Chroma/chroma/system/memory/abstract_allocator.c
2020-11-26 04:03:41 +00:00

798 lines
25 KiB
C

#include <stddef.h>
#include <stdbool.h>
#include <stdint.h>
#include <kernel/system/memory.h>
#include <kernel/system/io.h>
/************************
*** Team Kitty, 2020 ***
*** Chroma ***
***********************/
/************************************************
* C O N S T A N T S A N D M A C R O S
*************************************************/
#define BLOCK_FREE (1 << 0)
#define BLOCK_PREV_FREE (1 << 1)
#define BLOCK_OVERHEAD (sizeof(size_t))
#define BLOCK_OFFSET (offsetof(block_header_t, Size) + sizeof(size_t))
#define BLOCK_MIN_SIZE (sizeof(block_header_t) - sizeof(block_header_t*))
#define BLOCK_MAX_SIZE (CAST(size_t, 1) << FL_LIMIT)
#define static_assert _Static_assert
extern void SomethingWentWrong(const char* Message);
//#define ASSERT(X) _Static_assert(X)
/************************************************
* S A N I T Y C H E C K S
*************************************************/
//_Static_Assert(sizeof(int) * __CHAR_BIT__ == 32);
//_Static_Assert(sizeof(int) * __CHAR_BIT__ == 32);
//_Static_Assert(sizeof(size_t) * __CHAR_BIT__ >= 32);
//_Static_Assert(sizeof(size_t) * __CHAR_BIT__ <= 64);
//_Static_Assert(sizeof(unsigned int) * __CHAR_BIT__ >= SL_INDEX_COUNT);
//_Static_Assert(ALIGN_SIZE == SMALL_BLOCK_SIZE / SL_INDEX_COUNT);
/************************************************
* F F S A N D F L S
*************************************************/
#ifdef _cplusplus
#define alloc_decl inline
#else
#define alloc_decl static
#endif
alloc_decl int Alloc_FindFirstOne(unsigned int word) {
return __builtin_ffs(word) - 1;
}
alloc_decl int Alloc_FindLastOne(unsigned int word) {
const int bit = word ? 32 - __builtin_clz(word) : 0;
return bit -1;
}
alloc_decl int Alloc_FindLastOne_64(size_t size) {
int high = (int)(size >> 32);
int bits = 0;
if(high)
bits = 32 + Alloc_FindLastOne(high);
else
bits = Alloc_FindLastOne((int)size & 0xFFFFFFFF);
return bits;
}
#undef alloc_decl
/*********************************************
* T Y P E D E F I N I T I O N S
**********************************************/
enum Alloc_Public {
SL_LIMIT_LN = 5,
};
enum Alloc_Private {
ALIGN_SIZE_LN = 3,
ALIGN_SIZE = (1 << ALIGN_SIZE_LN),
FL_LIMIT = 32,
SL_INDEX_COUNT = (1 << SL_LIMIT_LN),
FL_INDEX_SHIFT = (SL_LIMIT_LN + ALIGN_SIZE_LN),
FL_INDEX_COUNT = (FL_LIMIT - FL_INDEX_SHIFT + 1),
SMALL_BLOCK_SIZE = (1 << FL_INDEX_SHIFT),
};
typedef struct block_header_t {
struct block_header_t* LastBlock;
size_t Size; // Not including this header
struct block_header_t* NextFreeBlock;
struct block_header_t* LastFreeBlock;
} block_header_t ;
typedef struct allocator_control_t {
block_header_t BlockNull;
unsigned int FirstLevel_Bitmap;
unsigned int SecondLevel_Bitmap[FL_INDEX_COUNT];
block_header_t* Blocks[FL_INDEX_COUNT][SL_INDEX_COUNT];
} allocator_control_t;
/**********************************************************************************
* B L O C K _ H E A D E R _ T M E M B E R F U N C T I O N S
************************************************************************************/
static size_t BlockSize(const block_header_t* Block) {
return Block->Size & ~(BLOCK_FREE | BLOCK_PREV_FREE);
}
static void BlockSetSize(block_header_t* Block, size_t Size) {
