/*
 * This is an example of terminal being the output for Mike Field's Tiny BASIC interpreter
 * Input comes from the serial monitor with the baud rate set to 9600. 
 *
 * Dave Curran 2013-09-28
 *
 * Arduino Terminal Library - Dave Curran (www.tynemouthsoftware.co.uk)
 * Concept and Microcontroller Firmware - Daryl Rictor, Grant Searle
 * Tiny BASIC - Mike Field
 *
 * The display microcontroller is wired as follows:
 * pin 28 (SCL) ==> Display pin 28 (SCL)
 * pin 27 (SDA) ==> Display pin 27 (SDA)
 * Arduino Reset ==> Display pin 1 (Reset) - Reset (Optional)
 *
 * The two I2C data lines need to be pulled high to 5V via 2K2 resistors.
 *
 */

#include <Terminal.h>

// Create a terminal in TWI mode
Terminal term;

#define ARDUINO 1

// ASCII Characters
#define CR		'\r'
#define NL		'\n'
#define TAB		'\t'
#define BELL	'\b'
#define SPACE   ' '
#define CTRLC	0x03
#define CTRLH	0x08
#define CTRLS	0x13
#define CTRLX	0x18

typedef short unsigned LINENUM;
#if ARDUINO
#define ECHO_CHARS 1
#else
#define ECHO_CHARS 0
#endif

static unsigned char program[1128]; // gives 1024 bytes free at startup,
static unsigned char *txtpos,*list_line;
static unsigned char expression_error;
static unsigned char *tempsp;

/***********************************************************/
// Keyword table and constants - the last character has 0x80 added to it
static unsigned char keywords[] = {
  'L','I','S','T'+0x80,
  'L','O','A','D'+0x80,
  'N','E','W'+0x80,
  'R','U','N'+0x80,
  'S','A','V','E'+0x80,
  'N','E','X','T'+0x80,
  'L','E','T'+0x80,
  'I','F'+0x80,
  'G','O','T','O'+0x80,
  'G','O','S','U','B'+0x80,
  'R','E','T','U','R','N'+0x80,
  'R','E','M'+0x80,
  'F','O','R'+0x80,
  'I','N','P','U','T'+0x80,
  'P','R','I','N','T'+0x80,
  'P','O','K','E'+0x80,
  'S','T','O','P'+0x80,
  'B','Y','E'+0x80,
  0
};

#define KW_LIST		0
#define KW_LOAD		1
#define KW_NEW		2
#define KW_RUN		3
#define KW_SAVE		4
#define KW_NEXT		5
#define KW_LET		6
#define KW_IF		7
#define KW_GOTO		8
#define KW_GOSUB	9
#define KW_RETURN	10
#define KW_REM		11
#define KW_FOR		12
#define KW_INPUT	13
#define KW_PRINT	14
#define KW_POKE		15
#define KW_STOP		16
#define KW_BYE		17
#define KW_DEFAULT	18

struct stack_for_frame {
  char frame_type;
  char for_var;
  short int terminal;
  short int step;
  unsigned char *current_line;
  unsigned char *txtpos;
};

struct stack_gosub_frame {
  char frame_type;
  unsigned char *current_line;
  unsigned char *txtpos;
};

static unsigned char func_tab[] = {
  'P','E','E','K'+0x80,
  'A','B','S'+0x80,
  0
};
#define FUNC_PEEK    0
#define FUNC_ABS	 1
#define FUNC_UNKNOWN 2

static unsigned char to_tab[] = {
  'T','O'+0x80,
  0
};

static unsigned char step_tab[] = {
  'S','T','E','P'+0x80,
  0
};

static unsigned char relop_tab[] = {
  '>','='+0x80,
  '<','>'+0x80,
  '>'+0x80,
  '='+0x80,
  '<','='+0x80,
  '<'+0x80,
  0
};

#define RELOP_GE		0
#define RELOP_NE		1
#define RELOP_GT		2
#define RELOP_EQ		3
#define RELOP_LE		4
#define RELOP_LT		5
#define RELOP_UNKNOWN	6

