Rewrote the memory allocation functions.

free(3) can now unify unused neighbor blocks, reducing mem usage.

libmaxsi/Makefile

@@ -48,7 +48,7 @@ c/h/sys/wait.h \
 c/h/stdio.h \
 c/h/signal.h \
 
-COMMONOBJS=c++.o memory.o string.o error.o format.o
+COMMONOBJS=c++.o memory.o heap.o string.o error.o format.o
 SORTIXOBJS:=$(addprefix sortix/,$(COMMONOBJS))
 LIBMAXSIOBJS:=$(COMMONOBJS) \
 sortix-keyboard.o \

libmaxsi/heap.cpp

@@ -0,0 +1,595 @@
+/******************************************************************************
+
+	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
+
+	This file is part of LibMaxsi.
+
+	LibMaxsi is free software: you can redistribute it and/or modify it under
+	the terms of the GNU Lesser General Public License as published by the Free
+	Software Foundation, either version 3 of the License, or (at your option)
+	any later version.
+
+	LibMaxsi is distributed in the hope that it will be useful, but WITHOUT ANY
+	WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+	FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
+	more details.
+
+	You should have received a copy of the GNU Lesser General Public License
+	along with LibMaxsi. If not, see <http://www.gnu.org/licenses/>.
+
+	heap.cpp
+	Functions that allocate/free memory from a dynamic memory heap.
+
+******************************************************************************/
+
+#include "platform.h"
+#include "memory.h"
+#include "error.h"
+
+#ifdef SORTIX_KERNEL
+#define HEAP_GROWS_DOWNWARDS
+#endif
+
+#define PARANOIA 0
+
+#ifdef SORTIX_KERNEL
+#include <sortix/platform.h>
+#include <sortix/log.h> // DEBUG
+#include <sortix/memorymanagement.h>
+#include <sortix/panic.h>
+#endif
+
+namespace Maxsi
+{
+	namespace Memory
+	{
+		//
+		// This first section is just magic compiler/platform stuff, you should
+		// skip ahead to the actual algorithm.
+		//
+
+#ifdef PLATFORM_X64
+		const size_t MAGIC = 0xDEADDEADDEADDEADUL;
+		const size_t ALIGNMENT = 16UL;
+#else
+		const size_t MAGIC = 0xDEADDEADUL;
+		const size_t ALIGNMENT = 8UL;
+#endif
+
+		const size_t PAGESIZE = 4UL * 1024UL; // 4 KiB
+		const size_t NUMBINS = 8UL * sizeof(size_t);
+
+		addr_t GetHeapStart()
+		{
+			#ifdef SORTIX_KERNEL
+				return Sortix::Memory::HEAPUPPER;
+			#endif
+			return 0; // TODO: Not implemented in User-Space yet!
+		}
+
+		size_t GetHeapMaxSize()
+		{
+			#ifdef SORTIX_KERNEL
+				return Sortix::Memory::HEAPUPPER - Sortix::Memory::HEAPLOWER;
+			#endif
+			return 0; // TODO: Not implemented in User-Space yet!
+		}
+
+#ifdef SORTIX_KERNEL
+		void FreeMemory(addr_t where, size_t bytes)
+		{
+			ASSERT( (bytes & (PAGESIZE-1UL)) == 0 );
+
+			while ( bytes )
+			{
+				addr_t page = Sortix::Memory::UnmapKernel(where);
+				Sortix::Page::Put(page);
+
+				bytes -= PAGESIZE;
+				where += PAGESIZE;
+			}
+		}
+
+		bool AllocateMemory(addr_t where, size_t bytes)
+		{
+			ASSERT( (bytes & (PAGESIZE-1UL)) == 0 );
+
+			addr_t pos = where;
+
+			while ( bytes )
+			{
+				addr_t page = Sortix::Page::Get();
+				if ( !page )
+				{
+					FreeMemory(where, pos-where);
+					return false;
+				}
+
+				if ( !Sortix::Memory::MapKernel(page, pos) )
+				{
+					Sortix::Page::Put(page);
+					FreeMemory(where, pos-where);
+					return false;
+				}
+
+				bytes -= PAGESIZE;
+				pos += PAGESIZE;
+			}
+
+			return true;
+		}
+#else
+		void FreeMemory(addr_t where, size_t bytes)
+		{
+		}
+
+		bool AllocateMemory(addr_t where, size_t bytes)
+		{
+			Error::Set(ENOMEM);
+			return false;
+		}
+#endif
+
+		// TODO: BitScanForward and BitScanReverse are x86 instructions, but
+		// directly using them messes with the optimizer. Once possible, use
+		// the inline assembly instead of the C-version of the functions.
+
+		// Returns the index of the most significant set bit.
