unit Adler32;{ZLib - Adler32 checksum function}interface(************************************************************************* DESCRIPTION : ZLib - Adler32 checksum function REQUIREMENTS : TP5-7, D1-D7/D9-D10/D12, FPC, VP EXTERNAL DATA : --- MEMORY USAGE : --- DISPLAY MODE : --- REFERENCES : RFC 1950 (http://tools.ietf.org/html/rfc1950) Version Date Author Modification ------- -------- ------- ------------------------------------------ 0.10 30.08.03 W.Ehrhardt Initial version based on MD5 layout 2.10 30.08.03 we Common vers., XL versions for Win32 2.20 27.09.03 we FPC/go32v2 2.30 05.10.03 we STD.INC, TP5.0 2.40 10.10.03 we common version, english comments 3.00 01.12.03 we Common version 3.0 3.01 22.05.05 we Adler32UpdateXL (i,n: integer) 3.02 17.12.05 we Force $I- in Adler32File 3.03 07.08.06 we $ifdef BIT32: (const fname: shortstring...) 3.04 10.02.07 we Adler32File: no eof, XL and filemode via $ifdef 3.05 04.07.07 we BASM16: speed-up factor 15 3.06 12.11.08 we uses BTypes, Ptr2Inc and/or Str255 3.07 25.04.09 we updated RFC URL(s) 3.08 19.07.09 we D12 fix: assign with typecast string(fname)**************************************************************************)(*------------------------------------------------------------------------- (C) Copyright 2002-2009 Wolfgang Ehrhardt This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution.----------------------------------------------------------------------------*)(*As per the license above, noting that this implementation of adler32 was stripped of everything we didn't need.That means no btypes, file loading, and the assembly version disabled.Also, the structure was removed to simplify C conversion*)function Adler32Update (var adler : longint; Msg :Pointer; Len :longint ) : longint;implementation(*$ifdef BASM16procedure Adler32Update(var adler: longint; Msg: pointer; Len: longint); //-update Adler32 with Msg dataconst BASE = 65521; // max. prime < 65536 NMAX = 5552; // max. n with 255n(n+1)/2 + (n+1)(BASE-1) < 2^32type LH = packed record L,H: word; end;var s1,s2: longint; n: integer;begin s1 := LH(adler).L; s2 := LH(adler).H; while Len > 0 do begin if Len<NMAX then n := Len else n := NMAX; //BASM increases speed from about 52 cyc/byte to about 3.7 cyc/byte asm mov cx,[n] db $66; mov ax,word ptr [s1] db $66; mov di,word ptr [s2] les si,[msg] @@1: db $66, $26, $0f, $b6, $1c // movzx ebx,es:[si] inc si db $66; add ax,bx // inc(s1, pByte(Msg)^) db $66; add di,ax // inc(s2, s1 dec cx jnz @@1 db $66; sub cx,cx mov cx,BASE db $66; sub dx,dx db $66; div cx db $66; mov word ptr [s1],dx // s1 := s1 mod BASE db $66; sub dx,dx db $66; mov ax,di db $66; div cx db $66; mov word ptr [s2],dx // s2 := s2 mod BASE mov word ptr [msg],si // save offset for next chunk end; dec(len, n); end; LH(adler).L := word(s1); LH(adler).H := word(s2);end;*)function Adler32Update(var adler:longint; Msg: Pointer; Len :longint) : longint; {-update Adler32 with Msg data} const BASE = 65521; {max. prime < 65536 } NMAX = 3854; {max. n with 255n(n+1)/2 + (n+1)(BASE-1) < 2^31} var s1, s2 : longint; i, n : integer; m : PByte; begin m := PByte(Msg); s1 := Longword(adler) and $FFFF; s2 := Longword(adler) shr 16; while Len>0 do begin if Len<NMAX then n := Len else n := NMAX; for i := 1 to n do begin inc(s1, m^); inc(m); inc(s2, s1); end; s1 := s1 mod BASE; s2 := s2 mod BASE; dec(len, n); end; Adler32Update:= (s2 shl 16) or s1; end;end.