快速内存比较函数CompareMem(Delphi SSE优化算法应用之二)

function CGCompareMem(P1, P2: Pointer; Length: Integer): Integer; assembler;asm PUSH ESI PUSH EDI PUSH ECX PUSH EBX MOV ESI,P1 MOV EDI,P2 CMP ESI,EDI JZ @Equal CMP ECX,1 JL @NotEqual MOV edx,ecx shr edx, 4 and ecx, 15 test ecx,ecx JZ @SSECMP2 mov eax,-16 sub esi,eax sub edi,eax@CompareLoop: mov ebx, [ESI + Eax] xor ebx, [EDI + Eax] jnz @Mismatch add Eax, 4 js @CompareLoop JMP @SSECMP@Mismatch: bsf ebx, ebx shr ebx, 3 sub eax,-16 add eax,ebx add eax,1 JMP @EXIT@SSECMP: sub esi,16 sub edi,16@SSECMP2: TEST edx,edx JZ @EXIT mov eax,ecx neg edx pxor xmm2,xmm2@SSECMPLOOP: movups xmm0,[ESI + Eax] movups xmm1,[EDI + Eax] pxor xmm0, xmm1 pcmpeqb xmm0, xmm2 pmovmskb ebx, xmm0 CMP ebx,$FFFF jnz @SSEMismatch add eax,16 inc edx js @SSECMPLOOP xor eax,eax JMP @EXIT@SSEMismatch: mov ebx, [ESI + Eax] xor ebx, [EDI + Eax] jnz @Mismatch2 add Eax, 4 jmp @SSEMismatch@Mismatch2: bsf ebx, ebx shr ebx, 3 add eax,ebx add eax,1 JMP @EXIT@NotEqual: MOV EAX,-1 JMP @EXIT@Equal: XOR EAX,EAX@EXIT: POP EBX POP ECX POP EDI POP ESIend;

 

经测试比常规算法快60%-110%