+		inline size_t BSR(size_t Value)
+		{
+#if 1
+			ASSERT(Value > 0);
+			for ( size_t I = 8*sizeof(size_t); I > 0; I-- )
+			{
+				if ( Value & ( 1 << (I-1) ) ) { return I-1; }
+			}
+			return 0;
+#else
+			size_t Result;
+			asm("bsr %0, %1" : "=r"(Result) : "r"(Value));
+			return Result;
+#endif
+		}
+
+		// Returns the index of the least significant set bit.
+		inline size_t BSF(size_t Value)
+		{
+#if 1
+			ASSERT(Value > 0);
+			for ( size_t I = 0; I < 8*sizeof(size_t); I++ )
+			{
+				if ( Value & ( 1 << I ) ) { return I; }
+			}
+			return 0;
+#else
+			size_t Result;
+			asm("bsf %0, %1" : "=r"(Result) : "r"(Value));
+			return Result;
+#endif
+		}
+
+		//
+		// This is where the actual memory allocation algorithm starts.
+		//
+
+		struct Chunk;
+		struct Trailer;
+
+		// The location where the heap originally grows from.
+		addr_t heapstart;
+
+		// If heap grows down: Location of the first mapped page.
+		// If heap grows up: Location of the first not-mapped page.
+		addr_t wilderness;
+
+		// How many bytes remain in the wilderness.
+		size_t wildernesssize;
+
+		// How many bytes are the heap allow to grow to (including wilderness).
+		size_t heapmaxsize;
+
+		// How many bytes are currently used for chunks in the heap, which
+		// excludes the wilderness.
+		size_t heapsize;
+
+		// bins[N] contain a linked list of chunks that are at least 2^(N+1)
+		// bytes, but less than 2^(N+2) bytes. By selecting the proper bin in
+		// constant time, we can allocate chunks in constant time.
+		Chunk* bins[NUMBINS];
+
+		// Bit N is set if bin[N] contains a chunk.
+		size_t bincontainschunks;
+
+		// A preamble to every chunk providing meta-information.
+		struct Chunk
+		{
+		public:
+			size_t size;
+			union
+			{
+				size_t magic;
+				Chunk* nextunused;
+			};
+
+		public:
+			bool IsUsed() { return magic == MAGIC; }
+			Trailer* GetTrailer();
+			Chunk* LeftNeighbor();
+			Chunk* RightNeighbor();
+			bool IsSane();
+
+		};
+
+		// A trailer ro every chunk providing meta-information.
+		struct Trailer
+		{
+		public:
+			union
+			{
+				size_t magic;
+				Chunk* prevunused;
+			};
+			size_t size;
+
+		public:
+			bool IsUsed() { return magic == MAGIC; }
+			Chunk* GetChunk();
+
+		};
+
+		// This is how a real chunk actually looks:
+		//struct RealChunk
+		//{
+		//	Chunk header;
+		//	byte data[...];
+		//	Trailer footer;
+		// };
+
+		Trailer* Chunk::GetTrailer()
+		{
+			return (Trailer*) (((addr_t) this) + size - sizeof(Trailer));
+		}
+
+		Chunk* Chunk::LeftNeighbor()
+		{
+			Trailer* trailer = (Trailer*) (((addr_t) this) - sizeof(Trailer));
+			return trailer->GetChunk();
+		}
+
+		Chunk* Chunk::RightNeighbor()
+		{
+			return (Chunk*) (((addr_t) this) + size);
+		}
+
+		Chunk* Trailer::GetChunk()
+		{
+			return (Chunk*) (((addr_t) this) + sizeof(Trailer) - size);
+		}
+
+		bool Chunk::IsSane()
+		{
+			size_t binindex = BSR(size);
+			Trailer* trailer = GetTrailer();
+			if ( trailer->size != size ) { return false; }
+			if ( IsUsed() )
+			{
+				if ( bins[binindex] == this ) { return false; }
+				if ( magic != MAGIC || trailer->magic != magic ) { return false; }
+			}
+			if ( !IsUsed() )
+			{
+				if ( ((addr_t) nextunused) & (ALIGNMENT-1UL) ) { return false; }
+				if ( ((addr_t) trailer->prevunused) & (ALIGNMENT-1UL) ) { return false; }
+				if ( nextunused && nextunused->GetTrailer()->prevunused != this ) { return false; }
+
+				if ( trailer->prevunused )
+				{
+					if ( bins[binindex] == this ) { return false; }
+					if ( trailer->prevunused->nextunused != this ) { return false; }
+				}
+				if ( !trailer->prevunused )
+				{
+					if ( bins[binindex] != this ) { return false; }
+					if ( !(bincontainschunks & (1UL << binindex)) ) { return false; }
+				}
+			}
+			return true;
+		}
+
+		void InsertChunk(Chunk* chunk)
+		{
+			// Insert the chunk into the right bin.
