Changeset 59745 in vbox

Timestamp:

Feb 19, 2016 9:54:11 PM (9 years ago)

Author:

vboxsync

Message:

sg.cpp/h: Some cleanups/optimizations.

Location:

trunk

Files:

• include/iprt/sg.h (modified) (1 diff)
• src/VBox/Runtime/common/misc/sg.cpp (modified) (13 diffs)

trunk/include/iprt/sg.h

@@ -149 +149 @@
  * @param   pSgBuf2      Second S/G buffer.
  * @param   cbCmp        How many bytes to compare.
- * @param   pcbOff       Where to store the offset of the first different byte
+ * @param   poffDiff     Where to store the offset of the first different byte
  *                       in the buffer starting from the position of the S/G
  *                       buffer before this call.

trunk/src/VBox/Runtime/common/misc/sg.cpp

@@ -35 +35 @@
 
 
-static void *sgBufGet(PRTSGBUF pSgBuf, size_t *pcbData)
+static void *rtSgBufGet(PRTSGBUF pSgBuf, size_t *pcbData)
 {
     size_t cbData;
@@ -127 +127 @@
         *pcbSeg = pSgBuf->cbSegLeft;
 
-    return sgBufGet(pSgBuf, pcbSeg);
+    return rtSgBufGet(pSgBuf, pcbSeg);
 }
 
@@ -137 +137 @@
 
     size_t cbLeft = cbCopy;
-
     while (cbLeft)
     {
         size_t cbThisCopy = RT_MIN(RT_MIN(pSgBufDst->cbSegLeft, cbLeft), pSgBufSrc->cbSegLeft);
+        if (!cbThisCopy)
+            break;
+
         size_t cbTmp = cbThisCopy;
-        void *pvBufDst;
-        void *pvBufSrc;
-
-        if (!cbThisCopy)
-            break;
-
-        pvBufDst = sgBufGet(pSgBufDst, &cbTmp);
+        void *pvBufDst = rtSgBufGet(pSgBufDst, &cbTmp);
         Assert(cbTmp == cbThisCopy);
-        pvBufSrc = sgBufGet(pSgBufSrc, &cbTmp);
+        void *pvBufSrc = rtSgBufGet(pSgBufSrc, &cbTmp);
         Assert(cbTmp == cbThisCopy);
 
@@ -167 +163 @@
     AssertPtrReturn(pSgBuf2, 0);
 
+    /* Set up the temporary buffers */
+    RTSGBUF SgBuf1;
+    RTSgBufClone(&SgBuf1, pSgBuf1);
+    RTSGBUF SgBuf2;
+    RTSgBufClone(&SgBuf2, pSgBuf2);
+
     size_t cbLeft = cbCmp;
-    RTSGBUF SgBuf1;
-    RTSGBUF SgBuf2;
-
-    /* Set up the temporary buffers */
-    RTSgBufClone(&SgBuf1, pSgBuf1);
-    RTSgBufClone(&SgBuf2, pSgBuf2);
-
     while (cbLeft)
     {
         size_t cbThisCmp = RT_MIN(RT_MIN(SgBuf1.cbSegLeft, cbLeft), SgBuf2.cbSegLeft);
+        if (!cbThisCmp)
+            break;
+
         size_t cbTmp = cbThisCmp;
-        void *pvBuf1;
-        void *pvBuf2;
-
-        if (!cbCmp)
-            break;
-
-        pvBuf1 = sgBufGet(&SgBuf1, &cbTmp);
+        void *pvBuf1 = rtSgBufGet(&SgBuf1, &cbTmp);
         Assert(cbTmp == cbThisCmp);
-        pvBuf2 = sgBufGet(&SgBuf2, &cbTmp);
+        void *pvBuf2 = rtSgBufGet(&SgBuf2, &cbTmp);
         Assert(cbTmp == cbThisCmp);
 
@@ -201 +193 @@
 
 
-RTDECL(int) RTSgBufCmpEx(PRTSGBUF pSgBuf1, PRTSGBUF pSgBuf2, size_t cbCmp,
-                         size_t *pcbOff, bool fAdvance)
+RTDECL(int) RTSgBufCmpEx(PRTSGBUF pSgBuf1, PRTSGBUF pSgBuf2, size_t cbCmp, size_t *poffDiff, bool fAdvance)
 {
     AssertPtrReturn(pSgBuf1, 0);
     AssertPtrReturn(pSgBuf2, 0);
 
-    size_t cbLeft = cbCmp;
-    size_t cbOff  = 0;
     RTSGBUF SgBuf1Tmp;
     RTSGBUF SgBuf2Tmp;
@@ -228 +217 @@
     }
 
