in hardware/mISDN/isdnhdlc.c [341:616]
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;
}
fallthrough;
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;
}