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Diffstat (limited to 'gr-pager/src/pager_flex_sync.cc')
| -rw-r--r-- | gr-pager/src/pager_flex_sync.cc | 340 |
1 files changed, 0 insertions, 340 deletions
diff --git a/gr-pager/src/pager_flex_sync.cc b/gr-pager/src/pager_flex_sync.cc deleted file mode 100644 index 6bcee8ede..000000000 --- a/gr-pager/src/pager_flex_sync.cc +++ /dev/null @@ -1,340 +0,0 @@ -/* - * Copyright 2004,2006 Free Software Foundation, Inc. - * - * This file is part of GNU Radio - * - * GNU Radio 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 3, or (at your option) - * any later version. - * - * GNU Radio 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 GNU Radio; see the file COPYING. If not, write to - * the Free Software Foundation, Inc., 51 Franklin Street, - * Boston, MA 02110-1301, USA. - */ - -#ifdef HAVE_CONFIG_H -#include "config.h" -#endif - -#include <pager_flex_sync.h> -#include <pageri_flex_modes.h> -#include <pageri_bch3221.h> -#include <pageri_util.h> -#include <gr_io_signature.h> -#include <gr_count_bits.h> -#include <cstdio> - -pager_flex_sync_sptr pager_make_flex_sync() -{ - return pager_flex_sync_sptr(new pager_flex_sync()); -} - -// FLEX sync block takes input from sliced baseband stream [0-3] at specified -// channel rate. Symbol timing is established based on receiving one of the -// defined FLEX protocol synchronization words. The block outputs one FLEX frame -// worth of bits on each output phase for the data portion of the frame. Unused phases -// get all zeros, which are considered idle code words. - -pager_flex_sync::pager_flex_sync() : - gr_block ("flex_sync", - gr_make_io_signature (1, 1, sizeof(unsigned char)), - gr_make_io_signature (4, 4, sizeof(unsigned char))), - d_sync(10) // Fixed at 10 samples per baud (@ 1600 baud) -{ - enter_idle(); -} - -void pager_flex_sync::forecast(int noutput_items, gr_vector_int &inputs_required) -{ - // samples per bit X number of outputs needed - int items = noutput_items*d_spb; - for (unsigned int i = 0; i < inputs_required.size(); i++) - inputs_required[i] = items; -} - -int pager_flex_sync::index_avg(int start, int end) -{ - // modulo average - if (start < end) - return (end + start)/2; - else - return ((end + start)/2 + d_spb/2) % d_spb; -} - -bool pager_flex_sync::test_sync(unsigned char sym) -{ - // 64-bit FLEX sync code: - // AAAA:BBBBBBBB:CCCC - // - // Where BBBBBBBB is always 0xA6C6AAAA - // and AAAA^CCCC is 0xFFFF - // - // Specific values of AAAA determine what bps and encoding the - // packet is beyond the frame information word - // - // First we match on the marker field with a hamming distance < 4 - // Then we match on the outer code with a hamming distance < 4 - - d_sync[d_index] = (d_sync[d_index] << 1) | (sym < 2); - gr_int64 val = d_sync[d_index]; - gr_int32 marker = ((val & 0x0000FFFFFFFF0000ULL)) >> 16; - - if (gr_count_bits32(marker^FLEX_SYNC_MARKER) < 4) { - gr_int32 code = ((val & 0xFFFF000000000000ULL) >> 32) | - (val & 0x000000000000FFFFULL); - - for (int i = 0; i < num_flex_modes; i++) { - if (gr_count_bits32(code^flex_modes[i].sync) < 4) { - d_mode = i; - return true; - } - } - - // Marker received but doesn't match known codes - // All codes have high word inverted to low word - unsigned short high = (code & 0xFFFF0000) >> 16; - unsigned short low = code & 0x0000FFFF; - unsigned short syn = high^low; - if (syn == 0xFFFF) - fprintf(stderr, "Unknown sync code detected: %08X\n", code); - } - - return false; -} - -void pager_flex_sync::enter_idle() -{ - d_state = ST_IDLE; - d_index = 0; - d_start = 0; - d_center = 0; - d_end = 0; - d_count = 0; - d_mode = 0; - d_baudrate = 1600; - d_levels = 2; - d_spb = 16000/d_baudrate; - d_bit_a = 0; - d_bit_b = 0; - d_bit_c = 0; - d_bit_d = 0; - d_hibit = false; - fflush(stdout); -} - -void pager_flex_sync::enter_syncing() -{ - d_start = d_index; - d_state = ST_SYNCING; -} - -void pager_flex_sync::enter_sync1() -{ - d_state = ST_SYNC1; - d_end = d_index; - d_center = index_avg(d_start, d_end); // Center of goodness - d_count = 0; -} - -void pager_flex_sync::enter_sync2() -{ - d_state = ST_SYNC2; - d_count = 0; - d_baudrate = flex_modes[d_mode].baud; - d_levels = flex_modes[d_mode].levels; - d_spb = 16000/d_baudrate; - - if (d_baudrate == 3200) { - // Oversampling buffer just got halved - d_center = d_center/2; - - // We're here at the center of a 1600 baud bit - // So this hack puts the index and bit counter - // in the right place for 3200 bps. - d_index = d_index/2-d_spb/2; - d_count = -1; - } -} - -void pager_flex_sync::enter_data() -{ - d_state = ST_DATA; - d_count = 0; -} - -void