Changeset 40127 in vbox for trunk/src/VBox/Runtime/common/vfs

Timestamp:

Feb 14, 2012 12:01:04 PM (13 years ago)

Author:

vboxsync

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

76271

Message:

vfsmemory: Fixed zero optimization in the write routine.

File:

• trunk/src/VBox/Runtime/common/vfs/vfsmemory.cpp (modified) (3 diffs)

trunk/src/VBox/Runtime/common/vfs/vfsmemory.cpp

@@ -5 +5 @@
 
 /*
- * Copyright (C) 2010 Oracle Corporation
+ * Copyright (C) 2010-2012 Oracle Corporation
  *
  * This file is part of VirtualBox Open Source Edition (OSE), as
@@ -462 +462 @@
         if (!fHit)
         {
-            Assert(!pExtent || (pExtent->off < offUnsigned && pExtent->off + pExtent->cb <= offUnsigned));
+            Assert(!pExtent || offUnsigned < pExtent->off);
 
             /* Skip leading zeros if there is a whole bunch of them. */
             uint8_t const *pbSrcNZ = (uint8_t const *)ASMMemIsAll8(pbSrc, cbLeftToWrite, 0);
-            if (!pbSrcNZ)
+            size_t         cbZeros = pbSrcNZ ? pbSrcNZ - pbSrc            : cbLeftToWrite;
+            if (cbZeros)
             {
-                offUnsigned  += cbLeftToWrite;
-                cbLeftToWrite = 0;
-                break;
-            }
-            size_t const cbZeros = pbSrcNZ - pbSrc;
-            if (cbZeros >= RT_MIN(pThis->cbExtent, _64K))
-            {
+                uint64_t const cbToNext = pExtent ? pExtent->off - offUnsigned : UINT64_MAX;
+                if (cbZeros > cbToNext)
+                    cbZeros = (size_t)cbToNext;
                 offUnsigned   += cbZeros;
                 cbLeftToWrite -= cbZeros;
-                pbSrc          = pbSrcNZ;
-                pExtent = rtVfsMemFile_LocateExtent(pThis, offUnsigned, &fHit);
-                break;
+                if (!cbLeftToWrite)
+                    break;
+
+                Assert(!pExtent || offUnsigned <= pExtent->off);
+                if (pExtent && pExtent->off == offUnsigned)
+                {
+                    fHit = true;
+                    continue;
+                }
             }
 
@@ -508 +511 @@
 
         /*
-         * Advance to the next extent.
+         * Advance to the next extent (emulate the lookup).
          */
-        PRTVFSMEMEXTENT pNext = RTListGetNext(&pThis->ExtentHead, pExtent, RTVFSMEMEXTENT, Entry);
-        Assert(!pNext || pNext->off >= offUnsigned);
-        if (pNext && pNext->off == offUnsigned)
-            pExtent = pNext;
-        else
-            fHit = false;
+        pExtent = RTListGetNext(&pThis->ExtentHead, pExtent, RTVFSMEMEXTENT, Entry);
+        fHit = pExtent && (offUnsigned - pExtent->off < pExtent->cb);
     }