Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 1 | /* |
| 2 | * isdnhdlc.c -- General purpose ISDN HDLC decoder. |
| 3 | * |
| 4 | * Copyright (C) |
| 5 | * 2009 Karsten Keil <keil@b1-systems.de> |
| 6 | * 2002 Wolfgang Mües <wolfgang@iksw-muees.de> |
| 7 | * 2001 Frode Isaksen <fisaksen@bewan.com> |
| 8 | * 2001 Kai Germaschewski <kai.germaschewski@gmx.de> |
| 9 | * |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 10 | * slightly adapted for use in userspace / osmocom envrionment by Harald Welte |
| 11 | * |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 12 | * This program is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU General Public License as published by |
| 14 | * the Free Software Foundation; either version 2 of the License, or |
| 15 | * (at your option) any later version. |
| 16 | * |
| 17 | * This program is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU General Public License for more details. |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 21 | */ |
| 22 | |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 23 | #include <string.h> |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 24 | |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 25 | #include <osmocom/core/crc16.h> |
| 26 | #include <osmocom/core/bits.h> |
| 27 | #include <osmocom/core/isdnhdlc.h> |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 28 | |
| 29 | enum { |
| 30 | HDLC_FAST_IDLE, HDLC_GET_FLAG_B0, HDLC_GETFLAG_B1A6, HDLC_GETFLAG_B7, |
| 31 | HDLC_GET_DATA, HDLC_FAST_FLAG |
| 32 | }; |
| 33 | |
| 34 | enum { |
| 35 | HDLC_SEND_DATA, HDLC_SEND_CRC1, HDLC_SEND_FAST_FLAG, |
| 36 | HDLC_SEND_FIRST_FLAG, HDLC_SEND_CRC2, HDLC_SEND_CLOSING_FLAG, |
| 37 | HDLC_SEND_IDLE1, HDLC_SEND_FAST_IDLE, HDLC_SENDFLAG_B0, |
| 38 | HDLC_SENDFLAG_B1A6, HDLC_SENDFLAG_B7, STOPPED, HDLC_SENDFLAG_ONE |
| 39 | }; |
| 40 | |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 41 | #define crc_ccitt_byte osmo_crc16_ccitt_byte |
| 42 | |
| 43 | void osmo_isdnhdlc_rcv_init(struct osmo_isdnhdlc_vars *hdlc, uint32_t features) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 44 | { |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 45 | memset(hdlc, 0, sizeof(*hdlc)); |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 46 | hdlc->state = HDLC_GET_DATA; |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 47 | if (features & OSMO_HDLC_F_56KBIT) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 48 | hdlc->do_adapt56 = 1; |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 49 | if (features & OSMO_HDLC_F_BITREVERSE) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 50 | hdlc->do_bitreverse = 1; |
| 51 | } |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 52 | |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 53 | void osmo_isdnhdlc_out_init(struct osmo_isdnhdlc_vars *hdlc, uint32_t features) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 54 | { |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 55 | memset(hdlc, 0, sizeof(*hdlc)); |
| 56 | if (features & OSMO_HDLC_F_DCHANNEL) { |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 57 | hdlc->dchannel = 1; |
| 58 | hdlc->state = HDLC_SEND_FIRST_FLAG; |