+			size_t binindex = BSR(chunk->size);
+			chunk->GetTrailer()->prevunused = NULL;
+			chunk->nextunused = bins[binindex];
+			if ( chunk->nextunused )
+			{
+				ASSERT(chunk->nextunused->IsSane());
+				chunk->nextunused->GetTrailer()->prevunused = chunk;
+			}
+			bins[binindex] = chunk;
+			bincontainschunks |= (1UL << binindex);
+			ASSERT(chunk->IsSane());
+		}
+
+		bool ValidateHeap()
+		{
+			#ifdef HEAP_GROWS_DOWNWARDS
+			Chunk* chunk = (Chunk*) (wilderness + wildernesssize);
+			while ( (addr_t) chunk < heapstart )
+			#else
+			Chunk* chunk = (Chunk*) heapstart;
+			while ( (addr_t) chunk < wilderness - wildernesssize )
+			#endif
+			{
+				if ( !chunk->IsSane() ) { return false; }
+				chunk = chunk->RightNeighbor();
+			}
+
+			return true;
+		}
+
+		void Init()
+		{
+			heapstart = GetHeapStart();
+			heapmaxsize = GetHeapMaxSize();
+			heapsize = 0;
+			wilderness = heapstart;
+			wildernesssize = 0;
+			for ( size_t i = 0; i < NUMBINS; i++ ) { bins[i] = NULL; }
+			bincontainschunks = 0;
+		}
+
+		// Attempts to expand the wilderness such that it contains at least
+		// bytesneeded bytes. This is done by mapping new pages onto into the
+		// virtual address-space.
+		bool ExpandWilderness(size_t bytesneeded)
+		{
+			if ( bytesneeded <= wildernesssize ) { return true; }
+
+			bytesneeded -= wildernesssize;
+
+			// Align the increase on page boundaries.
+			const size_t PAGEMASK = ~(PAGESIZE - 1UL);
+			bytesneeded = ( bytesneeded + PAGESIZE - 1UL ) & PAGEMASK;
+
+			ASSERT(bytesneeded >= PAGESIZE);
+
+			// TODO: Overflow MAY happen here!
+			if ( heapmaxsize <= heapsize + wildernesssize + bytesneeded )
+			{
+				Error::Set(ENOMEM);
+				return true;
+			}
+
+			#ifdef HEAP_GROWS_DOWNWARDS
+			addr_t newwilderness = wilderness - bytesneeded;
+			#else
+			addr_t newwilderness = wilderness + bytesneeded;
+			#endif
+
+			// Attempt to map pages so our wilderness grows.
+			if ( !AllocateMemory(newwilderness, bytesneeded) ) { return false; }
+
+			wildernesssize += bytesneeded;
+			wilderness = newwilderness;
+
+			return true;
+		}
+
+		DUAL_FUNCTION(void*, malloc, Allocate, (size_t size))
+		{
+			#if 0 < PARANOIA
+			ASSERT(ValidateHeap());
+			#endif
+
+			const size_t OVERHEAD = sizeof(Chunk) + sizeof(Trailer);
+			size += OVERHEAD;
+
+			// Round up to nearest alignment.
+			size = (size + ALIGNMENT - 1UL) & (~(ALIGNMENT-1UL));
+
+			// Find the index of the smallest usable bin.
+			size_t minbinindex = BSR(size-1UL)+1UL;
+
+			// Make a bitmask that filter away all bins that are too small.
+			size_t minbinmask = ~((1UL << minbinindex) - 1UL);
+
+			// Figure out which bins are usable for our chunk.
+			size_t availablebins = bincontainschunks & minbinmask;
+
+			if ( availablebins )
+			{
+				// Find the smallest available bin.
+				size_t binindex = BSF(availablebins);
+
+				Chunk* chunk = bins[binindex];
+				ASSERT(chunk->IsSane());
+				bins[binindex] = chunk->nextunused;
+
+				size_t binsize = 1UL << binindex;
+
+				// Mark the bin as empty if we emptied it.
+				if ( !bins[binindex] )
+				{
+					bincontainschunks ^= binsize;
+				}
+				else
+				{
+					Trailer* trailer = bins[binindex]->GetTrailer();
+					trailer->prevunused = NULL;
+				}
+
+				ASSERT(!bins[binindex] || bins[binindex]->IsSane());
+
+				// If we don't use the entire chunk.
+				if ( OVERHEAD <= binsize - size )
+				{
+					size_t left = binsize - size;
+					chunk->size -= left;
+					chunk->GetTrailer()->size = chunk->size;
+
+					size_t leftbinindex = BSR(left);
+					Chunk* leftchunk = chunk->RightNeighbor();
+					leftchunk->size = left;
+					Trailer* lefttrailer = leftchunk->GetTrailer();
+					lefttrailer->size = left;
+
+					InsertChunk(leftchunk);
+				}
+
+				chunk->magic = MAGIC;
+				chunk->GetTrailer()->magic = MAGIC;
+
+				#if 0 < PARANOIA
+				ASSERT(ValidateHeap());
+				#endif
+
+				addr_t result = ((addr_t) chunk) + sizeof(Chunk);
+				return (void*) result;
+			}
+
+			// If no bins are available, try to allocate from the wilderness.
