www.pudn.com > tcpipstack.rar > SEDSLIP.C

/* SEDSLIP.C - Use slip for tinytcp by emulating the sed entry points 
	This code is not derived in any way from the original Tiny-TCP 
	package. 
 
|===================================================================| 
|  My changes can be considered public domain.  Geof's statement    | 
|  will cover everything.                                           | 
|              - Rick Rodman 09/02/97                               | 
|===================================================================| 
 
	931213	rr	orig attempt 
	941010	rr	return int on all calls 
*/ 
 
/* #define DEBUG_SED */ 
 
#include "tinytcp.h" 
/* #include "sed.h" */ 
 
#include "casyncms.h"			/* async drivers for PC */ 
 
#ifdef PC 
/* #include  */ 
#endif 
#include  
 
/* ----- internal definitions --------------------------------------- */ 
 
#define	FR_END		0xC0	/* 0300 */ 
#define	FR_ESC		0xDB	/* 0333 */ 
#define	T_FR_END	0xDC	/* 0334 */ 
#define	T_FR_ESC	0xDD	/* 0335 */ 
 
#define	BUFFERSIZE	8192 
 
static	unsigned char	xmitbuffer[ BUFFERSIZE ]; 
static	unsigned char	recvbuffer[ BUFFERSIZE ]; 
 
/* ----- initialize the slip interface ------------------------------ */ 
 
int sed_Init() { 
	init_comm();		/* initialize the communications interface */ 
	inp_flush();		/* flush the input fifo */ 
 
	return 1; 
} 
 
/* ----- deinit the interface --------------------------------------- */ 
 
int sed_Deinit() { 
	uninit_comm(); 
	return 1; 
} 
 
/* ----- Format an ethernet header in the transmit buffer ----------- */ 
	/* return pointer to where to build the IP message */ 
 
Byte * sed_FormatPacket( destEAddr, ethType ) 
	Byte *destEAddr; int ethType; { 
 
	return ( Byte * ) &xmitbuffer[ 0 ];	/* return ptr to 1st Byte */ 
} 
 
/* ----- send a packet on the link ---------------------------------- */ 
 
int sed_Send( pkLengthInBytes ) int pkLengthInBytes; { 
	int		i; 
	unsigned char *	p_uc; 
 
	if( pkLengthInBytes <= 0 ) return 1;	/* nothing to do */  
 
	/* While sending, we have to process the escapes. 
		If we find an FR_END, change it to FR_ESC + T_FR_END. 
		If we find an FR_ESC, change it to FR_ESC + T_FR_ESC. */ 
 
	outp_char( FR_END );		/* send FR_END. */ 
	p_uc = &xmitbuffer[ 0 ]; 
 
	for( i = 0; i < pkLengthInBytes; ++i ) { 
		switch( *p_uc ) { 
		case FR_END: 
			outp_char( FR_ESC ); 
			outp_char( T_FR_END ); 
			break; 
		case FR_ESC: 
			outp_char( FR_ESC ); 
			outp_char( T_FR_ESC ); 
			break; 
		default: 
			outp_char( *p_uc ); 
		} 
		++p_uc; 
	} 
	outp_char( FR_END ); 
 
#ifdef DEBUG_SED 
	printf( "SEDSLIP: Sent a packet %d bytes.\n", pkLengthInBytes ); 
#endif 
	return 1; 
} 
 
/* ----- prepare to receive packets --------------------------------- */ 
 
	/* If the argument is zero, enable both buffers. 
		If the argument is nonzero, 
		take it as the address of the buffer to be enabled. 
		(i.e. that message has been processed) */ 
 
int sed_Receive( recBufLocation ) Byte *recBufLocation; { 
 
	/* This call can be ignored. */ 
	return 1; 
} 
 
/* ----- check for packet received ---------------------------------- */  
 
	/* Test for the arrival of a packet. The location of the packet is 
		returned. If no packet is returned, the routine returns 
		zero. (Timeout is irrelevant here.) */ 
 
Byte * sed_IsPacket() { 
	unsigned char		uc; 
 
	static	unsigned char *	p_begin_packet = &recvbuffer[ 0 ]; 
	static	unsigned char *	p_recv_next = &recvbuffer[ 0 ]; 
#ifdef DEBUG_SED 
	unsigned char *		p; 
#endif 
	static	int	end_count = 0; 
	static	int	b_esc_flag = 0; 
 
	/* See if there are more packets in the receiver */ 
 
	while( inp_status() != 0 ) { 	/* any chars to receive? */ 
		uc = ( unsigned char ) inp_char();	/* get one */ 
 
		if( b_esc_flag ) { 
			switch( uc ) { 
			case T_FR_ESC: 
				*p_recv_next++ = FR_ESC; 
				break; 
			case T_FR_END: 
				*p_recv_next++ = FR_END; 
				break; 
			default: 
				*p_recv_next++ = uc; 
			} 
			b_esc_flag = 0; 
		} else { 
			switch( uc ) { 
			case FR_ESC: 
				b_esc_flag = 1; 
				break; 
			case FR_END: 
				++end_count; 
				if( end_count == 1 ) 
					p_begin_packet = p_recv_next; 
				break; 
			default: 
				*p_recv_next++ = uc; 
			} 
		} 
		if( end_count == 2 ) break; 
	} 
 
	/* do we have a packet in the buffer? */ 
 
	if( end_count == 2 ) { 
 
#ifdef DEBUG_SED 
		printf( "SEDSLIP: Received a packet.\n" ); 
 
		p = p_begin_packet; 
		while( p != p_recv_next ) { 
			printf( "%02x ", *p++ ); 
		} 
		printf( "\n" ); 
#endif 
 
		p_recv_next = &recvbuffer[ 0 ]; 
		end_count = 0; 
 
		return p_begin_packet; 
 
	} else	return ( Byte * ) 0; 
} 
 
/* ----- check received packet for ethernet type -------------------- */ 
 
int sed_CheckPacket( recBufLocation, expectedType ) 
	Word *recBufLocation; Word expectedType; { 
 
	if( expectedType != 0x800 )		/* Must be IP */ 
		return 0; 
 
	return 1;			/* Yes, it's an IP */ 
} 
 
/* end of sed.c */