| 59 | } else { |
| 60 | hdlc->dchannel = 0; |
| 61 | hdlc->state = HDLC_SEND_FAST_FLAG; |
| 62 | hdlc->ffvalue = 0x7e; |
| 63 | } |
| 64 | hdlc->cbin = 0x7e; |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 65 | if (features & OSMO_HDLC_F_56KBIT) { |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 66 | hdlc->do_adapt56 = 1; |
| 67 | hdlc->state = HDLC_SENDFLAG_B0; |
| 68 | } else |
| 69 | hdlc->data_bits = 8; |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 70 | if (features & OSMO_HDLC_F_BITREVERSE) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 71 | hdlc->do_bitreverse = 1; |
| 72 | } |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 73 | |
| 74 | static int |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 75 | check_frame(struct osmo_isdnhdlc_vars *hdlc) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 76 | { |
| 77 | int status; |
| 78 | |
| 79 | if (hdlc->dstpos < 2) /* too small - framing error */ |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 80 | status = -OSMO_HDLC_FRAMING_ERROR; |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 81 | else if (hdlc->crc != 0xf0b8) /* crc error */ |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 82 | status = -OSMO_HDLC_CRC_ERROR; |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 83 | else { |
| 84 | /* remove CRC */ |
| 85 | hdlc->dstpos -= 2; |
| 86 | /* good frame */ |
| 87 | status = hdlc->dstpos; |
| 88 | } |
| 89 | return status; |
| 90 | } |
| 91 | |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 92 | /*! decodes HDLC frames from a transparent bit stream. |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 93 | |
| 94 | The source buffer is scanned for valid HDLC frames looking for |
| 95 | flags (01111110) to indicate the start of a frame. If the start of |
| 96 | the frame is found, the bit stuffing is removed (0 after 5 1's). |
| 97 | When a new flag is found, the complete frame has been received |
| 98 | and the CRC is checked. |
| 99 | If a valid frame is found, the function returns the frame length |
Harald Welte | 4ce820a | 2022-11-30 23:00:18 +0100 | [diff] [blame] | 100 | excluding the CRC. |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 101 | If the beginning of a valid frame is found, the function returns |
| 102 | the length. |
| 103 | If a framing error is found (too many 1s and not a flag) the function |
Harald Welte | 4ce820a | 2022-11-30 23:00:18 +0100 | [diff] [blame] | 104 | returns -OSMO_HDLC_FRAMING_ERROR. |
| 105 | If a CRC error is found the function returns -OSMO_HDLC_CRC_ERROR. |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 106 | If the frame length exceeds the destination buffer size, the function |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 107 | returns the length with the bit OSMO_HDLC_LENGTH_ERROR set. |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 108 | |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 109 | \param[in] src source buffer |
| 110 | \param[in] slen source buffer length |
| 111 | \param[out] count number of bytes removed (decoded) from the source buffer |
| 112 | \param[out] dst destination buffer |
| 113 | \param[in] dsize destination buffer size |