#define STACK_SIZE (sizeof(struct stack_for_frame)*5)
#define VAR_SIZE sizeof(short int) // Size of variables in bytes

static unsigned char *stack_limit;
static unsigned char *program_start;
static unsigned char *program_end;
static unsigned char *stack; // Software stack for things that should go on the CPU stack
static unsigned char *variables_begin;
static unsigned char *current_line;
static unsigned char *sp;
#define STACK_GOSUB_FLAG 'G'
#define STACK_FOR_FLAG 'F'
static unsigned char table_index;
static LINENUM linenum;

static const unsigned char okmsg[]		= "OK";
static const unsigned char whatmsg[]	= "What? ";
static const unsigned char howmsg[]		=	"How?";
static const unsigned char sorrymsg[]	= "Sorry!";
static const unsigned char initmsg[]	= "TinyBasic in C V0.02.";
static const unsigned char memorymsg[]	= " bytes free.";
static const unsigned char breakmsg[]	= "break!";
static const unsigned char unimplimentedmsg[]	= "Unimplemented";
static const unsigned char backspacemsg[]		= "\b \b";

static int inchar(void);
static void outchar(unsigned char c);
static void line_terminator(void);
static short int expression(void);
static unsigned char breakcheck(void);
/***************************************************************************/
static void ignore_blanks(void)
{
  while(*txtpos == SPACE || *txtpos == TAB)
    txtpos++;
}

/***************************************************************************/
static void scantable(unsigned char *table)
{
  int i = 0;
  table_index = 0;
  while(1)
  {
    // Run out of table entries?
    if(table[0] == 0)
      return;

    // Do we match this character?
    if(txtpos[i] == table[0])
    {
      i++;
      table++;
    }
    else
    {
      // do we match the last character of keywork (with 0x80 added)? If so, return
      if(txtpos[i]+0x80 == table[0])
      {
        txtpos += i+1;  // Advance the pointer to following the keyword
        ignore_blanks();
        return;
      }

      // Forward to the end of this keyword
      while((table[0] & 0x80) == 0)
        table++;

      // Now move on to the first character of the next word, and reset the position index
      table++;
      table_index++;
      ignore_blanks();
      i = 0;
    }
  }
}

/***************************************************************************/
static void pushb(unsigned char b)
{
  sp--;
  *sp = b;
}

/***************************************************************************/
static unsigned char popb()
{
  unsigned char b;
  b = *sp;
  sp++;
  return b;
}

/***************************************************************************/
static void printnum(int num)
{
  int digits = 0;

  if(num < 0)
  {
    num = -num;
    outchar('-');
  }

  do {
    pushb(num%10+'0');
    num = num/10;
    digits++;
  }
  while (num > 0);

  while(digits > 0)
  {
    outchar(popb());
    digits--;
  }
}
/***************************************************************************/
static unsigned short testnum(void)
{
  unsigned short num = 0;
  ignore_blanks();

  while(*txtpos>= '0' && *txtpos <= '9' )
  {
    // Trap overflows
    if(num >= 0xFFFF/10)
    {
      num = 0xFFFF;
      break;
    }

    num = num *10 + *txtpos - '0';
    txtpos++;
  }
  return	num;
}

/***************************************************************************/
static void printmsgNoNL(const unsigned char *msg)
{
  while(*msg)
  {
    outchar(*msg);
    msg++;
  }
}

/***************************************************************************/
static unsigned char print_quoted_string(void)
{
  int i=0;
  unsigned char delim = *txtpos;
  if(delim != '"' && delim != '\'')
    return 0;
  txtpos++;

  // Check we have a closing delimiter
  while(txtpos[i] != delim)
  {
    if(txtpos[i] == NL)
      return 0;
    i++;
  }

