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DecompCodeTo enable data compression for copied sections, decompression code and decompression data must be located on the target. Example:Locate DecompCode Expand LowMem Locate DecompData Buffer HighMem Both entities are discardable and thus will not reduce the amount of memory available to the application. Locate parameter Name is ignored. The Size parameter's default value supplied by RTLoc cannot be overridden. The following table summarizes all available entity types and specifies whether they have an image, can be copied or compressed, and whether they are discardable:
Just like the page tables, compressed page tables need some special treatment. Again, if a page table is compressed, RTLoc must make an estimate on how large the compressed image will be. Since the size of the page table can change during the locate process and because the achievable compression ratio varies, this estimate may be inaccurate. In this case, RTLoc will issue an appropriate error message and the size of the copied page table must be specified in the page table's Locate Copy command explicitly. RTLoc will estimate the compressed image size of a page table to be 3% of the page table's size rounded up to the copied section's alignment. If this size is too small, an error message is issued. If a smaller value would save memory at the current alignment value, an information message is issued. RTLoc's compression algorithm for page tables is very efficient. Typical compression ratios are 1% - 2%. In addition, the decompression of a page table is frequently faster than copying it without decompression. The achievable compression of other entities varies with the type of data. Program code will typically compress to 50% - 60% of its original size. Data compression is further discussed in section Using Data Compression.
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