[tkreuzer] 57283: [FREELDR] Finally commit the patch to improve freeldr disk performance by Carlo Bramini. Obviously someone wants to read 0 bytes and that should not fail.

Author: tkreuzer
Date: Tue Sep 11 21:15:39 2012
New Revision: 57283

URL: http://svn.reactos.org/svn/reactos?rev=57283&view=rev
Log:
[FREELDR]
Finally commit the patch to improve freeldr disk performance by Carlo Bramini.
Obviously someone wants to read 0 bytes and that should not fail.

Modified:
    trunk/reactos/boot/freeldr/freeldr/arch/i386/hwdisk.c

Modified: trunk/reactos/boot/freeldr/freeldr/arch/i386/hwdisk.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/boot/freeldr/freeldr/arch/…
==============================================================================
--- trunk/reactos/boot/freeldr/freeldr/arch/i386/hwdisk.c [iso-8859-1] (original)
+++ trunk/reactos/boot/freeldr/freeldr/arch/i386/hwdisk.c [iso-8859-1] Tue Sep 11 21:15:39
2012
@@ -114,31 +114,45 @@
 {
     DISKCONTEXT* Context = FsGetDeviceSpecific(FileId);
     UCHAR* Ptr = (UCHAR*)Buffer;
-    ULONG i, Length;
+    ULONG Length, TotalSectors, MaxSectors, ReadSectors;
     BOOLEAN ret;
-
-    *Count = 0;
-    i = 0;
-    while (N > 0)
-    {
-        Length = N;
-        if (Length > Context->SectorSize)
-            Length = Context->SectorSize;
+    ULONGLONG SectorOffset;
+
+    TotalSectors = (N + Context->SectorSize - 1) / Context->SectorSize;
+    MaxSectors   = DISKREADBUFFER_SIZE / Context->SectorSize;
+    SectorOffset = Context->SectorNumber + Context->SectorOffset;
+
+    ret = 1;
+
+    while (TotalSectors)
+    {
+        ReadSectors = TotalSectors;
+        if (ReadSectors > MaxSectors)
+            ReadSectors = MaxSectors;
+
         ret = MachDiskReadLogicalSectors(
             Context->DriveNumber,
-            Context->SectorNumber + Context->SectorOffset + i,
-            1,
+            SectorOffset,
+            ReadSectors,
             (PVOID)DISKREADBUFFER);
         if (!ret)
-            return EIO;
+            break;
+
+        Length = ReadSectors * Context->SectorSize;
+        if (Length > N)
+            Length = N;
+
         RtlCopyMemory(Ptr, (PVOID)DISKREADBUFFER, Length);
+
         Ptr += Length;
-        *Count += Length;
         N -= Length;
-        i++;
-    }
-
-    return ESUCCESS;
+        SectorOffset += ReadSectors;
+        TotalSectors -= ReadSectors;
+    }
+
+    *Count = Ptr - (UCHAR *)Buffer;
+
+    return (!ret) ? EIO : ESUCCESS;
 }
 
 static LONG DiskSeek(ULONG FileId, LARGE_INTEGER* Position, SEEKMODE SeekMode)