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  *
   8  * PROGRAMMERS:     David Welch (welch@mcmail.com)
   9  */
  10
  11 /* INCLUDES *****************************************************************/
  12
  13 #include <ntoskrnl.h>
  14 #define NDEBUG
  15 #include <internal/debug.h>
  16
  17 /* GLOBALS *******************************************************************/
  18
  19 #define TAG_MDL    TAG('M', 'D', 'L', ' ')
  20
  21 /* FUNCTIONS *****************************************************************/
  22
  23 /*
  24  * @implemented
  25  */
  26 PMDL
  27 STDCALL
  28 IoAllocateMdl(PVOID VirtualAddress,
  29                    ULONG Length,
  30                    BOOLEAN SecondaryBuffer,
  31                    BOOLEAN ChargeQuota,
  32                    PIRP Irp)
  33 {
  34    PMDL Mdl;
  35
  36    if (ChargeQuota)
  37      {
  38 //      Mdl = ExAllocatePoolWithQuota(NonPagedPool,
  39 //                                    MmSizeOfMdl(VirtualAddress,Length));
  40         Mdl = ExAllocatePoolWithTag(NonPagedPool,
  41                                     MmSizeOfMdl(VirtualAddress,Length),
  42                                     TAG_MDL);
  43      }
  44    else
  45      {
  46         Mdl = ExAllocatePoolWithTag(NonPagedPool,
  47                                     MmSizeOfMdl(VirtualAddress,Length),
  48                                     TAG_MDL);
  49      }
  50    MmInitializeMdl(Mdl, (char*)VirtualAddress, Length);
  51
  52    if (Irp)
  53    {
  54       if (SecondaryBuffer)
  55       {
  56          ASSERT(Irp->MdlAddress);
  57
  58          /* FIXME: add to end of list maybe?? */
  59          Mdl->Next = Irp->MdlAddress->Next;
  60          Irp->MdlAddress->Next = Mdl;
  61       }
  62       else
  63       {
  64          /*
  65           * What if there's allready an mdl at Irp->MdlAddress?
  66           * Is that bad and should we do something about it?
  67           */
  68          Irp->MdlAddress = Mdl;
  69       }
  70    }
  71
  72    return(Mdl);
  73 }
  74
  75 /*
  76  * @implemented
  77  *
  78  * You must IoFreeMdl the slave before freeing the master.
  79  *
  80  * IoBuildPartialMdl is more similar to MmBuildMdlForNonPagedPool, the difference
  81  * is that the former takes the physical addresses from the master MDL, while the
  82  * latter - from the known location of the NPP.
  83  */
  84 VOID
  85 STDCALL
  86 IoBuildPartialMdl(PMDL SourceMdl,
  87                        PMDL TargetMdl,
  88                        PVOID VirtualAddress,
  89                        ULONG Length)
  90 {
  91    PPFN_TYPE TargetPages = (PPFN_TYPE)(TargetMdl + 1);
  92    PPFN_TYPE SourcePages = (PPFN_TYPE)(SourceMdl + 1);
  93    ULONG Count;
  94    ULONG Delta;
  95
  96    DPRINT("VirtualAddress %x, SourceMdl->StartVa %x, SourceMdl->MappedSystemVa %x\n",
  97           VirtualAddress, SourceMdl->StartVa, SourceMdl->MappedSystemVa);
  98
  99    TargetMdl->StartVa = (PVOID)PAGE_ROUND_DOWN(VirtualAddress);
 100    TargetMdl->ByteOffset = (ULONG_PTR)VirtualAddress - (ULONG_PTR)TargetMdl->StartVa;
 101    TargetMdl->ByteCount = Length;
 102    TargetMdl->Process = SourceMdl->Process;
 103    Delta = (ULONG_PTR)VirtualAddress - ((ULONG_PTR)SourceMdl->StartVa + SourceMdl->ByteOffset);
 104    TargetMdl->MappedSystemVa = (char*)SourceMdl->MappedSystemVa + Delta;
 105
 106    TargetMdl->MdlFlags = SourceMdl->MdlFlags & (MDL_IO_PAGE_READ|MDL_SOURCE_IS_NONPAGED_POOL|MDL_MAPPED_TO_SYSTEM_VA);
 107    TargetMdl->MdlFlags |= MDL_PARTIAL;
 108
 109    Delta = ((ULONG_PTR)TargetMdl->StartVa - (ULONG_PTR)SourceMdl->StartVa) / PAGE_SIZE;
 110    Count = ADDRESS_AND_SIZE_TO_SPAN_PAGES(VirtualAddress,Length);
 111
 112    SourcePages += Delta;
 113
 114    DPRINT("Delta %d, Count %d\n", Delta, Count);
 115
 116    memcpy(TargetPages, SourcePages, Count * sizeof(PFN_TYPE));
 117
 118 }
 119
 120 /*
 121  * @implemented
 122  */
 123 VOID STDCALL
 124 IoFreeMdl(PMDL Mdl)
 125 {
 126    /*
 127     * This unmaps partial mdl's from kernel space but also asserts that non-partial
 128     * mdl's isn't still mapped into kernel space.
 129     */
 130    ASSERT(Mdl);
 131    ASSERT_IRQL(DISPATCH_LEVEL);
 132
 133    MmPrepareMdlForReuse(Mdl);
 134
 135    ExFreePool(Mdl);
 136 }
 137
 138
 139 /* EOF */