stv199_i.c

这是DVB tuner驱动部分和其它相关的源码和一些技术资料文档.

} /* DEMOD_GetAGC() */

/*****************************************************************************
Name: DEMOD_GetFECRate()
Description:
    Checks the VEN rate register to deduce the forward error correction
    setting that is currently in use.
Parameters:
    Demod_p,        pointer to the DEMOD device.
    FECRate_p,      pointer to area to store FEC rates in use.
Return Value:
    DEMOD_NO_ERROR,     the operation completed without error.
    STI2C_xxx,          there was a problem accessing the device.
See Also:
    Nothing.
*****************************************************************************/

static DEMOD_ErrorCode_t DEMOD_GetFECRate(DEMOD_Handle_t Handle,
                                          DEMOD_FECRate_t *FECRate_p)
{
    DEMOD_ErrorCode_t Error = DEMOD_NO_ERROR;
    DEMOD_FECRate_t FecRate = 0;

    Error = STV0199A_GetVENRate(STV0199A_HANDLE(Handle));

    if (Error == DEMOD_NO_ERROR)
    {
        U8 Data;
        Data = STV0199A_HANDLE(Handle)->VENRate;

        /* Convert venrate value to a DEMOD fecrate */
        switch (Data)
        {
            case STV0199A_VSTATUS_PR_1_2:
                FecRate = DEMOD_FEC_1_2;
                break;
                
            case STV0199A_VSTATUS_PR_2_3:
                FecRate = DEMOD_FEC_2_3;
                break;
                
            case STV0199A_VSTATUS_PR_3_4:
                FecRate = DEMOD_FEC_3_4;
                break;
                
            case STV0199A_VSTATUS_PR_5_6:
                FecRate = DEMOD_FEC_5_6;
                break;
                
            case STV0199A_VSTATUS_PR_7_8:
                FecRate = DEMOD_FEC_7_8;
                break;
        }

        /* Copy back for caller */
        *FECRate_p = FecRate;
    }

    return Error;
} /* DEMOD_GetFECRates() */

/*****************************************************************************
Name: DEMOD_SetFECRates()
Description:
    Sets the FEC rates to be used during demodulation.
Parameters:
    Demod_p,        pointer to DEMOD device.
    FECRates,       bitmask of FEC rates to be applied.
Return Value:
    DEMOD_NO_ERROR, the operation completed without error.
    STI2C_xxx,      there was a problem accessing the device.
See Also:
    Nothing.
*****************************************************************************/

static DEMOD_ErrorCode_t DEMOD_SetFECRates(DEMOD_Handle_t Handle,
                                           DEMOD_FECRate_t FECRates)
{
    DEMOD_ErrorCode_t Error = DEMOD_NO_ERROR;
    U8 Data = 0;

    /* Convert DEMOD FEC rates to a VENRATE value to be applied to the
     * STV0199A.
     */
    if (FECRates & DEMOD_FEC_1_2)
        Data |= STV0199A_VENRATE_E0_MSK;
    if (FECRates & DEMOD_FEC_2_3)
        Data |= STV0199A_VENRATE_E1_MSK;
    if (FECRates & DEMOD_FEC_3_4)
        Data |= STV0199A_VENRATE_E2_MSK;
    if (FECRates & DEMOD_FEC_5_6)
        Data |= STV0199A_VENRATE_E3_MSK;
    if (FECRates & DEMOD_FEC_7_8)
        Data |= STV0199A_VENRATE_E4_MSK;

    Error = STV0199A_SetVENRate(STV0199A_HANDLE(Handle),
                                Data);

    return Error;
} /* DEMOD_SetFECRates() */

/* Private utility functions ---------------------------------------------- */

/*****************************************************************************
Name: InitializeSearchTimers()
Description:
    Various delay times are calculated depending on the scan search
    criteria. e.g.,

    - Timing lock time = depends on damping factor and natural frequency
    - QPSK capture time = carrier lock algorithm depends on df and nf.
    - Data wait time = uses the viterbi decoder and synchronization search.

    ** This must be called prior to SearchQPSK().

Parameters:
    Demod_p,        pointer to the DEMOD parameters.
    ScanParams_p,   pointer to a scan params block.
Return Value:
    DEMOD_NO_ERROR,     the operation completed without error.
See Also:
    Nothing.
*****************************************************************************/

static DEMOD_ErrorCode_t InitializeSearchTimers(DEMOD_ControlBlock_t *Demod_p,
                                                DEMOD_ScanParams_t *ScanParams_p)
{
    DEMOD_ErrorCode_t Error = DEMOD_NO_ERROR;
    U16 ViterbiSearch, TimeOut, Hysteresis, HigherRate;
    U32 PhaseNumber[] = { 1, 3, 2, 6, 8 };
    U32 Averaging[] = { 1024, 4096, 16384, 65536 };
    U32 InnerCode;
    U32 L;

