Changeset 53474 in vbox

Timestamp:

Dec 6, 2014 4:17:43 AM (10 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

97204

Message:

SUPDrv.c: ASMMultU64ByU32DivByU32 could be replaced by 128-bit unsigned int math from iprt/uint128.h...

File:

• trunk/src/VBox/HostDrivers/Support/SUPDrv.c (modified) (3 diffs)

trunk/src/VBox/HostDrivers/Support/SUPDrv.c

@@ -55 +55 @@
 # include <iprt/path.h>
 #endif
+/*#include <iprt/uint128.h> - probably needs exporting. */
 #include <iprt/x86.h>
 
@@ -6171 +6172 @@
     {
         /* Try not to lose precision, the larger the interval the more likely we overflow. */
+#if 0  /** @todo r=bird: What about falling back on iprt/uint128.h here instead of
+         * trading accuracy for values that works with ASMMultU64ByU32DivByU32? Speed
+         * is hardly an issue at this point. */
+        RTUINT128U CpuHz, Tmp, Divisor;
+        RTUInt128MulU64ByU64(&Tmp, u64DeltaTsc, RT_NS_1SEC);
+        RTUInt128Div(&CpuHz, &Tmp, RTUInt128AssignU64(&Divisor, u64DeltaNanoTS));
+        pGip->u64CpuHz = CpuHz.s.Lo;
+#else
         if (   u64DeltaTsc < UINT64_MAX / RT_NS_100MS
             && u64DeltaNanoTS / 10 < UINT32_MAX)
@@ -6182 +6191 @@
         else /* Screw it. */
             pGip->u64CpuHz = u64DeltaTsc / (u64DeltaNanoTS / RT_NS_1SEC_64);
+#endif
     }