一个效率很高的BM算法 汇编实现的

{  The originial benchmark program was to demonstrate the speed difference  between the POS() in Turbo Pascal 4 or 5 brute-force  and the Boyer-Moore method function POSBM()  Program author: Costas Menico   Call: posbm(pat,buf,buflen);   or if you are using a string buffer:         posbm(pat,s[1],length(s));}program bufSearch;uses  dos, crt;{$F+}function posbm(pat:string; var buf; buflen:word):word; EXTERNAL;{$L BM.OBJ}{$F-}function bruteForce(var such:string; var buf; buflen:word):word; ASSEMBLER;ASM        cld        push ds        les        di,buf        mov        cx,buflen        jcxz @@30        lds        si,such        mov  al,[si]        or   al,al        je   @@30        xor  ah,ah        cmp  ax,cx        ja   @@30        mov  bx,si        dec  cx  @@10:        mov  si,bx        lodsw        xchg al,ah          { AH=Stringl刵ge, AL=Suchchar }        repne scasb        jne  @@30        dec  ah        or   ah,ah        je   @@20        inc  cx             { CX++ nach rep... }        xchg cx,ax        mov  cl,ch        xor  ch,ch        mov  dx,di        repe        cmpsb        mov  di,dx        mov  cx,ax        loopne @@10  @@20:        mov  ax,buflen        sub  ax,cx        dec  ax        jmp  @@40  @@30:        xor  ax,ax  @@40:        pop  dsend;procedure showtime(s : string; t : registers);begin  writeln(s, ' Hrs:', t.ch, ' Min:', t.cl, ' Sec:', t.dh, ' Milsec:', t.dl);end;var  pat    : string;  i,  j      : integer;  start,  finish : registers;  arr    : array[1..4096] of char;const  longloop = 5000;begin  clrscr;  randomize;  for i := 1 to 4096 do    arr[i] := chr(random(255)+1);  move(arr[4090],pat[1],5); pat[0]:=#5;  writeln('Search using Brute-Force Method ');  start.ah := $2C;  msdos(start);  for j := 1 to longloop do    i := bruteForce(pat,arr,4096);  finish.ah := $2C;  msdos(finish);  showtime('Start  ', start);  showtime('Finish ', finish);  writeln('Pattern found at position ', i);  writeln;  writeln('Search using Boyer-Moore Method ');  start.ah := $2C;  msdos(start);  for j := 1 to longloop do    i := posbm(pat, arr,4096);  finish.ah := $2C;  msdos(finish);  showtime('Start  ', start);  showtime('Finish ', finish);  writeln('Pattern found at position ', i);  writeln;  writeln('Done ... Press Enter');  readln;end.{ --------------------------   XX34 OBJECT CODE  ----------------------- }{ ------------------------- CUT OUT AND SAVE AS BM.XX  ------------------}{ ------------------------  USE XX3401 D BM.XX   ------------------------}*XX3401-000392-050693--68--85-03573----------BM.OBJ--1-OF--1U-M+32AuL3--IoB-H3l-IopQEYoiEJBBYcUU++++53FpQa7j623nQqJhMalZQW+UJaJmQqZjPW+n9X8NW-k+ECbfXgIO32AuL3--IoB-H3l-IopQEYoiEJBB+sU1+21dH7M0++-cW+A+E84IZUM+-2BDF2J3a+Q+OCQ++U2-1d+A+++--J-DIo7B++++rMU2+20W+N4Uuk+-++-JUSkA+Mjg5X9YzAKq4+4AbUM-f+f+REDdjU09m6Z4+6aq-+53hVE-X7s8+Mi42U29k5I1uO6+WIM0WPM6+MDt+LIPlPM2+On2jUU-Wos0weto+ya1+6jrUys0uqyEXLs2XB8Ckcd4+6fUiM++wuj3hUE-XJs2Wos+GMjRXKs2AiGgWzW60y9tf6jsW+i9uwKq0+4BTUG9JU78WoM+G19zzGjEQXE1w6cQBcc-0g-pwMjSWos+l9s2+Iw1yTCaR+ms+E0BTUG9wn9zuxK9lgKq0+2flUI0+Cg0Aw1w5sjZUQEA+Jr80U-fWU6++5E+***** END OF XX-BLOCK *****{ --------------------------   ASSEMBLER CODE  ------------------------- }{ ------------------------- CUT OUT AND SAVE AS BM.AMS ------------------}{ ------------------------  USE TASM TO ASSEMBLE ------------------------}; filename: BM.ASM; fast search routine to search strings in ARRAYS OF CHARS; function in Turbo Pascal >= 4. Based on the Boyer-Moore algorithm.; program author: Costas Menico.; Very small modifications for using an ARRAY OF CHAR buffer instead of; a string made by Jochen Magnus in May 93.; declare as follows:; {$F+}; {$L BM.OBJ}; function posbm(pat:string; var buffer; buflen:word):WORD; external;; call as follows from Turbo 4..7:; location := posbm(pat, buf, buflen);; call for a search in a string typed buffer:; location := posbm(pat, str[1], length(str));skiparrlength        equ        256; function work stackdstk                strucpatlen                dw        ?strlen                dw        ?skiparr                db        skiparrlength dup(?)pattxt                dd        0strtxt                dd        0dstk                ends; total stack (callers plus work stack)cstk                strucourdata                db        size dstk dup(?)bpsave                dw        0retaddr                dd        0paramlen       dw   0                                                           ; JOstraddr                dd        0pataddr                dd        0cstk                endsparamsize        equ        size pataddr+size straddr +size paramlen           ; +2  JOcode                segment        para public                assume cs:code; entry point to posbm functionposbm                proc        far                public        posbm                push        bp                         sub        sp, size dstk                         mov        bp, sp                         