sid_sync.cpp

实现3GPP的GSM中AMR语音的CODECS。

 FUNCTION NAME: sid_sync_exit
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    state = pointer containing a pointer to the state structure used for
            SID synchronization (void)

 Outputs:
    None

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 This function frees up the state structure used by sid_sync function. It
 stores NULL in *state.

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 sid_sync.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/
void sid_sync_exit(void **state)
{
    sid_syncState **st = (sid_syncState **) state;

    if (st == NULL || *st == NULL)
    {
        return;
    }

    /* deallocate memory */
    oscl_free(*st);
    *st = NULL;

    return;

}

/****************************************************************************/

/*
------------------------------------------------------------------------------
 FUNCTION NAME: sid_sync_set_handover_debt
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    st = pointer to the state structure used for SID synchronization
         (sid_syncState)
    debtFrames = number of handover debt frames (Word16)

 Outputs:
    st->sid_handover_debt is set to debtFrames

 Returns:
    return_value = 0

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 This function updates the handover debt to debtFrames. Extra SID_UPD are
 scheduled to update remote decoder CNI states, right after an handover.
 This is primarily for use on MS UL side.

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 sid_sync.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/
void sid_sync_set_handover_debt(sid_syncState *st,
                                Word16 debtFrames)
{
    /* debtFrames >= 0 */
    st->sid_handover_debt = debtFrames;
    return;
}


/****************************************************************************/

/*
------------------------------------------------------------------------------
 FUNCTION NAME: sid_sync
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    state = pointer to the state structure used for SID synchronization
            (sid_syncState)
    mode = codec mode (enum Mode)
    tx_frame_type = pointer to TX frame type store (enum TXFrameType)

 Outputs:
    tx_frame_type contains the new TX frame type

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 This function performs SID frame synchronization to ensure that the mode
 only switches to a neighbouring mode.

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 sid_sync.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/
void sid_sync(void *state,
              enum Mode mode,
              enum TXFrameType *tx_frame_type)
{

    sid_syncState *st = (sid_syncState *) state;

    if (mode == MRDTX)
    {

        st->sid_update_counter--;

        if (st->prev_ft == TX_SPEECH_GOOD)
        {
            *tx_frame_type = TX_SID_FIRST;
            st->sid_update_counter = 3;
        }
        else
        {
            /* TX_SID_UPDATE or TX_NO_DATA */
            if ((st->sid_handover_debt > 0) &&
                    (st->sid_update_counter > 2))
            {
                /* ensure extra updates are  properly delayed after
                   a possible SID_FIRST */
                *tx_frame_type = TX_SID_UPDATE;
                st->sid_handover_debt--;
            }
            else
            {
                if (st->sid_update_counter == 0)
                {
                    *tx_frame_type = TX_SID_UPDATE;
                    st->sid_update_counter = st->sid_update_rate;
                }
                else
                {
                    *tx_frame_type = TX_NO_DATA;
                }
            }
        }
    }
    else
    {
        st->sid_update_counter = st->sid_update_rate ;
        *tx_frame_type = TX_SPEECH_GOOD;
    }
    st->prev_ft = *tx_frame_type;
}