VisualDSP++ 4.5 Loader and Utilities Manual - Analog Devices

Loader/Splitter for Blackfin Processors
dialog box), then the decompressor must be re-built with the newly chosen
window size. For details on re-building of the decompressor init
project, refer to the readme.txt file located in …\Blackfin\ldr\zlib\src
subdirectory of the VisualDSP++ 4.5 installation directory.
While it is true that a larger compression window size results in better
compression ratios, the user must note that there are counter factors that
decrease the overall effective compression ratios with increasing window
sizes for Blackfin’s implementation of zlib. This is because of the limited
memory resources on an embedded target, such as a Blackfin processor.
For more information, refer to the readme.txt file in …\Blackfin\ldr\zlib\src
subdirectory of the VisualDSP++ 4.5 installation
directory.
The last 16 bits of the compressed header is the flag word. The only valid
compression flag assignments are shown in Figure 2-36.
15 13 0
0
1
Compression Flag:
Bit 13: 0 = Not Compression Mode
1 = Compression Block
Figure 2-36. Flag Word of Compressed Block Header
Uncompressed Streams
Following the compressed streams (see Figure 2-33), the loader file
includes the uncompressed streams. The uncompressed streams include
application codes, conflicted with the code in the initialization blocks in
the processor’s memory spaces, and a final block. The uncompressed
stream includes only a final block if there is no conflicted code. The final
block can have a zero byte count. The final block indicates the end of the
application to the initialization code.
VisualDSP++ 4.5 Loader and Utilities Manual 2-59