diff options
Diffstat (limited to 'src/osmo-bts-trx/tch_fr.c')
| -rw-r--r-- | src/osmo-bts-trx/tch_fr.c | 365 |
1 files changed, 0 insertions, 365 deletions
diff --git a/src/osmo-bts-trx/tch_fr.c b/src/osmo-bts-trx/tch_fr.c deleted file mode 100644 index 23130e94..00000000 --- a/src/osmo-bts-trx/tch_fr.c +++ /dev/null @@ -1,365 +0,0 @@ -/* - * tch_fr.c - * - * Copyright (c) 2013 Andreas Eversberg <jolly@eversberg.eu> - */ - -#include <stdio.h> -#include <stdint.h> -#include <string.h> - -#include <osmocom/core/bits.h> -#include <osmocom/core/conv.h> -#include <osmocom/core/crcgen.h> - -#include "xcch.h" -#include "tch_fr.h" - - -/* - * GSM TCH FR/EFR parity - * - * g(x) = x^3 + x + 1 - */ - -const struct osmo_crc8gen_code tch_fr_crc3 = { - .bits = 3, - .poly = 0x3, - .init = 0x0, - .remainder = 0x7, -}; - - -/* - * GSM TCH FR/EFR convolutional coding - * - * G_0 = 1 + x^3 + x^4 - * G_1 = 1 + x + x^3 + x^4 - */ - -static const uint8_t conv_tch_fr_next_output[][2] = { - { 0, 3 }, { 1, 2 }, { 0, 3 }, { 1, 2 }, - { 3, 0 }, { 2, 1 }, { 3, 0 }, { 2, 1 }, - { 3, 0 }, { 2, 1 }, { 3, 0 }, { 2, 1 }, - { 0, 3 }, { 1, 2 }, { 0, 3 }, { 1, 2 }, -}; - -static const uint8_t conv_tch_fr_next_state[][2] = { - { 0, 1 }, { 2, 3 }, { 4, 5 }, { 6, 7 }, - { 8, 9 }, { 10, 11 }, { 12, 13 }, { 14, 15 }, - { 0, 1 }, { 2, 3 }, { 4, 5 }, { 6, 7 }, - { 8, 9 }, { 10, 11 }, { 12, 13 }, { 14, 15 }, -}; - -static const struct osmo_conv_code conv_tch_fr = { - .N = 2, - .K = 5, - .len = 185, - .next_output = conv_tch_fr_next_output, - .next_state = conv_tch_fr_next_state, -}; - - -/* - * GSM TCH FR/EFR interleaving and burst mapping - * - * Interleaving: - * - * Given 456 coded input bits, form 8 blocks of 114 bits, - * where event bits of the first 4 block and off bits of the last 4 block - * are used: - * - * i(B, j) = c(n, k) k = 0, ..., 455 - * n = 0, ..., N, N + 1, ... - * B = B_0 + 4n + (k mod 8) - * j = 2(49k mod 57) + ((k mod 8) div 4) - * - * Mapping on Burst: - * - * e(B, j) = i(B, j) - * e(B, 59 + j) = i(B, 57 + j) j = 0, ..., 56 - * e(B, 57) = h_l(B) - * e(B, 58) = h_n(B) - * - * Where hl(B) and hn(B) are bits in burst B indicating flags. - */ - -static void -tch_fr_deinterleave(sbit_t *cB, sbit_t *iB) -{ - int j, k, B; - - for (k=0; k<456; k++) { - B = k & 7; - j = 2 * ((49 * k) % 57) + ((k & 7) >> 2); - cB[k] = iB[B * 114 + j]; - } -} - -static void -tch_fr_interleave(ubit_t *cB, ubit_t *iB) -{ - int j, k, B; - - for (k=0; k<456; k++) { - B = k & 7; - j = 2 * ((49 * k) % 57) + ((k & 7) >> 2); - iB[B * 114 + j] = cB[k]; - } -} - -static void -tch_fr_burst_unmap(sbit_t *iB, sbit_t *eB, sbit_t *h, int odd) -{ - int i; - - /* brainfuck: only copy even or