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 /* FUNCTIONS *****************************************************************/
  18
  19 /*
  20  * @implemented
  21  */
  22 PMDL
  23 STDCALL
  24 IoAllocateMdl(PVOID VirtualAddress,
  25                    ULONG Length,
  26                    BOOLEAN SecondaryBuffer,
  27                    BOOLEAN ChargeQuota,
  28                    PIRP Irp)
  29 {
  30    PMDL Mdl;
  31
  32    if (ChargeQuota)
  33      {
  34 //      Mdl = ExAllocatePoolWithQuota(NonPagedPool,
  35 //                                    MmSizeOfMdl(VirtualAddress,Length));
  36         Mdl = ExAllocatePoolWithTag(NonPagedPool,
  37                                     MmSizeOfMdl(VirtualAddress,Length),
  38                                     TAG_MDL);
  39      }
  40    else
  41      {
  42         Mdl = ExAllocatePoolWithTag(NonPagedPool,
  43                                     MmSizeOfMdl(VirtualAddress,Length),
  44                                     TAG_MDL);
  45      }
  46    MmInitializeMdl(Mdl, (char*)VirtualAddress, Length);
  47
  48    if (Irp)
  49    {
  50       if (SecondaryBuffer)
  51       {
  52          ASSERT(Irp->MdlAddress);
  53
  54          /* FIXME: add to end of list maybe?? */
  55          Mdl->Next = Irp->MdlAddress->Next;
  56          Irp->MdlAddress->Next = Mdl;
  57       }
  58       else
  59       {
  60          /*
  61           * What if there's allready an mdl at Irp->MdlAddress?
  62           * Is that bad and should we do something about it?
  63           */
  64          Irp->MdlAddress = Mdl;
  65       }
  66    }
  67
  68    return(Mdl);
  69 }
  70
  71 /*
  72  * @implemented
  73  *
  74  * You must IoFreeMdl the slave before freeing the master.
  75  *
  76  * IoBuildPartialMdl is more similar to MmBuildMdlForNonPagedPool, the difference
  77  * is that the former takes the physical addresses from the master MDL, while the
  78  * latter - from the known location of the NPP.
  79  */
  80 VOID
  81 STDCALL
  82 IoBuildPartialMdl(PMDL SourceMdl,
  83                        PMDL TargetMdl,
  84                        PVOID VirtualAddress,
  85                        ULONG Length)
  86 {
  87    PPFN_TYPE TargetPages = (PPFN_TYPE)(TargetMdl + 1);
  88    PPFN_TYPE SourcePages = (PPFN_TYPE)(SourceMdl + 1);
  89    ULONG Count;
  90    ULONG Delta;
  91
  92    DPRINT("VirtualAddress 0x%p, SourceMdl->StartVa 0x%p, SourceMdl->MappedSystemVa 0x%p\n",
  93           VirtualAddress, SourceMdl->StartVa, SourceMdl->MappedSystemVa);
  94
  95    TargetMdl->StartVa = (PVOID)PAGE_ROUND_DOWN(VirtualAddress);
  96    TargetMdl->ByteOffset = (ULONG_PTR)VirtualAddress - (ULONG_PTR)TargetMdl->StartVa;
  97    TargetMdl->ByteCount = Length;
  98    TargetMdl->Process = SourceMdl->Process;
  99    Delta = (ULONG_PTR)VirtualAddress - ((ULONG_PTR)SourceMdl->StartVa + SourceMdl->ByteOffset);
 100    TargetMdl->MappedSystemVa = (char*)SourceMdl->MappedSystemVa + Delta;
 101
 102    TargetMdl->MdlFlags = SourceMdl->MdlFlags & (MDL_IO_PAGE_READ|MDL_SOURCE_IS_NONPAGED_POOL|MDL_MAPPED_TO_SYSTEM_VA);
 103    TargetMdl->MdlFlags |= MDL_PARTIAL;
 104
 105    Delta = ((ULONG_PTR)TargetMdl->StartVa - (ULONG_PTR)SourceMdl->StartVa) / PAGE_SIZE;
 106    Count = ADDRESS_AND_SIZE_TO_SPAN_PAGES(VirtualAddress,Length);
 107
 108    SourcePages += Delta;
 109
 110    DPRINT("Delta %d, Count %d\n", Delta, Count);
 111
 112    memcpy(TargetPages, SourcePages, Count * sizeof(PFN_TYPE));
 113
 114 }
 115
 116 /*
 117  * @implemented
 118  */
 119 VOID STDCALL
 120 IoFreeMdl(PMDL Mdl)
 121 {
 122    /*
 123     * This unmaps partial mdl's from kernel space but also asserts that non-partial
 124     * mdl's isn't still mapped into kernel space.
 125     */
 126    ASSERT(Mdl);
 127    ASSERT_IRQL(DISPATCH_LEVEL);
 128
 129    MmPrepareMdlForReuse(Mdl);
 130
 131    ExFreePoolWithTag(Mdl, TAG_MDL);
 132 }
 133
 134
 135 /* EOF */