/**
 * tvm.c
 * By Jose Solorzano.
 * Some functions adapded from Kekoa Proudfoot's firmdl.c,
 * described in comment below. License information also below.
 */

/*
 *  firmdl.c
 *
 *  A hack to download firmware to the RCX.
 *
 *  usage: firmdl Firm0309.lgo
 *
 *  Under IRIX, Linux, and Solaris, you should be able to compile this
 *  program with cc firmdl.c -o firmdl.  I don't know about other versions
 *  of Unix, although I'd be interested in hearing about compatibility
 *  issues that you are able to fix.
 *
 *  Set DEFAULTTTY to the serial device you want to use.
 *  Set the RCXTTY environment variable to override DEFAULTTTY.
 *
 *  Based on send.c and srec.c.  Maybe someday I will distribute my tools
 *  as multiple files...
 *
 *  Some additional documentation is available at:
 *
 *     http://graphics.stanford.edu/~kekoa/rcx/tools.html
 *
 *  Acknowledgements:
 *
 *     Laurent Demailly pointed out I didn't transfer some fixes from
 *        send.c over to this file.  He also mentioned that this program
 *        compiles fine under Solaris 2.6.
 *     Allen Martin mentioned his modification of not sending all 4K if the
 *        firmware is shorter than that.  I discovered that the correct way 
 *        to do this was to send everything but the trailing zero bytes,
 *        and before I had a chance to implement this, Markus Noga sent me
 *        the changes needed to implement this.  I incorporated the changes
 *        with modifications, plus a few others to make the software a bit
 *        more robust.
 *     Markus forwarded a message from Gavin Smyth that pointed out a
 *        problem with an uninitialized variable.  Gavin also pointed out
 *        that this program compiles fine under Cygwin.
 *     In a separate message, Gavin suggested a small change to shorten the
 *        0.3 ms pause during the download.
 *     Luis Villa noticed a problem with certain s-record files; the
 *        problem turned out to be long S0 records generated by the linker.
 *        Changed the source to allow these (improper?) records.
 */

/*
 *  Copyright (C) 1998, 1999, Kekoa Proudfoot.  All Rights Reserved.
 *
 *  License to copy, use, and modify this software is granted provided that
 *  this notice is retained in any copies of any part of this software.
 *
 *  The author makes no guarantee that this software will compile or
 *  function correctly.  Also, if you use this software, you do so at your
 *  own risk.
 * 
 *  Kekoa Proudfoot
 *  kekoa@graphics.stanford.edu
 *  10/3/98
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>
#include <ctype.h>
#include <string.h>

#include <magic.h>

typedef unsigned char byte;

// This is for CygWin:

#ifndef O_BINARY
#define O_BINARY 0
#endif

#if defined(LINUX) || defined(linux)
#define DEFAULTTTY   "/dev/ttyS0" /* Linux - COM1 */
#elif defined (_WIN32) || defined(__CYGWIN32__)
#define DEFAULTTTY   "com1"       /* Cygwin - COM1 */
#elif defined (sun)
#define DEFAULTTTY   "/dev/ttya"  /* Solaris - first serial port - untested */
#else
#define DEFAULTTTY   "/dev/ttyd2" /* IRIX - second serial port */
#endif

#define DEBUG 0
#define ERR_NOECHO  -1
#define ERR_BADECHO -2

char *progname;

/* RCX routines */

#define BUFFERSIZE      4096
#define TOWRITEMAX      100
#define RETRIES         5
#define RESPONSE_LENGTH 11

long receive_packet (long fd, byte *buffer, long length);

long
rcx_init(char *tty)
{
    long fd;
    struct termios ios;

    if ((fd = open(tty, O_RDWR)) < 0) {
	perror("open");
	exit(1);
    }

    if (!isatty(fd)) {
	close(fd);
	fprintf(stderr, "%s: not a tty\n", tty);
	exit(1);
    }

    memset(&ios, 0, sizeof(ios));
    ios.c_cflag = CREAD | CLOCAL | CS8 | PARENB | PARODD;
    cfsetispeed(&ios, B2400);
    cfsetospeed(&ios, B2400);

    if (tcsetattr(fd, TCSANOW, &ios) == -1) {
	perror("tcsetattr");
	exit(1);
    }

    return fd;
}

static void sleep_us (unsigned long us)
{
  struct timeval tval;

  tval.tv_sec = us / 1000000;
  tval.tv_usec = us % 1000000;
  select (0, NULL, NULL, NULL, &tval);	
}

void
rcx_close(long fd)
{
    close(fd);
}

long send_message (long fd, byte opcode, byte *buffer, long length)
{
  byte *actualBuffer;
  byte *actualEcho;
  byte checkSum;
  long actualLength;
  long numWriten;
  long  i, response;