| 114 | \returns number of decoded bytes in the destination buffer and status flag. |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 115 | */ |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 116 | int osmo_isdnhdlc_decode(struct osmo_isdnhdlc_vars *hdlc, const uint8_t *src, int slen, |
| 117 | int *count, uint8_t *dst, int dsize) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 118 | { |
| 119 | int status = 0; |
| 120 | |
| 121 | static const unsigned char fast_flag[] = { |
| 122 | 0x00, 0x00, 0x00, 0x20, 0x30, 0x38, 0x3c, 0x3e, 0x3f |
| 123 | }; |
| 124 | |
| 125 | static const unsigned char fast_flag_value[] = { |
| 126 | 0x00, 0x7e, 0xfc, 0xf9, 0xf3, 0xe7, 0xcf, 0x9f, 0x3f |
| 127 | }; |
| 128 | |
| 129 | static const unsigned char fast_abort[] = { |
| 130 | 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff |
| 131 | }; |
| 132 | |
| 133 | #define handle_fast_flag(h) \ |
| 134 | do { \ |
| 135 | if (h->cbin == fast_flag[h->bit_shift]) { \ |
| 136 | h->ffvalue = fast_flag_value[h->bit_shift]; \ |
| 137 | h->state = HDLC_FAST_FLAG; \ |
| 138 | h->ffbit_shift = h->bit_shift; \ |
| 139 | h->bit_shift = 1; \ |
| 140 | } else { \ |
| 141 | h->state = HDLC_GET_DATA; \ |
| 142 | h->data_received = 0; \ |
| 143 | } \ |
| 144 | } while (0) |
| 145 | |
| 146 | #define handle_abort(h) \ |
| 147 | do { \ |
| 148 | h->shift_reg = fast_abort[h->ffbit_shift - 1]; \ |
| 149 | h->hdlc_bits1 = h->ffbit_shift - 2; \ |
| 150 | if (h->hdlc_bits1 < 0) \ |
| 151 | h->hdlc_bits1 = 0; \ |
| 152 | h->data_bits = h->ffbit_shift - 1; \ |
| 153 | h->state = HDLC_GET_DATA; \ |
| 154 | h->data_received = 0; \ |
| 155 | } while (0) |
| 156 | |
| 157 | *count = slen; |
| 158 | |
| 159 | while (slen > 0) { |
| 160 | if (hdlc->bit_shift == 0) { |
| 161 | /* the code is for bitreverse streams */ |
| 162 | if (hdlc->do_bitreverse == 0) |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 163 | hdlc->cbin = osmo_revbytebits_8(*src++); |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 164 | else |
| 165 | hdlc->cbin = *src++; |
| 166 | slen--; |
| 167 | hdlc->bit_shift = 8; |
| 168 | if (hdlc->do_adapt56) |
| 169 | hdlc->bit_shift--; |
| 170 | } |
| 171 | |
| 172 | switch (hdlc->state) { |
| 173 | case STOPPED: |
| 174 | return 0; |
| 175 | case HDLC_FAST_IDLE: |
| 176 | if (hdlc->cbin == 0xff) { |
| 177 | hdlc->bit_shift = 0; |
| 178 | break; |
| 179 | } |
| 180 | hdlc->state = HDLC_GET_FLAG_B0; |
| 181 | hdlc->hdlc_bits1 = 0; |
| 182 | hdlc->bit_shift = 8; |
| 183 | break; |
| 184 | case HDLC_GET_FLAG_B0: |
| 185 | if (!(hdlc->cbin & 0x80)) { |
| 186 | hdlc->state = HDLC_GETFLAG_B1A6; |
| 187 | hdlc->hdlc_bits1 = 0; |
| 188 | } else { |
| 189 | if ((!hdlc->do_adapt56) && |
| 190 | (++hdlc->hdlc_bits1 >= 8) && |
| 191 | (hdlc->bit_shift == 1)) |
| 192 | hdlc->state = HDLC_FAST_IDLE; |
| 193 | } |
| 194 | hdlc->cbin <<= 1; |
| 195 | hdlc->bit_shift--; |
| 196 | break; |
| 197 | case HDLC_GETFLAG_B1A6: |
| 198 | if (hdlc->cbin & 0x80) { |
| 199 | hdlc->hdlc_bits1++; |
| 200 | if (hdlc->hdlc_bits1 == 6) |
| 201 | hdlc->state = HDLC_GETFLAG_B7; |
| 202 | } else |
| 203 | hdlc->hdlc_bits1 = 0; |
| 204 | hdlc->cbin <<= 1; |
| 205 | hdlc->bit_shift--; |
| 206 | break; |
