/* TRAU frame handling according to GSM TS 08.60 */ /* (C) 2009 by Harald Welte * 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 #include #include #include #include #include #include #include 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: DEBUGP(DMUX, "can't decode unimplemented TRAU Frame Type 0x%02x\n", cbits5); return -1; break; default: DEBUGP(DMUX, "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: DEBUGP(DMUX, "unimplemented TRAU Frame Type 0x%02x\n", cbits5); return -1; break; default: DEBUGP(DMUX, "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: DEBUGP(DMUX, "unimplemented TRAU Frame Type 0x%02x\n", cbits5); return -1; break; default: DEBUGP(DMUX, "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; }