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 TPLZH v0.29 - Huffman Compression Engine   Joe Jared 29.10.95

Модуль для архивирования по алгоритму Хаффмана (LZH). Компилируется BP7 (real/protected mode).
Huffman Compression Engine v0.29 IBM Version. DPMI mode now supported Borland help files included with this release.



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----------------------------------------------------------------- Discription : Huffman Compression Engine w/TP : interface. IBM Version Platforms : Atari ST/TT/Jaguar, and IBM (Dos/DPMI) Author : Joe Jared 1:304/10.3@fidonet.org Topics: - What's new - How to use this utility in your programs - Legalities and distribution limitations - Version history: Refer to TPLZH.HST - Support ----------------------------------------------------------------- V0.29 (TPLZH028.zip) Added Borland help files for use with Borland's IDE Thanks to D.J. Murdoch V0.28 (TPLZH028.zip) Added DPMI interface ----------------------------------------------------------------- - Implementation: (IBM) The following is a basic structure of how the engine operates: ( Your program ) -------------+ | +---( Your program ) | +--->(Your procedure for handling input | | buffer) These must be far procedures | | +->(Your procedure for handling output v | | buffer) (Huffman Compression Engine) It's generally a good idea to have some sort of display related function in each of your iobuffer routines, and especially during initial setup. In the examples, position progress reports keep the user from being bored. Memory requirements: Memory requirements are as follows: {$M Stack, Minheap, Maxheap} {$M 1024, 56000, 56000} (Lzhasm.obj) Note: This does not include sample program space. Code space: 3693 bytes. Data space: 12 bytes The stack is probably higher than necessary, but heap memory is definitely accurate. (Some space is currently reserved for updates so there are no hassles Approximately 700 bytes) This unit is overlayable, and is designed to operate best when overlayed. (With minimum usage of data segment, it makes sense to overlay the engine, because its entire process can be contained in an overlay.) The following system variables are available for your interface to play with: Routines available in the engine: Public Decode, Encode ; Encode for compression, Decode for ; decompression. EXTERN LZHMemSeg : WORD ; Heap pointer to LZH Structure. (Note: No offset, because the engine expects to have an Addr:0000h) Note that both of these are FAR pointers to procedures. EXTERN WriteFromBuffer : FAR PTR ; External buffer handling. EXTERN ReadToBuffer : FAR PTR ; External buffer handling. EXTERN LZHERROR : WORD ; Errorlevel return {Future use} (Offset into LZHMem^. allocation) Text_Buf equ 0 ; array[0..N + F - 2] of byte; ; 5155 bytes ; Text_buf is not a buffer you should care about. ; It's placed in the top of the segment because it's most used. ; The following are variables you should care about. count Equ Text_Buf +N+F ; textsize Equ Count+4 ; LongInt = 0; textsize Equ count +4 ; LongInt = 0; codesize equ textsize +4 ; LongInt = 0; inptr equ codesize +4 ; Word inend equ inptr+2 ; word outptr equ inend+2 ; Word outend equ outptr+2 ; Word Ebytes equ outend+2 ; LongInt = 0; Inbuf equ Ebytes+4 ; IObuf Outbuf equ Inbuf +2800h ; IObuf ----------------------------------------------------------------- - Interfacing to Turbo Pascal: type IObuf = array[0..$2800-1] of byte; {These buffers are now FIXED!} LZHRec = Record {Segment:0 aligned} WorkSpace1 : Array [0..N+F-1] of byte; count : LongInt; textsize : LongInt; codesize : LongInt; inptr,inend,outptr,outend : Word; Ebytes : Longint; inbuf,outbuf : IObuf; {Buffersize and position are critical} WorkSpace : Array [0..$76c3] of byte; {LZHASM work space} {Some space reserved} End; {$L LZHASM} var WriteFromBuffer, ReadToBuffer: Procedure; These variables should "point" to your procedures for reading and writing of LZH compressed data. Before calling any LZH Functions, you must have the following lines of code in your routine, or some function thereof: {$F+} Myprocwrite {$F-} begin (Your procedure for handling data from LZHMem^.Inbuff) end; {$F+} Myprocread {$F-} begin (Your procedure for handling data from LZHMem^.Outbuff) end; Your startup for your program should have: WriteFromBuffer := Myprocwrite; ReadToBuffer := Myprocread; The actual procedure type MUST be a far Call, but the data within the procedure may be near. IObuf = array[0..$2800-1] of byte; {These buffers are now FIXED!