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AX = 4A12h
CX = 5354h ("ST")
DX = 4143h ("AC")
Return:
AX = 4F4Bh ("OK") if installed
CX = 7374h ("st") if installed
DX = 6163h ("ac") if installed
ES:DI -> entry point in LZSAPI server (usually, driver
STACKER.COM) containing far address of an actual
LZSINFO structure (see #02808)
See Also: AX=4A12h/CX=4D52h - INT 25/AX=CDCDh
Format of LZSINFO structure: Offset Size Description (Table 02808) 00h 6 BYTEs signature "LZSAPI" 06h WORD server version (200 (0C8h) for Stacker 4 and Stacker Anywhere) 08h 4 BYTEs vendor signature "STAC" = Stac Electronics, Inc. 0Ch 6 BYTEs ???
12h WORD bit flags:
Server status/capabilities (see #02809) 14h DWORD -> Stacker 3.X-compatible compression procedure 18h DWORD -> Stacker 3.X-compatible decompression procedure 1Ch 4 BYTEs reserved (always set to 0) 20h DWORD -> incremental Stacker 3.x-compatible compression procedure (see #02810) 24h 4 BYTEs ??? 28h DWORD -> incremental Stacker 3.x-compatible decompression procedure (see #02811) 2Ch 4 BYTES ??? 30h DWORD -> new (Stacker 4) compression procedure 34h 4 BYTEs ??? 38h DWORD -> new (Stacker 4) decompression procedure
Notes: Stacker 4 usally keeps two different data-compression algorithms in memory (preferably in XMA): 1) new (Stacker 4) data compression algorithm (4K LZ77 with hashing and static Huffman encoding), and 2) old (Stacker 3.x-compatible) one (2K LZ77 with hashing), which is used to work with STACVOL files created under older versions of Stacker.
Bitfields for LZSAPI capabilities: Bit(s) Description (Table 02809) 0 ??? 1 busy/error flag 2-10 ??? 11 maximum compressor/decompressor presented
(Table 02810) Call Stacker 3.x-style non-incremental functions with:.
STACK:
DWORD return address for compress/decompress procedure WORD compression algorithm parameters (see #02812) WORD size of destination buffer (in bytes) DWORD address of destination buffer WORD size of source buffer (in bytes) DWORD address of source buffer
Return:
(compression/decompression procedure) AX = size of resulting data in destination buffer 0000h if error (either destination buffer too small or error in compressed data)(Table 02811) Call Stacker 4-style incremental procedures with:.
STACK:
DWORD return address for compr./decompr. procedure DWORD address of LZSSWAP structure (see #02813) if 0000:0000, procedure uses non-incremental technique WORD compression algorithm parameters (see #02812) WORD size of destination buffer (in bytes) DWORD address of destination buffer WORD size of source buffer (in bytes) DWORD address of source buffer(Table 02812) Values for Compression algorithm parameters: Value Compression level (/P=xx parameter) 07F9h 1 0621h 2 0625h 3 0665h 4 0669h 5 06E9h 6 06EDh 7 07D1h 8 07D9h 9
Format of LZSSWAP structure: Offset Size Description (Table 02813) 00h 2 BYTEs signature "CS" 02h 6 BYTEs reserved 08h DWORD address of destination buffer swapping procedure 0Ch DWORD address of stack swapping procedure
Category: File/Disk Compression - Int 2Fh - S
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