+
+			// Check if the wilderness can meet our requirements.
+			if ( wildernesssize < size && !ExpandWilderness(size) )
+			{
+				Error::Set(ENOMEM);
+				return NULL;
+			}
+
+			// Carve a new chunk out of the wilderness and initialize it.
+			#ifdef HEAP_GROWS_DOWNWARDS
+			Chunk* chunk = (Chunk*) (wilderness + wildernesssize - size);
+			#else
+			Chunk* chunk = (Chunk*) (wilderness - wildernesssize);
+			#endif
+			wildernesssize -= size;
+			heapsize += size;
+			chunk->size = size;
+			Trailer* trailer = chunk->GetTrailer();
+			trailer->size = size;
+			chunk->magic = MAGIC;
+			trailer->magic = MAGIC;
+
+			#if 0 < PARANOIA
+			ASSERT(ValidateHeap());
+			#endif
+
+			addr_t result = ((addr_t) chunk) + sizeof(Chunk);
+			return (void*) result;
+		}
+
+		bool IsLeftmostChunk(Chunk* chunk)
+		{
+			#ifdef HEAP_GROWS_DOWNWARDS
+			return (addr_t) chunk <= wilderness + wildernesssize;
+			#else
+			return heapstart <= (addr_t) chunk;
+			#endif
+		}
+
+		bool IsRightmostChunk(Chunk* chunk)
+		{
+			#ifdef HEAP_GROWS_DOWNWARDS
+			return heapstart <= (addr_t) chunk + chunk->size;
+			#else
+			return (addr_t) chunk + chunk->size <= heapstart + heapsize;
+			#endif
+		}
+
+		// Removes a chunk from its bin.
+		void UnlinkChunk(Chunk* chunk)
+		{
+			ASSERT(chunk->IsSane());
+			Trailer* trailer = chunk->GetTrailer();
+			if ( trailer->prevunused )
+			{
+				ASSERT(trailer->prevunused->IsSane());
+				trailer->prevunused->nextunused = chunk->nextunused;
+				if ( chunk->nextunused )
+				{
+					ASSERT(chunk->nextunused->IsSane());
+					chunk->nextunused->GetTrailer()->prevunused = trailer->prevunused;
+				}
+			}
+			else
+			{
+				if ( chunk->nextunused )
+				{
+					ASSERT(chunk->nextunused->IsSane());
+					chunk->nextunused->GetTrailer()->prevunused = NULL;
+				}
+				size_t binindex = BSR(chunk->size);
+				ASSERT(bins[binindex] == chunk);
+				bins[binindex] = chunk->nextunused;
+				if ( !bins[binindex] ) { bincontainschunks ^= 1UL << binindex; }
+				else { ASSERT(bins[binindex]->IsSane()); }
+			}
+		}
+
+		// Transforms a chunk and its neighbors into a single chunk if possible.
+		void UnifyNeighbors(Chunk** chunk)
+		{
+			if ( !IsLeftmostChunk(*chunk) )
+			{
+				Chunk* neighbor = (*chunk)->LeftNeighbor();
+				if ( !neighbor->IsUsed() )
+				{
+					size_t size = neighbor->size;
+					size_t chunksize = (*chunk)->size;
+					UnlinkChunk(neighbor);
+					*chunk = neighbor;
+					(*chunk)->size = size + chunksize;
+					(*chunk)->GetTrailer()->size = (*chunk)->size;
+				}
+			}
+
+			if ( !IsRightmostChunk(*chunk) )
+			{
+				Chunk* neighbor = (*chunk)->RightNeighbor();
+				if ( !neighbor->IsUsed() )
+				{
+					UnlinkChunk(neighbor);
+					(*chunk)->size += neighbor->size;
+					(*chunk)->GetTrailer()->size = (*chunk)->size;
+				}
+			}
+		}
+
+		DUAL_FUNCTION(void, free, Free, (void* addr))
+		{
+			#if 0 < PARANOIA
+			ASSERT(ValidateHeap());
+			#endif
+
+			if ( !addr) { return; }
+
+			Chunk* chunk = (Chunk*) ((addr_t) addr - sizeof(Chunk));
+			ASSERT(chunk->IsUsed());
+			ASSERT(chunk->IsSane());
+
+			UnifyNeighbors(&chunk);
+
+			#ifdef HEAP_GROWS_DOWNWARDS
+			bool nexttowilderness = IsLeftmostChunk(chunk);
+			#else
+			bool nexttowilderness = IsRightmostChunk(chunk);
+			#endif
+
+			// If possible, let the wilderness regain the memory.