  // Print the characters
  while(*txtpos != delim)
  {
    outchar(*txtpos);
    txtpos++;
  }
  txtpos++; // Skip over the last delimiter

  return 1;
}

/***************************************************************************/
static void printmsg(const unsigned char *msg)
{
  printmsgNoNL(msg);
  line_terminator();
}

/***************************************************************************/
static void getln(char prompt)
{
  outchar(prompt);
  txtpos = program_end+sizeof(LINENUM);

  while(1)
  {
    char c = inchar();
    switch(c)
    {
    case NL:
      break;
    case CR:
      line_terminator();
      // Terminate all strings with a NL
      txtpos[0] = NL;
      return;
    case CTRLH:
      if(txtpos == program_end)
        break;
      txtpos--;
      printmsg(backspacemsg);
      break;
    default:
      // We need to leave at least one space to allow us to shuffle the line into order
      if(txtpos == variables_begin-2)
        outchar(BELL);
      else
      {
        txtpos[0] = c;
        txtpos++;
#if ECHO_CHARS
        outchar(c);
#endif
      }
    }
  }
}

/***************************************************************************/
static unsigned char *findline(void)
{
  unsigned char *line = program_start;
  while(1)
  {
    if(line == program_end)
      return line;

    if(((LINENUM *)line)[0] >= linenum)
      return line;

    // Add the line length onto the current address, to get to the next line;
    line += line[sizeof(LINENUM)];
  }
}

/***************************************************************************/
static void toUppercaseBuffer(void)
{
  unsigned char *c = program_end+sizeof(LINENUM);
  unsigned char quote = 0;

  while(*c != NL)
  {
    // Are we in a quoted string?
    if(*c == quote)
      quote = 0;
    else if(*c == '"' || *c == '\'')
      quote = *c;
    else if(quote == 0 && *c >= 'a' && *c <= 'z')
      *c = *c + 'A' - 'a';
    c++;
  }
}

/***************************************************************************/
void printline()
{
  LINENUM line_num;

  line_num = *((LINENUM *)(list_line));
  list_line += sizeof(LINENUM) + sizeof(char);

  // Output the line */
  printnum(line_num);
  outchar(' ');
  while(*list_line != NL)
  {
    outchar(*list_line);
    list_line++;
  }
  list_line++;
  line_terminator();
}

/***************************************************************************/
static short int expr4(void)
{

  if(*txtpos == '0')
  {
    txtpos++;
    return 0;
  }

  if(*txtpos >= '1' && *txtpos <= '9')
  {
    short int a = 0;
    do 	{
      a = a*10 + *txtpos - '0';
      txtpos++;
    } 
    while(*txtpos >= '0' && *txtpos <= '9');
    return a;
  }

  // Is it a function or variable reference?
  if(txtpos[0] >= 'A' && txtpos[0] <= 'Z')
  {
    short int a;
    // Is it a variable reference (single alpha)
    if(txtpos[1] < 'A' || txtpos[1] > 'Z')
    {
      a = ((short int *)variables_begin)[*txtpos - 'A'];
      txtpos++;
      return a;
    }

    // Is it a function with a single parameter
    scantable(func_tab);
    if(table_index == FUNC_UNKNOWN)
      goto expr4_error;

    unsigned char f = table_index;

    if(*txtpos != '(')
      goto expr4_error;

    txtpos++;
    a = expression();
    if(*txtpos != ')')
      goto expr4_error;
    txtpos++;
    switch(f)
    {
    case FUNC_PEEK:
      return program[a];
    case FUNC_ABS:
      if(a < 0) 
        return -a;
      return a;
    }
  }

  if(*txtpos == '(')
  {
    short int a;
    txtpos++;
    a = expression();
    if(*txtpos != ')')
      goto expr4_error;

    txtpos++;
    return a;
  }

expr4_error:
  expression_error = 1;
  return 0;

}

/***************************************************************************/
static short int expr3(void)
{
  short int a,b;

  a = expr4();
  while(1)
  {
    if(*txtpos == '*')
    {
      txtpos++;
      b = expr4();
      a *= b;
    }
    else if(*txtpos == '/')
    {
      txtpos++;
      b = expr4();
      if(b != 0)
        a /= b;
      else
        expression_error = 1;
    }
    else
      return a;
  }
}

