631 lines
15 KiB
C
631 lines
15 KiB
C
/*
|
|
* isdnhdlc.c -- General purpose ISDN HDLC decoder.
|
|
*
|
|
* Copyright (C)
|
|
* 2009 Karsten Keil <keil@b1-systems.de>
|
|
* 2002 Wolfgang Mües <wolfgang@iksw-muees.de>
|
|
* 2001 Frode Isaksen <fisaksen@bewan.com>
|
|
* 2001 Kai Germaschewski <kai.germaschewski@gmx.de>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/crc-ccitt.h>
|
|
#include <linux/isdn/hdlc.h>
|
|
#include <linux/bitrev.h>
|
|
|
|
/*-------------------------------------------------------------------*/
|
|
|
|
MODULE_AUTHOR("Wolfgang Mües <wolfgang@iksw-muees.de>, "
|
|
"Frode Isaksen <fisaksen@bewan.com>, "
|
|
"Kai Germaschewski <kai.germaschewski@gmx.de>");
|
|
MODULE_DESCRIPTION("General purpose ISDN HDLC decoder");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
/*-------------------------------------------------------------------*/
|
|
|
|
enum {
|
|
HDLC_FAST_IDLE, HDLC_GET_FLAG_B0, HDLC_GETFLAG_B1A6, HDLC_GETFLAG_B7,
|
|
HDLC_GET_DATA, HDLC_FAST_FLAG
|
|
};
|
|
|
|
enum {
|
|
HDLC_SEND_DATA, HDLC_SEND_CRC1, HDLC_SEND_FAST_FLAG,
|
|
HDLC_SEND_FIRST_FLAG, HDLC_SEND_CRC2, HDLC_SEND_CLOSING_FLAG,
|
|
HDLC_SEND_IDLE1, HDLC_SEND_FAST_IDLE, HDLC_SENDFLAG_B0,
|
|
HDLC_SENDFLAG_B1A6, HDLC_SENDFLAG_B7, STOPPED, HDLC_SENDFLAG_ONE
|
|
};
|
|
|
|
void isdnhdlc_rcv_init(struct isdnhdlc_vars *hdlc, u32 features)
|
|
{
|
|
memset(hdlc, 0, sizeof(struct isdnhdlc_vars));
|
|
hdlc->state = HDLC_GET_DATA;
|
|
if (features & HDLC_56KBIT)
|
|
hdlc->do_adapt56 = 1;
|
|
if (features & HDLC_BITREVERSE)
|
|
hdlc->do_bitreverse = 1;
|
|
}
|
|
EXPORT_SYMBOL(isdnhdlc_out_init);
|
|
|
|
void isdnhdlc_out_init(struct isdnhdlc_vars *hdlc, u32 features)
|
|
{
|
|
memset(hdlc, 0, sizeof(struct isdnhdlc_vars));
|
|
if (features & HDLC_DCHANNEL) {
|
|
hdlc->dchannel = 1;
|
|
hdlc->state = HDLC_SEND_FIRST_FLAG;
|
|
} else {
|
|
hdlc->dchannel = 0;
|
|
hdlc->state = HDLC_SEND_FAST_FLAG;
|
|
hdlc->ffvalue = 0x7e;
|
|
}
|
|
hdlc->cbin = 0x7e;
|
|
if (features & HDLC_56KBIT) {
|
|
hdlc->do_adapt56 = 1;
|
|
hdlc->state = HDLC_SENDFLAG_B0;
|
|
} else
|
|
hdlc->data_bits = 8;
|
|
if (features & HDLC_BITREVERSE)
|
|
hdlc->do_bitreverse = 1;
|
|
}
|
|
EXPORT_SYMBOL(isdnhdlc_rcv_init);
|
|
|
|
static int
|
|
check_frame(struct isdnhdlc_vars *hdlc)
|
|
{
|
|
int status;
|
|
|
|
if (hdlc->dstpos < 2) /* too small - framing error */
|
|
status = -HDLC_FRAMING_ERROR;
|
|
else if (hdlc->crc != 0xf0b8) /* crc error */
|
|
status = -HDLC_CRC_ERROR;
|
|
else {
|
|
/* remove CRC */
|
|
hdlc->dstpos -= 2;
|
|
/* good frame */
|
|
status = hdlc->dstpos;
|
|
}
|
|
return status;
|
|
}
|
|
|
|
/*
|
|
isdnhdlc_decode - decodes HDLC frames from a transparent bit stream.
