Philipp | 73f83d5 | 2016-09-02 13:38:01 +0200 | [diff] [blame] | 1 | /* GPRS SNDCP data compression handler */ |
| 2 | |
| 3 | /* (C) 2016 by sysmocom s.f.m.c. GmbH <info@sysmocom.de> |
| 4 | * All Rights Reserved |
| 5 | * |
| 6 | * Author: Philipp Maier |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU Affero General Public License as published by |
| 10 | * the Free Software Foundation; either version 3 of the License, or |
| 11 | * (at your option) any later version. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | * GNU Affero General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Affero General Public License |
| 19 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 20 | */ |
| 21 | |
| 22 | #pragma once |
| 23 | |
| 24 | #include <stdint.h> |
| 25 | #include <osmocom/core/linuxlist.h> |
| 26 | #include <openbsc/gprs_sndcp_comp.h> |
| 27 | |
| 28 | /* Note: The decompressed packet may have a maximum size of: |
| 29 | * Return value * MAX_DATADECOMPR_FAC */ |
| 30 | #define MAX_DATADECOMPR_FAC 10 |
| 31 | |
| 32 | /* Note: In unacknowledged mode (SN_UNITDATA), the comression state is reset |
| 33 | * for every NPDU. The compressor needs a reasonably large payload to operate |
| 34 | * effectively (yield positive compression gain). For packets shorter than 100 |
| 35 | * byte, no positive compression gain can be expected so we will skip the |
| 36 | * compression for short packets. */ |
| 37 | #define MIN_COMPR_PAYLOAD 100 |
| 38 | |
| 39 | /* Initalize data compression */ |
| 40 | int gprs_sndcp_dcomp_init(const void *ctx, struct gprs_sndcp_comp *comp_entity, |
| 41 | const struct gprs_sndcp_comp_field *comp_field); |
| 42 | |
| 43 | /* Terminate data compression */ |
| 44 | void gprs_sndcp_dcomp_term(struct gprs_sndcp_comp *comp_entity); |
| 45 | |
| 46 | /* Expand packet */ |
| 47 | int gprs_sndcp_dcomp_expand(uint8_t *data, unsigned int len, uint8_t pcomp, |
| 48 | const struct llist_head *comp_entities); |
| 49 | |
| 50 | /* Compress packet */ |
| 51 | int gprs_sndcp_dcomp_compress(uint8_t *data, unsigned int len, uint8_t *pcomp, |
| 52 | const struct llist_head *comp_entities, |
| 53 | uint8_t nsapi); |