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#include "slip.h"
#include <errno.h>
enum {
SLIPDEC_START_STATE,
SLIPDEC_IN_FRAME_STATE,
SLIPDEC_ESC_STATE
};
static int slip_decode_start(struct slip *slip, uint8_t rx_byte);
static int slip_decode_inframe(struct slip *slip, uint8_t rx_byte);
static int slip_decode_escseq(struct slip *slip, uint8_t rx_byte);
static inline void
store(uint8_t **cur, uint8_t *end, uint8_t byte)
{
if (*cur < end) *(*cur)++ = byte;
}
int
slip_decode_start(struct slip *slip, uint8_t rx_byte)
{
/* wait for packet start */
if (rx_byte == slip->start) {
slip->rx_index = 0;
slip->rx_state = SLIPDEC_IN_FRAME_STATE;
}
return 0;
}
int
slip_decode_inframe(struct slip *slip, uint8_t rx_byte)
{
int rc;
if (rx_byte == slip->end) {
/* end of packet */
slip->rx_packet(slip, slip->rx_buf, slip->rx_index,
slip->rx_packet_userdata);
slip->rx_state = SLIPDEC_START_STATE;
} else if (rx_byte == slip->start) {
/* malformed packet */
if (slip->rx_restart)
slip->rx_restart(slip, rx_byte);
slip->rx_index = 0;
slip->rx_state = SLIPDEC_START_STATE;
} else if (rx_byte == slip->esc) {
/* escape sequence */
slip->rx_state = SLIPDEC_ESC_STATE;
} else {
/* data byte */
rc = slip_decode_store(slip, rx_byte);
if (rc) return rc;
}
return 0;
}
int
slip_decode_escseq(struct slip *slip, uint8_t rx_byte)
{
uint8_t dec;
int rc;
dec = slip->esc_dec[rx_byte];
if (slip->esc_active[dec]) {
rc = slip_decode_store(slip, dec);
if (rc) return rc;
slip->rx_state = SLIPDEC_IN_FRAME_STATE;
} else {
/* invalid contents */
if (slip->rx_restart)
slip->rx_restart(slip, rx_byte);
slip->rx_state = SLIPDEC_START_STATE;
slip->rx_index = 0;
}
return 0;
}
int
slip_init(struct slip *slip)
{
int i;
slip->rx_state = SLIPDEC_START_STATE;
slip->rx_index = 0;
slip->rx_buflen = 0;
slip->rx_buf = NULL;
if (!slip->rx_packet) return -EINVAL;
if (!slip->realloc) return -EINVAL;
if (slip->esc == slip->start) return -EINVAL;
if (slip->esc == slip->end) return -EINVAL;
/* build decode table */
for (i = 0; i < 256; i++)
slip->esc_dec[slip->esc_enc[i]] = (uint8_t) i;
return 0;
}
void
slip_deinit(struct slip *slip)
{
free(slip->rx_buf);
}
int
slip_decode_store(struct slip *slip, uint8_t byte)
{
int rc;
if (slip->rx_index >= slip->rx_buflen) {
if (!slip->rx_buflen)
slip->rx_buflen = 256;
else
slip->rx_buflen *= 2;
rc = slip->realloc((void **)&slip->rx_buf, slip->rx_buflen);
if (rc) return rc;
}
slip->rx_buf[slip->rx_index++] = byte;
return 0;
}
int
slip_decode(struct slip *slip, uint8_t* data, size_t size)
{
uint8_t rx_byte;
size_t i;
int rc;
for (i = 0; i < size; i++) {
rx_byte = data[i];
switch (slip->rx_state) {
case SLIPDEC_START_STATE:
rc = slip_decode_start(slip, rx_byte);
break;
case SLIPDEC_IN_FRAME_STATE:
rc = slip_decode_inframe(slip, rx_byte);
break;
case SLIPDEC_ESC_STATE:
rc = slip_decode_escseq(slip, rx_byte);
break;
default:
rc = -EINVAL;
break;
}
if (rc) return rc;
}
return 0;
}
int
slip_encode(struct slip *slip, uint8_t* out, size_t *outlen, size_t outcap,
uint8_t* in, size_t inlen)
{
uint8_t *pos, *end;
size_t i;
pos = out;
end = out + outcap;
store(&pos, end, slip->start);
for (i = 0; i < inlen && pos < end; i++) {
if (slip->esc_active[in[i]]) {
store(&pos, end, slip->esc);
store(&pos, end, slip->esc_enc[in[i]]);
} else {
store(&pos, end, in[i]);
}
}
store(&pos, end, slip->end);
if (pos >= end) return -ENOBUFS;
*outlen = (size_t) (pos - out);
return 0;
}
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