X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=MdePkg%2FLibrary%2FBasePciExpressLib%2FPciLib.c;h=f7deedd6420015f5c85b5db69a26d514740a12a1;hb=3683e55034409db9b43758ee9ebf8fe3d897fbd7;hp=de33bf30555a5b4d89623b3d63777e26706a90ec;hpb=9a462b415d8c9636bfb29a2cfb141e69c3c092b7;p=mirror_edk2.git

diff --git a/MdePkg/Library/BasePciExpressLib/PciLib.c b/MdePkg/Library/BasePciExpressLib/PciLib.c
index de33bf3055..f7deedd642 100644
--- a/MdePkg/Library/BasePciExpressLib/PciLib.c
+++ b/MdePkg/Library/BasePciExpressLib/PciLib.c
@@ -31,13 +31,21 @@
   ASSERT (((A) & ~0xfffffff) == 0)
 
 
-UINTN
-EFIAPI
+/**
+  Gets the base address of PCI Express.
+  
+  This internal functions retrieves PCI Express Base Address via a PCD entry
+  PcdPciExpressBaseAddress.
+  
+  @return The base address of PCI Express.
+
+**/
+volatile VOID*
 GetPciExpressBaseAddress (
   VOID
   )
 {
-  return (UINTN)PcdGet64 (PcdPciExpressBaseAddress);
+  return (VOID*)(UINTN) PcdGet64 (PcdPciExpressBaseAddress);
 }
 
 /**
@@ -62,7 +70,7 @@ PciExpressRead8 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioRead8 (GetPciExpressBaseAddress () + Address);
+  return MmioRead8 ((UINTN) GetPciExpressBaseAddress () + Address);
 }
 
 /**
@@ -89,7 +97,7 @@ PciExpressWrite8 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioWrite8 (GetPciExpressBaseAddress () + Address, Value);
+  return MmioWrite8 ((UINTN) GetPciExpressBaseAddress () + Address, Value);
 }
 
 /**
@@ -120,7 +128,7 @@ PciExpressOr8 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioOr8 (GetPciExpressBaseAddress () + Address, OrData);
+  return MmioOr8 ((UINTN) GetPciExpressBaseAddress () + Address, OrData);
 }
 
 /**
@@ -151,7 +159,7 @@ PciExpressAnd8 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioAnd8 (GetPciExpressBaseAddress () + Address, AndData);
+  return MmioAnd8 ((UINTN) GetPciExpressBaseAddress () + Address, AndData);
 }
 
 /**
@@ -186,7 +194,7 @@ PciExpressAndThenOr8 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioAndThenOr8 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            AndData,
            OrData
            );
@@ -202,7 +210,7 @@ PciExpressAndThenOr8 (
   If Address > 0x0FFFFFFF, then ASSERT().
   If StartBit is greater than 7, then ASSERT().
   If EndBit is greater than 7, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to read.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -223,7 +231,7 @@ PciExpressBitFieldRead8 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldRead8 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit
            );
@@ -240,7 +248,7 @@ PciExpressBitFieldRead8 (
   If Address > 0x0FFFFFFF, then ASSERT().
   If StartBit is greater than 7, then ASSERT().
   If EndBit is greater than 7, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -263,7 +271,7 @@ PciExpressBitFieldWrite8 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldWrite8 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            Value
@@ -284,7 +292,7 @@ PciExpressBitFieldWrite8 (
   If Address > 0x0FFFFFFF, then ASSERT().
   If StartBit is greater than 7, then ASSERT().
   If EndBit is greater than 7, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -307,7 +315,7 @@ PciExpressBitFieldOr8 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldOr8 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            OrData
@@ -328,7 +336,7 @@ PciExpressBitFieldOr8 (
   If Address > 0x0FFFFFFF, then ASSERT().
   If StartBit is greater than 7, then ASSERT().
   If EndBit is greater than 7, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -351,7 +359,7 @@ PciExpressBitFieldAnd8 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldAnd8 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            AndData
@@ -374,7 +382,7 @@ PciExpressBitFieldAnd8 (
   If Address > 0x0FFFFFFF, then ASSERT().
   If StartBit is greater than 7, then ASSERT().
   If EndBit is greater than 7, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -399,7 +407,7 @@ PciExpressBitFieldAndThenOr8 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldAndThenOr8 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            AndData,
@@ -430,7 +438,7 @@ PciExpressRead16 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioRead16 (GetPciExpressBaseAddress () + Address);
+  return MmioRead16 ((UINTN) GetPciExpressBaseAddress () + Address);
 }
 