+			if ( nexttowilderness )
+			{
+				heapsize -= chunk->size;
+				wildernesssize += chunk->size;
+				return;
+			}
+
+			InsertChunk(chunk);
+
+			#if 0 < PARANOIA
+			ASSERT(ValidateHeap());
+			#endif
+		}
+	}
+}

libmaxsi/memory.cpp

@@ -18,63 +18,19 @@
 	along with LibMaxsi. If not, see <http://www.gnu.org/licenses/>.
 
 	memory.cpp
-	Useful functions for manipulating memory, as well as the implementation
+	Useful functions for manipulating and handling memory.
-	of the heap.
 
 ******************************************************************************/
 
 #include "platform.h"
 #include "memory.h"
 #include "error.h"
-#include "io.h" // DEBUG
+#ifndef SORTIX_KERNEL
-
-#ifdef SORTIX_KERNEL
-#include <sortix/platform.h>
-#include <sortix/log.h> // DEBUG
-
-#include <sortix/memorymanagement.h>
-#include <sortix/panic.h>
-
-#else // !SORTIX_KERNEL
-
 #include "syscall.h"
-
 #endif
 
-#define IsGoodChunkPosition(Chunk) ((uintptr_t) Wilderness + WildernessSize <= (uintptr_t) (Chunk) && (uintptr_t) (Chunk) <= (uintptr_t) HeapStart)
-#define IsGoodChunkInfo(Chunk) ( ( (UnusedChunkFooter*) (((byte*) (Chunk)) + (Chunk)->Size - sizeof(UnusedChunkFooter)) )->Size == (Chunk)->Size )
-#define IsGoodChunk(Chunk) (IsGoodChunkPosition(Chunk) && (Chunk)->Size >= 16 && IsGoodChunkPosition((uintptr_t) (Chunk) + (Chunk)->Size) && IsGoodChunkInfo(Chunk) )
-#define IsGoodUnusedChunk(Chunk) (  IsGoodChunk(Chunk)  &&  ( Chunk->NextUnused == NULL || IsGoodChunkPosition(Chunk->NextUnused) )  )
-#define IsGoodUsedChunk(Chunk) ( IsGoodChunk(Chunk) && Chunk->Magic == Magic )
-#ifdef PLATFORM_X64
-#define IsGoodBinIndex(Index) ( 3 <= Index && Index < 32 )
-#else
-#define IsGoodBinIndex(Index) ( 4 <= Index && Index < 64 )
-#endif
-#define IsAligned(Value, Alignment) ( (Value & (Alignment-1)) == 0 )
-
-#define BITS(x) (8UL*sizeof(x))
-
 namespace Maxsi
 {
-	// TODO: How should this API exist? Should it be publicly accessasble?
-	// Where should the C bindings (if relevant) be declared and defined?
-	// Is it part of the kernel or the standard library? What should it be
-	// called? Is it an extension? For now, I'll just leave this here, hidden
-	// away in libmaxsi until I figure out how libmaxsi/sortix should handle
-	// facilities currently only available on Sortix.
-	namespace System
-	{
-		namespace Memory
-		{
-			bool Allocate(void* /*position*/, size_t /*length*/)
-			{
-				// TODO: Implement a syscall for this!
-				return true;
-			}
-		}
-	}
-
 	namespace Memory
 	{
 #ifndef SORTIX_KERNEL
@@ -86,373 +42,6 @@ namespace Maxsi
 		}
 #endif
 
-		// This magic word is useful to see if the program has written into the
-		// chunk's header or footer, which means the program has malfunctioned
-		// and ought to be terminated.
-#ifdef PLATFORM_X64
-		const size_t Magic = 0xDEADDEADDEADDEADULL;
-#else
-		const size_t Magic = 0xDEADDEAD;
-#endif
-	
-		// All requsted sizes must be a multiple of this.
-		const size_t Alignment = 16ULL;
-
-		// Returns the index of the most significant set bit.
-		inline size_t BSR(size_t Value)
-		{
-#if 1
-			ASSERT(Value > 0);
-			for ( size_t I = 8*sizeof(size_t); I > 0; I-- )
-			{
-				if ( Value & ( 1 << (I-1) ) ) { return I-1; }
-			}
-			return 0;
-#else
-			size_t Result;
-			asm("bsr %0, %1" : "=r"(Result) : "r"(Value));
-			return Result;
-#endif
-		}
-
-		// Returns the index of the least significant set bit.
-		inline size_t BSF(size_t Value)
-		{
-#if 1
-			ASSERT(Value > 0);
-			for ( size_t I = 0; I < 8*sizeof(size_t); I++ )
-			{
-				if ( Value & ( 1 << I ) ) { return I; }
-			}
-			return 0;
-#else
-			size_t Result;
-			asm("bsf %0, %1" : "=r"(Result) : "r"(Value));
-			return Result;
-#endif
-		}
-		// NOTE: BSR(N) = Log2RoundedDown(N).