+    size_t cbLeft = cbCmp;
+    size_t off    = 0;
     while (cbLeft)
     {
         size_t cbThisCmp = RT_MIN(RT_MIN(pSgBuf1Tmp->cbSegLeft, cbLeft), pSgBuf2Tmp->cbSegLeft);
+        if (!cbThisCmp)
+            break;
+
         size_t cbTmp = cbThisCmp;
-        uint8_t *pbBuf1;
-        uint8_t *pbBuf2;
-
-        if (!cbCmp)
-            break;
-
-        pbBuf1 = (uint8_t *)sgBufGet(pSgBuf1Tmp, &cbTmp);
+        uint8_t *pbBuf1 = (uint8_t *)rtSgBufGet(pSgBuf1Tmp, &cbTmp);
         Assert(cbTmp == cbThisCmp);
-        pbBuf2 = (uint8_t *)sgBufGet(pSgBuf2Tmp, &cbTmp);
+        uint8_t *pbBuf2 = (uint8_t *)rtSgBufGet(pSgBuf2Tmp, &cbTmp);
         Assert(cbTmp == cbThisCmp);
 
-        int rc = memcmp(pbBuf1, pbBuf2, cbThisCmp);
-        if (rc)
-        {
-            if (pcbOff)
+        int iDiff = memcmp(pbBuf1, pbBuf2, cbThisCmp);
+        if (iDiff)
+        {
+            /* Locate the first byte that differs if the caller requested this. */
+            if (poffDiff)
             {
-                /* Search for the correct offset */
                 while (   cbThisCmp-- > 0
-                       && (*pbBuf1 == *pbBuf2))
+                       && *pbBuf1 == *pbBuf2)
                 {
                     pbBuf1++;
                     pbBuf2++;
-                    cbOff++;
+                    off++;
                 }
 
-                *pcbOff = cbOff;
+                *poffDiff = off;
             }
-            return rc;
+            return iDiff;
         }
 
         cbLeft -= cbThisCmp;
-        cbOff  += cbThisCmp;
+        off    += cbThisCmp;
     }
 
@@ -279 +267 @@
     {
         size_t cbThisSet = cbLeft;
-        void *pvBuf = sgBufGet(pSgBuf, &cbThisSet);
+        void *pvBuf = rtSgBufGet(pSgBuf, &cbThisSet);
 
         if (!cbThisSet)
@@ -303 +291 @@
     {
         size_t cbThisCopy = cbLeft;
-        void *pvSrc = sgBufGet(pSgBuf, &cbThisCopy);
+        void *pvSrc = rtSgBufGet(pSgBuf, &cbThisCopy);
 
         if (!cbThisCopy)
@@ -328 +316 @@
     {
         size_t cbThisCopy = cbLeft;
-        void *pvDst = sgBufGet(pSgBuf, &cbThisCopy);
+        void *pvDst = rtSgBufGet(pSgBuf, &cbThisCopy);
 
         if (!cbThisCopy)
@@ -348 +336 @@
 
     size_t cbLeft = cbAdvance;
-
     while (cbLeft)
     {
         size_t cbThisAdvance = cbLeft;
-        void *pv = sgBufGet(pSgBuf, &cbThisAdvance);
-
-        NOREF(pv);
-
+        rtSgBufGet(pSgBuf, &cbThisAdvance);
         if (!cbThisAdvance)
             break;
@@ -400 +384 @@
         {
             size_t  cbThisSeg = cbData;
-            void   *pvSeg     = NULL;
-
-            pvSeg = sgBufGet(pSgBuf, &cbThisSeg);
+            void *pvSeg = rtSgBufGet(pSgBuf, &cbThisSeg);
 
             if (!cbThisSeg)
@@ -427 +409 @@
 RTDECL(bool) RTSgBufIsZero(PRTSGBUF pSgBuf, size_t cbCheck)
 {
-    bool fIsZero = true;
-    size_t cbLeft = cbCheck;
     RTSGBUF SgBufTmp;
-
     RTSgBufClone(&SgBufTmp, pSgBuf);
 
+    bool   fIsZero = true;
+    size_t cbLeft  = cbCheck;
     while (cbLeft)
     {
         size_t cbThisCheck = cbLeft;
-        void *pvBuf = sgBufGet(&SgBufTmp, &cbThisCheck);
-
+        void *pvBuf = rtSgBufGet(&SgBufTmp, &cbThisCheck);
         if (!cbThisCheck)
             break;
 
+/** @todo fix this after asm.h gets updated.    */
         /* Use optimized inline assembler if possible. */
         if (   !(cbThisCheck % 4)
-            && (cbThisCheck * 8 <= UINT32_MAX))
+            && cbThisCheck * 8 <= UINT32_MAX)
         {
             if (ASMBitFirstSet((volatile void *)pvBuf, (uint32_t)cbThisCheck * 8) != -1)
@@ -453 +434 @@
         else
         {
-            for (unsigned i = 0; i < cbThisCheck; i++)
+            for (size_t i = 0; i < cbThisCheck; i++)
             {
                 char *pbBuf = (char *)pvBuf;