reactos/ntoskrnl/io/mdl.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS kernel
   4  * FILE:            ntoskrnl/io/mdl.c
   5  * PURPOSE:         Io manager mdl functions
   6  * PROGRAMMER:      David Welch (welch@mcmail.com)
   7  * UPDATE HISTORY:
   8  *                  Created 22/05/98
   9  */
  10
  11 /* INCLUDES *****************************************************************/
  12
  13 #include <internal/kernel.h>
  14 #include <internal/linkage.h>
  15 #include <internal/hal/page.h>
  16 #include <ddk/ntddk.h>
  17
  18 #include <internal/debug.h>
  19
  20 /* FUNCTIONS *****************************************************************/
  21
  22 PMDL IoAllocateMdl(PVOID VirtualAddress,
  23                    ULONG Length,
  24                    BOOLEAN SecondaryBuffer,
  25                    BOOLEAN ChargeQuota,
  26                    PIRP Irp)
  27 {
  28    PMDL Mdl;
  29
  30    if (ChargeQuota)
  31      {
  32         Mdl = ExAllocatePoolWithQuota(NonPagedPool,
  33                                       MmSizeOfMdl(VirtualAddress,Length));
  34      }
  35    else
  36      {
  37         Mdl = ExAllocatePool(NonPagedPool,MmSizeOfMdl(VirtualAddress,Length));
  38      }
  39    MmInitializeMdl(Mdl,VirtualAddress,Length);
  40    if (Irp!=NULL && !SecondaryBuffer)
  41      {
  42         Irp->MdlAddress = Mdl;
  43      }
  44    return(Mdl);
  45 }
  46
  47 VOID IoBuildPartialMdl(PMDL SourceMdl,
  48                        PMDL TargetMdl,
  49                        PVOID VirtualAddress,
  50                        ULONG Length)
  51 {
  52    PULONG TargetPages = (PULONG)(TargetMdl + 1);
  53    PULONG SourcePages = (PULONG)(SourceMdl + 1);
  54    ULONG Va;
  55    ULONG Delta = (PAGE_ROUND_DOWN(VirtualAddress) - (ULONG)SourceMdl->StartVa)/
  56                  PAGESIZE;
  57
  58    for (Va = 0; Va < (PAGE_ROUND_UP(Length)/PAGESIZE); Va++)
  59      {
  60         TargetPages[Va] = SourcePages[Va+Delta];
  61      }
  62 }
  63
  64 VOID IoFreeMdl(PMDL Mdl)
  65 {
  66    MmUnmapLockedPages(MmGetSystemAddressForMdl(Mdl),Mdl);
  67    MmUnlockPages(Mdl);
  68    ExFreePool(Mdl);
  69 }