/*
 *  Copyright (c) 2013 Croatia Control Ltd. (www.crocontrol.hr)
 *
 *  This file is part of Asterix.
 *
 *  Asterix is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  Asterix 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with Asterix.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 * AUTHORS: Damir Salantic, Croatia Control Ltd.
 *
 */

/**

 * @file asterixhdlcparsing.cxx
 *
 * @brief Reading anf parsing of HDLC packets.
 *        HDLC data is in following format:
 *        1 byte - 0x01 (addr)
 *        1 byte - 0x03 (ctrl)
 *        N bytes - Asterix packet
 *        2 bytes - FCS
 *
 *
 * Based on :
 *      AtxRecorder.cpp
 *      Verzija 1.2 (3.10.2007.)
 *      (P) HK, HKZP d.o.o.
 *
 */

#include "asterixhdlcparsing.h"

//
// Podaci za proracun FCS
//
#define FCS_INIT  0xffff
#define FCS_GOOD  0xf0b8
unsigned short FCStab[256] = {
      0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
      0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
      0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
      0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
      0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
      0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
      0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
      0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
      0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
      0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
      0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
      0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
      0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
      0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
      0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
      0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
      0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
      0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
      0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
      0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
      0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
      0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
      0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
      0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
      0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
      0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
      0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
      0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
      0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
      0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
      0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
      0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
//
// Podaci za detekciju pocetka HDLC paketa
//
#define MIN_BLK 10		// najmanja prihvatljiva duljina HDLC paketa
#define MSK_LEN	4		// broj pocetnih okteta koji se testiraju
unsigned char Msk1[MSK_LEN] = {	0xFF, 0xFF, 0xF8, 0xFF };
unsigned char Msk2[MSK_LEN] = {	0x01, 0x03, 0x00, 0x00 };
//
// Bufferi
//
unsigned char  RxBuf [MAX_RXBUF];	// buffer za ucitavanje podatka s COM
unsigned char  cBuf  [MAX_CBUF];	// cirkularni buffer za ulazne podatke
unsigned char  Frame [MAX_FRM];		// HDLC paket

//
// Indeksi i brojaci
//
int iBuf = 0;	// index za upis slijedeceg okteta u cirkularni buffer
int nAtx = 0;	// trenutna duljina ASTERIX bloka

int iF = -1;    // index pocetka HDLC paketa (ili -1)
int iC = -1;    // index pocetka HDLC paketa u cirkularnom bufferu

int iNorthOK = 0; // 1 - ako treba ažurirati tablicu

unsigned long nByteIn = 0;
unsigned long nFrmOK = 0;
unsigned long nFrmErr = 0;
unsigned long nBytesErr = 0;
unsigned long Cat001 = 0;
unsigned long Cat002 = 0;
unsigned long Cat008 = 0;
unsigned long Cat016 = 0;
unsigned long CatErr = 0;

unsigned short test_hdlc_fcs( int iF, int iL );

int test_frame_iF( int iS );
int get_hdlc_frame( int iS, int MinLen );
//int get_atx_rec( int iS );
int proc_hdlc_frame( int len );

int GetAndResetFailedBytes()
{
  int ret = nBytesErr;
  nBytesErr = 0;
  return ret;
}

#if 0
/*-----------------------------------------------------------------------------------------*/
int _tmain(int argc, _TCHAR* argv[])
/*-----------------------------------------------------------------------------------------*/
{
	int retv = 0;
	int cnt = 0;

	pDEB = fopen( "AtxRecorder.TXT", "wt" );
	pATX = fopen( "AtxRecorder.BIN", "wb" );