odd bits */ - for (i=odd; i<57; i+=2) - iB[i] = eB[i]; - for (i=58-odd; i<114; i+=2) - iB[i] = eB[i+2]; - - if (h && !odd) - *h = eB[58]; - - if (h && odd) - *h = eB[57]; -} - -static void -tch_fr_burst_map(ubit_t *iB, ubit_t *eB, ubit_t *h, int odd) -{ - int i; - - /* brainfuck: only copy even or odd bits */ - for (i=odd; i<57; i+=2) - eB[i] = iB[i]; - for (i=58-odd; i<114; i+=2) - eB[i+2] = iB[i]; - - if (h && !odd) - eB[58] = *h; - if (h && odd) - eB[57] = *h; -} - -/* this corresponds to the bit-lengths of the individual codec - * parameters as indicated in Table 1.1 of TS 06.10 */ -static const uint8_t gsm_fr_map[] = { - 6, 6, 5, 5, 4, 4, 3, 3, - 7, 2, 2, 6, 3, 3, 3, 3, - 3, 3, 3, 3, 3, 3, 3, 3, - 3, 7, 2, 2, 6, 3, 3, 3, - 3, 3, 3, 3, 3, 3, 3, 3, - 3, 3, 7, 2, 2, 6, 3, 3, - 3, 3, 3, 3, 3, 3, 3, 3, - 3, 3, 3, 7, 2, 2, 6, 3, - 3, 3, 3, 3, 3, 3, 3, 3, - 3, 3, 3, 3 -}; - -static void -tch_fr_reassemble(uint8_t *tch_data, ubit_t *b_bits) -{ - int i, j, k, l, o; - - tch_data[0] = 0xd << 4; - memset(tch_data + 1, 0, 32); - /* reassemble d-bits */ - i = 0; /* counts bits */ - j = 4; /* counts output bits */ - k = gsm_fr_map[0]-1; /* current number bit in element */ - l = 0; /* counts element bits */ - o = 0; /* offset input bits */ - while (i < 260) { - tch_data[j>>3] |= (b_bits[k+o] << (7-(j&7))); - if (--k < 0) { - o += gsm_fr_map[l]; - k = gsm_fr_map[++l]-1; - } - i++; - j++; - } - - /* rearrange according to Table 2 of TS 05.03 */ -} - -static void -tch_fr_disassemble(ubit_t *b_bits, uint8_t *tch_data) -{ - int i, j, k, l, o; - - i = 0; /* counts bits */ - j = 4; /* counts input bits */ - k = gsm_fr_map[0]-1; /* current number bit in element */ - l = 0; /* counts element bits */ - o = 0; /* offset output bits */ - while (i < 260) { - b_bits[k+o] = (tch_data[j>>3] >> (7-(j&7))) & 1; - if (--k < 0) { - o += gsm_fr_map[l]; - k = gsm_fr_map[++l]-1; - } - i++; - j++; - } - -} - - -/* b(0..259) from d(0..259) according to (corrected) Table 2 of T 05.03 */ -static uint16_t d_to_b_index[260] = { - 5, 52,108,164,220, 4, 11, 16, 3, 10, 15, 21, 42, 98,154,210, - 51,107,163,219, 9, 25, 29, 41, 97,153,209, 40, 96,152,208, 39, - 95,151,207, 38, 94,150,206, 50,106,162,218, 2, 20, 32, 37, 93, - 149,205, 24, 28, 44,100,156,212, 36, 92,148,204, 46,102,158,214, - 1, 8, 14, 35, 19, 23, 31, 43, 99,155,211, 49,105,161,217, 55, - 58, 61, 64, 67, 70, 73, 76, 79, 82, 85, 88, 91,111,114,117,120, - 123,126,129,132,135,138,141,144,147,167,170,173,176,179,182,185, - 188,191,194,197,200,203,223,226,229,232,235,238,241,244,247,250, - 253,256,259, 45,101,157,213, 48,104,160,216, 54, 57, 60, 63, 66, - 69, 72, 75, 78, 81, 84, 87, 90,110,113,116,119,122,125,128,131, - 