cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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slip_common.h (2279B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef __UM_SLIP_COMMON_H
      3#define __UM_SLIP_COMMON_H
      4
      5#define BUF_SIZE 1500
      6 /* two bytes each for a (pathological) max packet of escaped chars +  *
      7  * terminating END char + initial END char                            */
      8#define ENC_BUF_SIZE (2 * BUF_SIZE + 2)
      9
     10/* SLIP protocol characters. */
     11#define SLIP_END             0300	/* indicates end of frame	*/
     12#define SLIP_ESC             0333	/* indicates byte stuffing	*/
     13#define SLIP_ESC_END         0334	/* ESC ESC_END means END 'data'	*/
     14#define SLIP_ESC_ESC         0335	/* ESC ESC_ESC means ESC 'data'	*/
     15
     16static inline int slip_unesc(unsigned char c, unsigned char *buf, int *pos,
     17                             int *esc)
     18{
     19	int ret;
     20
     21	switch(c){
     22	case SLIP_END:
     23		*esc = 0;
     24		ret=*pos;
     25		*pos=0;
     26		return(ret);
     27	case SLIP_ESC:
     28		*esc = 1;
     29		return(0);
     30	case SLIP_ESC_ESC:
     31		if(*esc){
     32			*esc = 0;
     33			c = SLIP_ESC;
     34		}
     35		break;
     36	case SLIP_ESC_END:
     37		if(*esc){
     38			*esc = 0;
     39			c = SLIP_END;
     40		}
     41		break;
     42	}
     43	buf[(*pos)++] = c;
     44	return(0);
     45}
     46
     47static inline int slip_esc(unsigned char *s, unsigned char *d, int len)
     48{
     49	unsigned char *ptr = d;
     50	unsigned char c;
     51
     52	/*
     53	 * Send an initial END character to flush out any
     54	 * data that may have accumulated in the receiver
     55	 * due to line noise.
     56	 */
     57
     58	*ptr++ = SLIP_END;
     59
     60	/*
     61	 * For each byte in the packet, send the appropriate
     62	 * character sequence, according to the SLIP protocol.
     63	 */
     64
     65	while (len-- > 0) {
     66		switch(c = *s++) {
     67		case SLIP_END:
     68			*ptr++ = SLIP_ESC;
     69			*ptr++ = SLIP_ESC_END;
     70			break;
     71		case SLIP_ESC:
     72			*ptr++ = SLIP_ESC;
     73			*ptr++ = SLIP_ESC_ESC;
     74			break;
     75		default:
     76			*ptr++ = c;
     77			break;
     78		}
     79	}
     80	*ptr++ = SLIP_END;
     81	return (ptr - d);
     82}
     83
     84struct slip_proto {
     85	unsigned char ibuf[ENC_BUF_SIZE];
     86	unsigned char obuf[ENC_BUF_SIZE];
     87	int more; /* more data: do not read fd until ibuf has been drained */
     88	int pos;
     89	int esc;
     90};
     91
     92static inline void slip_proto_init(struct slip_proto * slip)
     93{
     94	memset(slip->ibuf, 0, sizeof(slip->ibuf));
     95	memset(slip->obuf, 0, sizeof(slip->obuf));
     96	slip->more = 0;
     97	slip->pos = 0;
     98	slip->esc = 0;
     99}
    100
    101extern int slip_proto_read(int fd, void *buf, int len,
    102			   struct slip_proto *slip);
    103extern int slip_proto_write(int fd, void *buf, int len,
    104			    struct slip_proto *slip);
    105
    106#endif