| 207 | case HDLC_GETFLAG_B7: |
| 208 | if (hdlc->cbin & 0x80) { |
| 209 | hdlc->state = HDLC_GET_FLAG_B0; |
| 210 | } else { |
| 211 | hdlc->state = HDLC_GET_DATA; |
| 212 | hdlc->crc = 0xffff; |
| 213 | hdlc->shift_reg = 0; |
| 214 | hdlc->hdlc_bits1 = 0; |
| 215 | hdlc->data_bits = 0; |
| 216 | hdlc->data_received = 0; |
| 217 | } |
| 218 | hdlc->cbin <<= 1; |
| 219 | hdlc->bit_shift--; |
| 220 | break; |
| 221 | case HDLC_GET_DATA: |
| 222 | if (hdlc->cbin & 0x80) { |
| 223 | hdlc->hdlc_bits1++; |
| 224 | switch (hdlc->hdlc_bits1) { |
| 225 | case 6: |
| 226 | break; |
| 227 | case 7: |
| 228 | if (hdlc->data_received) |
| 229 | /* bad frame */ |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 230 | status = -OSMO_HDLC_FRAMING_ERROR; |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 231 | if (!hdlc->do_adapt56) { |
| 232 | if (hdlc->cbin == fast_abort |
| 233 | [hdlc->bit_shift + 1]) { |
| 234 | hdlc->state = |
| 235 | HDLC_FAST_IDLE; |
| 236 | hdlc->bit_shift = 1; |
| 237 | break; |
| 238 | } |
| 239 | } else |
| 240 | hdlc->state = HDLC_GET_FLAG_B0; |
| 241 | break; |
| 242 | default: |
| 243 | hdlc->shift_reg >>= 1; |
| 244 | hdlc->shift_reg |= 0x80; |
| 245 | hdlc->data_bits++; |
| 246 | break; |
| 247 | } |
| 248 | } else { |
| 249 | switch (hdlc->hdlc_bits1) { |
| 250 | case 5: |
| 251 | break; |
| 252 | case 6: |
| 253 | if (hdlc->data_received) |
| 254 | status = check_frame(hdlc); |
| 255 | hdlc->crc = 0xffff; |
| 256 | hdlc->shift_reg = 0; |
| 257 | hdlc->data_bits = 0; |
| 258 | if (!hdlc->do_adapt56) |
| 259 | handle_fast_flag(hdlc); |
| 260 | else { |
| 261 | hdlc->state = HDLC_GET_DATA; |
| 262 | hdlc->data_received = 0; |
| 263 | } |
| 264 | break; |
| 265 | default: |
| 266 | hdlc->shift_reg >>= 1; |
| 267 | hdlc->data_bits++; |
| 268 | break; |
| 269 | } |
| 270 | hdlc->hdlc_bits1 = 0; |
| 271 | } |
| 272 | if (status) { |
| 273 | hdlc->dstpos = 0; |
| 274 | *count -= slen; |
| 275 | hdlc->cbin <<= 1; |
| 276 | hdlc->bit_shift--; |
| 277 | return status; |
| 278 | } |
| 279 | if (hdlc->data_bits == 8) { |
| 280 | hdlc->data_bits = 0; |
| 281 | hdlc->data_received = 1; |
| 282 | hdlc->crc = crc_ccitt_byte(hdlc->crc, |
| 283 | hdlc->shift_reg); |
| 284 | |
| 285 | /* good byte received */ |
| 286 | if (hdlc->dstpos < dsize) |
| 287 | dst[hdlc->dstpos++] = hdlc->shift_reg; |
| 288 | else { |
| 289 | /* frame too long */ |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 290 | status = -OSMO_HDLC_LENGTH_ERROR; |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 291 | hdlc->dstpos = 0; |
| 292 | } |
| 293 | } |
| 294 | hdlc->cbin <<= 1; |
| 295 | hdlc->bit_shift--; |
| 296 | break; |
| 297 | case HDLC_FAST_FLAG: |
| 298 | if (hdlc->cbin == hdlc->ffvalue) { |
| 299 | hdlc->bit_shift = 0; |
| 300 | break; |
| 301 | } else { |
| 302 | if (hdlc->cbin == 0xff) { |
| 303 | hdlc->state = HDLC_FAST_IDLE; |
| 304 | hdlc->bit_shift = 0; |
| 305 | } else if (hdlc->ffbit_shift == 8) { |
| 306 | hdlc->state = HDLC_GETFLAG_B7; |
| 307 | break; |
| 308 | } else |
| 309 | handle_abort(hdlc); |
| 310 | } |
| 311 | break; |
| 312 | default: |
| 313 | break; |
| 314 | } |
| 315 | } |
| 316 | *count -= slen; |
| 317 | return 0; |
