// ---------------------------------------------------------------------------
//   
//    New firmware for the Vaisala SPT11A manual paper tape reader
//    4/24/2016 by Erik Baigar, Munich, Germany
//    
//    No warranties - feel free to use as desired
//    Credits and link to my web page are highly welcome
//      http://www.baigar.de/
//      http://www.programmer-electronic-control.de/index.html
// 
//    To get in touch use email: erik@baigar.de
//   
// ---------------------------------------------------------------------------
// 

#include <stdio.h>
#include <stdlib.h>
#include <8051.h>

#define FALSE 0
#define TRUE  1

// -- RAM-Anschluesse
#define Sprocket P3_2
#define Red      P3_4
#define Green    P3_3
#define Yellow   P3_5

#define PRINTF printf

// ----------------------------------------------------------------
#define BUFFER_SIZE 8
volatile unsigned char data tx_tail;             // Transmit interrupt index.
volatile unsigned char data tx_head;             // Transmit write index.
static bit is_txing;                             // True when transmitting a character.
static unsigned char data tx_buf[BUFFER_SIZE];   // Transmit queue.

// ----------------------------------------------------------------
//  ####              #    #    #     #     #####
// #                  #    ##   #     #       #
//  ####   #####      #    # #  #     #       #
//      #             #    #  # #     #       #
// #    #             #    #   ##     #       #
//  ####              #    #    #     #       #
// ----------------------------------------------------------------
void init_ser (void)
{
  tx_tail = 0;
  tx_head = 0;
  is_txing = FALSE;                              // Not transmitting
  SCON = 0x50;
  TMOD = (TMOD & 0x0F) | 0x20;
  TH1 = 252;                                     // 256-(12000000/192)/2400 = 256-4 = 252
  PCON = 0x80;                                   // Double-clock, no power-down
  TR1 = 1;
  ES = 1;
  EA = 1;
}

// ---------------------------------------------------------------- 
//  ###   ######   #####
//   #    #     # #     #
//   #    #     # #     #
//   #    ######  #     #
//   #    #   #   #   # #
//   #    #    #  #    #
//  ###   #     #  #### #
// ---------------------------------------------------------------- 
void SerInt (void) interrupt 4 using 2
{
  if (RI)                                        // Receive character?
    {
      RI = 0;                                    // clear receive flag
    }

  if (TI)                                        // Transmit character?
    {
      TI = 0;                                    // Clear transmitter flag.
      if (tx_head == tx_tail)                    // Check to see if anymore characters to send?
        is_txing = FALSE;                        // No, indicate to ser_write_byte to set TI next time.
      else
        {
          is_txing = TRUE;                       // TI interrupt will occur at end of this character.
          SBUF = tx_buf[tx_tail++];              // Transmit character out serial port.
          if (tx_tail >= BUFFER_SIZE)            // Wrap pointer to beginning of buffer if at end.
            tx_tail = 0;
        }
    }
}

// ---------------------------------------------------------------------------
// 
//  #####   #    #   #####   ####   #    #    ##    #####
//  #    #  #    #     #    #    #  #    #   #  #   #    #
//  #    #  #    #     #    #       ######  #    #  #    #
//  #####   #    #     #    #       #    #  ######  #####
//  #       #    #     #    #    #  #    #  #    #  #   #
//  #        ####      #     ####   #    #  #    #  #    #
//           
// ---------------------------------------------------------------------------
void putchar (char buf)
{
  unsigned char next_head;

  tx_buf[tx_head] = buf;
  next_head = tx_head + 1;

  if (next_head >= BUFFER_SIZE)
    next_head = 0;

  // Wait until we can stick the next character into the queue.
  // prevent buffer over write
  while (next_head == tx_tail) { Red=0; };

  tx_head = next_head;
  if (is_txing == FALSE)
    TI = TRUE;
}


// ------------------------------------------------------------------------------
//
// #    #    ##       #    #    #
// ##  ##   #  #      #    ##   #
// # ## #  #    #     #    # #  #
// #    #  ######     #    #  # #
// #    #  #    #     #    #   ##
// #    #  #    #     #    #    #
//      
// ------------------------------------------------------------------------------
int j;

main ()
{
  Red   = 1;                                   
  Green = 0;
  Yellow= 1;

  Green = 1;

  init_ser ();

  PRINTF ("Manual PTR, FW1.01, 4/24/2016\r\nErik Baigar, Germany\r\n\r\n");

  Red=0;
  Green= 0;

  while (1==1) {
    j = 0;
    while (j<5) { if (Sprocket==0) { j++; } else { j=0;} ; }
    putchar((char)P1);
    Yellow=0;
    j = 0;
    while (j<5) { if (Sprocket==1) { j++; } else { j=0;} ; }
    Yellow=1;
    }
}