Wavecom PXGF streaming format (GEW) V1.24 - Manual (Page 17)

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GSY-0D8-SE RESTRICTED Interface Requirement Specification for PXGF Streaming and File Format
identify the file format as a PXGF file. For more information about what type of data is stored, the
remaining chunks before the EOH_ chunk should be evaluated. This chunk uses the same chunk type
number as the SOFH chunk that replaces it.
Element Type Description
iFormat int32 Identifier for the format used in a file. It is recommended that the
numeric value of the data chunk name used in the file be used for this,
e.g. SSIQ or GSIQ.
Table 3.21: Deprecated SOF_ chunk
3.6.2 End Of Header – EOH_ chunk. Use EOFH instead
This chunk must contain an empty data block, i.e. the size must be 0. It is used to indicate the end of
the header at the start of a file. This chunk uses the same chunk type number as the EOFH chunk.
Element Type Description
Table 3.22: Deprecated EOH_ chunk
3.7 SYNCHRONISATION
If an application is reading a file from the beginning there will be no trouble synchronising unless the
file has become corrupted. However, if the application is connecting to an output stream in this format
which has been running since prior to the connection, then it is necessary to ensure that the
application becomes synchronised with the stream. Synchronisation is largely hidden from the
developer as it is handled by the libraries for reading and writing PXGF streams.
The procedure to obtain synchronisation is as follows:
Step 1. Obtain synchronisation
1. Read the stream until the 4 byte sync pattern is recognised.
2. Reset state information in the application.
3. Move on to step 2.1.
Step 2. Attempt to process a chunk
1. Read the type and length of the chunk.
2. If the length is more than 65536 bytes return to step 1.1.
3. If there is a registered handler for the type then process it otherwise skip over the data of the
chunk.
4. Move on to step 3.1.
Step 3. Check synchronisation
1. Read the sync pattern from the stream. If sync pattern matches move to step 2.1 otherwise
move back to step1.1.
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2009-01-13 RESTRICTED Page 16
Issue 1.24