Block->Size = Size | (Block->Size & (BLOCK_FREE | BLOCK_PREV_FREE));
}
static int BlockIsLast(const block_header_t* Block) {
return BlockSize(Block) == 0;
}
static int BlockIsFree(const block_header_t* Block) {
return CAST(int, Block->Size & BLOCK_FREE);
}
static void BlockSetFree(block_header_t* Block) {
Block->Size |= BLOCK_FREE;
}
static void BlockSetUsed(block_header_t* Block) {
Block->Size &= ~BLOCK_FREE;
}
static int BlockPrevIsFree(const block_header_t* Block) {
return CAST(int, Block->Size & BLOCK_PREV_FREE);
}
static void BlockSetPrevFree(block_header_t* Block) {
Block->Size |= BLOCK_PREV_FREE;
}
static void BlockSetPrevUsed(block_header_t* Block) {
Block->Size &= ~BLOCK_PREV_FREE;
}
static block_header_t* WhichBlock(const void* Address) {
return CAST(block_header_t*, CAST(unsigned char*, Address) - BLOCK_OFFSET);
}
static void* WhereBlock(const block_header_t* Block) {
return CAST(void*, CAST(unsigned char*, Block) + BLOCK_OFFSET);
}
static block_header_t* OffsetToBlock(const void* Address, size_t Size) {
return CAST(block_header_t*, CAST(ptrdiff_t, Address) + Size);
}
static block_header_t* BlockGetPrevious(const block_header_t* Current) {
ASSERT(BlockPrevIsFree(Current), "BlockGetPrevious: Previous block NOT free");
return Current->LastBlock;
}
static block_header_t* BlockGetNext(const block_header_t* Current) {
block_header_t* NextBlock = OffsetToBlock(WhereBlock(Current), BlockSize(Current) - BLOCK_OVERHEAD);
ASSERT(!BlockIsLast(Current), "BlockGetNext: Current block is last!");
return NextBlock;
}
static block_header_t* BlockLinkToNext(block_header_t* Current) {
block_header_t* NextBlock = BlockGetNext(Current);
NextBlock->LastBlock = Current;
return NextBlock;
}
static void BlockMarkFree(block_header_t* Current) {
block_header_t* NextBlock = BlockLinkToNext(Current);
BlockSetPrevFree(NextBlock);
BlockSetFree(Current);
}
static void BlockMarkUsed(block_header_t* Current) {
block_header_t* NextBlock = BlockGetNext(Current);
BlockSetPrevUsed(NextBlock);
BlockSetUsed(Current);
}
/***********************************************************************************
* P O I N T E R A L I G N M E N T F U N C T I O N S
************************************************************************************/
size_t AlignUpwards(size_t Pointer, size_t Alignment) {
//ASSERT(((Alignment & (Alignment - 1)) == 0));
return (Pointer + (Alignment - 1)) & ~(Alignment - 1);
}
size_t AlignDownwards(size_t Pointer, size_t Alignment) {
//ASSERT((Alignment & (Alignment - 1) == 0));
return (Pointer - (Pointer & (Alignment - 1)));
}
void* AlignPointer(const void* Pointer, size_t Alignment) {
const ptrdiff_t AlignedPointer =
((
CAST(ptrdiff_t, Pointer)
+ (Alignment - 1))
& ~(Alignment - 1)
);
ASSERT(((Alignment & (Alignment - 1)) == 0), "AlignPointer: Requested alignment not aligned!");
return CAST(void*, AlignedPointer);
}
/***********************************************************************************
* M E M O R Y B L O C K M A N A G E M E N T
************************************************************************************/
static size_t AlignRequestSize(size_t Size, size_t Alignment) {
size_t Adjustment = 0;
if(Size) {
const size_t Aligned = AlignUpwards(Size, Alignment);
if(Aligned < BLOCK_MAX_SIZE)
