VisualDSP++ 4.5 Loader and Utilities Manual - Analog Devices

Blackfin Processor Booting
Booting Compressed Streams
The Figure 2-37 shows the booting sequence of a loader file with compressed
streams. The loader file is pre-stored in the flash memory.
1. The boot ROM is pointing to the start of the flash memory. The
boot ROM reads the initialization code header and boots the initialization
code.
2. The boot ROM jumps to and starts executing the initialization
code.
3. (A) The initialization code scans the header for any compressed
streams (see the compression flag structure in Figure 2-36). The
code decompresses the streams to the decompression window (in
parts) and runs the initialization kernel on the decompressed data.
(B) The initialization kernel boots the data into various memories
just as the boot ROM kernel does.
4. The initialization code sets the boot ROM to boot the uncompressed
blocks and the final block (FINAL flag is set in the block
header’s flag word). The boot ROM boots the final payload, overwriting
any areas used by the initialization code. Because the final
flag is set in the header, the boot ROM jumps to EVT1
(0xffa00000) to start application code execution.
Decompression Initialization Files
As stated before, a decompression initialization .dxe file must be used
when building a loader file with compressed streams. The decompression
initialization .dxe file has a built-in decompression engine to decompress
the compressed streams from the loader file.
The decompression initialization file can be specified from the loader
property page or from the loader command line via the -init filename.dxe
switch. VisualDSP++ includes the default decompression initialization
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