| 318 | } |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 319 | /*! encodes HDLC frames to a transparent bit stream. |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 320 | |
| 321 | The bit stream starts with a beginning flag (01111110). After |
| 322 | that each byte is added to the bit stream with bit stuffing added |
| 323 | (0 after 5 1's). |
| 324 | When the last byte has been removed from the source buffer, the |
| 325 | CRC (2 bytes is added) and the frame terminates with the ending flag. |
| 326 | For the dchannel, the idle character (all 1's) is also added at the end. |
| 327 | If this function is called with empty source buffer (slen=0), flags or |
| 328 | idle character will be generated. |
| 329 | |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 330 | \param[in] src source buffer |
| 331 | \param[in] slen source buffer length |
| 332 | \param[out] count number of bytes removed (encoded) from source buffer |
| 333 | \param[out] dst destination buffer |
| 334 | \param[in] dsize destination buffer size |
| 335 | \returns - number of encoded bytes in the destination buffer |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 336 | */ |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 337 | int osmo_isdnhdlc_encode(struct osmo_isdnhdlc_vars *hdlc, const uint8_t *src, uint16_t slen, |
| 338 | int *count, uint8_t *dst, int dsize) |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 339 | { |
| 340 | static const unsigned char xfast_flag_value[] = { |
| 341 | 0x7e, 0x3f, 0x9f, 0xcf, 0xe7, 0xf3, 0xf9, 0xfc, 0x7e |
| 342 | }; |
| 343 | |
| 344 | int len = 0; |
| 345 | |
| 346 | *count = slen; |
| 347 | |
| 348 | /* special handling for one byte frames */ |
| 349 | if ((slen == 1) && (hdlc->state == HDLC_SEND_FAST_FLAG)) |
| 350 | hdlc->state = HDLC_SENDFLAG_ONE; |
| 351 | while (dsize > 0) { |
| 352 | if (hdlc->bit_shift == 0) { |
| 353 | if (slen && !hdlc->do_closing) { |
| 354 | hdlc->shift_reg = *src++; |
| 355 | slen--; |
| 356 | if (slen == 0) |
| 357 | /* closing sequence, CRC + flag(s) */ |
| 358 | hdlc->do_closing = 1; |
| 359 | hdlc->bit_shift = 8; |
| 360 | } else { |
| 361 | if (hdlc->state == HDLC_SEND_DATA) { |
| 362 | if (hdlc->data_received) { |
| 363 | hdlc->state = HDLC_SEND_CRC1; |
| 364 | hdlc->crc ^= 0xffff; |
| 365 | hdlc->bit_shift = 8; |
| 366 | hdlc->shift_reg = |
| 367 | hdlc->crc & 0xff; |
| 368 | } else if (!hdlc->do_adapt56) |
| 369 | hdlc->state = |
| 370 | HDLC_SEND_FAST_FLAG; |
| 371 | else |
| 372 | hdlc->state = |
| 373 | HDLC_SENDFLAG_B0; |
| 374 | } |
| 375 | |
| 376 | } |
| 377 | } |
| 378 | |
| 379 | switch (hdlc->state) { |
| 380 | case STOPPED: |
| 381 | while (dsize--) |
| 382 | *dst++ = 0xff; |
| 383 | return dsize; |
| 384 | case HDLC_SEND_FAST_FLAG: |
| 385 | hdlc->do_closing = 0; |
| 386 | if (slen == 0) { |
| 387 | /* the code is for bitreverse streams */ |
| 388 | if (hdlc->do_bitreverse == 0) |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 389 | *dst++ = osmo_revbytebits_8(hdlc->ffvalue); |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 390 | else |
| 391 | *dst++ = hdlc->ffvalue; |
| 392 | len++; |
| 393 | dsize--; |
| 394 | break; |
| 395 | } |
| 396 | /* fall through */ |