-
-		// NOTE: BSR(N-1)+1 = Log2RoundedUp(N), N > 1.
-		// PROOF: If X=2^N is a power of two, then BSR(X) = Log2(X) = N.
-		// If X is not a power of two, then BSR(X) will return the previous
-		// power of two.
-		// If we want the next power of two for a non-power-of-two then
-		// BSR(X)+1 would work. However, this causes problems for X=2^N, where
-		// it returns a value one too big.
-		// BSR(X-1)+1 = BSR(X)+1 give the same value for all X that is not a
-		// power of two. For X=2^N, BSR(X-1)+1 will be one lower, which is
-		// exactly what we want. QED.
-
-		// Now declare some structures that are put around the allocated data.
-		struct UnusedChunkHeader
-		{
-			size_t Size;
-			UnusedChunkHeader* NextUnused;
-		};
-
-		struct UnusedChunkFooter
-		{
-			void* Unused;
-			size_t Size;
-		};
-
-		struct UsedChunkHeader
-		{
-			size_t Size;
-			size_t Magic;
-		};
-
-		struct UsedChunkFooter
-		{
-			size_t Magic;
-			size_t Size;
-		};
-		
-		// How much extra space will our headers use?
-		const size_t ChunkOverhead = sizeof(UsedChunkHeader) + sizeof(UsedChunkFooter);
-		size_t GetChunkOverhead() { return ChunkOverhead; }
-
-		// A bin for each power of two.
-		UnusedChunkHeader* Bins[BITS(size_t)];
-
-		// INVARIANT: A bit is set for each bin if it contains anything.
-		size_t BinContainsChunks;
-
-		// And south of everything, there is nothing allocated, at which
-		// extra space can be added on-demand.
-		// INVARIANT: Wilderness is always page-aligned!
-		const byte* HeapStart;
-		const byte* Wilderness;
-		size_t WildernessSize;
-
-		// Initializes the heap system.
-		void Init()
-		{
-			Memory::Set(Bins, 0, sizeof(Bins));
-#ifdef SORTIX_KERNEL			 
-			Wilderness = (byte*) Sortix::Memory::HEAPUPPER;
-#else
-			// TODO: This is very 32-bit specific!
-			Wilderness = (byte*) 0x80000000UL;
-#endif
-			HeapStart = Wilderness;
-			WildernessSize = 0;
-			BinContainsChunks = 0;
-		}
-
-		// Expands the wilderness block (the heap grows downwards).
-		bool ExpandWilderness(size_t NeededSize)
-		{
-			if ( NeededSize <= WildernessSize ) { return true; }
-
-			ASSERT(Wilderness != NULL);
-
-			// Check if we are going too far down (beneath the NULL position!).
-			if ( (uintptr_t) Wilderness < NeededSize ) { return false; }
-
-#ifdef SORTIX_KERNEL
-			// Check if the wilderness would grow larger than the kernel memory area.
-			if ( ( ((uintptr_t) Wilderness) - Sortix::Memory::HEAPLOWER ) < NeededSize ) { return false; }
-#endif
-
-			// Figure out how where the new wilderness will be.
-			uintptr_t NewWilderness = ((uintptr_t) Wilderness) + WildernessSize - NeededSize;
-
-			// And now align downwards to the page boundary.
-			NewWilderness &= ~(0xFFFUL);
-
-			ASSERT(NewWilderness < (uintptr_t) Wilderness);
-
-			// Figure out where and how much memory we need.
-			byte* MemoryStart = (byte*) NewWilderness;
-			size_t MemorySize = (uintptr_t) Wilderness - (uintptr_t) NewWilderness;
-
-#ifndef SORTIX_KERNEL // We are user-space.
-
-			// Ask the kernel to map memory to the needed region!
-			if ( !System::Memory::Allocate(MemoryStart, MemorySize) ) { return false; }
-
-#else // We are Sortix.
-
-			// Figure out how many pages we need.
-			size_t NumPages = MemorySize / 4096;
-			size_t PagesLeft = NumPages;
-
-			ASSERT(NumPages > 0);
-
-			// Attempt to allocate and map each of them.
-			while ( PagesLeft > 0 )
-			{
-				PagesLeft--;
-
-				// Get a raw unused physical page.
-				addr_t Page = Sortix::Page::Get();
-
-				// Map the physical page to a virtual one.
-				addr_t VirtualAddr = NewWilderness + 4096 * PagesLeft;
-
-				if ( Page == 0 || !Sortix::Memory::MapKernel(Page, VirtualAddr) )
-				{
-					if ( Page != 0 ) { Sortix::Page::Put(Page); }
-
-					// If none is available, simply let the allocation fail
-					// and unallocate everything we did allocate so far.