Adjustment = MAX(Aligned, BLOCK_MIN_SIZE);
}
return Adjustment;
}
static void InsertMapping(size_t Size, int* FirstLevelIndex, int* SecondLevelIndex) {
int FirstLevel, SecondLevel;
if(Size < SMALL_BLOCK_SIZE) {
FirstLevel = 0;
SecondLevel = CAST(int, Size) / (SMALL_BLOCK_SIZE / SL_INDEX_COUNT);
} else {
FirstLevel = Alloc_FindLastOne_64(Size);
SecondLevel = CAST(int, Size >> (FirstLevel - SL_LIMIT_LN)) ^ (1 << SL_LIMIT_LN);
FirstLevel -= (FL_INDEX_SHIFT - 1);
}
*FirstLevelIndex = FirstLevel;
*SecondLevelIndex = SecondLevel;
}
static void RoundUpBlockSize(size_t Size, int* FirstLevelIndex, int* SecondLevelIndex) {
if(Size >= SMALL_BLOCK_SIZE) {
const size_t Rounded = (1 << (Alloc_FindLastOne_64(Size) - SL_LIMIT_LN)) - 1;
Size += Rounded;
}
InsertMapping(Size, FirstLevelIndex, SecondLevelIndex);
}
static block_header_t* FindSuitableBlock(allocator_control_t* Controller, int* FirstLevelIndex, int* SecondLevelIndex) {
int FirstLevel = *FirstLevelIndex;
int SecondLevel = *SecondLevelIndex;
unsigned int SLMap = Controller->SecondLevel_Bitmap[FirstLevel] & (~0U << SecondLevel);
if(!SLMap) {
const unsigned int FLMap = Controller->FirstLevel_Bitmap & (~0U << (FirstLevel + 1));
if(!FLMap)
return 0;
FirstLevel = Alloc_FindFirstOne(FLMap);
*FirstLevelIndex = FirstLevel;
SLMap = Controller->SecondLevel_Bitmap[FirstLevel];
}
ASSERT(SLMap, "FindSuitableBlock: Second level bitmap not present!");
SecondLevel = Alloc_FindFirstOne(SLMap);
*SecondLevelIndex = SecondLevel;
return Controller->Blocks[FirstLevel][SecondLevel];
}
static void RemoveFreeBlock(allocator_control_t* Controller, block_header_t* Block, int FirstLevel, int SecondLevel) {
block_header_t* PreviousBlock = Block->LastFreeBlock;
block_header_t* NextBlock = Block->NextFreeBlock;
ASSERT(PreviousBlock, "RemoveFreeBlock: PreviousBlock is null!");
ASSERT(NextBlock, "RemoveFreeBlock: NextBlock is null!");
NextBlock->LastFreeBlock = PreviousBlock;
PreviousBlock->NextFreeBlock = NextBlock;
if(Controller->Blocks[FirstLevel][SecondLevel] == Block) {
Controller->Blocks[FirstLevel][SecondLevel] = NextBlock;
if(NextBlock == &Controller->BlockNull) {
Controller->SecondLevel_Bitmap[FirstLevel] &= ~(1U << SecondLevel);
if(!Controller->SecondLevel_Bitmap[FirstLevel]) {
Controller->FirstLevel_Bitmap &= ~(1U << FirstLevel);
}
}
}
}
static void InsertFreeBlock(allocator_control_t* Controller, block_header_t* NewBlock, int FirstLevel, int SecondLevel) {
block_header_t* Current = Controller->Blocks[FirstLevel][SecondLevel];
ASSERT(Current, "InsertFreeBlock: Current Block is null!");
if(!Current) {
SerialPrintf("Extra info: \r\n\tFirst Level: %x Second Level: %x\r\nFirst Level bitmap: %x, Second Level bitmap: %x\r\n\tBlocks %x, BlocksAddress: %x", FirstLevel, SecondLevel, Controller->FirstLevel_Bitmap, Controller->SecondLevel_Bitmap, Controller->Blocks, Controller->Blocks[FirstLevel][SecondLevel]);
for(;;){}
}
ASSERT(NewBlock, "InsertFreeBlock: New Block is null!");
NewBlock->NextFreeBlock = Current;
NewBlock->LastFreeBlock = &Controller->BlockNull;
Current->LastFreeBlock = NewBlock;
ASSERT(WhereBlock(NewBlock) == AlignPointer(WhereBlock(NewBlock), ALIGN_SIZE), "InsertFreeBlock: Current block is not memory aligned!");
Controller->Blocks[FirstLevel][SecondLevel] = NewBlock;