/***************************************************************************/
static short int expr2(void)
{
  short int a,b;

  if(*txtpos == '-' || *txtpos == '+')
    a = 0;
  else
    a = expr3();

  while(1)
  {
    if(*txtpos == '-')
    {
      txtpos++;
      b = expr3();
      a -= b;
    }
    else if(*txtpos == '+')
    {
      txtpos++;
      b = expr3();
      a += b;
    }
    else
      return a;
  }
}
/***************************************************************************/
static short int expression(void)
{
  short int a,b;

  a = expr2();
  // Check if we have an error
  if(expression_error)	return a;

  scantable(relop_tab);
  if(table_index == RELOP_UNKNOWN)
    return a;

  switch(table_index)
  {
  case RELOP_GE:
    b = expr2();
    if(a >= b) return 1;
    break;
  case RELOP_NE:
    b = expr2();
    if(a != b) return 1;
    break;
  case RELOP_GT:
    b = expr2();
    if(a > b) return 1;
    break;
  case RELOP_EQ:
    b = expr2();
    if(a == b) return 1;
    break;
  case RELOP_LE:
    b = expr2();
    if(a <= b) return 1;
    break;
  case RELOP_LT:
    b = expr2();
    if(a < b) return 1;
    break;
  }
  return 0;
}

/***************************************************************************/
void loop()
{
  unsigned char *start;
  unsigned char *newEnd;
  unsigned char linelen;

  program_start = program;
  program_end = program_start;
  sp = program+sizeof(program);  // Needed for printnum
  stack_limit = program+sizeof(program)-STACK_SIZE;
  variables_begin = stack_limit - 27*VAR_SIZE;
  printmsg(initmsg);
  printnum(variables_begin-program_end);
  printmsg(memorymsg);

warmstart:
  // this signifies that it is running in 'direct' mode.
  current_line = 0;
  sp = program+sizeof(program);  
  printmsg(okmsg);

prompt:
  getln('>');
  toUppercaseBuffer();

  txtpos = program_end+sizeof(unsigned short);

  // Find the end of the freshly entered line
  while(*txtpos != NL)
    txtpos++;

  // Move it to the end of program_memory
  {
    unsigned char *dest;
    dest = variables_begin-1;
    while(1)
    {
      *dest = *txtpos;
      if(txtpos == program_end+sizeof(unsigned short))
        break;
      dest--;
      txtpos--;
    }
    txtpos = dest;
  }

  // Now see if we have a line number
  linenum = testnum();
  ignore_blanks();
  if(linenum == 0)
    goto direct;

  if(linenum == 0xFFFF)
    goto qhow;

  // Find the length of what is left, including the (yet-to-be-populated) line header
  linelen = 0;
  while(txtpos[linelen] != NL)
    linelen++;
  linelen++; // Include the NL in the line length
  linelen += sizeof(unsigned short)+sizeof(char); // Add space for the line number and line length

  // Now we have the number, add the line header.
  txtpos -= 3;
  *((unsigned short *)txtpos) = linenum;
  txtpos[sizeof(LINENUM)] = linelen;


  // Merge it into the rest of the program
  start = findline();

  // If a line with that number exists, then remove it
  if(start != program_end && *((LINENUM *)start) == linenum)
  {
    unsigned char *dest, *from;
    unsigned tomove;

    from = start + start[sizeof(LINENUM)];
    dest = start;

    tomove = program_end - from;
    while( tomove > 0)
    {
      *dest = *from;
      from++;
      dest++;
      tomove--;
    }	
    program_end = dest;
  }

  if(txtpos[sizeof(LINENUM)+sizeof(char)] == NL) // If the line has no txt, it was just a delete
    goto prompt;