|
|
|
|
The source buffer is scanned for valid HDLC frames looking for
|
|
flags (01111110) to indicate the start of a frame. If the start of
|
|
the frame is found, the bit stuffing is removed (0 after 5 1's).
|
|
When a new flag is found, the complete frame has been received
|
|
and the CRC is checked.
|
|
If a valid frame is found, the function returns the frame length
|
|
excluding the CRC with the bit HDLC_END_OF_FRAME set.
|
|
If the beginning of a valid frame is found, the function returns
|
|
the length.
|
|
If a framing error is found (too many 1s and not a flag) the function
|
|
returns the length with the bit HDLC_FRAMING_ERROR set.
|
|
If a CRC error is found the function returns the length with the
|
|
bit HDLC_CRC_ERROR set.
|
|
If the frame length exceeds the destination buffer size, the function
|
|
returns the length with the bit HDLC_LENGTH_ERROR set.
|
|
|
|
src - source buffer
|
|
slen - source buffer length
|
|
count - number of bytes removed (decoded) from the source buffer
|
|
dst _ destination buffer
|
|
dsize - destination buffer size
|
|
returns - number of decoded bytes in the destination buffer and status
|
|
flag.
|
|
*/
|
|
int isdnhdlc_decode(struct isdnhdlc_vars *hdlc, const u8 *src, int slen,
|
|
int *count, u8 *dst, int dsize)
|
|
{
|
|
int status = 0;
|
|
|
|
static const unsigned char fast_flag[] = {
|
|
0x00, 0x00, 0x00, 0x20, 0x30, 0x38, 0x3c, 0x3e, 0x3f
|
|
};
|
|
|
|
static const unsigned char fast_flag_value[] = {
|
|
0x00, 0x7e, 0xfc, 0xf9, 0xf3, 0xe7, 0xcf, 0x9f, 0x3f
|
|
};
|
|
|
|
static const unsigned char fast_abort[] = {
|
|
0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff
|
|
};
|
|
|
|
#define handle_fast_flag(h) \
|
|
do { \
|
|
if (h->cbin == fast_flag[h->bit_shift]) { \
|
|
h->ffvalue = fast_flag_value[h->bit_shift]; \
|
|
h->state = HDLC_FAST_FLAG; \
|
|
h->ffbit_shift = h->bit_shift; \
|
|
h->bit_shift = 1; \
|
|
} else { \
|
|
h->state = HDLC_GET_DATA; \
|
|
h->data_received = 0; \
|
|
} \
|
|
} while (0)
|
|
|
|
#define handle_abort(h) \
|
|
do { \
|
|
h->shift_reg = fast_abort[h->ffbit_shift - 1]; \
|
|
h->hdlc_bits1 = h->ffbit_shift - 2; \
|
|
if (h->hdlc_bits1 < 0) \
|
|
h->hdlc_bits1 = 0; \
|
|
h->data_bits = h->ffbit_shift - 1; \
|
|
h->state = HDLC_GET_DATA; \
|
|
h->data_received = 0; \
|
|
} while (0)
|
|
|
|
*count = slen;
|
|
|
|
while (slen > 0) {
|
|
if (hdlc->bit_shift == 0) {
|
|
/* the code is for bitreverse streams */
|
|
if (hdlc->do_bitreverse == 0)
|
|
hdlc->cbin = bitrev8(*src++);
|
|
else
|
|
hdlc->cbin = *src++;
|
|
slen--;
|
|
hdlc->bit_shift = 8;
|
|
if (hdlc->do_adapt56)
|
|
