From 68285022692160e5e429c0750d9b4732a694eade Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Sat, 1 Aug 2015 21:48:06 +0000
Subject: [PATCH] [NTVDM] Implement XMS function 0Fh (Reallocate Extended
 Memory Block).

svn path=/trunk/; revision=68592
---
 .../mvdm/ntvdm/dos/dos32krnl/himem.c          | 127 +++++++++++++-----
 1 file changed, 90 insertions(+), 37 deletions(-)

diff --git a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c
index dce3da29a5b..998244c6407 100644
--- a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c
+++ b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c
@@ -272,6 +272,89 @@ static UCHAR XmsAlloc(WORD Size, PWORD Handle)
     return XMS_STATUS_OUT_OF_MEMORY;
 }
 
+static UCHAR XmsRealloc(WORD Handle, WORD NewSize)
+{
+    DWORD BlockNumber;
+    PXMS_HANDLE HandleEntry = GetHandleRecord(Handle);
+    DWORD CurrentIndex = 0;
+    ULONG RunStart;
+    ULONG RunSize;
+
+    if (!ValidateHandle(HandleEntry))
+        return XMS_STATUS_INVALID_HANDLE;
+
+    if (HandleEntry->LockCount)
+        return XMS_STATUS_LOCKED;
+
+    /* Get the block number */
+    BlockNumber = (HandleEntry->Address - XMS_ADDRESS) / XMS_BLOCK_SIZE;
+
+    if (NewSize < HandleEntry->Size)
+    {
+        /* Just reduce the size of this block */
+        RtlClearBits(&AllocBitmap, BlockNumber + NewSize, HandleEntry->Size - NewSize);
+        FreeBlocks += HandleEntry->Size - NewSize;
+        HandleEntry->Size = NewSize;
+    }
+    else if (NewSize > HandleEntry->Size)
+    {
+        /* Check if we can expand in-place */
+        if (RtlAreBitsClear(&AllocBitmap,
+                            BlockNumber + HandleEntry->Size,
+                            NewSize - HandleEntry->Size))
+        {
+            /* Just increase the size of this block */
+            RtlSetBits(&AllocBitmap,
+                       BlockNumber + HandleEntry->Size,
+                       NewSize - HandleEntry->Size);
+            FreeBlocks -= NewSize - HandleEntry->Size;
+            HandleEntry->Size = NewSize;
+
+            /* We're done */
+            return XMS_STATUS_SUCCESS;
+        }
+
+        /* Deallocate the current block range */
+        RtlClearBits(&AllocBitmap, BlockNumber, HandleEntry->Size);
+
+        /* Find a new place for this block */
+        while (CurrentIndex < XMS_BLOCKS)
+        {
+            RunSize = RtlFindNextForwardRunClear(&AllocBitmap, CurrentIndex, &RunStart);
+            if (RunSize == 0) break;
+
+            if (RunSize >= NewSize)
+            {
+                /* Allocate the new range */
+                RtlSetBits(&AllocBitmap, RunStart, NewSize);
+
+                /* Move the data to the new location */
+                RtlMoveMemory((PVOID)REAL_TO_PHYS(XMS_ADDRESS + RunStart * XMS_BLOCK_SIZE),
+                              (PVOID)REAL_TO_PHYS(HandleEntry->Address),
+                              HandleEntry->Size * XMS_BLOCK_SIZE);
+
+                /* Update the handle entry */
+                HandleEntry->Address = XMS_ADDRESS + RunStart * XMS_BLOCK_SIZE;
+                HandleEntry->Size = NewSize;
+
+                /* Update the free block counter */
+                FreeBlocks -= NewSize - HandleEntry->Size;
+
+                return XMS_STATUS_SUCCESS;
+            }
+
+            /* Keep searching */
+            CurrentIndex = RunStart + RunSize;
+        }
+
+        /* Restore the old block range */
+        RtlSetBits(&AllocBitmap, BlockNumber, HandleEntry->Size);
+        return XMS_STATUS_OUT_OF_MEMORY;
+    }
+    
+    return XMS_STATUS_SUCCESS;
+}
+
 static UCHAR XmsFree(WORD Handle)
 {
     DWORD BlockNumber;
@@ -478,7 +561,7 @@ static VOID WINAPI XmsBopProcedure(LPWORD Stack)
             WORD Handle;
             UCHAR Result = XmsAlloc(getDX(), &Handle);
 
-            if (Result >= 0)
+            if (Result == XMS_STATUS_SUCCESS)
             {
                 setAX(1);
                 setDX(Handle);
@@ -497,7 +580,7 @@ static VOID WINAPI XmsBopProcedure(LPWORD Stack)
         {
             UCHAR Result = XmsFree(getDX());
 
-            setAX(Result >= 0);
+            setAX(Result == XMS_STATUS_SUCCESS);
             setBL(Result);
             break;
         }
@@ -571,7 +654,7 @@ static VOID WINAPI XmsBopProcedure(LPWORD Stack)
             DWORD Address;
             UCHAR Result = XmsLock(getDX(), &Address);
 
-            if (Result >= 0)
+            if (Result == XMS_STATUS_SUCCESS)
             {
                 setAX(1);
 
@@ -593,7 +676,7 @@ static VOID WINAPI XmsBopProcedure(LPWORD Stack)
         {
             UCHAR Result = XmsUnlock(getDX());
 
-            setAX(Result >= 0);
+            setAX(Result == XMS_STATUS_SUCCESS);
             setBL(Result);
             break;
         }
@@ -627,40 +710,10 @@ static VOID WINAPI XmsBopProcedure(LPWORD Stack)
         /* Reallocate Extended Memory Block */
         case 0x0F:
         {
-            PXMS_HANDLE HandleEntry = GetHandleRecord(getDX());
-            WORD NewSize = getBX();
+            UCHAR Result = XmsRealloc(getDX(), getBX());
 
-            if (!ValidateHandle(HandleEntry))
-            {
-                setAX(0);
-                setBL(XMS_STATUS_INVALID_HANDLE);
-                break;
-            }
-
-            if (HandleEntry->LockCount)
-            {
-                setAX(0);
-                setBL(XMS_STATUS_LOCKED);
-                break;
-            }
-
-            /* Check for reduction or enlargement */
-            if (NewSize < HandleEntry->Size)
-            {
-                /* Reduction, the easy case: just update the size */
-                HandleEntry->Size = NewSize;
-            }
-            else
-            {
-                /* Enlargement: we need to reallocate elsewhere */
-                UNIMPLEMENTED;
-                setAX(0);
-                setBL(XMS_STATUS_NOT_IMPLEMENTED);
-                break;
-            }
-
-            setAX(1);
-            setBL(XMS_STATUS_SUCCESS);
+            setAX(Result == XMS_STATUS_SUCCESS);
+            setBL(Result);
             break;
         }