = 0;
        SU->TxEnable = 0;
      }
    }
  }
}

// Soft Uart Receive Data Process
void SoftUartRxDataBitProcess(SoftUart_S *SU, uint8_t B0_1) {
  if (SU->RxEnable) {
    // Start
    if (SU->RxBitCounter == 0) {
      // Start Bit is 0
      if (B0_1) return;

      SU->RxBitShift = 0;
      SU->RxBitCounter++;
      SU->Buffer->Rx[SU->RxIndex] = 0;
    }
    // Data
    else if (SU->RxBitCounter < (SoftUart_DATA_LEN + 1)) {
      SU->Buffer->Rx[SU->RxIndex] |= ((B0_1 & 0x01) << SU->RxBitShift);
      SU->RxBitCounter++;
      SU->RxBitShift++;
    }
    // Parity
    else if (SU->RxBitCounter < SoftUart_IDEF_LEN_C1) {
      // Need to be check
      // B0_1;
      SU->RxBitCounter++;
    }
    // Stop & Complete
    else if (SU->RxBitCounter < SoftUart_IDEF_LEN_C2) {
      SU->RxBitCounter = 0;
      SU->RxTimingFlag = 0;

      // Stop Bit must be 1
      if (B0_1) {
        // Received successfully
        // Change RX Buffer Index
        if ((SU->RxIndex) < (SoftUartRxBufferSize - 1)) (SU->RxIndex)++;
      }
      // if not : ERROR -> Overwrite data
    }
  }
}

// Wait Until Transmit Completed
// You do not usually need to use this function!
void SoftUartWaitUntilTxComplate() { while (SUart.TxNComplated); }

// Copy Data to Transmit Buffer and Start Sending
SoftUartState_E SoftUartPuts(uint8_t *Data, uint8_t Len) {
  int i;
  if (SUart.TxNComplated) return SoftUart_Error;
  SUart.TxIndex = 0;
  SUart.TxSize = Len;
  for (i = 0; i < Len; i++) {
    SUart.Buffer->Tx[i] = Data[i];
  }
  SUart.TxNComplated = 1;
  SUart.TxEnable = 1;
  return SoftUart_OK;
}

// Capture RX and Get BitOffset
uint8_t SoftUartScanRxPorts(SoftUart_S *SU) {
  uint8_t Buffer = 0x00, Bit;
  // Read RX GPIO Value
  Bit = SU->RxPinValue;
  // Starting conditions
  if (!SUart.RxBitCounter && !SUart.RxTimingFlag && !Bit) {
    // Save RX Bit Offset
    // Calculate middle position of data puls
    SUart.RxBitOffset = ((SU_Timer + 2) % 5);
    // Timing Offset is Set
    SUart.RxTimingFlag = 1;
  }
  // Add all RX GPIO State to Buffer
  Buffer |= (Bit & 0x01);
  return Buffer;
}

// SoftUartHandler must call in interrupt every 0.2*(1/BR)
// if BR=9600 then 0.2*(1/9600)=20.8333333 uS
void SoftUartHandler(void) {
  uint8_t SU_DBuffer;

  // Capture RX and Get BitOffset
  SU_DBuffer = SoftUartScanRxPorts(&SUart);
  // Receive Data if we in middle data pulse position
  if (SUart.RxBitOffset == SU_Timer) {
    SoftUartRxDataBitProcess(&SUart, (SU_DBuffer & 0x01));
  }

  // Sending always happens in the first time slot
  if (SU_Timer == 0) {
    // Transmit Data
    SoftUartTxProcess(&SUart);
  }

  // Timing process
  SU_Timer++;
  if (SU_Timer >= 5) SU_Timer = 0;
}