/*
 * FreeModbus Libary: NuttX Port
 * Based on the FreeModbus Linux port by:
 *
 *   Copyright (C) 2006 Christian Walter <wolti@sil.at>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * File: $Id: portserial.c,v 1.3 2006/10/12 08:35:34 wolti Exp $
 */

/* ----------------------- Standard includes --------------------------------*/

#include <nuttx/config.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/select.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>

#ifdef CONFIG_SERIAL_TERMIOS
#  include <termios.h>
#endif

#include "port.h"

/* ----------------------- Modbus includes ----------------------------------*/

#include <apps/modbus/mb.h>
#include <apps/modbus/mbport.h>

/* ----------------------- Defines  -----------------------------------------*/

#ifdef CONFIG_MB_ASCII_ENABLED
#define BUF_SIZE    513         /* must hold a complete ASCII frame. */
#else
#define BUF_SIZE    256         /* must hold a complete RTU frame. */
#endif

/* ----------------------- Static variables ---------------------------------*/

static int      iSerialFd = -1;
static bool     bRxEnabled;
static bool     bTxEnabled;

static uint32_t ulTimeoutMs;
static uint8_t  ucBuffer[BUF_SIZE];
static int      uiRxBufferPos;
static int      uiTxBufferPos;

#ifdef CONFIG_SERIAL_TERMIOS
static struct termios xOldTIO;
#endif

/* ----------------------- Function prototypes ------------------------------*/

static bool     prvbMBPortSerialRead(uint8_t *pucBuffer, uint16_t usNBytes, uint16_t *usNBytesRead);
static bool     prvbMBPortSerialWrite(uint8_t *pucBuffer, uint16_t usNBytes);

/* ----------------------- Begin implementation -----------------------------*/

void vMBPortSerialEnable(bool bEnableRx, bool bEnableTx)
{
  /* it is not allowed that both receiver and transmitter are enabled. */

  ASSERT(!bEnableRx || !bEnableTx);

  if (bEnableRx)
    {
#ifdef CONFIG_SERIAL_TERMIOS
      (void)tcflush(iSerialFd, TCIFLUSH);
#endif
      uiRxBufferPos = 0;
      bRxEnabled = true;
    }
  else
    {
      bRxEnabled = false;
    }

  if (bEnableTx)
    {
      bTxEnabled = true;
      uiTxBufferPos = 0;
    }
  else
    {
      bTxEnabled = false;
    }
}

bool xMBPortSerialInit(uint8_t ucPort, uint32_t ulBaudRate,
                       uint8_t ucDataBits, eMBParity eParity)
{
  char szDevice[16];
  bool bStatus = true;

#ifdef CONFIG_SERIAL_TERMIOS
  struct termios xNewTIO;
#endif

  snprintf(szDevice, 16, "/dev/ttyS%d", ucPort);

  if ((iSerialFd = open(szDevice, O_RDWR | O_NOCTTY)) < 0)
    {
      vMBPortLog(MB_LOG_ERROR, "SER-INIT", "Can't open serial port %s: %d\n",
                 szDevice, errno);
    }

#ifdef CONFIG_SERIAL_TERMIOS
  else if (tcgetattr(iSerialFd, &xOldTIO) != 0)
    {
      vMBPortLog(MB_LOG_ERROR, "SER-INIT", "Can't get settings from port %s: %d\n",
                 szDevice, errno);
    }
  else
    {
      bzero(&xNewTIO, sizeof(struct termios));

      xNewTIO.c_iflag |= IGNBRK | INPCK;
      xNewTIO.c_cflag |= CREAD | CLOCAL;
      switch (eParity)
        {
          case MB_PAR_NONE:
            break;
          case MB_PAR_EVEN:
            xNewTIO.c_cflag |= PARENB;
            break;
          case MB_PAR_ODD:
            xNewTIO.c_cflag |= PARENB | PARODD;
            break;
          default:
            bStatus = false;
        }

      switch (ucDataBits)
        {
          case 8:
            xNewTIO.c_cflag |= CS8;
            break;
          case 7:
            xNewTIO.c_cflag |= CS7;
            break;
          default:
            bStatus = false;
        }

      if (bStatus)
        {
          /* Set the new baud using the (non-standard) BOTHER mechanism
           * supported by NuttX.
           */
 
          xNewTIO.c_ispeed = (speed_t)ulBaudRate;
          xNewTIO.c_ospeed = (speed_t)ulBaudRate;

