| /* TRAU frame handling according to GSM TS 08.60 */ |
| |
| /* (C) 2009 by Harald Welte <laforge@gnumonks.org> |
| * All Rights Reserved |
| * |
| * 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., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| */ |
| |
| #include <unistd.h> |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <errno.h> |
| |
| #include <openbsc/trau_frame.h> |
| #include <openbsc/subchan_demux.h> |
| #include <openbsc/debug.h> |
| |
| static u_int32_t get_bits(const u_int8_t *bitbuf, int offset, int num) |
| { |
| int i; |
| u_int32_t ret = 0; |
| |
| for (i = offset; i < offset + num; i++) { |
| ret = ret << 1; |
| if (bitbuf[i]) |
| ret |= 1; |
| } |
| return ret; |
| } |
| |
| /* Decode according to 3.1.1 */ |
| static void decode_fr(struct decoded_trau_frame *fr, const u_int8_t *trau_bits) |
| { |
| int i; |
| int d_idx = 0; |
| |
| /* C1 .. C15 */ |
| memcpy(fr->c_bits+0, trau_bits+17, 15); |
| /* C16 .. C21 */ |
| memcpy(fr->c_bits+15, trau_bits+310, 6); |
| /* T1 .. T4 */ |
| memcpy(fr->t_bits+0, trau_bits+316, 4); |
| /* D1 .. D255 */ |
| for (i = 32; i < 304; i+= 16) { |
| memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15); |
| d_idx += 15; |
| } |
| /* D256 .. D260 */ |
| memcpy(fr->d_bits + d_idx, trau_bits + 305, 5); |
| } |
| |
| /* Decode according to 3.1.2 */ |
| static void decode_amr(struct decoded_trau_frame *fr, const u_int8_t *trau_bits) |
| { |
| int i; |
| int d_idx = 0; |
| |
| /* C1 .. C15 */ |
| memcpy(fr->c_bits+0, trau_bits+17, 15); |
| /* C16 .. C25 */ |
| memcpy(fr->c_bits+15, trau_bits+33, 10); |
| /* T1 .. T4 */ |
| memcpy(fr->t_bits+0, trau_bits+316, 4); |
| /* D1 .. D5 */ |
| memcpy(fr->d_bits, trau_bits+43, 5); |
| /* D6 .. D245 */ |
| for (i = 48; i < 304; i += 16) { |
| memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15); |
| d_idx += 15; |
| } |
| /* D246 .. D256 */ |
| memcpy(fr->d_bits + d_idx, trau_bits + 305, 11); |
| } |
| |
| int decode_trau_frame(struct decoded_trau_frame *fr, const u_int8_t *trau_bits) |
| { |
| u_int8_t cbits5 = get_bits(trau_bits, 17, 5); |
| |
| switch (cbits5) { |
| case TRAU_FT_FR_UP: |
| case TRAU_FT_FR_DOWN: |
| case TRAU_FT_IDLE_UP: |
| case TRAU_FT_IDLE_DOWN: |
| case TRAU_FT_EFR: |
| decode_fr(fr, trau_bits); |
| break; |
| case TRAU_FT_AMR: |
| decode_amr(fr, trau_bits); |
| break; |
| case TRAU_FT_OM_UP: |
| case TRAU_FT_OM_DOWN: |
| case TRAU_FT_DATA_UP: |
| case TRAU_FT_DATA_DOWN: |
| case TRAU_FT_D145_SYNC: |
| case TRAU_FT_EDATA: |
| LOGP(DMUX, LOGL_NOTICE, "can't decode unimplemented TRAU " |
| "Frame Type 0x%02x\n", cbits5); |
| return -1; |
| break; |
| default: |
| LOGP(DMUX, LOGL_NOTICE, "can't decode unknown TRAU " |
| "Frame Type 0x%02x\n", cbits5); |
| return -1; |
| break; |
| } |
| |
| return 0; |
| } |
| |
| const u_int8_t ft_fr_down_bits[] = { 1, 1, 1, 0, 0 }; |
| const u_int8_t ft_idle_down_bits[] = { 0, 1, 1, 1, 0 }; |
| |
| /* modify an uplink TRAU frame so we can send it downlink */ |
| int trau_frame_up2down(struct decoded_trau_frame *fr) |
| { |
| u_int8_t cbits5 = get_bits(fr->c_bits, 0, 5); |
| |
| switch (cbits5) { |
| case TRAU_FT_FR_UP: |
| memcpy(fr->c_bits, ft_fr_down_bits, 5); |
| /* clear time alignment */ |