} For your reference, precede all variables with "LZHMem^.". LZHRec = Record count : LongInt; {LZHMEM^.Count} Current position of compression of input data. This counter will continue to count, until encode or decode is called again. textsize : LongInt; Size of input text data codesize : LongInt; Size of output code data. These variables are available to provide user interface for ratios. inptr,inend,outptr,outend : Word; Inptr points to the position of valid data in your input buffer as does outptr for your output buffer. These are counters to determine where in the appropriate buffer to place the next byte of data, and how much of your buffer is valid data. (See example LZ.PAS for details of implementation). inend, Outend: These variables point to the last valid byte in the appropriate buffer. You MUST set these values to the pointer. You can adjust the size that the engine thinks it has by adjusting these values. (From 0..10239] (Again see LZ.PAS for details) Ebytes : Longint; EBytes is a count of total bytes to compress. You MUST set this variable to the total number of bytes you wish to compress. inbuf,outbuf : IObuf; These are input/output buffers for the compression engine. In previous versions, these were separate from LZHMem^, but it seemed more practical to have one call to allocate memory. If someone complains loud enough I'll "Put em back" to separate independent pointers. WorkSpace : Array [0..$8657] of byte; {LZHASM work space} This variable array is work space for LZHASM.OBJ. Please do not adjust it or change the data while encode or decode is active. If you wish to keep the space active on your heap, you can use it in between runs for other things. End; LZHMem: ^LZHRec; LZHMemSeg : WORD; Notice that there is no offset variable. This is intentional, and the reason is simple: SPEED! In LZH.PAS, there is a sample routine for allocating memory that is segment:0 aligned. The difference in memory allocated using this method is up to 32 bytes. (For allocations of 55k, who cares!) procedure Encode ; compresses data procedure Decode; decompresses data Procedure InitLZH; Segment:0 aligned memory allocation Procedure DInitLZH; Memory de-allocation. (Pay attention to this section in future versions) The proper sequence is as follows: Set writetobuffer and readfrombuffer to point to your procedures for handling of buffer data. Make sure that at bare minimum, that the procedure "call" is of far type. loops within the procedure may be near type. {$F+} Procedure YourProc; {$F-} InitLzh If compressing: Set LZHMEM^.Ebytes to the size of the data you wish to compress. (If compressing) Call encode to compress, or decode to decompress. The memory buffers will have the decompressed data, and your procedures will then process the data as buffers are filled. ----------------------------------------------------------------- -Legalities: -Compression of this archive: As far as compression type is concerned, I could personally care less, as long as the software used to re-compress is freely available. Please to not re-compress this archive with crippleware, and do not add useless banner files. The contents of this archive should contain the following: + means compatible with language v x.xx and higher. .model small,pascal LZHASM.OBJ -=> The huffman compression object file TPLZH.HST -=> Version history TPLZH.DOC -=> This document. LZ.PAS -=> Sample TP 6.0+ version LZH.PAS -=> Base unit for all pascal platforms LZO.PAS -=> OOPS examples for TP 6.0+ TESTLZO.PAS -=> OOPS examples for TP 6.0+ LZ.exe -=> Compiled Lz.pas using Turbo Pascal 7.0 Anything additional shall be considered twit behavior. If this object is used in any utility you write for public or commercial use, please give credit to the following people in your documentation or credits banner (as applicable): (These people always) Haruyasu YOSHIZAKI : Original lharc program. Kenji RIKITAKE : English translation to C Peter Sawatzki : Pascal interface(TP 5.0+} Wayne Sullivan : Pascal interface(TP 5.0+) Joe Jared : Assembler optimization {TP 5.0+} : Assembler routines for 680x0 machines. : Interface to Atari ST/TT/Jaguar : Dos Protected mode interface (These people as appropriate) Andres Cvitkovich : Object Oriented version (TP 5.5+) D.J. Murdoch : For his excellent SCANHELP utility -Distribution No fee may be charged for distribution of this package, and it CANNOT be sold for any reason. All code is property of the developers listed for their part in the project. Exceptions: The disk this program is on, may be sold for the cost of the disk. (Not to exceed $1.00)+exact mail costs if mailed. CD-ROM distribution. Unrestricted, but please either download or freq the latest prior to distribution. Whether in a shareware or commercial package, no additional charges may be added for the use of this "module". This is a MILITANTLY FREEWARE implementation of huffman compression. -Support For basic support, please read all examples first, and send me either netmail to 1:103/400.1 or send to Joe.Jared@sasbbs.com. If you are developing an alternate interface other than those listed, please do contact me, as I am looking forward to your additions to this file. -----------------------------------------------------------------