          /* NOTE: In NuttX, cfset[i|o]speed always return OK.  Failures will
           * only be reported when tcsetattr() is called.
           */

          if (cfsetispeed(&xNewTIO, BOTHER) != 0 || cfsetospeed(&xNewTIO, BOTHER) != 0)
            {
              vMBPortLog(MB_LOG_ERROR, "SER-INIT", "Can't set baud rate %ld for port %s: %d\n",
                         ulBaudRate, szDevice, errno);
            }
          else if (tcsetattr(iSerialFd, TCSANOW, &xNewTIO) != 0)
            {
              vMBPortLog(MB_LOG_ERROR, "SER-INIT", "Can't set settings for port %s: %d\n",
                         szDevice, errno);
            }
          else
            {
              vMBPortSerialEnable(false, false);
              bStatus = true;
            }
        }
    }
#endif

  return bStatus;
}

bool xMBPortSerialSetTimeout(uint32_t ulNewTimeoutMs)
{
  if (ulNewTimeoutMs > 0)
    {
      ulTimeoutMs = ulNewTimeoutMs;
    }
  else
    {
      ulTimeoutMs = 1;
    }

  return true;
}

void vMBPortClose(void)
{
  if (iSerialFd != -1)
    {
#ifdef CONFIG_SERIAL_TERMIOS
      (void)tcsetattr(iSerialFd, TCSANOW, &xOldTIO);
#endif
      (void)close(iSerialFd);
      iSerialFd = -1;
    }
}

bool prvbMBPortSerialRead(uint8_t *pucBuffer, uint16_t usNBytes, uint16_t *usNBytesRead)
{
  bool            bResult = true;
  ssize_t         res;
  fd_set          rfds;
  struct timeval  tv;

  tv.tv_sec = 0;
  tv.tv_usec = 50000;
  FD_ZERO(&rfds);
  FD_SET(iSerialFd, &rfds);

  /* Wait until character received or timeout. Recover in case of an
   * interrupted read system call.
   */

  do
    {
      if (select(iSerialFd + 1, &rfds, NULL, NULL, &tv) == -1)
        {
          if (errno != EINTR)
            {
              bResult = false;
            }
        }
      else if (FD_ISSET(iSerialFd, &rfds))
        {
          if ((res = read(iSerialFd, pucBuffer, usNBytes)) == -1)
            {
              bResult = false;
            }
          else
            {
              *usNBytesRead = (uint16_t)res;
              break;
            }
        }
      else
        {
          *usNBytesRead = 0;
          break;
        }
    }

  while(bResult == true);
  return bResult;
}

bool prvbMBPortSerialWrite(uint8_t *pucBuffer, uint16_t usNBytes)
{
  ssize_t res;
  size_t  left = (size_t) usNBytes;
  size_t  done = 0;

  while(left > 0)
    {
      if ((res = write(iSerialFd, pucBuffer + done, left)) == -1)
        {
          if (errno != EINTR)
            {
              break;
            }

          /* call write again because of interrupted system call. */
          continue;
        }

      done += res;
      left -= res;
    }

  return left == 0 ? true : false;
}

bool
xMBPortSerialPoll()
{
    bool            bStatus = true;
    uint16_t        usBytesRead;
    int             i;

    while(bRxEnabled)
    {
        if (prvbMBPortSerialRead(&ucBuffer[0], BUF_SIZE, &usBytesRead))
        {
            if (usBytesRead == 0)
            {
                /* timeout with no bytes. */
                break;
            }
            else if (usBytesRead > 0)
            {
                for(i = 0; i < usBytesRead; i++)
                {
                    /* Call the modbus stack and let him fill the buffers. */
                    (void)pxMBFrameCBByteReceived();
                }
                uiRxBufferPos = 0;
            }
        }
        else
        {
            vMBPortLog(MB_LOG_ERROR, "SER-POLL", "read failed on serial device: %d\n",
                        errno);
            bStatus = false;
        }
    }
    if (bTxEnabled)
    {
        while(bTxEnabled)
        {
            (void)pxMBFrameCBTransmitterEmpty();
            /* Call the modbus stack to let him fill the buffer. */
        }
        if (!prvbMBPortSerialWrite(&ucBuffer[0], uiTxBufferPos))
        {
            vMBPortLog(MB_LOG_ERROR, "SER-POLL", "write failed on serial device: %d\n",
                        errno);
            bStatus = false;
        }
    }

    return bStatus;
}

bool
xMBPortSerialPutByte(int8_t ucByte)
{
    ASSERT(uiTxBufferPos < BUF_SIZE);
    ucBuffer[uiTxBufferPos] = ucByte;
    uiTxBufferPos++;
    return true;
}

bool
xMBPortSerialGetByte(int8_t *pucByte)
{
    ASSERT(uiRxBufferPos < BUF_SIZE);
    *pucByte = ucBuffer[uiRxBufferPos];
    uiRxBufferPos++;
    return true;
}