    /* Timing loop capture time (Ms) */
    if (STV0199A_HANDLE(Demod_p)->DampingFactor2 >= 707)
    {
        /* Damping factor greater than the optimum value */
        ScanParams_p->TimingLoopParams.TimingLoopWait = 1 +
            (U16)((2 * STV0199A_HANDLE(Demod_p)->DampingFactor2) /
                  STV0199A_HANDLE(Demod_p)->NaturalFrequency2);
    }
    else
    {
        /* Damping factor lower than the optimum value */
        ScanParams_p->TimingLoopParams.TimingLoopWait = 1 +
            (U16)((1000000 /
                   STV0199A_HANDLE(Demod_p)->DampingFactor2) /
                  STV0199A_HANDLE(Demod_p)->NaturalFrequency2);
    }

    /* QPSK capture time (ms) -- for the carrier damping factor, the true value
     * decrease strongly with the C/N ratio. With a C/N equal to 3 dB, the
     * damping factor is 2 or 3 times over the true equivalent damping factor.
     */
    if (STV0199A_HANDLE(Demod_p)->DampingFactor1 >= 707)
    {
        /* damping factor greater than the optimum value */
        ScanParams_p->QPSKParams.QPSKWaitValue = 1 +
            (U16)(2 * STV0199A_HANDLE(Demod_p)->DampingFactor1 /
                  STV0199A_HANDLE(Demod_p)->NaturalFrequency1);
    }
    else
    {
        /* damping factor lower than the optimum value */
        ScanParams_p->QPSKParams.QPSKWaitValue = 1 +
            (U16)((1000000 /
                   STV0199A_HANDLE(Demod_p)->DampingFactor1) /
                  STV0199A_HANDLE(Demod_p)->NaturalFrequency1);
    }

    /* Data capture time (ms) -- this time is due to the Viterbi
     * synchronisation.
     * For each authorized inner code, the Viterbi search time is calculated,
     * and the results are cumulated in Viterbi search.
     */
    Error = STV0199A_GetE(STV0199A_HANDLE(Demod_p)); /* Rate indicator (VENRATE register) */
    if (Error != DEMOD_NO_ERROR)
        goto timers_done;

    Error = STV0199A_GetSN(STV0199A_HANDLE(Demod_p)); /* Averaging period indicator (VSEARCH register) */
    if (Error != DEMOD_NO_ERROR)
        goto timers_done;

    ViterbiSearch = 0 ;
    InnerCode  = 1000; /* InnerCode = 1000* the inner code */
    HigherRate = 1000;

    if ((STV0199A_HANDLE(Demod_p)->E & 0x01) == 0x01)
    {
        /* Inner code 1/2  */
        InnerCode = 2000; /* 2.0 */
        ViterbiSearch += (U16)((PhaseNumber[0] *
                                Averaging[STV0199A_HANDLE(Demod_p)->SN] *
                                InnerCode) /
                               STV0199A_HANDLE(Demod_p)->SymbolRate);
        if (HigherRate < 2000)
            HigherRate = 2000;
    }
    
    if (((STV0199A_HANDLE(Demod_p)->E >> 1) & 0x01) == 0x01)
    {
        /* Inner code 2/3 */
        InnerCode = 1500; /* 1.5 */
        ViterbiSearch += (U16)((PhaseNumber[1] *
                                Averaging[STV0199A_HANDLE(Demod_p)->SN] *
                                InnerCode) /
                               STV0199A_HANDLE(Demod_p)->SymbolRate);
        if (HigherRate < 1500 )
            HigherRate = 1500;
    }

    if (((STV0199A_HANDLE(Demod_p)->E >> 2) & 0x01) == 0x01)
    {
        /* Inner code 3/4  */
        InnerCode = 1333; /* 1.333 */
        ViterbiSearch += (U16)((PhaseNumber[2] *
                                Averaging[STV0199A_HANDLE(Demod_p)->SN] *
                                InnerCode) /
                               STV0199A_HANDLE(Demod_p)->SymbolRate);
        if (HigherRate < 1333)
            HigherRate = 1333;
    }

    if (((STV0199A_HANDLE(Demod_p)->E >> 3) & 0x01) == 0x01)
    {
        /* Inner code 5/6  */
        InnerCode = 1200; /* 1.2 */
        ViterbiSearch += (U16)((PhaseNumber[3] *
                                Averaging[STV0199A_HANDLE(Demod_p)->SN] *
                                InnerCode) /
                               STV0199A_HANDLE(Demod_p)->SymbolRate);
        if (HigherRate < 1200)
            HigherRate = 1200;
    }

    if (((STV0199A_HANDLE(Demod_p)->E >> 4) & 0x01) == 0x01)
    {
        /* Inner code 7/8 */
        InnerCode = 1143; /* 1.143 */
        ViterbiSearch += (U16)((PhaseNumber[4] *
                                Averaging[STV0199A_HANDLE(Demod_p)->SN] *
                                InnerCode) /
                               STV0199A_HANDLE(Demod_p)->SymbolRate);
        if (HigherRate < 1143)
            HigherRate = 1143;
    }