pager_flex_sync::parse_fiw() -{ - // Nothing is done with these now, but these will end up getting - // passed as metadata when mblocks are available - - // Bits 31-28 are frame number related, but unknown function - // This might be a checksum - d_unknown2 = pageri_reverse_bits8((d_fiw >> 24) & 0xF0); - - // Cycle is bits 27-24, reversed - d_cycle = pageri_reverse_bits8((d_fiw >> 20) & 0xF0); - - // Frame is bits 23-17, reversed - d_frame = pageri_reverse_bits8((d_fiw >> 16) & 0xFE); - - // Bits 16-11 are some sort of marker, usually identical across - // many frames but sometimes changes between frames or modes - d_unknown1 = (d_fiw >> 11) & 0x3F; - - //printf("CYC:%02i FRM:%03i\n", d_cycle, d_frame); -} - -int pager_flex_sync::output_symbol(unsigned char sym) -{ - // Here is where we output a 1 or 0 on each phase according - // to current FLEX mode and symbol value. Unassigned phases - // are zero from the enter_idle() initialization. - // - // FLEX can transmit the data portion of the frame at either - // 1600 bps or 3200 bps, and can use either two- or four-level - // FSK encoding. - // - // At 1600 bps, 2-level, a single "phase" is transmitted with bit - // value '0' using level '3' and bit value '1' using level '0'. - // - // At 1600 bps, 4-level, a second "phase" is transmitted, and the - // di-bits are encoded with a gray code: - // - // Symbol Phase 1 Phase 2 - // ------ ------- ------- - // 0 1 1 - // 1 1 0 - // 2 0 0 - // 3 0 1 - // - // At 1600 bps, 4-level, these are called PHASE A and PHASE B. - // - // At 3200 bps, the same 1 or 2 bit encoding occurs, except that - // additionally two streams are interleaved on alternating symbols. - // Thus, PHASE A (and PHASE B if 4-level) are decoded on one symbol, - // then PHASE C (and PHASE D if 4-level) are decoded on the next. - - int bits = 0; - - if (d_baudrate == 1600) { - d_bit_a = (sym < 2); - if (d_levels == 4) - d_bit_b = (sym == 0) || (sym == 3); - - *d_phase_a++ = d_bit_a; - *d_phase_b++ = d_bit_b; - *d_phase_c++ = d_bit_c; - *d_phase_d++ = d_bit_d; - bits++; - } - else { - if (!d_hibit) { - d_bit_a = (sym < 2); - if (d_levels == 4) - d_bit_b = (sym == 0) || (sym == 3); - d_hibit = true; - } - else { - d_bit_c = (sym < 2); - if (d_levels == 4) - d_bit_d = (sym == 0) || (sym == 3); - d_hibit = false; - - *d_phase_a++ = d_bit_a; - *d_phase_b++ = d_bit_b; - *d_phase_c++ = d_bit_c; - *d_phase_d++ = d_bit_d; - bits++; - } - } - - return bits; -} - -int pager_flex_sync::general_work(int noutput_items, - gr_vector_int &ninput_items, - gr_vector_const_void_star &input_items, - gr_vector_void_star &output_items) -{ - const unsigned char *in = (const unsigned char *)input_items[0]; - d_phase_a = (unsigned char *)output_items[0]; - d_phase_b = (unsigned char *)output_items[1]; - d_phase_c = (unsigned char *)output_items[2]; - d_phase_d = (unsigned char *)output_items[3]; - - int i = 0, j = 0; - int ninputs = ninput_items[0]; - - while (i < ninputs && j < noutput_items) { - unsigned char sym = *in++; i++; - d_index = ++d_index % d_spb; - - switch (d_state) { - case ST_IDLE: - // Continually compare the received symbol stream - // against the known FLEX sync words. - if (test_sync(sym)) - enter_syncing(); - break; - - case ST_SYNCING: - // Wait until we stop seeing sync, then calculate - // the center of the bit period (d_center) - if (!test_sync(sym)) - enter_sync1(); - break; - - case ST_SYNC1: - // Skip 16 bits of dotting, then accumulate 32 bits - // of Frame Information Word. - if (d_index == d_center) { - d_fiw = (d_fiw << 1) | (sym > 1); - if (++d_count == 48) { - // FIW is accumulated, call BCH to error correct it - pageri_bch3221(d_fiw); - parse_fiw(); - enter_sync2(); - } - } - break; - - case ST_SYNC2: - // This part and the remainder of the frame are transmitted - // at either 1600 bps or 3200 bps based on the received - // FLEX sync word. The second SYNC header is 25ms of idle bits - // at either speed. - if (d_index == d_center) { - // Skip 25 ms = 40 bits @ 1600 bps, 80 @ 3200 bps - if (++d_count == d_baudrate/40) - enter_data(); - } - break; - - case ST_DATA: - // The data portion of the frame is 1760 ms long at either - // baudrate. This is 2816 bits @ 1600 bps and 5632 bits @ 3200 bps. - // The output_symbol() routine decodes and doles out the bits - // to each of the four transmitted phases of FLEX interleaved codes. - if (d_index == d_center) { - j += output_symbol(sym); - if (++d_count == d_baudrate*1760/1000) - enter_idle(); - } - break; - - default: - assert(0); // memory corruption of d_state if ever gets here - break; - } - } - - consume_each(i); - return j; -} |