// ucitaj podatke iz AtxRecorder.INI
	if( (retv = read_ini()) ) {
		printf( "\nError: read_ini() = %d", retv );
		getch();
		return 0;
	}
// otvori port za ASTERIX
	if( (retv = atx_open()) ) {
		printf( "\nError: atx_open() = %d", retv );
		getch();
		return 0;
	}
// testiraj i ocisti ulazni buffer
	if( !TestFile ) {
		if( atx_read() < 0 )
			hComAtx = INVALID_HANDLE_VALUE;
		if( atx_read() < 0 )
			hComAtx = INVALID_HANDLE_VALUE;
	}
	iBuf = 0;
//
// glavni proces
//
	int iF = -1;	// index pocetka HDLC paketa (ili -1)
	int iC = -1;	// index pocetka HDLC paketa u cirkularnom bufferu

	printf( "\n AtxRecorder _____________________________________________________________\n" );
	printf( "\n Ver 1.20, (P)2006 Hrvoje Kalinovcic" );
	printf( "\n Copyright (C)2006 Croatia Control Ltd. All rights reserved.\n" );
	printf( "\n Port = %s\n", ComAtx );
	printf( "\n -------------------------------------------------------------------------" );
	printf( "\n       Byte   Frames   Frames" );
	printf( "\n      Count    Valid      Bad   Cat001   Cat002   Cat008   Cat016   CatErr" );
	printf( "\n -------------------------------------------------------------------------\n" );

	// beskonacna petlja
	while( hComAtx != INVALID_HANDLE_VALUE ) {
		if( (retv = atx_read()) < 0 )
			hComAtx = INVALID_HANDLE_VALUE;
		nByteIn += retv;

		// bilo koja tipka prekida program
		while( kbhit() ) {
			getch();
			hComAtx = INVALID_HANDLE_VALUE;
		}

		// da li se u primljenim podacima nalazi kraj prethodnog paketa?
		if( iF != -1 ) {
			int len = get_hdlc_frame( iF, MIN_BLK );	// duljina HDLC paketa
			if( len ) {
				if( proc_hdlc_frame( len ) )
					iF = -1;
			}
		}

		// da li se u primljenim podacima nalazi pocetak novog HDLC paketa
		int i = (iC+1) % MAX_CBUF;
		while( i != iBuf ) {
			if( test_frame_iF( i ) ) {
				if( iF == -1 ) nFrmOK++;
				else           nFrmErr++;
				iF = iC = i;						// pocetak HDLC paketa
				break;
			}
			i = (i + 1) % MAX_CBUF;
		}

		printf( "%c%11lu%9lu%9lu%9lu%9lu%9lu%9lu%9lu",
			0x0D, nByteIn, nFrmOK, nFrmErr, Cat001, Cat002, Cat008, Cat016, CatErr );
	}
	printf( "\n\nAtxRecorder Stopped\n" );
	getch();
}
#endif


/*-----------------------------------------------------------------------------------------*/
int copy_to_cbuf( unsigned char* RxBuf, int Cnt )
//
// Copy Cnt bytes from RxBuf to cBuf
//
/*-----------------------------------------------------------------------------------------*/
{
	int j = 0;
	if( Cnt ) {
		for( j = 0; j < (int)Cnt; j++ ) {	// kopiraj u CBuf
			cBuf[iBuf++] = RxBuf[j];
			iBuf %= MAX_CBUF;
		}
	}
	return Cnt;	// ucitano Cnt novih podataka (moguce je i Cnt = 0)
}

unsigned char* get_next_hdlc_frame(int* pRetLen)
{
  // da li se u primljenim podacima nalazi kraj prethodnog paketa?
  if( iF != -1 )
  {
    int len = get_hdlc_frame( iF, MIN_BLK );        // duljina HDLC paketa
    if( len )
    {
      if( proc_hdlc_frame( len ) )
      {
        iF = -1;
        *pRetLen = len-4; // minus HDLC header and checksum
        return &Frame[2];
      }
    }
  }

  // da li se u primljenim podacima nalazi pocetak novog HDLC paketa
  int i = (iC+1) % MAX_CBUF;
  while( i != iBuf )
  {
    if( test_frame_iF( i ) )
    {
      if( iF == -1 )
      {
        nFrmOK++;
      }
      else
      {
        nBytesErr += i-iF;
        nFrmErr++;
      }
      iF = iC = i;                                            // pocetak HDLC paketa
      break;
    }
    i = (i + 1) % MAX_CBUF;
  }