hdlc->bit_shift--;
|
|
}
|
|
|
|
switch (hdlc->state) {
|
|
case STOPPED:
|
|
return 0;
|
|
case HDLC_FAST_IDLE:
|
|
if (hdlc->cbin == 0xff) {
|
|
hdlc->bit_shift = 0;
|
|
break;
|
|
}
|
|
hdlc->state = HDLC_GET_FLAG_B0;
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->bit_shift = 8;
|
|
break;
|
|
case HDLC_GET_FLAG_B0:
|
|
if (!(hdlc->cbin & 0x80)) {
|
|
hdlc->state = HDLC_GETFLAG_B1A6;
|
|
hdlc->hdlc_bits1 = 0;
|
|
} else {
|
|
if ((!hdlc->do_adapt56) &&
|
|
(++hdlc->hdlc_bits1 >= 8) &&
|
|
(hdlc->bit_shift == 1))
|
|
hdlc->state = HDLC_FAST_IDLE;
|
|
}
|
|
hdlc->cbin <<= 1;
|
|
hdlc->bit_shift--;
|
|
break;
|
|
case HDLC_GETFLAG_B1A6:
|
|
if (hdlc->cbin & 0x80) {
|
|
hdlc->hdlc_bits1++;
|
|
if (hdlc->hdlc_bits1 == 6)
|
|
hdlc->state = HDLC_GETFLAG_B7;
|
|
} else
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->cbin <<= 1;
|
|
hdlc->bit_shift--;
|
|
break;
|
|
case HDLC_GETFLAG_B7:
|
|
if (hdlc->cbin & 0x80) {
|
|
hdlc->state = HDLC_GET_FLAG_B0;
|
|
} else {
|
|
hdlc->state = HDLC_GET_DATA;
|
|
hdlc->crc = 0xffff;
|
|
hdlc->shift_reg = 0;
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->data_bits = 0;
|
|
hdlc->data_received = 0;
|
|
}
|
|
hdlc->cbin <<= 1;
|
|
hdlc->bit_shift--;
|
|
break;
|
|
case HDLC_GET_DATA:
|
|
if (hdlc->cbin & 0x80) {
|
|
hdlc->hdlc_bits1++;
|
|
switch (hdlc->hdlc_bits1) {
|
|
case 6:
|
|
break;
|
|
case 7:
|
|
if (hdlc->data_received)
|
|
/* bad frame */
|
|
status = -HDLC_FRAMING_ERROR;
|
|
if (!hdlc->do_adapt56) {
|
|
if (hdlc->cbin == fast_abort
|
|
[hdlc->bit_shift + 1]) {
|
|
hdlc->state =
|
|
HDLC_FAST_IDLE;
|
|
hdlc->bit_shift = 1;
|
|
break;
|
|
}
|
|
} else
|
|
hdlc->state = HDLC_GET_FLAG_B0;
|
|
break;
|
|
default:
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->shift_reg |= 0x80;
|
|
hdlc->data_bits++;
|
|
break;
|
|
}
|
|
} else {
|
|
switch (hdlc->hdlc_bits1) {
|
|
case 5:
|
|
break;
|
|
case 6:
|
|
if (hdlc->data_received)
|
|
status = check_frame(hdlc);
|
|
hdlc->crc = 0xffff;
|
|
hdlc->shift_reg = 0;
|
|
hdlc->data_bits = 0;
|
|
if (!hdlc->do_adapt56)
|
|
handle_fast_flag(hdlc);
|
|
else {
|
|
hdlc->state = HDLC_GET_DATA;
|
|
hdlc->data_received = 0;
|
|
}
|
|
break;
|
|
default:
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->data_bits++;
|
|
break;
|
|
}
|
|
hdlc->hdlc_bits1 = 0;
|
|
}
|
|
if (status) {
|
|
hdlc->dstpos = 0;
|
|
*count -= slen;
|
|
hdlc->cbin <<= 1;
|
|
hdlc->bit_shift--;
|
|
return status;
|
|
}
|
|
if (hdlc->data_bits == 8) {
|
|
hdlc->data_bits = 0;
|
|
hdlc->data_received = 1;
|
|
hdlc->crc = crc_ccitt_byte(hdlc->crc,
|
|
hdlc->shift_reg);
|
|
|
|
/* good byte received */