 /**
@@ -458,7 +466,7 @@ PciExpressWrite16 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioWrite16 (GetPciExpressBaseAddress () + Address, Value);
+  return MmioWrite16 ((UINTN) GetPciExpressBaseAddress () + Address, Value);
 }
 
 /**
@@ -490,7 +498,7 @@ PciExpressOr16 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioOr16 (GetPciExpressBaseAddress () + Address, OrData);
+  return MmioOr16 ((UINTN) GetPciExpressBaseAddress () + Address, OrData);
 }
 
 /**
@@ -522,7 +530,7 @@ PciExpressAnd16 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioAnd16 (GetPciExpressBaseAddress () + Address, AndData);
+  return MmioAnd16 ((UINTN) GetPciExpressBaseAddress () + Address, AndData);
 }
 
 /**
@@ -558,7 +566,7 @@ PciExpressAndThenOr16 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioAndThenOr16 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            AndData,
            OrData
            );
@@ -575,7 +583,7 @@ PciExpressAndThenOr16 (
   If Address is not aligned on a 16-bit boundary, then ASSERT().
   If StartBit is greater than 15, then ASSERT().
   If EndBit is greater than 15, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to read.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -596,7 +604,7 @@ PciExpressBitFieldRead16 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldRead16 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit
            );
@@ -614,7 +622,7 @@ PciExpressBitFieldRead16 (
   If Address is not aligned on a 16-bit boundary, then ASSERT().
   If StartBit is greater than 15, then ASSERT().
   If EndBit is greater than 15, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -637,7 +645,7 @@ PciExpressBitFieldWrite16 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldWrite16 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            Value
@@ -659,7 +667,7 @@ PciExpressBitFieldWrite16 (
   If Address is not aligned on a 16-bit boundary, then ASSERT().
   If StartBit is greater than 15, then ASSERT().
   If EndBit is greater than 15, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -682,7 +690,7 @@ PciExpressBitFieldOr16 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldOr16 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            OrData
@@ -704,7 +712,7 @@ PciExpressBitFieldOr16 (
   If Address is not aligned on a 16-bit boundary, then ASSERT().
   If StartBit is greater than 15, then ASSERT().
   If EndBit is greater than 15, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -727,7 +735,7 @@ PciExpressBitFieldAnd16 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldAnd16 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            AndData
@@ -751,7 +759,7 @@ PciExpressBitFieldAnd16 (
   If Address is not aligned on a 16-bit boundary, then ASSERT().
   If StartBit is greater than 15, then ASSERT().
   If EndBit is greater than 15, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -776,7 +784,7 @@ PciExpressBitFieldAndThenOr16 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldAndThenOr16 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            AndData,
@@ -807,7 +815,7 @@ PciExpressRead32 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioRead32 (GetPciExpressBaseAddress () + Address);
+  return MmioRead32 ((UINTN) GetPciExpressBaseAddress () + Address);
 }
 
 /**
@@ -835,7 +843,7 @@ PciExpressWrite32 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioWrite32 (GetPciExpressBaseAddress () + Address, Value);
+  return MmioWrite32 ((UINTN) GetPciExpressBaseAddress () + Address, Value);
 }
 
 /**
@@ -867,7 +875,7 @@ PciExpressOr32 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioOr32 (GetPciExpressBaseAddress () + Address, OrData);
+  return MmioOr32 ((UINTN) GetPciExpressBaseAddress () + Address, OrData);
 }
 
 /**
@@ -899,7 +907,7 @@ PciExpressAnd32 (
   )
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
-  return MmioAnd32 (GetPciExpressBaseAddress () + Address, AndData);
+  return MmioAnd32 ((UINTN) GetPciExpressBaseAddress () + Address, AndData);
 }
 