  // Make room for the new line, either all in one hit or lots of little shuffles
  while(linelen > 0)
  {	
    unsigned int tomove;
    unsigned char *from,*dest;
    unsigned int space_to_make;

    space_to_make = txtpos - program_end;

    if(space_to_make > linelen)
      space_to_make = linelen;
    newEnd = program_end+space_to_make;
    tomove = program_end - start;


    // Source and destination - as these areas may overlap we need to move bottom up
    from = program_end;
    dest = newEnd;
    while(tomove > 0)
    {
      from--;
      dest--;
      *dest = *from;
      tomove--;
    }

    // Copy over the bytes into the new space
    for(tomove = 0; tomove < space_to_make; tomove++)
    {
      *start = *txtpos;
      txtpos++;
      start++;
      linelen--;
    }
    program_end = newEnd;
  }
  goto prompt;

unimplemented:
  printmsg(unimplimentedmsg);
  goto prompt;

qhow:	
  printmsg(howmsg);
  goto prompt;

qwhat:	
  printmsgNoNL(whatmsg);
  if(current_line != NULL)
  {
    unsigned char tmp = *txtpos;
    if(*txtpos != NL)
      *txtpos = '^';
    list_line = current_line;
    printline();
    *txtpos = tmp;
  }
  line_terminator();
  goto prompt;

qsorry:	
  printmsg(sorrymsg);
  goto warmstart;

run_next_statement:
  while(*txtpos == ':')
    txtpos++;
  ignore_blanks();
  if(*txtpos == NL)
    goto execnextline;
  goto interperateAtTxtpos;

direct: 
  txtpos = program_end+sizeof(LINENUM);
  if(*txtpos == NL)
    goto prompt;

interperateAtTxtpos:
  if(breakcheck())
  {
    printmsg(breakmsg);
    goto warmstart;
  }

  scantable(keywords);

  switch(table_index)
  {
  case KW_LIST:
    goto list;
  case KW_LOAD:
    goto unimplemented; /////////////////
  case KW_NEW:
    if(txtpos[0] != NL)
      goto qwhat;
    program_end = program_start;
    goto prompt;
  case KW_RUN:
    current_line = program_start;
    goto execline;
  case KW_SAVE:
    goto unimplemented; //////////////////////
  case KW_NEXT:
    goto next;
  case KW_LET:
    goto assignment;
  case KW_IF:
    short int val;
    expression_error = 0;
    val = expression();
    if(expression_error || *txtpos == NL)
      goto qhow;
    if(val != 0)
      goto interperateAtTxtpos;
    goto execnextline;

  case KW_GOTO:
    expression_error = 0;
    linenum = expression();
    if(expression_error || *txtpos != NL)
      goto qhow;
    current_line = findline();
    goto execline;

  case KW_GOSUB:
    goto gosub;
  case KW_RETURN:
    goto gosub_return; 
  case KW_REM:	
    goto execnextline;	// Ignore line completely
  case KW_FOR:
    goto forloop; 
  case KW_INPUT:
    goto input; 
  case KW_PRINT:
    goto print;
  case KW_POKE:
    goto poke;
  case KW_STOP:
    // This is the easy way to end - set the current line to the end of program attempt to run it
    if(txtpos[0] != NL)
      goto qwhat;
    current_line = program_end;
    goto execline;
  case KW_BYE:
    // Leave the basic interperater
    return;
  case KW_DEFAULT:
    goto assignment;
  default:
    break;
  }

execnextline:
  if(current_line == NULL)		// Processing direct commands?
    goto prompt;
  current_line +=	 current_line[sizeof(LINENUM)];

execline:
  if(current_line == program_end) // Out of lines to run
    goto warmstart;
  txtpos = current_line+sizeof(LINENUM)+sizeof(char);
  goto interperateAtTxtpos;

input:
  {
    unsigned char var;
    ignore_blanks();
    if(*txtpos < 'A' || *txtpos > 'Z')
      goto qwhat;
    var = *txtpos;
    txtpos++;
    ignore_blanks();
    if(*txtpos != NL && *txtpos != ':')
      goto qwhat;
    ((short int *)variables_begin)[var-'A'] = 99;