|
|
if (hdlc->dstpos < dsize)
|
|
dst[hdlc->dstpos++] = hdlc->shift_reg;
|
|
else {
|
|
/* frame too long */
|
|
status = -HDLC_LENGTH_ERROR;
|
|
hdlc->dstpos = 0;
|
|
}
|
|
}
|
|
hdlc->cbin <<= 1;
|
|
hdlc->bit_shift--;
|
|
break;
|
|
case HDLC_FAST_FLAG:
|
|
if (hdlc->cbin == hdlc->ffvalue) {
|
|
hdlc->bit_shift = 0;
|
|
break;
|
|
} else {
|
|
if (hdlc->cbin == 0xff) {
|
|
hdlc->state = HDLC_FAST_IDLE;
|
|
hdlc->bit_shift = 0;
|
|
} else if (hdlc->ffbit_shift == 8) {
|
|
hdlc->state = HDLC_GETFLAG_B7;
|
|
break;
|
|
} else
|
|
handle_abort(hdlc);
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
*count -= slen;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(isdnhdlc_decode);
|
|
/*
|
|
isdnhdlc_encode - encodes HDLC frames to a transparent bit stream.
|
|
|
|
The bit stream starts with a beginning flag (01111110). After
|
|
that each byte is added to the bit stream with bit stuffing added
|
|
(0 after 5 1's).
|
|
When the last byte has been removed from the source buffer, the
|
|
CRC (2 bytes is added) and the frame terminates with the ending flag.
|
|
For the dchannel, the idle character (all 1's) is also added at the end.
|
|
If this function is called with empty source buffer (slen=0), flags or
|
|
idle character will be generated.
|
|
|
|
src - source buffer
|
|
slen - source buffer length
|
|
count - number of bytes removed (encoded) from source buffer
|
|
dst _ destination buffer
|
|
dsize - destination buffer size
|
|
returns - number of encoded bytes in the destination buffer
|
|
*/
|
|
int isdnhdlc_encode(struct isdnhdlc_vars *hdlc, const u8 *src, u16 slen,
|
|
int *count, u8 *dst, int dsize)
|
|
{
|
|
static const unsigned char xfast_flag_value[] = {
|
|
0x7e, 0x3f, 0x9f, 0xcf, 0xe7, 0xf3, 0xf9, 0xfc, 0x7e
|
|
};
|
|
|
|
int len = 0;
|
|
|
|
*count = slen;
|
|
|
|
/* special handling for one byte frames */
|
|
if ((slen == 1) && (hdlc->state == HDLC_SEND_FAST_FLAG))
|
|
hdlc->state = HDLC_SENDFLAG_ONE;
|
|
while (dsize > 0) {
|
|
if (hdlc->bit_shift == 0) {
|
|
if (slen && !hdlc->do_closing) {
|
|
hdlc->shift_reg = *src++;
|
|
slen--;
|
|
if (slen == 0)
|
|
/* closing sequence, CRC + flag(s) */
|
|
hdlc->do_closing = 1;
|
|
hdlc->bit_shift = 8;
|
|
} else {
|
|
if (hdlc->state == HDLC_SEND_DATA) {
|
|
if (hdlc->data_received) {
|
|
hdlc->state = HDLC_SEND_CRC1;
|
|
hdlc->crc ^= 0xffff;
|
|
hdlc->bit_shift = 8;
|
|
hdlc->shift_reg =
|
|
hdlc->crc & 0xff;
|
|
} else if (!hdlc->do_adapt56)
|
|
hdlc->state =
|
|
HDLC_SEND_FAST_FLAG;
|
|
else
|
|
hdlc->state =
|
|
HDLC_SENDFLAG_B0;
|
|
}
|
|
|
|
}
|
|
}
|
|
|
|
switch (hdlc->state) {
|
|
case STOPPED:
