Как проверить, является ли число простым?

function IsPrime(N: Cardinal): Boolean; register; 
  // test if N is prime, do some small Strong Pseudo Prime test in certain bounds 
  // copyright (c) 2000 Hagen Reddmann, don't remove 
asm 
      TEST  EAX,1            { Odd(N) ?? } 
      JNZ   @@1 
      CMP   EAX,2            { N == 2 ?? } 
      SETE  AL 
      RET 
@@1:  CMP   EAX,73           { N        JB    @@C } 
      JE    @@E              { N == 73 ?? } 
      PUSH  ESI 
      PUSH  EDI 
      PUSH  EBX 
      PUSH  EBP 
      PUSH  EAX              { save N as Param for @@5 } 
      LEA   EBP,[EAX - 1]    {  M == N -1, Exponent } 
      MOV   ECX,32           { calc remaining Bits of M and shift M' } 
      MOV   ESI,EBP 
@@2:  DEC   ECX 
      SHL   ESI,1 
      JNC   @@2 
      PUSH  ECX              { save Bits as Param for @@5 } 
      PUSH  ESI              {  save M' as Param for @@5 } 
      CMP   EAX,08A8D7Fh     {  N = 9080191 ?? } 
      JAE   @@3 
      // now if (N       MOV   EAX,31 
      CALL  @@5              { 31^((N-1)(2^s)) mod N } 
      JC    @@4 
      MOV   EAX,73           { 73^((N-1)(2^s)) mod N } 
      PUSH  OFFSET @@4 
      JMP   @@5 
      // now if (N @@3:   MOV   EAX,2 
      CALL  @@5 
      JC    @@4 
      MOV   EAX,7 
      CALL  @@5 
      JC    @@4 
      MOV   EAX,61 
      CALL  @@5 
@@4:  SETNC AL 
      ADD   ESP,4 * 3 
      POP   EBP 
      POP   EBX 
      POP   EDI 
      POP   ESI 
      RET 
// do a Strong Pseudo Prime Test 
@@5:  MOV   EBX,[ESP + 12]     { N on stack } 
      MOV   ECX,[ESP +  8]     { remaining Bits } 
      MOV   ESI,[ESP +  4]     { M' } 
      MOV   EDI,EAX            { T = b, temp. Base } 
@@6:  DEC   ECX 
      MUL   EAX 
      DIV   EBX 
      MOV   EAX,EDX 
      SHL   ESI,1 
      JNC   @@7 
      MUL   EDI 
      DIV   EBX 
      AND   ESI,ESI 
      MOV   EAX,EDX 
@@7:  JNZ   @@6 
      CMP   EAX,1      { b^((N -1)(2^s)) mod N ==  1 mod N ?? } 
      JE    @@A 
@@8:  CMP   EAX,EBP    { b^((N -1)(2^s)) mod N == -1 mod N ?? , EBP = N -1 } 
      JE    @@A 
      DEC   ECX        { second part to 2^s } 
      JNG   @@9 
      MUL   EAX 
      DIV   EBX 
      CMP   EDX,1 
      MOV   EAX,EDX 
      JNE   @@8 
@@9:  STC 
@@A:  RET 
@@B:  DB    3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71 
@@C:  MOV   EDX,OFFSET @@B 
      MOV   ECX,18 
@@D:  CMP   AL,[EDX + ECX] 
      JE    @@E 
      DEC   ECX 
      JNL   @@D 
@@E:  SETE  AL 
end; 
 
procedure TForm1.Button1Click(Sender: TObject); 
begin 
  if IsPrime(3453451) then 
    ShowMessage('yes'); 
end; 
 
{**** Another function ***} 
 
function IsPrime(Prim: Longint): Boolean; 
var 
  Z: Real; 
  Max: LongInt; 
  Divisor: LongInt; 
begin 
  Prime := False; 
  if (Prim and 1) = 0 then Exit; 
  Z       := Sqrt(Prim); 
  Max     := Trunc(Z) + 1; 
  Divisor := 3; 
  while Max > Divisor do 
  begin 
    if (Prim mod Divisor) = 0 then Exit; 
    Inc(Divisor, 2); 
    if (Prim mod Divisor) = 0 then Exit; 
    Inc(Divisor, 4); 
  end; 
  Prime := True; 
end; 

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