 /**
@@ -935,7 +943,7 @@ PciExpressAndThenOr32 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioAndThenOr32 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            AndData,
            OrData
            );
@@ -952,7 +960,7 @@ PciExpressAndThenOr32 (
   If Address is not aligned on a 32-bit boundary, then ASSERT().
   If StartBit is greater than 31, then ASSERT().
   If EndBit is greater than 31, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to read.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -973,7 +981,7 @@ PciExpressBitFieldRead32 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldRead32 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit
            );
@@ -991,7 +999,7 @@ PciExpressBitFieldRead32 (
   If Address is not aligned on a 32-bit boundary, then ASSERT().
   If StartBit is greater than 31, then ASSERT().
   If EndBit is greater than 31, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -1014,7 +1022,7 @@ PciExpressBitFieldWrite32 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldWrite32 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            Value
@@ -1036,7 +1044,7 @@ PciExpressBitFieldWrite32 (
   If Address is not aligned on a 32-bit boundary, then ASSERT().
   If StartBit is greater than 31, then ASSERT().
   If EndBit is greater than 31, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -1059,7 +1067,7 @@ PciExpressBitFieldOr32 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldOr32 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            OrData
@@ -1081,7 +1089,7 @@ PciExpressBitFieldOr32 (
   If Address is not aligned on a 32-bit boundary, then ASSERT().
   If StartBit is greater than 31, then ASSERT().
   If EndBit is greater than 31, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -1104,7 +1112,7 @@ PciExpressBitFieldAnd32 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldAnd32 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            AndData
@@ -1128,7 +1136,7 @@ PciExpressBitFieldAnd32 (
   If Address is not aligned on a 32-bit boundary, then ASSERT().
   If StartBit is greater than 31, then ASSERT().
   If EndBit is greater than 31, then ASSERT().
-  If EndBit is less than or equal to StartBit, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
 
   @param  Address   PCI configuration register to write.
   @param  StartBit  The ordinal of the least significant bit in the bit field.
@@ -1153,7 +1161,7 @@ PciExpressBitFieldAndThenOr32 (
 {
   ASSERT_INVALID_PCI_ADDRESS (Address);
   return MmioBitFieldAndThenOr32 (
-           GetPciExpressBaseAddress () + Address,
+           (UINTN) GetPciExpressBaseAddress () + Address,
            StartBit,
            EndBit,
            AndData,
@@ -1174,8 +1182,7 @@ PciExpressBitFieldAndThenOr32 (
 
   If StartAddress > 0x0FFFFFFF, then ASSERT().
   If ((StartAddress & 0xFFF) + Size) > 0x1000, then ASSERT().
-  If (StartAddress + Size - 1)  > 0x0FFFFFFF, then ASSERT().
-  If Buffer is NULL, then ASSERT().
+  If Size > 0 and Buffer is NULL, then ASSERT().
 
   @param  StartAddress  Starting address that encodes the PCI Bus, Device,
                         Function and Register.
@@ -1193,59 +1200,70 @@ PciExpressReadBuffer (
   OUT     VOID                      *Buffer
   )
 {
-  UINTN                             EndAddress;
+  UINTN                             ReturnValue;
 
   ASSERT_INVALID_PCI_ADDRESS (StartAddress);
   ASSERT (((StartAddress & 0xFFF) + Size) <= 0x1000);
-  ASSERT ((StartAddress + Size - 1) <= 0x0FFFFFFF);
+
+  if (Size == 0) {
+    return Size;
+  }
+
   ASSERT (Buffer != NULL);
 
-  EndAddress = StartAddress + Size;
+  //
+  // Save Size for return
+  //
+  ReturnValue = Size;
 
-  if (StartAddress < EndAddress && (StartAddress & 1)) {
+  if ((StartAddress & 1) != 0) {
     //
     // Read a byte if StartAddress is byte aligned
     //
-    *(UINT8*)Buffer = PciExpressRead8 (StartAddress);
+    *(volatile UINT8 *)Buffer = PciExpressRead8 (StartAddress);
     StartAddress += sizeof (UINT8);
+    Size -= sizeof (UINT8);
     Buffer = (UINT8*)Buffer + 1;
   }
 
-  if (StartAddress < EndAddress && (StartAddress & 2)) {
+  if (Size >= sizeof (UINT16) && (StartAddress & 2) != 0) {
     //
     // Read a word if StartAddress is word aligned
     //
-    *(UINT16*)Buffer = PciExpressRead16 (StartAddress);
+    *(volatile UINT16 *)Buffer = PciExpressRead16 (StartAddress);
     StartAddress += sizeof (UINT16);
+    Size -= sizeof (UINT16);
     Buffer = (UINT16*)Buffer + 1;
   }
 
