Delphi:高效的哈希函数

wuchang555 2011-06-07 1542

控制/MCU

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01.function BKDRHash(buf: Pointer; count: Integer) : Cardinal; assembler;
02.asm
03.       PUSH  EBX;
04.       XOR EBX, EBX
05.       MOV ECX, EAX
06.       XOR EAX, EAX
07.@LOOP:
08.       TEST  EDX, EDX
09.       JZ @EXIT
10.       MOV BL,  [ECX]
11.       IMUL  EAX, 131
12.       ADD EAX, EBX
13.       INC ECX
14.       DEC EDX
15.       JMP @LOOP
16.@EXIT:
17.       POP EBX
18.//----------------------------
19.// Pascal:
20.//
21.//  Result := 0;
22.//  while count > 0 do
23.//  begin
24.// Result := (Result * 131) + PByte(buf)^;
25.// Inc(PByte(buf));
26.// Dec(count);
27.//  end;
28.end;
29.function DJBHash(buf: Pointer; count: Integer) : Cardinal; assembler;
30.asm
31.       PUSH  EDI
32.       PUSH  EBX
33.       XOR EBX, EBX
34.       MOV ECX, EAX
35.       MOV EAX, 5381
36.@LOOP:
37.       TEST  EDX, EDX
38.       JZ @EXIT
39.       MOV EDI, EAX
40.       SHL EDI, 5
41.       ADD EAX, EDI
42.       MOV BL, [ECX]
43.       ADD EAX, EBX
44.       INC ECX
45.       DEC EDX
46.       JMP @LOOP
47.@EXIT:
48.       POP EBX
49.       POP EDI
50.//----------------------------
51.// Pascal:
52.//
53.//  Result := 5381;
54.//  while count > 0 do
55.//  begin
56.// Result := ((Result shl 5) + Result) + PByte(buf)^;
57.// Inc(PByte(buf));
58.// Dec(count);
59.//  end;
60.end;
function BKDRHash(buf: Pointer; count: Integer) : Cardinal; assembler;
asm
      PUSH  EBX;
      XOR EBX, EBX
      MOV ECX, EAX
      XOR EAX, EAX
@LOOP:
      TEST  EDX, EDX
      JZ @EXIT
      MOV BL,  [ECX]
      IMUL  EAX, 131
      ADD EAX, EBX
      INC ECX
      DEC EDX
      JMP @LOOP
@EXIT:
      POP EBX
//----------------------------
// Pascal:
//
//  Result := 0;
//  while count > 0 do
//  begin
// Result := (Result * 131) + PByte(buf)^;
// Inc(PByte(buf));
// Dec(count);
//  end;
end;
function DJBHash(buf: Pointer; count: Integer) : Cardinal; assembler;
asm
      PUSH  EDI
      PUSH  EBX
      XOR EBX, EBX
      MOV ECX, EAX
      MOV EAX, 5381
@LOOP:
      TEST  EDX, EDX
      JZ @EXIT
      MOV EDI, EAX
      SHL EDI, 5
      ADD EAX, EDI
      MOV BL, [ECX]
      ADD EAX, EBX
      INC ECX
      DEC EDX
      JMP @LOOP
@EXIT:
      POP EBX
      POP EDI
//----------------------------
// Pascal:
//
//  Result := 5381;
//  while count > 0 do
//  begin
// Result := ((Result shl 5) + Result) + PByte(buf)^;
// Inc(PByte(buf));
// Dec(count);
//  end;
end;

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