Controller->FirstLevel_Bitmap |= (1U << FirstLevel);
Controller->SecondLevel_Bitmap[FirstLevel] |= (1U << SecondLevel);
}
static void RemoveBlock(allocator_control_t* Controller, block_header_t* Block) {
int FirstLevel, SecondLevel;
InsertMapping(BlockSize(Block), &FirstLevel, &SecondLevel);
RemoveFreeBlock(Controller, Block, FirstLevel, SecondLevel);
}
static void InsertBlock(allocator_control_t* Controller, block_header_t* Block) {
int FirstLevel, SecondLevel;
InsertMapping(BlockSize(Block), &FirstLevel, &SecondLevel);
InsertFreeBlock(Controller, Block, FirstLevel, SecondLevel);
}
static int CanBlockSplit(block_header_t* Block, size_t NewSize) {
return BlockSize(Block) >= sizeof(block_header_t) + NewSize;
}
static block_header_t* SplitBlock(block_header_t* Block, size_t NewSize) {
block_header_t* Overlap = OffsetToBlock(WhereBlock(Block), NewSize - BLOCK_OVERHEAD);
const size_t RemainingSize = BlockSize(Block) - (NewSize + BLOCK_OVERHEAD);
ASSERT(WhereBlock(Overlap) == AlignPointer(WhereBlock(Overlap), ALIGN_SIZE), "SplitBlock: Requested size results in intermediary block which is not aligned!");
ASSERT(BlockSize(Block) == RemainingSize + NewSize + BLOCK_OVERHEAD, "SplitBlock: Maths error!");
BlockSetSize(Overlap, RemainingSize);
ASSERT(BlockSize(Overlap) >= BLOCK_MIN_SIZE, "SplitBlock: Requested size results in new block that is too small!");
BlockSetSize(Block, NewSize);
BlockMarkFree(Overlap);
return Overlap;
}
static block_header_t* MergeBlockDown(block_header_t* Previous, block_header_t* Block) {
ASSERT(!BlockIsLast(Previous), "MergeBlockDown: Previous block is the last block! (Current block is first block?)");
Previous->Size += BlockSize(Block) + BLOCK_OVERHEAD;
BlockLinkToNext(Previous);
return Previous;
}
static block_header_t* MergeEmptyBlockDown(allocator_control_t* Controller, block_header_t* Block) {
if(BlockPrevIsFree(Block)) {
block_header_t* Previous = BlockGetPrevious(Block);
ASSERT(Previous, "MergeEmptyBlockDown: Previous block is null!");
ASSERT(BlockIsFree(Previous), "MergeEmptyBlockDown: Previous block is free!");
RemoveBlock(Controller, Previous);
Block = MergeBlockDown(Previous, Block);
}
return Block;
}
static block_header_t* MergeNextBlockDown(allocator_control_t* Controller, block_header_t* Block) {
block_header_t* NextBlock = BlockGetNext(Block);
ASSERT(NextBlock, "MergeNextBlockDown: Next Block is null!");
if(BlockIsFree(NextBlock)) {
ASSERT(!BlockIsLast(Block), "MergeNextBlockDown: Current block is the last block!");
RemoveBlock(Controller, NextBlock);
Block = MergeBlockDown(Block, NextBlock);
}
return Block;
}
static void TrimBlockFree(allocator_control_t* Controller, block_header_t* Block, size_t Size) {
ASSERT(BlockIsFree(Block), "TrimBlockFree: Current block is wholly free!");
if(CanBlockSplit(Block, Size)) {
block_header_t* RemainingBlock = SplitBlock(Block, Size);
BlockLinkToNext(Block);
BlockSetPrevFree(RemainingBlock);
InsertBlock(Controller, RemainingBlock);
}
}
static void TrimBlockUsed(allocator_control_t* Controller, block_header_t* Block, size_t Size) {
ASSERT(!BlockIsFree(Block), "TrimBlockUsed: The current block is wholly used!");
if(CanBlockSplit(Block, Size)) {
block_header_t* RemainingBlock = SplitBlock(Block, Size);
BlockSetPrevUsed(RemainingBlock);