| memset(fr->c_bits+5, 0, 6); |
| /* FIXME: SP / BFI in case of DTx */ |
| /* C12 .. C21 are spare and coded as '1' */ |
| memset(fr->c_bits+11, 0x01, 10); |
| break; |
| case TRAU_FT_EFR: |
| /* clear time alignment */ |
| memset(fr->c_bits+5, 0, 6); |
| /* FIXME: set UFE appropriately */ |
| /* FIXME: SP / BFI in case of DTx */ |
| break; |
| case TRAU_FT_IDLE_UP: |
| memcpy(fr->c_bits, ft_idle_down_bits, 5); |
| /* clear time alignment */ |
| memset(fr->c_bits+5, 0, 6); |
| /* FIXME: SP / BFI in case of DTx */ |
| /* C12 .. C21 are spare and coded as '1' */ |
| memset(fr->c_bits+11, 0x01, 10); |
| break; |
| case TRAU_FT_FR_DOWN: |
| case TRAU_FT_IDLE_DOWN: |
| case TRAU_FT_OM_DOWN: |
| case TRAU_FT_DATA_DOWN: |
| /* we cannot convert a downlink to a downlink frame */ |
| return -EINVAL; |
| break; |
| case TRAU_FT_AMR: |
| case TRAU_FT_OM_UP: |
| case TRAU_FT_DATA_UP: |
| case TRAU_FT_D145_SYNC: |
| case TRAU_FT_EDATA: |
| LOGP(DMUX, LOGL_NOTICE, "unimplemented TRAU Frame Type " |
| "0x%02x\n", cbits5); |
| return -1; |
| break; |
| default: |
| LOGP(DMUX, LOGL_NOTICE, "unknown TRAU Frame Type " |
| "0x%02x\n", cbits5); |
| return -1; |
| break; |
| } |
| |
| return 0; |
| |
| } |
| |
| static void encode_fr(u_int8_t *trau_bits, const struct decoded_trau_frame *fr) |
| { |
| int i; |
| int d_idx = 0; |
| |
| trau_bits[16] = 1; |
| /* C1 .. C15 */ |
| memcpy(trau_bits+17, fr->c_bits+0, 15); |
| /* D1 .. D255 */ |
| for (i = 32; i < 304; i+= 16) { |
| trau_bits[i] = 1; |
| memcpy(trau_bits+i+1, fr->d_bits + d_idx, 15); |
| d_idx += 15; |
| } |
| /* D256 .. D260 */ |
| trau_bits[304] = 1; |
| memcpy(trau_bits + 305, fr->d_bits + d_idx, 5); |
| /* C16 .. C21 */ |
| memcpy(trau_bits+310, fr->c_bits+15, 6); |
| |
| /* FIXME: handle timing adjustment */ |
| |
| /* T1 .. T4 */ |
| memcpy(trau_bits+316, fr->t_bits+0, 4); |
| } |
| |
| |
| int encode_trau_frame(u_int8_t *trau_bits, const struct decoded_trau_frame *fr) |
| { |
| u_int8_t cbits5 = get_bits(fr->c_bits, 0, 5); |
| |
| /* 16 bits of sync header */ |
| memset(trau_bits, 0, 16); |
| |
| switch (cbits5) { |
| case TRAU_FT_FR_UP: |
| case TRAU_FT_FR_DOWN: |
| case TRAU_FT_IDLE_UP: |
| case TRAU_FT_IDLE_DOWN: |
| case TRAU_FT_EFR: |
| encode_fr(trau_bits, fr); |
| break; |
| case TRAU_FT_AMR: |
| case TRAU_FT_OM_UP: |
| case TRAU_FT_OM_DOWN: |
| case TRAU_FT_DATA_UP: |
| case TRAU_FT_DATA_DOWN: |
| case TRAU_FT_D145_SYNC: |
| case TRAU_FT_EDATA: |
| LOGP(DMUX, LOGL_NOTICE, "unimplemented TRAU Frame Type " |
| "0x%02x\n", cbits5); |
| return -1; |
| break; |
| default: |
| LOGP(DMUX, LOGL_NOTICE, "unknown TRAU Frame Type " |
| "0x%02x\n", cbits5); |
| return -1; |
| break; |
| } |
| |
| return 0; |
| } |
| |
| static struct decoded_trau_frame fr_idle_frame = { |
| .c_bits = { 0, 1, 1, 1, 0 }, /* IDLE DOWNLINK 3.5.5 */ |
| .t_bits = { 1, 1, 1, 1 }, |
| }; |
| static u_int8_t encoded_idle_frame[TRAU_FRAME_BITS]; |
| static int dbits_initted; |
| |
| u_int8_t *trau_idle_frame(void) |
| { |
| /* only initialize during the first call */ |
| if (!dbits_initted) { |
| /* set all D-bits to 1 */ |
| memset(&fr_idle_frame.d_bits, 0x01, 260); |
| encode_fr(encoded_idle_frame, &fr_idle_frame); |
| } |
| return encoded_idle_frame; |
| } |