| 397 | case HDLC_SENDFLAG_ONE: |
| 398 | if (hdlc->bit_shift == 8) { |
| 399 | hdlc->cbin = hdlc->ffvalue >> |
| 400 | (8 - hdlc->data_bits); |
| 401 | hdlc->state = HDLC_SEND_DATA; |
| 402 | hdlc->crc = 0xffff; |
| 403 | hdlc->hdlc_bits1 = 0; |
| 404 | hdlc->data_received = 1; |
| 405 | } |
| 406 | break; |
| 407 | case HDLC_SENDFLAG_B0: |
| 408 | hdlc->do_closing = 0; |
| 409 | hdlc->cbin <<= 1; |
| 410 | hdlc->data_bits++; |
| 411 | hdlc->hdlc_bits1 = 0; |
| 412 | hdlc->state = HDLC_SENDFLAG_B1A6; |
| 413 | break; |
| 414 | case HDLC_SENDFLAG_B1A6: |
| 415 | hdlc->cbin <<= 1; |
| 416 | hdlc->data_bits++; |
| 417 | hdlc->cbin++; |
| 418 | if (++hdlc->hdlc_bits1 == 6) |
| 419 | hdlc->state = HDLC_SENDFLAG_B7; |
| 420 | break; |
| 421 | case HDLC_SENDFLAG_B7: |
| 422 | hdlc->cbin <<= 1; |
| 423 | hdlc->data_bits++; |
| 424 | if (slen == 0) { |
| 425 | hdlc->state = HDLC_SENDFLAG_B0; |
| 426 | break; |
| 427 | } |
| 428 | if (hdlc->bit_shift == 8) { |
| 429 | hdlc->state = HDLC_SEND_DATA; |
| 430 | hdlc->crc = 0xffff; |
| 431 | hdlc->hdlc_bits1 = 0; |
| 432 | hdlc->data_received = 1; |
| 433 | } |
| 434 | break; |
| 435 | case HDLC_SEND_FIRST_FLAG: |
| 436 | hdlc->data_received = 1; |
| 437 | if (hdlc->data_bits == 8) { |
| 438 | hdlc->state = HDLC_SEND_DATA; |
| 439 | hdlc->crc = 0xffff; |
| 440 | hdlc->hdlc_bits1 = 0; |
| 441 | break; |
| 442 | } |
| 443 | hdlc->cbin <<= 1; |
| 444 | hdlc->data_bits++; |
| 445 | if (hdlc->shift_reg & 0x01) |
| 446 | hdlc->cbin++; |
| 447 | hdlc->shift_reg >>= 1; |
| 448 | hdlc->bit_shift--; |
| 449 | if (hdlc->bit_shift == 0) { |
| 450 | hdlc->state = HDLC_SEND_DATA; |
| 451 | hdlc->crc = 0xffff; |
| 452 | hdlc->hdlc_bits1 = 0; |
| 453 | } |
| 454 | break; |
| 455 | case HDLC_SEND_DATA: |
| 456 | hdlc->cbin <<= 1; |
| 457 | hdlc->data_bits++; |
| 458 | if (hdlc->hdlc_bits1 == 5) { |
| 459 | hdlc->hdlc_bits1 = 0; |
| 460 | break; |
| 461 | } |
| 462 | if (hdlc->bit_shift == 8) |
| 463 | hdlc->crc = crc_ccitt_byte(hdlc->crc, |
| 464 | hdlc->shift_reg); |
| 465 | if (hdlc->shift_reg & 0x01) { |
| 466 | hdlc->hdlc_bits1++; |
| 467 | hdlc->cbin++; |
| 468 | hdlc->shift_reg >>= 1; |
| 469 | hdlc->bit_shift--; |
| 470 | } else { |
| 471 | hdlc->hdlc_bits1 = 0; |
| 472 | hdlc->shift_reg >>= 1; |
| 473 | hdlc->bit_shift--; |
| 474 | } |
| 475 | break; |
| 476 | case HDLC_SEND_CRC1: |
| 477 | hdlc->cbin <<= 1; |
| 478 | hdlc->data_bits++; |
| 479 | if (hdlc->hdlc_bits1 == 5) { |
| 480 | hdlc->hdlc_bits1 = 0; |
| 481 | break; |
| 482 | } |
| 483 | if (hdlc->shift_reg & 0x01) { |
| 484 | hdlc->hdlc_bits1++; |
| 485 | hdlc->cbin++; |
| 486 | hdlc->shift_reg >>= 1; |
| 487 | hdlc->bit_shift--; |
| 488 | } else { |
| 489 | hdlc->hdlc_bits1 = 0; |
| 490 | hdlc->shift_reg >>= 1; |
| 491 | hdlc->bit_shift--; |
| 492 | } |
| 493 | if (hdlc->bit_shift == 0) { |
| 494 | hdlc->shift_reg = (hdlc->crc >> 8); |
| 495 | hdlc->state = HDLC_SEND_CRC2; |
| 496 | hdlc->bit_shift = 8; |
| 497 | } |
| 498 | break; |
| 499 | case HDLC_SEND_CRC2: |
| 500 | hdlc->cbin <<= 1; |
| 501 | hdlc->data_bits++; |
| 502 | if (hdlc->hdlc_bits1 == 5) { |
| 503 | hdlc->hdlc_bits1 = 0; |
| 504 | break; |
| 505 | } |
| 506 | if (hdlc->shift_reg & 0x01) { |