    /* Time out calculation -- this value indicates the maximum duration of
     * the synchro word research.
     */
    STV0199A_GetTO(STV0199A_HANDLE(Demod_p)); /* time out value (VSearch register) */

    L = (U32)(STV0199A_HANDLE(Demod_p)->TO + 1);
    TimeOut   = (U16)((HigherRate * 16384 * L) /
                      (2 * STV0199A_HANDLE(Demod_p)->SymbolRate));

    /* Calculate hysteresis duration */
    STV0199A_GetH(STV0199A_HANDLE(Demod_p)); /* hysteresis value (VSearch register) */

    L = (U32)(STV0199A_HANDLE(Demod_p)->H + 1);
    Hysteresis = (U16)((HigherRate * 26112 * L) /
                       (2 * STV0199A_HANDLE(Demod_p)->SymbolRate));

    /* 26112 = 16*204*8 bits -- a guard time of 1 mS is added */
    ScanParams_p->QPSKParams.DataWaitValue = 1 + ViterbiSearch + TimeOut +
                                             Hysteresis;

timers_done:
    return Error;
}

/*****************************************************************************
Name: SubRangeSetting()
Description:
    The derotator control bandwidth is [-Fs/16,+Fs/16].  This routine is
    responsible for computing how many frequency intervals of width less
    than Fs/8 can be spanned over the range [-MaxLNBOffset,MaxLNBOffset].
    To ensure there is an overlap between the intervals the computation is
    made with Fs/8 minus one derotator step (usually 6).

    The range used will be [-127,+127] -- derotator settings.

		-lnb_max                                       lnb_max
			 ||-srl | ... |  -1 |  0  |  1  | ... | srl ||
			 ||  |  |  |  |  |  |  |  |  |  |  |  |  |  ||
			 ||_____|_____|_____|_____|_____|_____|_____||
                                 <--->
             (srl = sub range limit)
                                   sub range size (<= Fs/8)
Parameters:
    Demod_p,        pointer to the DEMOD device.
    ScanParams_p,   pointer to scan parameters in use.
Return Value:
    None.
See Also:
    Nothing.
*****************************************************************************/

static void SubRangeSetting(DEMOD_ControlBlock_t *Demod_p,
                            DEMOD_ScanParams_t *ScanParams_p)
{
    U16 I;
    U32 L;

    /* In order to avoid frontier effects ("twilight zones"), an overlap of
     * at least 'DerotatorStep' derotator steps is garantized.
     */
    L = STV0199A_HANDLE(Demod_p)->SymbolRate / 8 -
        (STV0199A_HANDLE(Demod_p)->SymbolRate *
         ScanParams_p->DerotatorParams.DerotatorStep) / 2048; /* 2048=8*256 */
    I = (U16)((2 * ScanParams_p->MaxLNBOffset)/L) + 1;

    /* range = [-sub_range_limit,+sub_range_limit] */
    ScanParams_p->SubRangeParams.SubRangeLimit = I/2;

    /* Once the number of subranges computed, the subrange size is increased
	 * with derotator_step*Fs/8, in order to guarantee the overlap
	 * The interval size must be a multiple of TunerStep, which is the
	 * resolution of the tuner.
     */
    L = (2 * ScanParams_p->MaxLNBOffset) /
        (2 * ScanParams_p->SubRangeParams.SubRangeLimit + 1);
    L += (ScanParams_p->DerotatorParams.DerotatorStep *
          STV0199A_HANDLE(Demod_p)->SymbolRate) / 2048; /* Overlap guarantee */
    ScanParams_p->SubRangeParams.SubRangeSize =
                     (U16)((L / ScanParams_p->TunerStep) + 1)
                     * (ScanParams_p->TunerStep / 1000); /* in KHz */

    if (ScanParams_p->SubRangeParams.SubRangeSize >
        (STV0199A_HANDLE(Demod_p)->SymbolRate / 8000))
    {
        ScanParams_p->SubRangeParams.SubRangeSize =
            STV0199A_HANDLE(Demod_p)->SymbolRate / 8000;
    }

    /* Will be initialised by Scan(), in case of SCPC */
    ScanParams_p->SubRangeParams.SubRangeInit = 0;
}

/*****************************************************************************
Name: FastSearch()
Description:
    This routine sets the tuner frequency and checks the AGC integrator in
    order to detect whether or not there is a signal.
Parameters:
    Demod_p,        pointer to demod device.
    Frequency,      tuner IF.
    NewFrequency_p, the new frequency value to store -- may be different to
                    required setting.
    AGCLevelGood_p, boolean to set to indicate whether or not there is a
                    signal.
Return Value:
    DEMOD_NO_ERROR,     the operation completed without error.
    STI2C_xxx,          there was a problem accessing the device.
See Also:
    Nothing.
*****************************************************************************/

static DEMOD_ErrorCode_t FastSearch(DEMOD_ControlBlock_t *Demod_p,
                                    U32 Frequency,
                                    U32 *NewFrequency_p,
                                    BOOL *AGCLevelGood_p)