|
|
while (dsize--)
|
|
*dst++ = 0xff;
|
|
return dsize;
|
|
case HDLC_SEND_FAST_FLAG:
|
|
hdlc->do_closing = 0;
|
|
if (slen == 0) {
|
|
/* the code is for bitreverse streams */
|
|
if (hdlc->do_bitreverse == 0)
|
|
*dst++ = bitrev8(hdlc->ffvalue);
|
|
else
|
|
*dst++ = hdlc->ffvalue;
|
|
len++;
|
|
dsize--;
|
|
break;
|
|
}
|
|
/* fall through */
|
|
case HDLC_SENDFLAG_ONE:
|
|
if (hdlc->bit_shift == 8) {
|
|
hdlc->cbin = hdlc->ffvalue >>
|
|
(8 - hdlc->data_bits);
|
|
hdlc->state = HDLC_SEND_DATA;
|
|
hdlc->crc = 0xffff;
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->data_received = 1;
|
|
}
|
|
break;
|
|
case HDLC_SENDFLAG_B0:
|
|
hdlc->do_closing = 0;
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->state = HDLC_SENDFLAG_B1A6;
|
|
break;
|
|
case HDLC_SENDFLAG_B1A6:
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
hdlc->cbin++;
|
|
if (++hdlc->hdlc_bits1 == 6)
|
|
hdlc->state = HDLC_SENDFLAG_B7;
|
|
break;
|
|
case HDLC_SENDFLAG_B7:
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
if (slen == 0) {
|
|
hdlc->state = HDLC_SENDFLAG_B0;
|
|
break;
|
|
}
|
|
if (hdlc->bit_shift == 8) {
|
|
hdlc->state = HDLC_SEND_DATA;
|
|
hdlc->crc = 0xffff;
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->data_received = 1;
|
|
}
|
|
break;
|
|
case HDLC_SEND_FIRST_FLAG:
|
|
hdlc->data_received = 1;
|
|
if (hdlc->data_bits == 8) {
|
|
hdlc->state = HDLC_SEND_DATA;
|
|
hdlc->crc = 0xffff;
|
|
hdlc->hdlc_bits1 = 0;
|
|
break;
|
|
}
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
if (hdlc->shift_reg & 0x01)
|
|
hdlc->cbin++;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
if (hdlc->bit_shift == 0) {
|
|
hdlc->state = HDLC_SEND_DATA;
|
|
hdlc->crc = 0xffff;
|
|
hdlc->hdlc_bits1 = 0;
|
|
}
|
|
break;
|
|
case HDLC_SEND_DATA:
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
if (hdlc->hdlc_bits1 == 5) {
|
|
hdlc->hdlc_bits1 = 0;
|
|
break;
|
|
}
|
|
if (hdlc->bit_shift == 8)
|
|
hdlc->crc = crc_ccitt_byte(hdlc->crc,
|
|
hdlc->shift_reg);
|
|
if (hdlc->shift_reg & 0x01) {
|
|
hdlc->hdlc_bits1++;
|
|
hdlc->cbin++;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
} else {
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
}
|
|
break;
|
|
case HDLC_SEND_CRC1:
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
if (hdlc->hdlc_bits1 == 5) {
|
|
hdlc->hdlc_bits1 = 0;
|
|
break;
|
|
}
|
|
if (hdlc->shift_reg & 0x01) {
|
|
hdlc->hdlc_bits1++;
|
|
hdlc->cbin++;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
} else {
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
}
|
|
if (hdlc->bit_shift == 0) {
|
|
hdlc->shift_reg = (hdlc->crc >> 8);
