slip_proto.h

来自「优龙2410linux2.6.8内核源代码」· C头文件 代码 · 共 94 行

/* 
 * Copyright (C) 2002 Jeff Dike ([e-mail])
 * Licensed under the GPL
 */

#ifndef __UM_SLIP_PROTO_H__
#define __UM_SLIP_PROTO_H__

/* SLIP protocol characters. */
#define SLIP_END             0300	/* indicates end of frame	*/
#define SLIP_ESC             0333	/* indicates byte stuffing	*/
#define SLIP_ESC_END         0334	/* ESC ESC_END means END 'data'	*/
#define SLIP_ESC_ESC         0335	/* ESC ESC_ESC means ESC 'data'	*/

static inline int slip_unesc(unsigned char c,char *buf,int *pos, int *esc)
{
	int ret;

	switch(c){
	case SLIP_END:
		*esc = 0;
		ret=*pos;
		*pos=0;
		return(ret);
	case SLIP_ESC:
		*esc = 1;
		return(0);
	case SLIP_ESC_ESC:
		if(*esc){
			*esc = 0;
			c = SLIP_ESC;
		}
		break;
	case SLIP_ESC_END:
		if(*esc){
			*esc = 0;
			c = SLIP_END;
		}
		break;
	}
	buf[(*pos)++] = c;
	return(0);
}

static inline int slip_esc(unsigned char *s, unsigned char *d, int len)
{
	unsigned char *ptr = d;
	unsigned char c;

	/*
	 * Send an initial END character to flush out any
	 * data that may have accumulated in the receiver
	 * due to line noise.
	 */

	*ptr++ = SLIP_END;

	/*
	 * For each byte in the packet, send the appropriate
	 * character sequence, according to the SLIP protocol.
	 */

	while (len-- > 0) {
		switch(c = *s++) {
		case SLIP_END:
			*ptr++ = SLIP_ESC;
			*ptr++ = SLIP_ESC_END;
			break;
		case SLIP_ESC:
			*ptr++ = SLIP_ESC;
			*ptr++ = SLIP_ESC_ESC;
			break;
		default:
			*ptr++ = c;
			break;
		}
	}
	*ptr++ = SLIP_END;
	return (ptr - d);
}

#endif

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-file-style: "linux"
 * End:
 */