push    ds                         xor        ah, ah                         cld; get and save the length and address of the pattern                lds        si, [bp.pataddr]                         mov        word ptr [bp.pattxt][2], ds                         lodsb                         or        al, al                         jne        notnullp                         jmp        nomatchnotnullp:                mov        cx, ax                         mov        [bp.patlen], ax                         mov        word ptr [bp.pattxt], si; get and save the length and address of the string text                lds        si, [bp.straddr]                         mov        word ptr [bp.strtxt][2], ds                         mov ax,[bp.paramlen]                                          ; JO                         or  ax,ax                                                              ; JO                         jne        notnulls                         jmp        nomatchnotnulls:                mov        [bp.strlen], ax                         mov        word ptr [bp.strtxt], si                         cmp        cx, 1                         jne        do_boyer_moore                         lds        si, [bp.pattxt]                         lodsb                         les        di, [bp.strtxt]                         mov        cx, [bp.strlen]                         repne        scasb                         jz        match1                         jmp        nomatchmatch1:                mov        si, di                         sub        si, 2                         jmp        exactmatchdo_boyer_moore:; fill the ASCII character skiparray with the; length of the pattern                lea        di, [bp.skiparr]                         mov        dx, ss                         mov        es, dx                         mov        al, byte ptr [bp.patlen]                         mov        ah, al                         mov        cx, skiparrlength/2                         rep        stosw; replace in the ASCII skiparray the corresponding; character offset from the end of the pattern minus 1                lds        si, [bp.pattxt]                         lea        bx, [bp.skiparr]                         mov        cx, [bp.patlen]                         dec        cx                         mov        bx, bp                         lea        bp, [bp.skiparr]                         xor        ah, ahfill_skiparray:                lodsb                         mov        di, ax                         mov        [bp+di], cl                         loop        fill_skiparray                         lodsb                         mov        di, ax                         mov        [bp+di], cl                         mov        bp, bx; now initialize our pattern and string text pointers to; start searching                lds        si, [bp.strtxt]                         lea        di, [bp.skiparr]                         mov        dx, [bp.strlen]                         dec        dx                         mov        ax, [bp.patlen]                         dec        ax                         xor        bh, bh                         std; get character from text. use the character as an index; into the skiparray, looking for a skip value of 0.; if found, execute a brute-force search on the patternsearchlast:                sub        dx, ax                         jc        nomatch                         add        si, ax                         mov        bl, [si]                         mov        al, ss:[di+bx]                         or        al, al                         jne        searchlast; we have a possible match, therefore; do the reverse brute-force compare                mov        bx, si                         mov        cx, [bp.patlen]                         les        di, [bp.pattxt]                         dec        di                         add        di, cx                         repe        cmpsb                         je        exactmatch                         mov        ax, 1                         lea        di, [bp.skiparr]                         mov        si, bx                         xor        bh, bh                         jmp        short searchlastexactmatch:                mov        ax, si                         lds        si, [bp.strtxt]                         sub        ax, si                         add        ax, 2                         jmp        short endsearchnomatch:                xor        ax, axendsearch:                cld                         pop        ds                         mov        sp, bp                         add        sp, size dstk                         pop        bp                         ret        paramsizeposbm                endpcode                ends                end{-----------------------   END OF ASSEMBLER CODE -------------------------}  

没细看, 也没测试...哪天要用在看吧