/// <summary>
/// Returns a pointer size of largest continuous block of free ram
/// DOES NOT ALLOCATE ANYTHING so it can be used before Memory Management is initalised
/// </summary>
/// <returns>The size of the largest block in bytes</returns>
public static unsafe RawMemoryMapBlock *GetLargestMemoryBlock()
{
if (!Multiboot2.MemoryMapExists())
{
return(null);
}
var baseMap = (RawMemoryMapBlock *)((uint *)Multiboot2.MemoryMap + (uint)16);
var currentMap = baseMap;
uint totalSize = Multiboot2.MemoryMap->Size - 16;
uint entrySize = Multiboot2.MemoryMap->EntrySize;
RawMemoryMapBlock *BestMap = null;
int counter = 0;
ulong bestSize = 0;
while ((uint)currentMap < ((uint)baseMap + totalSize) && counter < 64)
{
currentMap = (RawMemoryMapBlock *)((uint)currentMap + entrySize);
if (currentMap->Type == 1)
{
if (currentMap->Length > bestSize)
{
BestMap = currentMap;
bestSize = currentMap->Length;
}
}
}
return(BestMap);
}
/// Get the Memory Map Information from Multiboot
/// </summary>
/// <returns>Returns an array of MemoryMaps containing the Multiboot Memory Map information. The array may have empty values at the end.</returns>
public static unsafe MemoryMapBlock[] GetMemoryMap()
{
if (!Multiboot2.MemoryMapExists())
{
throw new Exception("No Memory Map was returned by Multiboot");
}
var rawMap = new RawMemoryMapBlock[64];
var baseMap = (RawMemoryMapBlock *)((uint *)Multiboot2.MemoryMap + (uint)16);
var currentMap = baseMap;
uint totalSize = Multiboot2.MemoryMap->Size - 16;
uint entrySize = Multiboot2.MemoryMap->EntrySize;
int counter = 0;
while ((uint)currentMap < ((uint)baseMap + totalSize) && counter < 64)
{
rawMap[counter++] = *currentMap;
currentMap = (RawMemoryMapBlock *)((uint)currentMap + entrySize);
}
if (counter >= 64)
{
throw new Exception("Memory Map returned too many segments");
}
var entireMap = new MemoryMapBlock[counter];
for (int i = 0; i < counter; i++)
{
var rawMemoryMap = rawMap[i];
entireMap[i] = new MemoryMapBlock
{
Address = rawMemoryMap.Address,
Length = rawMemoryMap.Length,
Type = rawMemoryMap.Type
};
}
return(entireMap);
}