MulDiv simplify code in limited range
long long llFreq, llTime, llStart;
QueryPerformanceFrequency(&llFreq);
QueryPerformanceCounter(&llStart);
...
QueryPerformanceCounter(&llTime);
llTime = MulDiv(llTime - llStart, 1000, llFreq);
LOCAL llFreq:QWORD, llTime:QWORD, llStart:QWORD
invoke QueryPerformanceFrequency, addr llFreq
invoke QueryPerformanceCounter, addr llStart
...
invoke QueryPerformanceCounter, addr llTime
mov eax, DWORD PTR llTime
;mov ecx, DWORD PTR llTime + 4
sub eax, DWORD PTR llStart
;sbb ecx, DWORD PTR llStart + 4
invoke MulDiv, eax, 1000, DWORD PTR llFreq
EDIT: using FPU
double dTime = (ll2-ll1) * 1000.0 / llf;