-					while ( PagesLeft < NumPages )
-					{
-						PagesLeft++;
-
-						addr_t OldVirtual = NewWilderness + 4096 * PagesLeft;
-						addr_t OldPage = Sortix::Memory::UnmapKernel(OldVirtual);
-						Sortix::Page::Put(OldPage);
-					}
-					return false;
-				}
-			}
-#endif
-
-			// Update the wilderness information now that it is safe.
-			Wilderness = MemoryStart;
-			WildernessSize += MemorySize;
-
-			ASSERT(WildernessSize >= NeededSize);
-
-			return true;
-		}
-
-		// Allocates a continious memory region of Size bytes that must be deallocated using Free.
-		DUAL_FUNCTION(void*, malloc, Allocate, (size_t Size))
-		{
-			// Always allocate a multiple of alignment (round up to nearest aligned size).
-			// INVARIANT: Size is always aligned after this statement.
-			Size = (Size + Alignment - 1) & ~(Alignment-1);
-
-			// Account for the overhead of the headers and footers.
-			Size += ChunkOverhead;
-
-			ASSERT((Size & (Alignment-1)) == 0);
-
-			// Find the index of the smallest usable bin.
-			// INVARIANT: Size is always at least ChunkOverhead bytes, thus
-			// Size-1 will never be 0, and thus BSR is always defined.
-			size_t MinBinIndex = BSR(Size-1)+1;
-			ASSERT(IsGoodBinIndex(MinBinIndex));
-
-			// Make a bitmask that filters away all bins that are too small.
-			size_t MinBinMask = ~((1 << MinBinIndex) - 1);
-			ASSERT( ( (1 << (MinBinIndex-1)) & MinBinMask ) == 0);
-			
-			// Now filter all bins away that are too small.
-			size_t AvailableBins = BinContainsChunks & MinBinMask;
-
-			// Does any bin contain an usable chunk?
-			if ( AvailableBins > 0 )
-			{
-				// Now find the smallest usable bin.
-				size_t BinIndex = BSF( AvailableBins );
-				ASSERT(IsGoodBinIndex(BinIndex));
-
-				// And pick the first thing in it.
-				UnusedChunkHeader* Chunk = Bins[BinIndex];
-				ASSERT(IsGoodUnusedChunk(Chunk));
-
-				// Increment the bin's linked list.
-				Bins[BinIndex] = Chunk->NextUnused;
-				ASSERT(Chunk->NextUnused == NULL || IsGoodUnusedChunk(Chunk->NextUnused));
-
-				// Find the size of this bin (also the value of this bins flag).
-				size_t BinSize = 1 << BinIndex;
-				ASSERT(BinSize >= Size);
-
-				// If we emptied the bin, then remove the flag that says this bin is usable.
-				ASSERT(BinContainsChunks & BinSize);
-				if ( Chunk->NextUnused == NULL ) { BinContainsChunks ^= BinSize; }
-
-				// Figure out where the chunk ends.
-				uintptr_t ChunkEnd = ((uintptr_t) Chunk) + Chunk->Size;
-
-				// If we were to split the chunk into one used part, and one unused part, then
-				// figure out where the unused part would begin.
-				uintptr_t NewChunkStart = ((uintptr_t) Chunk) + Size;
-
-				// INVARIANT: NewChunkStart is always less or equal to ChunkEnd,
-				// because Size is less or equal to Chunk->Size (otherwise this
-				// chunk could not have been selected above).
-				ASSERT(NewChunkStart <= ChunkEnd);
-				// INVARIANT: NewChunkStart is aligned because Chunk is (this
-				// is made sure when chunks are made when expanding into the
-				// wilderness, when splitting blocks, and when combining them),
-				// and because Size is aligned (first thing we make sure).
-				ASSERT( IsAligned(NewChunkStart, Alignment) );
-
-				// Find the size of the possible new chunk.
-				size_t NewChunkSize = ChunkEnd - NewChunkStart;
-
-				UsedChunkHeader* ResultHeader = (UsedChunkHeader*) Chunk;
-
-				// See if it's worth it to split the chunk into two, if any space is left in it.
-				if ( NewChunkSize >= sizeof(UnusedChunkHeader) + sizeof(UnusedChunkFooter) )
-				{
-					// Figure out which bin to put the new chunk in.
-					size_t NewBinIndex = BSR(NewChunkSize);
-					ASSERT(IsGoodBinIndex(NewBinIndex));
-
-					// Mark that a chunk is available for this bin.
-					BinContainsChunks |= (1 << NewBinIndex);
-
-					// Now write some headers and footers for the new chunk.