RemainingBlock = MergeNextBlockDown(Controller, RemainingBlock);
InsertBlock(Controller, RemainingBlock);
}
}
static block_header_t* TrimBlockLeadingFree(allocator_control_t* Controller, block_header_t* Block, size_t Size) {
block_header_t* RemainingBlock = Block;
if(CanBlockSplit(Block, Size)) {
RemainingBlock = SplitBlock(Block, Size - BLOCK_OVERHEAD);
BlockSetPrevFree(RemainingBlock);
BlockLinkToNext(Block);
InsertBlock(Controller, Block);
}
return RemainingBlock;
}
static block_header_t* LocateFreeBlock(allocator_control_t* Controller, size_t Size) {
int FirstLevel = 0, SecondLevel = 0;
block_header_t* Block = 0;
if(Size) {
RoundUpBlockSize(Size, &FirstLevel, &SecondLevel);
if(FirstLevel < FL_INDEX_COUNT) {
Block = FindSuitableBlock(Controller, &FirstLevel, &SecondLevel);
}
}
if(Block) {
ASSERT(BlockSize(Block) >= Size, "LocateFreeBlock: Found a block that is too small!");
RemoveFreeBlock(Controller, Block, FirstLevel, SecondLevel);
}
return Block;
}
static void* PrepareUsedBlock(allocator_control_t* Controller, block_header_t* Block, size_t Size) {
void* Pointer = 0;
if(Block){
ASSERT(Size, "PrepareUsedBlock: Size is 0!");
TrimBlockFree(Controller, Block, Size);
BlockMarkUsed(Block);
Pointer = WhereBlock(Block);
}
return Pointer;
}
/***********************************************************************************
* C O N T R O L L E R M A N A G E M E N T
************************************************************************************/
static void ConstructController(allocator_control_t* Controller) {
int i, j;
Controller->BlockNull.NextFreeBlock = &Controller->BlockNull;
Controller->BlockNull.LastFreeBlock = &Controller->BlockNull;
Controller->FirstLevel_Bitmap = 0;
for ( i = 0; i < FL_INDEX_COUNT; i++) {
Controller->SecondLevel_Bitmap[i] = 0;
for (j = 0; j < SL_INDEX_COUNT; j++) {
Controller->Blocks[i][j] = &Controller->BlockNull;
}
}
}
/***********************************************************************************
* H E A D E R ( A P I ) F U N C T I O N S
************************************************************************************/
size_t AllocatorGetBlockSize(void* Memory) {
size_t Size = 0;
if(Memory) {
const block_header_t* Block = WhichBlock(Memory);
Size = BlockSize(Block);
}
return Size;
}
size_t AllocatorSize(void) {
return sizeof(allocator_control_t);
}
size_t AllocatorAlignSize(void) {
return ALIGN_SIZE;
}
size_t AllocatorMinBlockSize(void) {
return BLOCK_MIN_SIZE;
}
size_t AllocatorMaxBlockSize(void) {
return BLOCK_MAX_SIZE;
}
size_t AllocatorPoolOverhead(void) {
return 2* BLOCK_OVERHEAD; // Free block + Sentinel block
}
size_t AllocatorAllocateOverhead(void) {
return BLOCK_OVERHEAD;
}
mempool_t AddPoolToAllocator(allocator_t Allocator, void* Address, size_t Size) {
block_header_t* Block;
block_header_t* NextBlock;
const size_t PoolOverhead = AllocatorPoolOverhead();
const size_t PoolBytes = AlignDownwards(Size - PoolOverhead, ALIGN_SIZE);
if(((ptrdiff_t) Address % ALIGN_SIZE) != 0) {
SerialPrintf("Memory manager error at [%s:%x]: Memory not properly aligned.\r\n", __FILE__, __LINE__);
return 0;
}
if( PoolBytes < BLOCK_MIN_SIZE || PoolBytes > BLOCK_MAX_SIZE) {
SerialPrintf("Memory manager error at [%s:%x]: Memory Size out of bounds: 0x%x-0x%x: 0x%x.\r\n", __FILE__, __LINE__, (unsigned int)(PoolOverhead + BLOCK_MIN_SIZE), (unsigned int)(PoolOverhead + BLOCK_MAX_SIZE) / 256, PoolBytes);
