mirror of https://github.com/dzavalishin/oskit/
53 lines
1.5 KiB
C
Executable File
53 lines
1.5 KiB
C
Executable File
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#include <sys/types.h>
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/*
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* Magic number when image is compressed
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*/
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#define COMPRESSED_MAGIC 0x69696969
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/*
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* Each compressed block of the file has this little header on it.
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* Since each subblock is independently compressed, we need to know
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* its internal size (it will probably be shorter than 1MB) since we
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* have to know exactly how much to give the inflator.
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*/
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struct blockhdr {
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int magic;
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unsigned long size; /* Size of compressed part */
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int blockindex;
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int blocktotal;
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int regionsize;
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int regioncount;
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};
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/*
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* This little struct defines the pair. Each number is in sectors. An array
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* of these come after the header above, and is padded to a 1K boundry.
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* The region says where to write the next part of the input file, which is
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* how we skip over parts of the disk that do not need to be written
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* (swap, free FS blocks).
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*/
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struct region {
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unsigned long start;
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unsigned long size;
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};
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/*
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* In the new model, each sub region has its own region header info.
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* But there is no easy way to tell how many regions before compressing.
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* Just leave a page, and hope that 512 regions is enough!
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*
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* This number must be a multiple of the NFS read size in netdisk.
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*/
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#define DEFAULTREGIONSIZE (1024 * 4)
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/*
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* Ah, the frisbee protocol. The new world order is to break up the
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* file into fixed 1MB chunks, with the region info prepended to each
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* chunk so that it can be layed down on disk independently of all the
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* chunks in the file.
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*/
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#define SUBBLOCKSIZE (1024 * 1024)
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#define SUBBLOCKMAX (SUBBLOCKSIZE - DEFAULTREGIONSIZE)
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