7.6. DF_IOTT -- Fax Transmit Data Description

• 7.6.1. DF_IOTT Definition
• 7.6.2. DF_IOTT Field Descriptions

The DF_IOTT structure describes the characteristics of the fax data for one fax document to be transmitted.

Your application can build an array, linked list or any combination of linked list and array of DF_IOTT structures to specify multiple fax documents for transmission using the send fax function. When the send function is issued, each DF_IOTT structure is checked for valid parameters. A pointer argument in the send fax function points to the DF_IOTT table.

The structure can define raw, TIFF/F or ASCII data.

For usage information, see Section 4.5. Specifying Fax Data for Transmission in a DF_IOTT Table Entry on page 44 and the code examples in the fx_sendfax( ) function reference on page 249.

7.6.1. DF_IOTT Definition

The DF_IOTT structure consists of the following fields.

typedef struct df_iott DF_IOTT;  
struct df_iott {  
     unsigned long io_offset;     /* Starting page number or offset */  
     unsigned long io_length;     /* Number of pages or length of data */  
     char *io_bufferp;            /* Memory transfer start buffer location */  
     DF_IOTT *io_prevp;           /* (Optional) Pointer to previous DF_IOTT */  
     DF_IOTT *io_nextp;           /* Pointer to next DF_IOTT entry (for linked list) */  
     void *io_datap;              /* Pointer to additional data associated */  
                                  /* with io_datatype */  
     int io_fhandle;              /* File descriptor */  
     unsigned short io_type;      /* Entry type (file, memory; linked, contiguous, */  
                                  /* last structure; select user-defined I/O */  
                                  /* functions for transmit) */  
     unsigned short io_datatype;  /* Type of data to transmit */  
     unsigned short io_phdcont;   /* Phase D continuation value to send */  
     unsigned short io_width;     /* Width of image  (raw and ASCII) */  
     unsigned char io_resln;      /* Vertical resolution of image (raw and ASCII) */  
     unsigned char io_coding;     /* Encoding of stored data (raw) */  
     unsigned char rfu[2];        /* Reserved for future use */  
};

The following defines are used with the DF_IOTT structure for clarity:

     
#define io_firstpg     io_offset  
#define io_pgcount     io_length




7.6.2. DF_IOTT Field Descriptions

For reference, the fields in the DF_IOTT structure are described in alphabetical order in Table 19. DF_IOTT Fields.

Table 19. DF_IOTT Fields

Field	Description
io_bufferp	Memory transfer start buffer location.
io_coding	Used for raw files only. Indicates the encoding scheme of the stored raw data. Valid values:   DF_MH -- Modified Huffman. One-dimensional encoding.   DF_MMR -- Modified Modified Read. Two-dimensional encoding.
io_datap	Pointer to additional data associated with io_datatype (cast as void *).
io_datatype	The source of the data to be transmitted. Valid values:   DF_RAW -- source of data is raw file   DF_TIFF -- source of data is TIFF/F file   DF_ASCII -- source of data is ASCII file For more usage information, see Sections 4.5.5. Sending Raw Files (page 47), 4.5.6. Sending TIFF/F Files (page 49) and 4.5.7. Sending ASCII Files (page 50).
io_fhandle	File descriptor. For more information, see Section 7.7. DF_UIO -- User-Defined I/O on page 115.
io_firstpg	Used for TIFF/F files only. Indicates the starting page number (decimal value) or the first page to send. Note that page numbering begins at zero. Valid values: _0
io_length	For raw files, indicates the number of bytes to transfer. For ASCII files, indicates the number of bytes of ASCII data to read. >0 = number of bytes to transfer or to read -1 = transfer entire raw file or read entire ASCII file
io_nextp	Pointer to next DF_IOTT entry (for linked list).
io_offset	For raw files, indicates the starting byte location (offset) to start data transfer. For ASCII files, indicates the byte offset in the ASCII file (or memory) to start reading ASCII data. A value of 0 means no offset. Valid values: _0
io_pgcount	Used for TIFF/F files only. Indicates the number of consecutive pages to send. Valid values: >0 = Number of consecutive pages to send -1 = Send all remaining pages from specified page number
io_phdcont	The continuation value for Phase D (post-message procedure) of the T.30 protocol. Valid values:   DFC_AUTO -- Automatic Phase D Messaging. The fax driver automatically determines the T.30 Phase D continuation value based on the width, resolution and position of the DF_IOTT entries.   DFC_MPG -- Merge-Page. The data specified for the DF_IOTT entry directly following the current DF_IOTT entry is concatenated to the same page.   DFC_EOP -- End of Procedure (T.30). Terminate current fax session, progress to Phase E and end fax call.   DFC_MPS -- Multi-Page Signal (T.30). End of current fax document page; next fax document page is in the same format as the current page; proceed directly to Phase C.   DFC_EOM -- End of Message (T.30). End of current fax document page; more fax data to follow at different resolution or width; return to Phase B and negotiate parameters for next fax document page. For more usage information, see Section 4.5.9. Setting Phase D Continuation Values on page 53.
io_prevp	Pointer to previous DF_IOTT (optional).
io_resln	Used for raw and ASCII files only. Indicates the vertical resolution of the image in lines per inch:   DF_RESHI -- high or fine vertical resolution (196 lpi)   DF_RESLO -- low or coarse vertical resolution (98 lpi) The horizontal resolution of a fax image is fixed at 203 lines per inch across the page.
io_type	Default: IO_CONT This is a bit masked logical OR field that specifies (a) whether the fax data is in a file or in memory, (b) whether the structure entry is an array, a linked list or the last DF_IOTT entry, and (c) whether the structure entry selects user-defined I/O functions.   IO_DEV -- Transfers fax from a file   IO_MEM -- Transfers fax from memory (raw or ASCII data only)   IO_CONT -- Next DF_IOTT entry is contiguous in memory (default)   IO_LINK -- Next DF_IOTT entry is linked to the current entry   IO_EOT -- Indicates the last DF_IOTT entry   IO_UIO -- Selects user-defined I/O functions for fax transmission For more information on using the io_type field, see Sections 4.5.2. Connecting DF_IOTT Table Entries (page 46), 4.5.3. Sending Data from Device or Memory (page 46), 4.11. Creating User-Defined I/O Functions (page 71) and 7.7. DF_UIO -- User-Defined I/O (page 115).
io_width	Used for raw and ASCII files only. Indicates the width of the image:   DF_WID1728 -- 1728 pixels per line   DF_WID2048 -- 2048 pixels per line   DF_WID2432 -- 2432 pixels per line
rfu[2]	Reserved for future use.

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