  // Compute checksum
  checkSum = 0;
  for (i = 0; i < length; i++)
    checkSum += buffer[i];
  checkSum += opcode;

  // Create header of actual bufer to be sent
  actualLength = (length + 2) * 2 + 3;
  actualBuffer = (byte *) malloc (actualLength);
  actualEcho = (byte *) malloc (actualLength);
  actualBuffer[0] = 0x55;
  actualBuffer[1] = 0xFF;
  actualBuffer[2] = 0x00;
  actualBuffer[3] = opcode;
  actualBuffer[4] = ~opcode;

  // Create rest of packet
  for (i = 0; i < length; i++)
  {  
    actualBuffer[i*2 + 5] = buffer[i];
    actualBuffer[i*2 + 6] = ~buffer[i];
  }
  actualBuffer[i*2 + 5] = checkSum;
  actualBuffer[i*2 + 6] = ~checkSum;

  #if DEBUG > 1
  for (i = 0; i < actualLength; i++)
  {
    printf ("%X ", (int) actualBuffer[i]);
  }
  printf ("\n");
  #endif  

  numWriten = write (fd, actualBuffer, actualLength);
  if (numWriten != actualLength)
  {
    fprintf (stderr, "Write error: Wrote only %d of %d bytes. Probably a "
                     "resource allocation problem.\n", (int) numWriten, (int) actualLength);
    exit (1);
  }

  #if DEBUG > 1
  printf ("Wrote %d bytes.\n", (int) numWriten);
  #endif

  response = receive_packet (fd, actualEcho, actualLength);
  if (response == -1)
    response = ERR_NOECHO;
  else
  {
    for (i = 0; i < actualLength; i++)
    {
      if (actualBuffer[i] != actualEcho[i])
      {
        #if DEBUG > 1
        printf ("%d != %d\n", (int) actualBuffer[i], (int) actualEcho[i]);
        #endif
        break;
      }
    }
    if (i < actualLength)
      response = ERR_BADECHO;
    else
      response = numWriten;
  }
  free (actualBuffer);
  free (actualEcho);
  return response;
}

long send_byte (long fd, byte data)
{
  return send_message (fd, (byte) 0xF7, &data, 1);
}

ushort get_checksum (byte *data, long length)
{
  long i;
  ushort checksum = 0;

  for (i = 0; i < length; i++)
    checksum += data[i];
  return checksum;
}

long start_firmware_download (long fd, ushort address, byte *data, long length)
{
  ushort checksum;
  byte buffer[5];

  checksum = get_checksum (data, length);
  buffer[0] = (byte) ((address >> 0) & 0xFF);
  buffer[1] = (byte) ((address >> 8) & 0xFF);
  buffer[2] = (byte) ((checksum >> 0) & 0xFF);
  buffer[3] = (byte) ((checksum >> 8) & 0xFF);
  buffer[4] = 0;
  return send_message (fd, 0x75, buffer, 5);
}

long transfer_data (long fd, ushort index, byte *buffer, long length)
{
  byte *actualBuffer;
  byte checkSum;
  long  actualLength;
  long  r, i;

  actualLength = length + 5;
  actualBuffer = (byte *) malloc (actualLength);
  actualBuffer[0] = (byte) ((index >> 0) & 0xFF);
  actualBuffer[1] = (byte) ((index >> 8) & 0xFF);
  actualBuffer[2] = (byte) ((length >> 0) & 0xFF);
  actualBuffer[3] = (byte) ((length >> 8) & 0xFF);
  checkSum = 0;
  for (i = 0; i < length; i++)
  {
    checkSum += buffer[i];
    actualBuffer[4 + i] = buffer[i];
  }
  actualBuffer[4 + i] = checkSum;
  r = send_message (fd, 0x45, actualBuffer, actualLength);
  free (actualBuffer);
  return r;
}

long receive_packet (long fd, byte *buffer, long length)
{
  long i;
  fd_set fds;
  struct timeval tv;
  long count;
  long offset;
  long numTries;

  offset = 0;
  numTries = 10;  
  while (numTries--)
  {
    while (offset < length)
    {
      FD_ZERO(&fds);
      FD_SET(fd, &fds);
      tv.tv_sec = 0;
      tv.tv_usec = 300000;
      if (select(FD_SETSIZE, &fds, NULL, NULL, &tv) == -1) {
        perror("select");
        exit(1);
      }
      if (!FD_ISSET(fd, &fds))
      {
        #if DEBUG > 1
        printf ("Retrying: %d\n", (int) numTries);
        #endif
        break;
      }
      if ((count = read(fd, &buffer[offset], length - offset)) == -1) {
	printf ("read error\n");
	exit(1);
      }
      #if DEBUG > 2
      printf ("Received %d bytes\n", (int) count);
      printf ("     ");
      for (i = offset; i < offset + count; i++)
      {
        printf ("%X ", (int) buffer[i]);
      }
      printf ("\n");
      #endif
      offset += count;
      if (offset >= length)
      {
        #if DEBUG > 1
        printf ("RCX responds: ");
        for (i = 0; i < length; i++)
        {
          printf ("%X ", (int) buffer[i]);
        }
        printf ("\n");
        #endif  
        return offset;
      }
    }
  }
  return -1;
}