return 0;
}
Block = OffsetToBlock(Address, -(ptrdiff_t)BLOCK_OVERHEAD);
BlockSetSize(Block, PoolBytes);
BlockSetFree(Block);
BlockSetPrevUsed(Block);
InsertBlock(CAST(allocator_control_t*, Allocator), Block);
NextBlock = BlockLinkToNext(Block);
BlockSetSize(NextBlock, 0);
BlockSetUsed(NextBlock);
BlockSetPrevFree(NextBlock);
return Address;
}
void RemovePoolFromAllocator(allocator_t Allocator, mempool_t Pool){
allocator_control_t* Controller = CAST(allocator_control_t*, Allocator);
block_header_t* Block = OffsetToBlock(Pool, -(int)BLOCK_OVERHEAD);
int FirstLevel = 0, SecondLevel = 0;
ASSERT(BlockIsFree(Block), "RemovePoolFromAllocator: Current block is free!");
ASSERT(!BlockIsFree(BlockGetNext(Block)), "RemovePoolFromAllocator: Next Block is not free!");
ASSERT(BlockSize(BlockGetNext(Block)) == 0, "RemovePoolFromAllocator: Next block is size 0!");
RoundUpBlockSize(BlockSize(Block), &FirstLevel, &SecondLevel);
RemoveFreeBlock(Controller, Block, FirstLevel, SecondLevel);
}
int TestBuiltins() {
/* Verify ffs/fls work properly. */
int TestsFailed = 0;
TestsFailed += (Alloc_FindFirstOne(0) == -1) ? 0 : 0x1;
TestsFailed += (Alloc_FindLastOne(0) == -1) ? 0 : 0x2;
TestsFailed += (Alloc_FindFirstOne(1) == 0) ? 0 : 0x4;
TestsFailed += (Alloc_FindLastOne(1) == 0) ? 0 : 0x8;
TestsFailed += (Alloc_FindFirstOne(0x80000000) == 31) ? 0 : 0x10;
TestsFailed += (Alloc_FindFirstOne(0x80008000) == 15) ? 0 : 0x20;
TestsFailed += (Alloc_FindLastOne(0x80000008) == 31) ? 0 : 0x40;
TestsFailed += (Alloc_FindLastOne(0x7FFFFFFF) == 30) ? 0 : 0x80;
TestsFailed += (Alloc_FindLastOne_64(0x80000000) == 31) ? 0 : 0x100;
TestsFailed += (Alloc_FindLastOne_64(0x100000000) == 32) ? 0 : 0x200;
TestsFailed += (Alloc_FindLastOne_64(0xffffffffffffffff) == 63) ? 0 : 0x400;
if (TestsFailed) {
SerialPrintf("TestBuiltins: %x ffs/fls tests failed.\n", TestsFailed);
}
return TestsFailed;
}
allocator_t CreateAllocator(void* Memory) {
if(TestBuiltins())
return 0;
if (((ptrdiff_t) Memory % ALIGN_SIZE) != 0) {
SerialPrintf("Memory manager error at [%s:%x]: Memory not properly aligned.\r\n", __FILE__, __LINE__);
return 0;
}
ConstructController(CAST(allocator_control_t*, Memory));
return CAST(allocator_t, Memory);
}
allocator_t CreateAllocatorWithPool(void* Memory, size_t Bytes) {
allocator_t Allocator = CreateAllocator(Memory);
AddPoolToAllocator(Allocator, (char*)Memory + AllocatorSize(), Bytes - AllocatorSize());
return Allocator;
}
void DestroyAllocator(allocator_t Allocator) {
(void) Allocator;
}
mempool_t GetPoolFromAllocator(allocator_t Allocator) {
return CAST(mempool_t, (char*)Allocator + AllocatorSize());
}
/***********************************************************************************
* S T D L I B A L L O C A T E F U N C T I O N S
************************************************************************************/
void* AllocatorMalloc(allocator_t Allocator, size_t Size) {
allocator_control_t* Controller = CAST(allocator_control_t*, Allocator);
const size_t Adjustment = AlignRequestSize(Size, ALIGN_SIZE);
block_header_t* Block = LocateFreeBlock(Controller, Adjustment);
return PrepareUsedBlock(Controller, Block, Adjustment);
}