-  while (EndAddress - StartAddress >= 4) {
+  while (Size >= sizeof (UINT32)) {
     //
     // Read as many double words as possible
     //
-    *(UINT32*)Buffer = PciExpressRead32 (StartAddress);
+    *(volatile UINT32 *)Buffer = PciExpressRead32 (StartAddress);
     StartAddress += sizeof (UINT32);
+    Size -= sizeof (UINT32);
     Buffer = (UINT32*)Buffer + 1;
   }
 
-  if ((EndAddress & 2) != 0) {
+  if (Size >= sizeof (UINT16)) {
     //
     // Read the last remaining word if exist
     //
-    *(UINT16*)Buffer = PciExpressRead16 (StartAddress);
+    *(volatile UINT16 *)Buffer = PciExpressRead16 (StartAddress);
     StartAddress += sizeof (UINT16);
+    Size -= sizeof (UINT16);
     Buffer = (UINT16*)Buffer + 1;
   }
 
-  if (EndAddress & 1) {
+  if (Size >= sizeof (UINT8)) {
     //
     // Read the last remaining byte if exist
     //
-    *(UINT8*)Buffer = PciExpressRead8 (StartAddress);
+    *(volatile UINT8 *)Buffer = PciExpressRead8 (StartAddress);
   }
 
-  return Size;
+  return ReturnValue;
 }
 
 /**
@@ -1262,8 +1280,7 @@ PciExpressReadBuffer (
 
   If StartAddress > 0x0FFFFFFF, then ASSERT().
   If ((StartAddress & 0xFFF) + Size) > 0x1000, then ASSERT().
-  If (StartAddress + Size - 1)  > 0x0FFFFFFF, then ASSERT().
-  If Buffer is NULL, then ASSERT().
+  If Size > 0 and Buffer is NULL, then ASSERT().
 
   @param  StartAddress  Starting address that encodes the PCI Bus, Device,
                         Function and Register.
@@ -1281,57 +1298,68 @@ PciExpressWriteBuffer (
   IN      VOID                      *Buffer
   )
 {
-  UINTN                             EndAddress;
+  UINTN                             ReturnValue;
 
   ASSERT_INVALID_PCI_ADDRESS (StartAddress);
   ASSERT (((StartAddress & 0xFFF) + Size) <= 0x1000);
-  ASSERT ((StartAddress + Size - 1) <= 0x0FFFFFFF);
+
+  if (Size == 0) {
+    return 0;
+  }
+
   ASSERT (Buffer != NULL);
 
-  EndAddress = StartAddress + Size;
+  //
+  // Save Size for return
+  //
+  ReturnValue = Size;
 
-  if ((StartAddress < EndAddress) && ((StartAddress & 1)!= 0)) {
+  if ((StartAddress & 1) != 0) {
     //
     // Write a byte if StartAddress is byte aligned
     //
     PciExpressWrite8 (StartAddress, *(UINT8*)Buffer);
     StartAddress += sizeof (UINT8);
+    Size -= sizeof (UINT8);
     Buffer = (UINT8*)Buffer + 1;
   }
 
-  if (StartAddress < EndAddress && (StartAddress & 2)) {
+  if (Size >= sizeof (UINT16) && (StartAddress & 2) != 0) {
     //
     // Write a word if StartAddress is word aligned
     //
     PciExpressWrite16 (StartAddress, *(UINT16*)Buffer);
     StartAddress += sizeof (UINT16);
+    Size -= sizeof (UINT16);
     Buffer = (UINT16*)Buffer + 1;
   }
 
-  while (EndAddress - StartAddress >= 4) {
+  while (Size >= sizeof (UINT32)) {
     //
     // Write as many double words as possible
     //
     PciExpressWrite32 (StartAddress, *(UINT32*)Buffer);
     StartAddress += sizeof (UINT32);
+    Size -= sizeof (UINT32);
     Buffer = (UINT32*)Buffer + 1;
   }
 
-  if (EndAddress & 2) {
+  if (Size >= sizeof (UINT16)) {
     //
     // Write the last remaining word if exist
     //
     PciExpressWrite16 (StartAddress, *(UINT16*)Buffer);
     StartAddress += sizeof (UINT16);
+    Size -= sizeof (UINT16);
     Buffer = (UINT16*)Buffer + 1;
   }
 
-  if (EndAddress & 1) {
+  if (Size >= sizeof (UINT8)) {
     //
     // Write the last remaining byte if exist
     //
     PciExpressWrite8 (StartAddress, *(UINT8*)Buffer);
   }
 
-  return Size;
+  return ReturnValue;
 }