Can we use _sleep(0) like a short delay in a loop?
You can, but your CPU will run hot. If you use Sleep(1) instead, it will stay cool. Test it...
PellesC and MS _sleep() functions are not compatible.
PellesC _sleep() is POSIX style, delay in seconds.
msvcrt _sleep() is wrapper for API Sleep() function and with value 0 it always add 1 before calling Sleep() function.
void __cdecl _sleep(unsigned long dwDuration)
{
if (dwDuration == 0) {
dwDuration++;
}
Sleep(dwDuration);
}
EDIT:
this example gives replacement for PellesC.
Define project preprosessor symbols: _sleep=_ms_sleep
//ms_sleep.c for library
__declspec(dllimport) void __stdcall Sleep(long);
void __cdecl _ms_sleep(unsigned long dwDuration)
{
if (dwDuration == 0) {
dwDuration++;
}
Sleep(dwDuration);
}or//ms_sleep.c for library
__declspec(dllimport) long __stdcall SleepEx(long,long);
void __cdecl _ms_sleep(unsigned long dwDuration)
{
if (dwDuration == 0) {
dwDuration++;
}
SleepEx(dwDuration,0);
}//void __cdecl __sleep(unsigned long dwDuration);
//#define _sleep _ms_sleep
//#pragma comment(lib, "ms_sleep.lib")
int main(int argc, char **argv)
{
_sleep(0);
return 0;
}Sleep(0) (https://blogs.msdn.microsoft.com/oldnewthing/20051004-09/?p=33923)
Sometimes a look under the hood is a good idea: _asm int 3;
Sleep(0);
_asm nop;
_asm nop;
_asm nop;
_asm int 3;
_sleep(0);
_asm nop;
_asm nop;
_asm nop;
CPU Disasm
Address Hex dump Command Comments
00401003 ³. CD 03 int 3
00401005 ³. 6A 00 push 0 ; ÚTime = 0
00401007 ³. FF15 D8504000 call near [<&KERNEL32.Sleep>] ; ÀKERNEL32.Sleep
0040100D ³. 90 nop
0040100E ³. 90 nop
0040100F ³. 90 nop
00401010 ³. CD 03 int 3
00401012 ³. 6A 00 push 0 ; ÚArg1 = 0
00401014 ³. E8 27000000 call 00401040 ; ÀC_HelloWorldCon.00401040
00401019 ³. 83C4 04 add esp, 4
...
CPU Disasm
Address Hex dump Command Comments
00401040 Ú$ 8B4424 04 mov eax, [esp+4] ; C_HelloWorldCon.00401040(guessed Arg1)
00401044 ³. BA FFFF0000 mov edx, 0FFFF
00401049 ³. 3D FFFF0000 cmp eax, 0FFFF
0040104E ³. 0F47C2 cmova eax, edx
00401051 ³. 69C0 E8030000 imul eax, eax, 3E8
00401057 ³. 50 push eax ; ÚTime ***** null! *****
00401058 ³. FF15 D8504000 call near [<&KERNEL32.Sleep>] ; ÀKERNEL32.Sleep
0040105E ³. 31C0 xor eax, eax
00401060 À. C3 retn