void check_status (int code)
{
  switch (code)
  {
    case ERR_NOECHO:
      printf ("No echo from RCX. Try again.\n");
      exit(1);
    case ERR_BADECHO:
      printf ("Bad echo from RCX. Try again.\n");
      exit(1);
  }
}

int
main(int argc, char **argv)
{
    byte *pBinary;
    byte *pSend;
    byte response[RESPONSE_LENGTH];
    long i;
    long numRead;
    char *tty;
    long fd;
    long pDesc, pLength, pTotal;
    long r, index, rest, numToWrite, offset;

    if (argc != 2) {
        fprintf(stderr, "%s downloads a file written by the linker.\n", argv[0]);
	fprintf(stderr, "Use: %s filename\n", argv[0]);
	exit(1);
    }

    if ((pDesc = open(argv[1], O_RDONLY | O_BINARY)) == -1) {
	fprintf(stderr, "%s: failed to open file %s\n", argv[0], argv[1]);
	exit(1);
    }

    /* Open the serial port */

    tty = getenv("RCXTTY");
    if (tty == NULL)
    {
      printf ("RCXTTY not defined. Using: %s\n", DEFAULTTTY);
      tty = DEFAULTTTY;
    }

    fd = rcx_init(tty);

    pLength = lseek (pDesc, 0, SEEK_END);
    if (pLength > 0xFFFF)
    {
      printf ("Huge file: %d bytes\n", (int) pLength);
      exit (1);
    }
    lseek (pDesc, 0, SEEK_SET);
    pBinary = (void *) malloc (pLength);
    pTotal = 0;
    while (pTotal < pLength)
    {
      r = read (pDesc, pBinary + pTotal, pLength - pTotal);
      if (r == -1 || r == 0)
      {
        printf ("Unexpected EOF in %s. Read only %ld bytes.\n", argv[1], pTotal);
        exit (1);
      }
      pTotal += r;
    }
    if (pBinary[0] != ((MAGIC >> 8) & 0xFF) ||
        pBinary[1] != ((MAGIC >> 0) & 0xFF))
    {
      printf ("Magic number is not right. Linker used was for emulation only?\n");
      exit (1);
    }

    // Set program-download message
    
    response[0] = (byte) (MAGIC >> 8);
    response[1] = (byte) (MAGIC & 0xFF);
    send_message (fd, (byte) 0x12, response, 2);
    numRead = receive_packet (fd, response, RESPONSE_LENGTH);
    sleep_us (1000);
    if (numRead != RESPONSE_LENGTH)
    {
      printf (numRead == -1 ? "No response from RCX. " : "Bad response from RCX. ");
      printf ("Please make sure RCX has leJOS firmware "
              "and is in range. The firmware must be in program download mode. "
	      "Turn RCX off and on if necessary.\n");
      exit (1);
    }
    
    #if 0
    if (numRead != -1)
    {
      for (index = 0; index < numRead; index++)
      {
	printf ("byte %d = 0x%X\n", (int) index, (int) response[index]);
      }
    }
    #endif
    
    if (response[5] != (byte) (MAGIC >> 8) || response[7] != (byte) (MAGIC & 0xFF))
    {
      printf ("Unexpected response from RCX. The RCX either doesn't have valid leJOS firmware or "
              "it is not in program-download mode. (lejosfirmdl downloads firmware).\n");
      exit (1);
    }

    sleep_us (10000);    
    
    // Transfer data
    
    index = 0;
    rest = pLength;
    offset = 0;
    do {
      numToWrite = (rest > TOWRITEMAX) ? TOWRITEMAX : rest;
      index = (rest > TOWRITEMAX) ? index + 1 : 0;
      //printf ("transfering %ld\n", (long) index);
      transfer_data (fd, index, pBinary + offset, numToWrite);
      if (index != 0)
      {
        sleep_us (10000);
        numRead = receive_packet (fd, response, 9);
        //printf ("numread = %ld\n", numRead);
        if (numRead != 9)
        {
  	  fprintf (stderr, "transfer data: invalid response length.\n");
	  exit (1);
	}
        if (response[5] != 0)
        {
	  fprintf (stderr, "transfer data: RCX says there's an error.\n");
	  exit (1);
        }
      }
      rest -= numToWrite;
      offset += numToWrite;
      sleep_us (1000);
    } while (index != 0);   
    rcx_close(fd);
    exit(0);
}