reactos/boot/freeldr/freeldr/disk/ramdisk.c

   1 /*
   2  * PROJECT:         ReactOS Boot Loader
   3  * LICENSE:         BSD - See COPYING.ARM in the top level directory
   4  * FILE:            boot/freeldr/arch/i386/ramdisk.c
   5  * PURPOSE:         Implements routines to support booting from a RAM Disk
   6  * PROGRAMMERS:     ReactOS Portable Systems Group
   7  */
   8
   9 /* INCLUDES *******************************************************************/
  10
  11 #include <freeldr.h>
  12 #define NDEBUG
  13 #include <debug.h>
  14
  15 /* GLOBALS ********************************************************************/
  16
  17 PVOID gRamDiskBase;
  18 ULONG gRamDiskSize;
  19
  20 /* FUNCTIONS ******************************************************************/
  21
  22 FORCEINLINE
  23 PVOID
  24 RamDiskGetDataAtOffset(IN PVOID Offset)
  25 {
  26     //
  27     // Return data from our RAM Disk
  28     //
  29     ASSERT(((ULONG_PTR)gRamDiskBase + (ULONG_PTR)Offset) <
  30            ((ULONG_PTR)gRamDiskBase + (ULONG_PTR)gRamDiskSize));
  31     return (PVOID)((ULONG_PTR)gRamDiskBase + (ULONG_PTR)(Offset));
  32 }
  33
  34 ULONG
  35 RamDiskGetCacheableBlockCount(IN ULONG Reserved)
  36 {
  37     //
  38     // Allow 32KB transfers (64 sectors), emulating BIOS LBA
  39     //
  40     ASSERT(Reserved == 0x49);
  41     return 64;
  42 }
  43
  44 BOOLEAN
  45 RamDiskGetDriveGeometry(IN ULONG Reserved,
  46                         OUT PGEOMETRY Geometry)
  47 {
  48     //
  49     // Should never be called when the caller expects valid Geometry!
  50     //
  51     ASSERT(Reserved == 0x49);
  52     return TRUE;
  53 }
  54
  55 BOOLEAN
  56 RamDiskReadLogicalSectors(IN ULONG Reserved,
  57                           IN ULONGLONG SectorNumber,
  58                           IN ULONG SectorCount,
  59                           IN PVOID Buffer)
  60 {
  61     PVOID StartAddress;
  62     ULONG Length;
  63     ASSERT(Reserved == 0x49);
  64
  65     //
  66     // Get actual pointers and lengths
  67     //
  68     StartAddress = (PVOID)((ULONG_PTR)SectorNumber * 512);
  69     Length = SectorCount * 512;
  70
  71     //
  72     // Don't allow reads past our image
  73     //
  74     if (((ULONG_PTR)StartAddress + Length) > gRamDiskSize) return FALSE;
  75
  76     //
  77     // Do the read
  78     //
  79     RtlCopyMemory(Buffer, RamDiskGetDataAtOffset(StartAddress), Length);
  80     return TRUE;
  81 }
  82
  83 VOID
  84 NTAPI
  85 RamDiskLoadVirtualFile(IN PCHAR FileName)
  86 {
  87     PFILE RamFile;
  88     ULONG TotalRead, ChunkSize;
  89         PCHAR MsgBuffer = "Loading ramdisk...";
  90     ULONG PercentPerChunk, Percent;
  91
  92     //
  93     // Display progress
  94     //
  95     UiDrawProgressBarCenter(1, 100, MsgBuffer);
  96
  97     //
  98     // Try opening the ramdisk file (this assumes the boot volume was opened)
  99     //
 100     RamFile = FsOpenFile(FileName);
 101     if (RamFile)
 102     {
 103         //
 104         // Get the file size
 105         //
 106         gRamDiskSize = FsGetFileSize(RamFile);
 107         if (!gRamDiskSize) return;
 108
 109         //
 110         // Allocate memory for it
 111         //
 112         ChunkSize = 8 * 1024 * 1024;
 113         Percent = PercentPerChunk = 100 / (gRamDiskSize / ChunkSize);
 114         gRamDiskBase = MmAllocateMemory(gRamDiskSize);
 115         if (!gRamDiskBase) return;
 116
 117         //
 118         // Read it in chunks
 119         //
 120         for (TotalRead = 0; TotalRead < gRamDiskSize; TotalRead += ChunkSize)
 121         {
 122             //
 123             // Check if we're at the last chunk
 124             //
 125             if ((gRamDiskSize - TotalRead) < ChunkSize)
 126             {
 127                 //
 128                 // Only need the actual data required
 129                 //
 130                 ChunkSize = gRamDiskSize - TotalRead;
 131             }
 132
 133             //
 134             // Draw progress
 135             //
 136             UiDrawProgressBarCenter(Percent, 100, MsgBuffer);
 137             Percent += PercentPerChunk;
 138
 139             //
 140             // Copy the contents
 141             //
 142
 143             if (!FsReadFile(RamFile,
 144                             ChunkSize,
 145                             NULL,
 146                             (PVOID)((ULONG_PTR)gRamDiskBase + TotalRead)))
 147             {
 148                 //
 149                 // Fail
 150                 //
 151                 UiMessageBox("Failed to read ramdisk\n");
 152             }
 153         }
 154     }
 155 }
 156
 157 VOID
 158 NTAPI
 159 RamDiskSwitchFromBios(VOID)
 160 {
 161     extern ULONG BootDrive, BootPartition;
 162
 163     //
 164     // Check if we have a ramdisk, in which case we need to switch routines
 165     //
 166     if (gRamDiskBase)
 167     {
 168         //
 169         // Don't use the BIOS for reads anymore
 170         //
 171         MachVtbl.DiskReadLogicalSectors = RamDiskReadLogicalSectors;
 172         MachVtbl.DiskGetDriveGeometry = RamDiskGetDriveGeometry;
 173         MachVtbl.DiskGetCacheableBlockCount = RamDiskGetCacheableBlockCount;
 174
 175         //
 176         // Switch to ramdisk boot partition
 177         //
 178         BootDrive = 0x49;
 179         BootPartition = 0;
 180     }
 181 }