    goto run_next_statement;
  }
forloop:
  {
    unsigned char var;
    short int initial, step, terminal;
    ignore_blanks();
    if(*txtpos < 'A' || *txtpos > 'Z')
      goto qwhat;
    var = *txtpos;
    txtpos++;
    ignore_blanks();
    if(*txtpos != '=')
      goto qwhat;
    txtpos++;
    ignore_blanks();

    expression_error = 0;
    initial = expression();
    if(expression_error)
      goto qwhat;

    scantable(to_tab);
    if(table_index != 0)
      goto qwhat;

    terminal = expression();
    if(expression_error)
      goto qwhat;

    scantable(step_tab);
    if(table_index == 0)
    {
      step = expression();
      if(expression_error)
        goto qwhat;
    }
    else
      step = 1;
    ignore_blanks();
    if(*txtpos != NL && *txtpos != ':')
      goto qwhat;


    if(!expression_error && *txtpos == NL)
    {
      struct stack_for_frame *f;
      if(sp + sizeof(struct stack_for_frame) < stack_limit)
        goto qsorry;

      sp -= sizeof(struct stack_for_frame);
      f = (struct stack_for_frame *)sp;
      ((short int *)variables_begin)[var-'A'] = initial;
      f->frame_type = STACK_FOR_FLAG;
      f->for_var = var;
      f->terminal = terminal;
      f->step     = step;
      f->txtpos   = txtpos;
      f->current_line = current_line;
      goto run_next_statement;
    }
  }
  goto qhow;

gosub:
  expression_error = 0;
  linenum = expression();
  if(!expression_error && *txtpos == NL)
  {
    struct stack_gosub_frame *f;
    if(sp + sizeof(struct stack_gosub_frame) < stack_limit)
      goto qsorry;

    sp -= sizeof(struct stack_gosub_frame);
    f = (struct stack_gosub_frame *)sp;
    f->frame_type = STACK_GOSUB_FLAG;
    f->txtpos = txtpos;
    f->current_line = current_line;
    current_line = findline();
    goto execline;
  }
  goto qhow;

next:
  // Fnd the variable name
  ignore_blanks();
  if(*txtpos < 'A' || *txtpos > 'Z')
    goto qhow;
  txtpos++;
  ignore_blanks();
  if(*txtpos != ':' && *txtpos != NL)
    goto qwhat;

gosub_return:
  // Now walk up the stack frames and find the frame we want, if present
  tempsp = sp;
  while(tempsp < program+sizeof(program)-1)
  {
    switch(tempsp[0])
    {
    case STACK_GOSUB_FLAG:
      if(table_index == KW_RETURN)
      {
        struct stack_gosub_frame *f = (struct stack_gosub_frame *)tempsp;
        current_line	= f->current_line;
        txtpos			= f->txtpos;
        sp += sizeof(struct stack_gosub_frame);
        goto run_next_statement;
      }
      // This is not the loop you are looking for... so Walk back up the stack
      tempsp += sizeof(struct stack_gosub_frame);
      break;
    case STACK_FOR_FLAG:
      // Flag, Var, Final, Step
      if(table_index == KW_NEXT)
      {
        struct stack_for_frame *f = (struct stack_for_frame *)tempsp;
        // Is the the variable we are looking for?
        if(txtpos[-1] == f->for_var)
        {
          short int *varaddr = ((short int *)variables_begin) + txtpos[-1] - 'A'; 
          *varaddr = *varaddr + f->step;
          // Use a different test depending on the sign of the step increment
          if((f->step > 0 && *varaddr <= f->terminal) || (f->step < 0 && *varaddr >= f->terminal))
          {
            // We have to loop so don't pop the stack
            txtpos = f->txtpos;
            current_line = f->current_line;
            goto run_next_statement;
          }
          // We've run to the end of the loop. drop out of the loop, popping the stack
          sp = tempsp + sizeof(struct stack_for_frame);
          goto run_next_statement;
        }
      }
      // This is not the loop you are looking for... so Walk back up the stack
      tempsp += sizeof(struct stack_for_frame);
      break;
    default:
      printf("Stack is stuffed!\n");
      goto warmstart;
    }
  }
  // Didn't find the variable we've been looking for
  goto qhow;

