internal static void Initialize(MultibootHeader* pMultibootHeader)
{
int memoryMapCount = (int)(pMultibootHeader->MemoryMapsSize / sizeof(MultibootMemoryMap));
ulong lastMemoryMapAddress = pMultibootHeader->MemoryMaps[memoryMapCount - 1].AddressLower | ((ulong)pMultibootHeader->MemoryMaps[memoryMapCount - 1].AddressUpper << 32);
ulong lastMemoryMapLength = pMultibootHeader->MemoryMaps[memoryMapCount - 1].LengthLower | ((ulong)pMultibootHeader->MemoryMaps[memoryMapCount - 1].LengthUpper << 32);
ulong totalMemory = lastMemoryMapAddress + lastMemoryMapLength;
if (totalMemory < MinimumTotalMemory) Panic();
ulong totalMemoryHighestBit = 0;
int totalMemoryHighestBitShiftOff = 0;
for (int bit = 63; bit >= 0; --bit)
{
++totalMemoryHighestBitShiftOff;
if ((totalMemory & ((ulong)1 << bit)) != 0)
{
totalMemoryHighestBit = (ulong)1 << bit;
break;
}
}
if ((totalMemory << totalMemoryHighestBitShiftOff) != 0) totalMemoryHighestBit <<= 1;
int shiftsForTotalMemory = 64 - totalMemoryHighestBitShiftOff;
TreeLevels = (byte)((shiftsForTotalMemory - ShiftsForMinimumPageSize) + 1);
ulong bytesRequiredForTree = ((ulong)1 << TreeLevels) >> 3;
ulong treeStartAddress = pMultibootHeader->Modules[pMultibootHeader->ModulesCount - 1].End;
if ((treeStartAddress & 0x03) != 0) treeStartAddress += 4 - (treeStartAddress & 0x03);
Tree = (uint*)treeStartAddress;
ulong treeElementCount = bytesRequiredForTree >> 2;
for (ulong index = 0; index < treeElementCount; ++index) Tree[index] = 0;
SetBitsInTree((byte)(TreeLevels - 1), 0, (treeStartAddress + (treeElementCount << 2)) >> ShiftsForMinimumPageSize, true);
MultibootMemoryMap* memoryMap = null;
ulong memoryMapAddress = 0;
ulong memoryMapLength = 0;
for (int memoryMapIndex = 0; memoryMapIndex < memoryMapCount; ++memoryMapIndex)
{
memoryMap = &pMultibootHeader->MemoryMaps[memoryMapIndex];
if (memoryMap->Type != 1)
{
memoryMapAddress = memoryMap->AddressLower | ((ulong)memoryMap->AddressUpper << 32);
memoryMapLength = memoryMap->LengthLower | ((ulong)memoryMap->LengthUpper << 32);
SetBitsInTree((byte)(TreeLevels - 1), memoryMapAddress >> ShiftsForMinimumPageSize, memoryMapLength >> ShiftsForMinimumPageSize, true);
}
}
ulong lengthOfOutOfBoundsMemory = totalMemoryHighestBit - totalMemory;
if (lengthOfOutOfBoundsMemory > 0) SetBitsInTree((byte)(TreeLevels - 1), totalMemory >> ShiftsForMinimumPageSize, lengthOfOutOfBoundsMemory >> ShiftsForMinimumPageSize, true);
}
internal static void Initialize(uint pMultibootMagic, MultibootHeader* pMultibootHeader)
{
//sUsableMemory = usableMemory;
}