• 4.7.1. ADSI_XFERSTRUC: ADSI Data Buffer
• 4.7.2. ADSI API Functions

4.7. Support for ADSI 2-Way FSK

ADSI (Analog Display Services Interface) 2-way FSK (Frequency Shift Keying) is supported. Because this functionality was previously not supported in Linux, the three pertinent functions-that is, dx_RxIottData( ), dx_TxIottData( ), dx_TxRxIottData( )-are described here in their entirety. The ADSI_XFERSTRUC data structure which is used by these functions is also described here.

In support of ADSI 2-way FSK, the following has been added to the voice API in addition to the new functions:

• DX_MAXDATA termination condition, stored in the tp_termno field of the DV_TPT data structure. Specify a valid value in tp_length field. Valid values are 1 through 65535. A Transmit/Receive FSK session is terminated when the specified value of FSK DX_MAXDATA (in bytes) is transmitted/received.
• TM_MAXDATA return value, returned by ATDX_TERMMSK( ) when the last I/O function terminates on DX_MAXDATA.
• DXCH_FSKINTERBLKTIMEOUT channel parameter, set and obtained by the dx_setparm( ) and dx_getparm( ) functions, respectively. Measured in milliseconds. The firmware gets FSK data in bursts. This parameter specifies how long the firmware should wait for the next burst of FSK data before it can conclude that no more data will be coming and can terminate the receive session. In short, this parameter denotes the maximum time between any two FSK data bursts in one receive session. This property can only be supplied for reception of FSK data with dx_RxIottdata( ).

NOTE:

To maintain compatibility with the way other termination conditions are specified, you can also specify TF_MAXDATA in the tp_flags field of the DV_TPT, but the library does not take note of that flag.

4.7.1. ADSI_XFERSTRUC: ADSI Data Buffer

The ADSI_XFERSTRUC data structure contains parameters for the reception and transmission of ADSI data.

The ADSI_XFERSTRUC is used to specify parameters for ADSI data transmission and reception using the dx_RxIottData( ), dx_TxIottData( ), and dx_TxRxIottData( ) functions.

This structure is declared as follows:

typedef struct_ADSI_XFERSTRUC{  
        UINT          cbSize;  
        DWORD         dwTxDataMode;  
        DWORD         dwRxDataMode;  
}ADSI_XFERSTRUC;

The parameters used by this structure are:

Parameter	Description
cbSize	Specifies the size of the structure, in bytes
dwTxDataMode	Specifies one of the following data transmission modes:
	ADSI_ALERT for FSK with Alert (CAS)   ADSI_NOALERT for FSK without Alert (CAS)   ADSI_ONHOOK_SEIZURE for On-Hook with Seizure   ADSI_ONHOOK_NOSEIZURE for On-Hook without Seizure
dwRxDataMode	Specifies one of the following data reception modes:
	ADSI_ALERT for FSK with Alert (CAS)   ADSI_NOALERT for FSK without Alert (CAS)   ADSI_ONHOOK_SEIZURE for On-Hook with Seizure   ADSI_ONHOOK_NOSEIZURE for On-Hook without Seizure

4.7.2. ADSI API Functions

The dx_RxIottData( ), dx_TxIottData( ), dx_TxRxIottData( ) functions are described next.

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