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106 lines
2.2 KiB
106 lines
2.2 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __UM_SLIP_COMMON_H |
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#define __UM_SLIP_COMMON_H |
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#define BUF_SIZE 1500 |
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/* two bytes each for a (pathological) max packet of escaped chars + * |
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* terminating END char + initial END char */ |
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#define ENC_BUF_SIZE (2 * BUF_SIZE + 2) |
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/* SLIP protocol characters. */ |
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#define SLIP_END 0300 /* indicates end of frame */ |
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#define SLIP_ESC 0333 /* indicates byte stuffing */ |
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#define SLIP_ESC_END 0334 /* ESC ESC_END means END 'data' */ |
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#define SLIP_ESC_ESC 0335 /* ESC ESC_ESC means ESC 'data' */ |
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static inline int slip_unesc(unsigned char c, unsigned char *buf, int *pos, |
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int *esc) |
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{ |
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int ret; |
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switch(c){ |
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case SLIP_END: |
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*esc = 0; |
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ret=*pos; |
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*pos=0; |
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return(ret); |
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case SLIP_ESC: |
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*esc = 1; |
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return(0); |
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case SLIP_ESC_ESC: |
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if(*esc){ |
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*esc = 0; |
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c = SLIP_ESC; |
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} |
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break; |
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case SLIP_ESC_END: |
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if(*esc){ |
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*esc = 0; |
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c = SLIP_END; |
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} |
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break; |
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} |
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buf[(*pos)++] = c; |
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return(0); |
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} |
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static inline int slip_esc(unsigned char *s, unsigned char *d, int len) |
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{ |
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unsigned char *ptr = d; |
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unsigned char c; |
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/* |
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* Send an initial END character to flush out any |
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* data that may have accumulated in the receiver |
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* due to line noise. |
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*/ |
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*ptr++ = SLIP_END; |
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/* |
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* For each byte in the packet, send the appropriate |
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* character sequence, according to the SLIP protocol. |
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*/ |
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while (len-- > 0) { |
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switch(c = *s++) { |
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case SLIP_END: |
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*ptr++ = SLIP_ESC; |
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*ptr++ = SLIP_ESC_END; |
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break; |
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case SLIP_ESC: |
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*ptr++ = SLIP_ESC; |
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*ptr++ = SLIP_ESC_ESC; |
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break; |
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default: |
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*ptr++ = c; |
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break; |
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} |
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} |
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*ptr++ = SLIP_END; |
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return (ptr - d); |
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} |
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struct slip_proto { |
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unsigned char ibuf[ENC_BUF_SIZE]; |
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unsigned char obuf[ENC_BUF_SIZE]; |
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int more; /* more data: do not read fd until ibuf has been drained */ |
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int pos; |
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int esc; |
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}; |
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static inline void slip_proto_init(struct slip_proto * slip) |
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{ |
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memset(slip->ibuf, 0, sizeof(slip->ibuf)); |
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memset(slip->obuf, 0, sizeof(slip->obuf)); |
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slip->more = 0; |
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slip->pos = 0; |
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slip->esc = 0; |
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} |
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extern int slip_proto_read(int fd, void *buf, int len, |
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struct slip_proto *slip); |
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extern int slip_proto_write(int fd, void *buf, int len, |
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struct slip_proto *slip); |
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#endif
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