| 507 | hdlc->hdlc_bits1++; |
| 508 | hdlc->cbin++; |
| 509 | hdlc->shift_reg >>= 1; |
| 510 | hdlc->bit_shift--; |
| 511 | } else { |
| 512 | hdlc->hdlc_bits1 = 0; |
| 513 | hdlc->shift_reg >>= 1; |
| 514 | hdlc->bit_shift--; |
| 515 | } |
| 516 | if (hdlc->bit_shift == 0) { |
| 517 | hdlc->shift_reg = 0x7e; |
| 518 | hdlc->state = HDLC_SEND_CLOSING_FLAG; |
| 519 | hdlc->bit_shift = 8; |
| 520 | } |
| 521 | break; |
| 522 | case HDLC_SEND_CLOSING_FLAG: |
| 523 | hdlc->cbin <<= 1; |
| 524 | hdlc->data_bits++; |
| 525 | if (hdlc->hdlc_bits1 == 5) { |
| 526 | hdlc->hdlc_bits1 = 0; |
| 527 | break; |
| 528 | } |
| 529 | if (hdlc->shift_reg & 0x01) |
| 530 | hdlc->cbin++; |
| 531 | hdlc->shift_reg >>= 1; |
| 532 | hdlc->bit_shift--; |
| 533 | if (hdlc->bit_shift == 0) { |
| 534 | hdlc->ffvalue = |
| 535 | xfast_flag_value[hdlc->data_bits]; |
| 536 | if (hdlc->dchannel) { |
| 537 | hdlc->ffvalue = 0x7e; |
| 538 | hdlc->state = HDLC_SEND_IDLE1; |
| 539 | hdlc->bit_shift = 8-hdlc->data_bits; |
| 540 | if (hdlc->bit_shift == 0) |
| 541 | hdlc->state = |
| 542 | HDLC_SEND_FAST_IDLE; |
| 543 | } else { |
| 544 | if (!hdlc->do_adapt56) { |
| 545 | hdlc->state = |
| 546 | HDLC_SEND_FAST_FLAG; |
| 547 | hdlc->data_received = 0; |
| 548 | } else { |
| 549 | hdlc->state = HDLC_SENDFLAG_B0; |
| 550 | hdlc->data_received = 0; |
| 551 | } |
| 552 | /* Finished this frame, send flags */ |
| 553 | if (dsize > 1) |
| 554 | dsize = 1; |
| 555 | } |
| 556 | } |
| 557 | break; |
| 558 | case HDLC_SEND_IDLE1: |
| 559 | hdlc->do_closing = 0; |
| 560 | hdlc->cbin <<= 1; |
| 561 | hdlc->cbin++; |
| 562 | hdlc->data_bits++; |
| 563 | hdlc->bit_shift--; |
| 564 | if (hdlc->bit_shift == 0) { |
| 565 | hdlc->state = HDLC_SEND_FAST_IDLE; |
| 566 | hdlc->bit_shift = 0; |
| 567 | } |
| 568 | break; |
| 569 | case HDLC_SEND_FAST_IDLE: |
| 570 | hdlc->do_closing = 0; |
| 571 | hdlc->cbin = 0xff; |
| 572 | hdlc->data_bits = 8; |
| 573 | if (hdlc->bit_shift == 8) { |
| 574 | hdlc->cbin = 0x7e; |
| 575 | hdlc->state = HDLC_SEND_FIRST_FLAG; |
| 576 | } else { |
| 577 | /* the code is for bitreverse streams */ |
| 578 | if (hdlc->do_bitreverse == 0) |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 579 | *dst++ = osmo_revbytebits_8(hdlc->cbin); |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 580 | else |
| 581 | *dst++ = hdlc->cbin; |
| 582 | hdlc->bit_shift = 0; |
| 583 | hdlc->data_bits = 0; |
| 584 | len++; |
| 585 | dsize = 0; |
| 586 | } |
| 587 | break; |
| 588 | default: |
| 589 | break; |
| 590 | } |
| 591 | if (hdlc->do_adapt56) { |
| 592 | if (hdlc->data_bits == 7) { |
| 593 | hdlc->cbin <<= 1; |
| 594 | hdlc->cbin++; |
| 595 | hdlc->data_bits++; |
| 596 | } |
| 597 | } |
| 598 | if (hdlc->data_bits == 8) { |
| 599 | /* the code is for bitreverse streams */ |
| 600 | if (hdlc->do_bitreverse == 0) |
Harald Welte | 9da77ab | 2018-05-11 17:39:21 +0200 | [diff] [blame] | 601 | *dst++ = osmo_revbytebits_8(hdlc->cbin); |
Harald Welte | 85b9fba | 2018-05-11 17:36:13 +0200 | [diff] [blame] | 602 | else |
| 603 | *dst++ = hdlc->cbin; |
| 604 | hdlc->data_bits = 0; |
| 605 | len++; |
| 606 | dsize--; |
| 607 | } |
| 608 | } |
| 609 | *count -= slen; |
| 610 | |
| 611 | return len; |
| 612 | } |