EmbeddedPkg/PrePiMemoryAllocationLib: Add ReallocatePool

Add implementation of ReallocatePool which is defined in the
MemoryAllocationLib header file to allow components to not
need special handling for PrePi module types.

Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>

EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c

@@ -269,3 +269,60 @@ FreePool (
 {
   // Not implemented yet
 }
+
+/**
+  Reallocates a buffer of type EfiBootServicesData.
+
+  Allocates and zeros the number bytes specified by NewSize from memory of type
+  EfiBootServicesData.  If OldBuffer is not NULL, then the smaller of OldSize and
+  NewSize bytes are copied from OldBuffer to the newly allocated buffer, and
+  OldBuffer is freed.  A pointer to the newly allocated buffer is returned.
+  If NewSize is 0, then a valid buffer of 0 size is  returned.  If there is not
+  enough memory remaining to satisfy the request, then NULL is returned.
+
+  If the allocation of the new buffer is successful and the smaller of NewSize and OldSize
+  is greater than (MAX_ADDRESS - OldBuffer + 1), then ASSERT().
+
+  @param  OldSize        The size, in bytes, of OldBuffer.
+  @param  NewSize        The size, in bytes, of the buffer to reallocate.
+  @param  OldBuffer      The buffer to copy to the allocated buffer.  This is an optional
+                         parameter that may be NULL.
+
+  @return A pointer to the allocated buffer or NULL if allocation fails.
+
+**/
+VOID *
+EFIAPI
+ReallocatePool (
+  IN UINTN  OldSize,
+  IN UINTN  NewSize,
+  IN VOID   *OldBuffer  OPTIONAL
+  )
+{
+  VOID  *NewBuffer;
+
+  // Validate the OldBuffer is HobAllocated.
+  DEBUG_CODE_BEGIN ();
+  EFI_HOB_HANDOFF_INFO_TABLE  *HandOffHob;
+
+  if (OldBuffer != NULL) {
+    HandOffHob = GetHobList ();
+    ASSERT (((EFI_PHYSICAL_ADDRESS)(UINTN)OldBuffer >= HandOffHob->EfiMemoryBottom));
+    ASSERT (((EFI_PHYSICAL_ADDRESS)(UINTN)(OldBuffer + OldSize) <= HandOffHob->EfiFreeMemoryBottom));
+  }
+
+  DEBUG_CODE_END ();
+
+  // If new buffer would be smaller just return old buffer as FreePool isn't supported.
+  if ((OldBuffer != NULL) && (OldSize >= NewSize)) {
+    return OldBuffer;
+  }
+
+  NewBuffer = AllocateZeroPool (NewSize);
+  if ((NewBuffer != NULL) && (OldBuffer != NULL)) {
+    CopyMem (NewBuffer, OldBuffer, MIN (OldSize, NewSize));
+    FreePool (OldBuffer);
+  }
+
+  return NewBuffer;
+}