reactos/ntoskrnl/io/mdl.c

   1 /* $Id$
   2  *
   3  * COPYRIGHT:       See COPYING in the top level directory
   4  * PROJECT:         ReactOS kernel
   5  * FILE:            ntoskrnl/io/mdl.c
   6  * PURPOSE:         Io manager mdl functions
   7  * PROGRAMMER:      David Welch (welch@mcmail.com)
   8  * UPDATE HISTORY:
   9  *                  Created 22/05/98
  10  */
  11
  12 /* INCLUDES *****************************************************************/
  13
  14 #include <ntoskrnl.h>
  15 #define NDEBUG
  16 #include <internal/debug.h>
  17
  18 /* GLOBALS *******************************************************************/
  19
  20 #define TAG_MDL    TAG('M', 'D', 'L', ' ')
  21
  22 /* FUNCTIONS *****************************************************************/
  23
  24 /*
  25  * @implemented
  26  */
  27 PMDL
  28 STDCALL
  29 IoAllocateMdl(PVOID VirtualAddress,
  30                    ULONG Length,
  31                    BOOLEAN SecondaryBuffer,
  32                    BOOLEAN ChargeQuota,
  33                    PIRP Irp)
  34 {
  35    PMDL Mdl;
  36
  37    if (ChargeQuota)
  38      {
  39 //      Mdl = ExAllocatePoolWithQuota(NonPagedPool,
  40 //                                    MmSizeOfMdl(VirtualAddress,Length));
  41         Mdl = ExAllocatePoolWithTag(NonPagedPool,
  42                                     MmSizeOfMdl(VirtualAddress,Length),
  43                                     TAG_MDL);
  44      }
  45    else
  46      {
  47         Mdl = ExAllocatePoolWithTag(NonPagedPool,
  48                                     MmSizeOfMdl(VirtualAddress,Length),
  49                                     TAG_MDL);
  50      }
  51    MmInitializeMdl(Mdl, (char*)VirtualAddress, Length);
  52
  53    if (Irp)
  54    {
  55       if (SecondaryBuffer)
  56       {
  57          ASSERT(Irp->MdlAddress);
  58
  59          /* FIXME: add to end of list maybe?? */
  60          Mdl->Next = Irp->MdlAddress->Next;
  61          Irp->MdlAddress->Next = Mdl;
  62       }
  63       else
  64       {
  65          /*
  66           * What if there's allready an mdl at Irp->MdlAddress?
  67           * Is that bad and should we do something about it?
  68           */
  69          Irp->MdlAddress = Mdl;
  70       }
  71    }
  72
  73    return(Mdl);
  74 }
  75
  76 /*
  77  * @implemented
  78  *
  79  * You must IoFreeMdl the slave before freeing the master.
  80  *
  81  * IoBuildPartialMdl is more similar to MmBuildMdlForNonPagedPool, the difference
  82  * is that the former takes the physical addresses from the master MDL, while the
  83  * latter - from the known location of the NPP.
  84  */
  85 VOID
  86 STDCALL
  87 IoBuildPartialMdl(PMDL SourceMdl,
  88                        PMDL TargetMdl,
  89                        PVOID VirtualAddress,
  90                        ULONG Length)
  91 {
  92    PPFN_TYPE TargetPages = (PPFN_TYPE)(TargetMdl + 1);
  93    PPFN_TYPE SourcePages = (PPFN_TYPE)(SourceMdl + 1);
  94    ULONG Count;
  95    ULONG Delta;
  96
  97    DPRINT("VirtualAddress %x, SourceMdl->StartVa %x, SourceMdl->MappedSystemVa %x\n",
  98           VirtualAddress, SourceMdl->StartVa, SourceMdl->MappedSystemVa);
  99
 100    TargetMdl->StartVa = (PVOID)PAGE_ROUND_DOWN(VirtualAddress);
 101    TargetMdl->ByteOffset = (ULONG_PTR)VirtualAddress - (ULONG_PTR)TargetMdl->StartVa;
 102    TargetMdl->ByteCount = Length;
 103    TargetMdl->Process = SourceMdl->Process;
 104    Delta = (ULONG_PTR)VirtualAddress - ((ULONG_PTR)SourceMdl->StartVa + SourceMdl->ByteOffset);
 105    TargetMdl->MappedSystemVa = (char*)SourceMdl->MappedSystemVa + Delta;
 106
 107    TargetMdl->MdlFlags = SourceMdl->MdlFlags & (MDL_IO_PAGE_READ|MDL_SOURCE_IS_NONPAGED_POOL|MDL_MAPPED_TO_SYSTEM_VA);
 108    TargetMdl->MdlFlags |= MDL_PARTIAL;
 109
 110    Delta = ((ULONG_PTR)TargetMdl->StartVa - (ULONG_PTR)SourceMdl->StartVa) / PAGE_SIZE;
 111    Count = ADDRESS_AND_SIZE_TO_SPAN_PAGES(VirtualAddress,Length);
 112
 113    SourcePages += Delta;
 114
 115    DPRINT("Delta %d, Count %d\n", Delta, Count);
 116
 117    memcpy(TargetPages, SourcePages, Count * sizeof(PFN_TYPE));
 118
 119 }
 120
 121 /*
 122  * @implemented
 123  */
 124 VOID STDCALL
 125 IoFreeMdl(PMDL Mdl)
 126 {
 127    /*
 128     * This unmaps partial mdl's from kernel space but also asserts that non-partial
 129     * mdl's isn't still mapped into kernel space.
 130     */
 131    MmPrepareMdlForReuse(Mdl);
 132
 133    ExFreePool(Mdl);
 134 }
 135
 136
 137 /* EOF */