+++ /dev/null
-/*
- * 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;
-}
projects / debian / gnuradio / blobdiff