void* AllocatorMalign(allocator_t Allocator, size_t Alignment, size_t Size) {
allocator_control_t* Controller = CAST(allocator_control_t*, Allocator);
const size_t Adjustment = AlignRequestSize(Size, ALIGN_SIZE);
const size_t MinimumGap = sizeof(block_header_t);
const size_t SizeWithGap = AlignRequestSize(Adjustment + Alignment + MinimumGap, Alignment);
const size_t AlignedSize = (Adjustment && Alignment > ALIGN_SIZE) ? SizeWithGap : Adjustment;
block_header_t* Block = LocateFreeBlock(Controller, AlignedSize);
ASSERT(sizeof(block_header_t) == BLOCK_MIN_SIZE + BLOCK_OVERHEAD, "AllocatorMalign: Maths error!");
if(Block) {
void* Address = WhereBlock(Block);
void* AlignedAddress = AlignPointer(Address, Alignment);
size_t Gap = CAST(size_t, CAST(ptrdiff_t, AlignedAddress) - CAST(ptrdiff_t, Address));
if(Gap) {
if(Gap << MinimumGap) {
const size_t GapRemaining = MinimumGap - Gap;
const size_t Offset = MAX(GapRemaining, Alignment);
const void* NextAlignedAddress = CAST(void*, CAST(ptrdiff_t, AlignedAddress) + Offset);
AlignedAddress = AlignPointer(NextAlignedAddress, Alignment);
Gap = CAST(size_t, CAST(ptrdiff_t, AlignedAddress) - CAST(ptrdiff_t, Address));
}
ASSERT(Gap >= MinimumGap, "AllocatorMalign: Maths error 2!");
Block = TrimBlockLeadingFree(Controller, Block, Gap);
}
}
return PrepareUsedBlock(Controller, Block, Adjustment);
}
void AllocatorFree(allocator_t Allocator, void* Address) {
if(Address) {
allocator_control_t* Controller = CAST(allocator_control_t*, Allocator);
block_header_t* Block = WhichBlock(Address);
ASSERT(!BlockIsFree(Block), "AllocatorFree: Attempting to free a freed block!");
BlockMarkFree(Block);
Block = MergeEmptyBlockDown(Controller, Block);
Block = MergeNextBlockDown(Controller, Block);
InsertBlock(Controller, Block);
}
}
/*
* Realloc should, with:
* * A valid size with an invalid pointer:
* - Allocate space
* * An invalid size with a valid pointer:
* - Free Space
* * An invalid request:
* - Do nothing
* * A valid extension request:
* - Leave the new area as it is
* // TODO: memset this area to 0.
*/
void* AllocatorRealloc(allocator_t Allocator, void* Address, size_t NewSize) {
allocator_control_t* Controller = CAST(allocator_control_t*, Allocator);
void* Pointer = 0;
// Valid address, invalid size; free
if(Address && NewSize == 0)
AllocatorFree(Allocator, Address);
else if (!Address) // Invalid address; alloc
AllocatorMalloc(Allocator, NewSize);
else {
block_header_t* Block = WhichBlock(Address);
block_header_t* NextBlock = BlockGetNext(Block);
const size_t CurrentSize = BlockSize(Block);
const size_t CombinedSize = CurrentSize + BlockSize(NextBlock) + BLOCK_OVERHEAD;
const size_t AdjustedSize = AlignRequestSize(NewSize, ALIGN_SIZE);
ASSERT(!BlockIsFree(Block), "AllocatorRealloc: Requested block is not free!");
if(AdjustedSize > CurrentSize && (!BlockIsFree(NextBlock) || AdjustedSize > CombinedSize)) {
// We're going to need more room
Pointer = AllocatorMalloc(Allocator, NewSize);
if(Pointer) {
const size_t MinimumSize = MIN(CurrentSize, NewSize);
memcpy(Pointer, Address, MinimumSize);
AllocatorFree(Allocator, Address);
}
} else {
if( AdjustedSize > CurrentSize) {
MergeNextBlockDown(Controller, Block);
BlockMarkUsed(Block);
}
TrimBlockUsed(Controller, Block, AdjustedSize);
Pointer = Address;
}
}
return Pointer;
}