Dialogic 6.2 Manuale Utente

Developing a Fax Application

November 2009

83

The function calls BfvFaxSendPage and BfvFaxNextPage are 

typically used in a loop. Both read infopkts from the infopkt stream 

for processing.

BfvFaxSendPage reads infopkts and processes them in a loop. 

When data (embedded or indirect) or strip parameter type infopkts 

are encountered, the indicated parameters and data format (ASCII 

or G3) commands are sent to the channel, the data is downloaded to 

the driver buffer, and the next infopkt is read. If any other type of 

infopkt is encountered, the current position in the infopkt stream 

remains unchanged, and the function returns to the calling routine.

BfvFaxNextPage reads infopkts from the current position in the 

infopkt stream. All consecutive infopkts of a new-page type,

INFOPKT_PAGE_PARAMETERS,
INFOPKT_T30_PARAMETERS,
INFOPKT_BEGINNING_OF_PAGE, or
INFOPKT_DOCUMENT_PARAMETERS,

are processed, and relevant data and a single end-of-page command 

are sent to the channel. If no infopkts of a new-page type are found, 

the current position in the infopkt stream remains unchanged, and 

the function returns to the calling routine.

A program to read a file containing infopkts could look like this:

BT_ZERO(args_infopkt);

 

args_infopkt.fname = "filename";

 

args_infopkt.fmode = "r";

 

ips = BfvInfopktOpen(&args_infopkt);

 

for (;;)

 

{

 

    BT_ZERO(args_infopkt);

 

    args_infopkt.ips = ips;

 

    args_infopkt.i_mode = INDIR_MODE_FOLLOW;

 

    if ((ip = BfvInfopktGet(&args_infopkt)) == NULL)

 

        break;

 

    process(ip);

 

}

With the flag set to INDIR_MODE_FOLLOW or 
INDIR_MODE_FOLLOW_NOUSER

, BfvInfopktGet follows indirect 

infopkt links automatically, so the user sees only the actual data. 

Other flags let the user examine a file without following indirect 

infopkt links. See the BfvInfopktUser function in Volume 4, Fax