assignment:
  {
    short int value;
    short int *var;

    if(*txtpos < 'A' || *txtpos > 'Z')
      goto qhow;
    var = (short int *)variables_begin + *txtpos - 'A';
    txtpos++;

    ignore_blanks();

    if (*txtpos != '=')
      goto qwhat;
    txtpos++;
    ignore_blanks();
    expression_error = 0;
    value = expression();
    if(expression_error)
      goto qwhat;
    // Check that we are at the end of the statement
    if(*txtpos != NL && *txtpos != ':')
      goto qwhat;
    *var = value;
  }
  goto run_next_statement;
poke:
  {
    short int value;
    unsigned char *address;

    // Work out where to put it
    expression_error = 0;
    value = expression();
    if(expression_error)
      goto qwhat;
    address = (unsigned char *)value;

    // check for a comma
    ignore_blanks();
    if (*txtpos != ',')
      goto qwhat;
    txtpos++;
    ignore_blanks();

    // Now get the value to assign
    expression_error = 0;
    value = expression();
    if(expression_error)
      goto qwhat;
    printf("Poke %p value %i\n",address, (unsigned char)value);
    // Check that we are at the end of the statement
    if(*txtpos != NL && *txtpos != ':')
      goto qwhat;
  }
  goto run_next_statement;

list:
  linenum = testnum(); // Retuns 0 if no line found.

  // Should be EOL
  if(txtpos[0] != NL)
    goto qwhat;

  // Find the line
  list_line = findline();
  while(list_line != program_end)
    printline();
  goto warmstart;

print:
  // If we have an empty list then just put out a NL
  if(*txtpos == ':' )
  {
    line_terminator();
    txtpos++;
    goto run_next_statement;
  }
  if(*txtpos == NL)
  {
    goto execnextline;
  }

  while(1)
  {
    ignore_blanks();
    if(print_quoted_string())
    {
      ;
    }
    else if(*txtpos == '"' || *txtpos == '\'')
      goto qwhat;
    else
    {
      short int e;
      expression_error = 0;
      e = expression();
      if(expression_error)
        goto qwhat;
      printnum(e);
    }

    // At this point we have three options, a comma or a new line
    if(*txtpos == ',')
      txtpos++;	// Skip the comma and move onto the next
    else if(txtpos[0] == ';' && (txtpos[1] == NL || txtpos[1] == ':'))
    {
      txtpos++; // This has to be the end of the print - no newline
      break;
    }
    else if(*txtpos == NL || *txtpos == ':')
    {
      line_terminator();	// The end of the print statement
      break;
    }
    else
      goto qwhat;	
  }
  goto run_next_statement;
}

/***************************************************************************/
static void line_terminator(void)
{
  outchar(NL);
  outchar(CR);
}

/***********************************************************/
void setup()
{
#if ARDUINO
  Serial.begin(9600);	// opens serial port, sets data rate to 9600 bps
#endif
}

/***********************************************************/
static unsigned char breakcheck(void)
{
#if ARDUINO
  if(Serial.available())
    return Serial.read() == CTRLC;
  return 0;
#else
  if(kbhit())
    return getch() == CTRLC;
  else
    return 0;
#endif
}
/***********************************************************/
static int inchar()
{
#if ARDUINO
  while(1)
  {
    if(Serial.available())
      return Serial.read();
  }
#else
  return getchar();
#endif
}

/***********************************************************/
static void outchar(unsigned char c)
{
#if ARDUINO
  //Serial.write(c);
  term.send(c);
#else
  putchar(c);
#endif
}