134,137,140,143,146,166,169,172,175,178,181,184,187,190,193,196, - 199,202,222,225,228,231,234,237,240,243,246,249,252,255,258, 0, - 7, 13, 27, 30, 34, 33, 12, 18, 17, 22, 47,103,159,215, 53, 56, - 59, 62, 65, 68, 71, 74, 77, 80, 83, 86, 89,109,112,115,118,121, - 124,127,130,133,136,139,142,145,165,168,171,174,177,180,183,186, - 189,192,195,198,201,221,224,227,230,233,236,239,242,245,248,251, - 254,257, 6, 26, -}; - - -static void -tch_fr_d_to_b(ubit_t *b_bits, ubit_t *d_bits) -{ - int i; - - for (i = 0; i < 260; i++) - b_bits[d_to_b_index[i]] = d_bits[i]; -} - -static void -tch_fr_b_to_d(ubit_t *d_bits, ubit_t *b_bits) -{ - int i; - - for (i = 0; i < 260; i++) - d_bits[i] = b_bits[d_to_b_index[i]]; -} - -static void -tch_fr_unreorder(ubit_t *d, ubit_t *p, ubit_t *u) -{ - int i; - - for (i=0; i<91; i++) { - d[i<<1] = u[i]; - d[(i<<1)+1] = u[184-i]; - } - for (i=0; i<3; i++) - p[i] = u[91+i]; -} - -static void -tch_fr_reorder(ubit_t *u, ubit_t *d, ubit_t *p) -{ - int i; - - for (i=0; i<91; i++) { - u[i] = d[i<<1]; - u[184-i] = d[(i<<1)+1]; - } - for (i=0; i<3; i++) - u[91+i] = p[i]; -} - -int -tch_fr_decode(uint8_t *tch_data, sbit_t *bursts, int network_order) -{ - sbit_t iB[912], cB[456], h; - ubit_t conv[185], b[260], d[260], p[3]; - int i, rv, len, steal = 0; - - for (i=0; i<8; i++) { - tch_fr_burst_unmap(&iB[i * 114], &bursts[i * 116], &h, i>>2); - if (h < 0) - steal++; - } - - tch_fr_deinterleave(cB, iB); - - if (steal < 4) { - osmo_conv_decode(&conv_tch_fr, cB, conv); - - tch_fr_unreorder(d, p, conv); - - for (i=0; i<78; i++) - d[i+182] = (cB[i+378] < 0) ? 1:0; - - rv = osmo_crc8gen_check_bits(&tch_fr_crc3, d, 50, p); - if (rv) - return -1; - - if (network_order) { - tch_fr_d_to_b(b, d); - - tch_fr_reassemble(tch_data, b); - } else - tch_fr_d_to_b(tch_data, d); - - len = 33; - } else { - rv = xcch_decode_cB(tch_data, cB); - if (rv) - return -1; - - len = 23; - } - - return len; -} - -int -tch_fr_encode(ubit_t *bursts, uint8_t *tch_data, int len, int network_order) -{ - ubit_t iB[912], cB[456], h; - ubit_t conv[185], b[260], d[260], p[3]; - int i; - - switch (len) { - case 33: /* TCH FR */ - if (network_order) { - tch_fr_disassemble(b, tch_data); - - tch_fr_b_to_d(d, b); - } else - tch_fr_b_to_d(d, tch_data); - - osmo_crc8gen_set_bits(&tch_fr_crc3, d, 50, p); - - tch_fr_reorder(conv, d, p); - - memcpy(cB+378, d+182, 78); - - osmo_conv_encode(&conv_tch_fr, conv, cB); - - h = 0; - - break; - case 23: /* FACCH */ - xcch_encode_cB(cB, tch_data); - - h = 1; - - break; - default: - return -1; - } - - tch_fr_interleave(cB, iB); - - for (i=0; i<8; i++) - tch_fr_burst_map(&iB[i * 114], &bursts[i * 116], &h, i>>2); - - return 0; -} |