www.pudn.com > layer1.rar > wait_for_sync.h
/*
*******************************************************************************
*
* COPYRIGHT (C) 2000 BY ERICSSON EUROLAB DEUTSCHLAND GmbH
* 90411 NUERNBERG, GERMANY, Tel Int + 49 911 5217 100
*
* The program(s) may be used and/or copied only with the
* written permission from Ericsson or in accordance
* with the terms and conditions stipulated in the agreement or
* contract under which the program(s) have been supplied.
*
*******************************************************************************
*
* File : wait_for_sync.h
* Purpose : synchronization routine for the deinterleaver
*
*******************************************************************************
*/
#ifndef wait_for_sync_h
#define wait_for_sync_h "$Id: $"
/*
*******************************************************************************
* INCLUDE FILES
*******************************************************************************
*/
#include "ctm_typedefs.h"
/*
*******************************************************************************
* DECLARATION OF PROTOTYPES
*******************************************************************************
*/
typedef struct {
WORD16 *shift_reg; /* shift register */
WORD16 *m_sequence; /* maximum length sequence (preamble) */
WORD16 *m_sequence_resync; /* maximum length sequence (resync) */
WORD16 *sync_index_vec; /* positions/indices of the preamble */
WORD16 *resync_index_vec; /* positions/indices of the resync sequence */
WORD16 length_shift_reg; /* length of the vector shift_reg */
WORD16 offset; /* */
WORD16 num_sync_bits; /* length of the preamble */
BOOL sync_found; /* true if receiver is "in sync" */
BOOL alreadyCTMreceived; /* true if burst has been received earlier */
WORD16 *xcorr1_shiftreg;
WORD16 *xcorr2_shiftreg;
UWORD16 cntSymbolsSinceEndOfBurst;
} wait_for_sync_state_t;
/* ----------------------------------------------------------------------- */
/* Function init_wait_for_sync() */
/* ***************************** */
/* Initialization of the synchronization detector. The dimensions of the */
/* corresponding interleaver at the TX side must be specified: */
/* B (horizontal) blocklength */
/* D (vertical) interlace factor */
/* num_sync_lines2 number of interleaver lines with additional sync bits */
/* ptr_wait_state pointer to the state variable of the sync detector */
/* ----------------------------------------------------------------------- */
void init_wait_for_sync(wait_for_sync_state_t *ptr_wait_state,
WORD16 B, WORD16 D,
WORD16 num_sync_lines2);
/*
***********************************************************************
* Shutdown_wait_for_sync() *
* ************************ *
* Deallocate dyamically created buffers. *
* *
* Input variables: *
* intl_state : pointer to a variable of wait_for_sync_state_t *
* containing the wait_for_sync state machine. *
***********************************************************************
*/
void Shutdown_wait_for_sync(wait_for_sync_state_t *ptr_wait_state);
/* ----------------------------------------------------------------------- */
/* Function reinit_wait_for_sync() */
/* ******************************* */
/* Reinitialization of synchronization detector. This function is used in */
/* case that a burst has been finished and the transmitter has switched */
/* into idle mode. After calling reinit_wait_for_sync(), the function */
/* wait_for_sync() inhibits the transmission of the demodulated bits to */
/* the deinterleaver, until the next synchronization sequence can be */
/* detected. */
/* ----------------------------------------------------------------------- */
void reinit_wait_for_sync(wait_for_sync_state_t *ptr_wait_state);
/* ----------------------------------------------------------------------- */
/* Function wait_for_sync() */
/* ************************ */
/* This function shall be inserted between the demodulator and the */
/* deinterleaver. The function searches the synchronization bitstream */
/* and cuts all received heading bits. As long as no sync is found, this */
/* function returns *ptr_num_valid_out_bits=0 so that the main program */
/* is able to skip the deinterleaver as long as no valid bits are */
/* available. If the sync info is found, the complete internal shift */
/* register is copied to out_bits so that wait_for_sync can be transparent */
/* and causes no delay for future calls. */
/* *ptr_wait_interval returns a value of 0 after such a synchronization */
/* indicating that this was a regular synchronization. */
/* */
/* Regularly, the initial preamble of each burst is used as sync info. */
/* In addition, the resynchronization sequences, which occur periodically */
/* during a running burst, are used as "back-up" synchronization in order */
/* to avoid loosing all characters of a burst, if the preamble was not */
/* detected. */
/* If the receiver is already synchronized on a running burst */
/* and the resynchronization sequence is detected, *ptr_resync_detected */
/* returns a non-negative value in the range 0...num_in_bits-1 indicating */
/* at which bit the resynchronization sequence has been detected. If no */
/* resynchronization has been detected, *ptr_resync_detected is -1. */
/* If the receiver is NOT synchronized and the resynchronization sequence */
/* is detected, the resynchronization sequence is used as initial */
/* synchronization. *ptr_wait_interval returns a value of 32 in this case */
/* due to the different alignments of the synchronizations based on the */
/* preamble or the resynchronization sequence, respectively. */
/* */
/* In order to carry all bits, the minimum length of the vector out_bits */
/* must be: */
/* in_bits.size()-1 + ptr_wait_state->shift_reg_length */
/* */
/* in_bits Vector with bits from the demodulator. The */
/* vector's length can be arbitrarily chosen, */
/* i.e. according to the block length of the */
/* signal processing of the main program. */
/* num_in_bits length of vector in_bits */
/* num_received_idle_symbols number of idle symbols received coherently */
/* out_bits Vector with bits for the deinterleaver. */
/* The number of the valid bits is indicated */
/* by *ptr_num_valid_out_bits. */
/* *ptr_num_valid_out_bits returns the number of valid output bits */
/* *ptr_wait_interval returns either 0 or 32 */
/* *ptr_resync_detected returns a value -1, 0,...num_in_bits */
/* *ptr_early_muting_required returns whether the original audio signal */
/* must not be forwarded. This is to guarantee */
/* that the preamble or resync sequence is */
/* detected only by the first CTM device, if */
/* several CTM devices are cascaded */
/* subsequently. */
/* *ptr_wait_state state information. This variable must be */
/* initialized with init_wait_for_sync() */
/* ----------------------------------------------------------------------- */
#if(TTY_SYNC_MCU_2 == 0)
BOOL wait_for_sync(WORD16 *out_bits,
WORD16 *in_bits,
WORD16 num_in_bits,
WORD16 num_received_idle_symbols,
WORD16 *ptr_num_valid_out_bits,
WORD16 *ptr_wait_interval,
WORD16 *ptr_resync_detected,
BOOL *ptr_early_muting_required,
wait_for_sync_state_t *ptr_wait_state);
#else
BOOL wait_for_sync(WORD16 *out_bits,
WORD16 *in_bits,
WORD16 num_in_bits,
WORD16 num_received_idle_symbols,
WORD16 *ptr_num_valid_out_bits,
WORD16 *ptr_wait_interval,
WORD16 *ptr_resync_detected,
BOOL *ptr_early_muting_required,
wait_for_sync_state_t *ptr_wait_state,
BOOL *sync_after_resync);
#endif
/* ----------------------------------------------------------------------- */
/* Function generate_resync_sequence() */
/* *********************************** */
/* Generation of the sequence for resynchronization. The sequence, which */
/* has a length according to the value of the constant RESYNC_SEQ_LENGTH, */
/* is written to the vector *sequence, which must have been allocated */
/* before calling this function. */
/* ----------------------------------------------------------------------- */
void generate_resync_sequence(WORD16 *sequence);
#endif