  // da li se u primljenim podacima nalazi kraj prethodnog paketa?
  if( iF != -1 )
  {
    int len = get_hdlc_frame( iF, MIN_BLK );        // duljina HDLC paketa
    if( len )
    {
      if( proc_hdlc_frame( len ) )
      {
        iF = -1;
        *pRetLen = len-4; // minus HDLC header and checksum
        return &Frame[2];
      }
    }
  }

  return 0;
}

/*-----------------------------------------------------------------------------------------*/
int test_frame_iF( int iS )
//
// provjerava da li cBuf[iS] moze biti pocetak novog HDLC paketa
//
/*-----------------------------------------------------------------------------------------*/
{
	int i = iS;
	int m = 0;
	for( m = 0; m < MSK_LEN; m++ ) {
		if( i == iBuf )
			return 0;					// NE, kraj cirkularnog buffera
		if( (cBuf[i++] & Msk1[m]) ^ Msk2[m] )
			return 0;					// NE, ovaj byte nije prosao test
		i %= MAX_CBUF;
	}
	return 1; // DA, zadani "iS" moze biti pocetak novog HDLC paketa
}
/*-----------------------------------------------------------------------------------------*/
int get_hdlc_frame( int iF, int MinLen )
//
// vadi HDLC paket iz cirkularnog buffera i vraca duljinu HDLC paketa
// po kriteriju ispravnog HDLC FCS
// iF		- pocetak paketa u cBuf
// MinLen	- najmanja duljina HDLC paketa
//
/*-----------------------------------------------------------------------------------------*/
{
	int i = iF;
	int j = 0;
	while( i != iBuf ) {				// kopiraj podatke u buffer
		Frame[j++] = cBuf[i++];
		i %= MAX_CBUF;
		if( j >= MAX_FRM )
			break;
	}
	if( MinLen < MSK_LEN )				// ovo je besmisleno
		return 0;
	if( j < MinLen )
		return 0;						// nema jos dovoljno novih podataka

	for( i = MinLen-1; i < j; i++ ) {
		if( !test_hdlc_fcs( 0, i ) )
			return i+1;					// i je moguci zavrsetak HDLC paketa
	}
	return 0; // nema FCS_GOOD za ovaj IF
}
/*-----------------------------------------------------------------------------------------*/
unsigned short test_hdlc_fcs( int iF, int iL )
//
// provjerava HDLC FCS za dio buffera od &Frame[iF] do &Frame[iL]
// ako zadnja dva okteta daju ispravan HDLC FCS, rutina ce vratiti 0x0000
//
/*-----------------------------------------------------------------------------------------*/
{
    int len = iL-iF+1;
    unsigned short fcs = FCS_INIT;
    unsigned char *cp = &Frame[iF];

	while( len-- )
		fcs = (fcs >> 8) ^ FCStab[0xFF & (fcs ^ (*cp++))];

	return( fcs ^ FCS_GOOD );	// ispravan paket vraca 0x0000
}


/*-----------------------------------------------------------------------------------------*/
int proc_hdlc_frame( int len )
/*-----------------------------------------------------------------------------------------*/
{
/* Check if there are correct Asterix packet(s) in HDLC frame
 * HDLC frame format:
 * ----------------- ---------Asterix record 1-------    ---------Asterix record N-------       -----HDLC checksum---
 * [HLEN_H] [HLEN_L] [CAT] [ALEN_H] [ALEN_L] [payload] { [CAT] [ALEN_H] [ALEN_L] [payload]} ... [CHKSUM_H] [CHKSUM_L]
 */

  int len_to_check = len - 4; // len - [HLEN_H] [HLEN_L] [CHKSUM_H] [CHKSUM_L]
  int offset = 2;

  while(len_to_check > 0)
  {
    int cat = (int)Frame[offset]; // [CAT]
    int packet_len = (int)Frame[offset+1]; // [ALEN_H]
    packet_len <<= 8;
    packet_len |= (int)Frame[offset+2]; // [ALEN_L]

    switch( cat )
    {
            case 1:         Cat001++; break;
            case 2:         Cat002++; break;
            case 8:         Cat008++; break;
            case 16:        Cat016++; break;
            default:        CatErr++;
    }

    offset += packet_len;
    len_to_check -= packet_len;
  }

  return (len_to_check == 0);
}