|
|
hdlc->state = HDLC_SEND_CRC2;
|
|
hdlc->bit_shift = 8;
|
|
}
|
|
break;
|
|
case HDLC_SEND_CRC2:
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
if (hdlc->hdlc_bits1 == 5) {
|
|
hdlc->hdlc_bits1 = 0;
|
|
break;
|
|
}
|
|
if (hdlc->shift_reg & 0x01) {
|
|
hdlc->hdlc_bits1++;
|
|
hdlc->cbin++;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
} else {
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
}
|
|
if (hdlc->bit_shift == 0) {
|
|
hdlc->shift_reg = 0x7e;
|
|
hdlc->state = HDLC_SEND_CLOSING_FLAG;
|
|
hdlc->bit_shift = 8;
|
|
}
|
|
break;
|
|
case HDLC_SEND_CLOSING_FLAG:
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
if (hdlc->hdlc_bits1 == 5) {
|
|
hdlc->hdlc_bits1 = 0;
|
|
break;
|
|
}
|
|
if (hdlc->shift_reg & 0x01)
|
|
hdlc->cbin++;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
if (hdlc->bit_shift == 0) {
|
|
hdlc->ffvalue =
|
|
xfast_flag_value[hdlc->data_bits];
|
|
if (hdlc->dchannel) {
|
|
hdlc->ffvalue = 0x7e;
|
|
hdlc->state = HDLC_SEND_IDLE1;
|
|
hdlc->bit_shift = 8-hdlc->data_bits;
|
|
if (hdlc->bit_shift == 0)
|
|
hdlc->state =
|
|
HDLC_SEND_FAST_IDLE;
|
|
} else {
|
|
if (!hdlc->do_adapt56) {
|
|
hdlc->state =
|
|
HDLC_SEND_FAST_FLAG;
|
|
hdlc->data_received = 0;
|
|
} else {
|
|
hdlc->state = HDLC_SENDFLAG_B0;
|
|
hdlc->data_received = 0;
|
|
}
|
|
/* Finished this frame, send flags */
|
|
if (dsize > 1)
|
|
dsize = 1;
|
|
}
|
|
}
|
|
break;
|
|
case HDLC_SEND_IDLE1:
|
|
hdlc->do_closing = 0;
|
|
hdlc->cbin <<= 1;
|
|
hdlc->cbin++;
|
|
hdlc->data_bits++;
|
|
hdlc->bit_shift--;
|
|
if (hdlc->bit_shift == 0) {
|
|
hdlc->state = HDLC_SEND_FAST_IDLE;
|
|
hdlc->bit_shift = 0;
|
|
}
|
|
break;
|
|
case HDLC_SEND_FAST_IDLE:
|
|
hdlc->do_closing = 0;
|
|
hdlc->cbin = 0xff;
|
|
hdlc->data_bits = 8;
|
|
if (hdlc->bit_shift == 8) {
|
|
hdlc->cbin = 0x7e;
|
|
hdlc->state = HDLC_SEND_FIRST_FLAG;
|
|
} else {
|
|
/* the code is for bitreverse streams */
|
|
if (hdlc->do_bitreverse == 0)
|
|
*dst++ = bitrev8(hdlc->cbin);
|
|
else
|
|
*dst++ = hdlc->cbin;
|
|
hdlc->bit_shift = 0;
|
|
hdlc->data_bits = 0;
|
|
len++;
|
|
dsize = 0;
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
if (hdlc->do_adapt56) {
|
|
if (hdlc->data_bits == 7) {
|
|
hdlc->cbin <<= 1;
|
|
hdlc->cbin++;
|
|
hdlc->data_bits++;
|
|
}
|
|
}
|
|
if (hdlc->data_bits == 8) {
|
|
/* the code is for bitreverse streams */
|
|
if (hdlc->do_bitreverse == 0)
|
|
*dst++ = bitrev8(hdlc->cbin);
|
|
else
|
|
*dst++ = hdlc->cbin;
|
|
hdlc->data_bits = 0;
|
|
len++;
|
|
dsize--;
|
|
}
|
|
}
|
|
*count -= slen;
|
|
|
|
return len;
|
|
}
|
|
EXPORT_SYMBOL(isdnhdlc_encode);
|