KonstantinSeurer
/
mesa
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

util/u_atomic: Provide a _InterlockedCompareExchange8 for older MSVC. 

Fixes build with Windows SDK 7.0.7600.

Tested with u_atomic_test, both on x86 and x86_64.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
This commit is contained in:
José Fonseca 2015-01-20 23:36:50 +00:00 committed by Jose Fonseca
parent d7f2dfb67e
commit fbc3e030e6
1 changed files with 29 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
src/util/u_atomic.h
View File

@ -84,7 +84,35 @@
#include <intrin.h>
#include <assert.h>
#pragma intrinsic(_InterlockedCompareExchange8)
#if _MSC_VER < 1600
/* Implement _InterlockedCompareExchange8 in terms of InterlockedCompareExchange16 */
static __inline
char _InterlockedCompareExchange8(char volatile *Destination8, char Exchange8, char Comparand8)
{
INT_PTR DestinationAddr = (INT_PTR)Destination8;
short volatile *Destination16 = (short volatile *)(DestinationAddr & ~1);
const short Shift8 = (DestinationAddr & 1) * 8;
const short Mask8 = 0xff << Shift8;
short Initial16 = *Destination16;
char Initial8 = Initial16 >> Shift8;
while (Initial8 == Comparand8) {
/* initial *Destination8 matches, so try exchange it while keeping the
* neighboring byte untouched */
short Exchange16 = (Initial16 & ~Mask8) | ((short)Exchange8 << Shift8);
short Comparand16 = Initial16;
short Initial16 = InterlockedCompareExchange16(Destination16, Exchange16, Comparand16);
if (Initial16 == Comparand16) {
/* succeeded */
return Comparand8;
}
/* something changed, retry with the new initial value */
Initial8 = Initial16 >> Shift8;
}
return Initial8;
}
#endif /* _MSC_VER < 1600 */
/* MSVC supports decltype keyword, but it's only supported on C++ and doesn't
* quite work here; and if a C++-only solution is worthwhile, then it would be