-					UnusedChunkHeader* NewChunkHeader = (UnusedChunkHeader*) NewChunkStart;
-					ASSERT(IsGoodChunkPosition(NewChunkStart));
-
-					NewChunkHeader->Size = NewChunkSize;
-					NewChunkHeader->NextUnused = Bins[NewBinIndex];
-					ASSERT(NewChunkHeader->NextUnused == NULL || IsGoodChunk(NewChunkHeader->NextUnused));
-
-					UnusedChunkFooter* NewChunkFooter = (UnusedChunkFooter*) (ChunkEnd - sizeof(UnusedChunkFooter));
-					NewChunkFooter->Size = NewChunkSize;
-					NewChunkFooter->Unused = NULL;
-
-					// Put the new chunk in front of our linked list.
-					ASSERT(IsGoodUnusedChunk(NewChunkHeader));
-					Bins[NewBinIndex] = NewChunkHeader;
-
-					// We need to modify our resulting chunk to be smaller.
-					ResultHeader->Size = Size;
-				}
-
-				// Set the required magic values.
-				UsedChunkFooter* ResultFooter = (UsedChunkFooter*) ( ((byte*) ResultHeader) + ResultHeader->Size - sizeof(UsedChunkFooter) );
-				ResultHeader->Magic = Magic;
-				ResultFooter->Magic = Magic;
-				ResultFooter->Size = Size;
-
-				ASSERT(IsGoodUsedChunk(ResultHeader));
-
-				return ((byte*) ResultHeader) + sizeof(UnusedChunkHeader);
-			}
-			else
-			{
-				// We have no free chunks that are big enough, let's expand our heap into the unknown, if possible.
-				if ( WildernessSize < Size && !ExpandWilderness(Size) ) { Error::Set(ENOMEM); return NULL; }
-
-				// Write some headers and footers around our newly allocated data.
-				UsedChunkHeader* ResultHeader = (UsedChunkHeader*) (Wilderness + WildernessSize - Size);
-				UsedChunkFooter* ResultFooter = (UsedChunkFooter*) (Wilderness + WildernessSize - sizeof(UsedChunkFooter));
-				WildernessSize -= Size;
-
-				ResultHeader->Size = Size;
-				ResultHeader->Magic = Magic;
-				ResultFooter->Size = Size;
-				ResultFooter->Magic = Magic;
-
-				ASSERT(IsGoodUsedChunk(ResultHeader));
-
-				return ((byte*) ResultHeader) + sizeof(UsedChunkHeader);
-			}	
-		}
-
-		// Frees a continious memory region allocated by Allocate.
-		DUAL_FUNCTION(void, free, Free, (void* Addr))
-		{
-			// Just ignore NULL-pointers.
-			if ( Addr == NULL ) { return; }
-
-			// Restore the chunk information structures.
-			UsedChunkHeader* ChunkHeader = (UsedChunkHeader*) ( ((byte*) Addr) - sizeof(UsedChunkHeader) );
-			UsedChunkFooter* ChunkFooter = (UsedChunkFooter*) ( ((byte*) ChunkHeader) + ChunkHeader->Size - sizeof(UsedChunkFooter) );
-		
-			ASSERT(IsGoodUsedChunk(ChunkHeader));
-
-			// If you suspect a chunk of bein' a witch, report them immediately. I cannot stress that enough. Witchcraft will not be tolerated.
-			if ( ChunkHeader->Magic != Magic || ChunkFooter->Magic != Magic || ChunkHeader->Size != ChunkFooter->Size )
-			{
-#ifdef SORTIX_KERNEL
-				Sortix::PanicF("Witchcraft detected!\n", ChunkHeader);
-#endif
-				// TODO: Report witchcraft (terminating the process is probably a good idea).
-			}
-
-			// TODO: Combine this chunk with its neighbors, if they are also unused.
-
-			// Calculate which bin this chunk belongs to.
-			size_t BinIndex = BSR(ChunkHeader->Size);
-			ASSERT(IsGoodBinIndex(BinIndex));
-
-			// Mark that a chunk is available for this bin.
-			BinContainsChunks |= (1 << BinIndex);
-
-			UnusedChunkHeader* UnChunkHeader = (UnusedChunkHeader*) ChunkHeader;
-			UnusedChunkFooter* UnChunkFooter = (UnusedChunkFooter*) ChunkFooter;
-
-			// Now put this chunk back in the linked list.
-			ASSERT(Bins[BinIndex] == NULL || IsGoodUnusedChunk(Bins[BinIndex]));
-			UnChunkHeader->NextUnused = Bins[BinIndex];
-			UnChunkFooter->Unused = NULL;
-
-			ASSERT(IsGoodUnusedChunk(UnChunkHeader));
-			Bins[BinIndex] = UnChunkHeader;
-		}
-
 		DUAL_FUNCTION(void*, memcpy, Copy, (void* Dest, const void* Src, size_t Length))
 		{
 			char* D = (char*) Dest; const char* S = (const char*) Src;