karina
101 lines
3.4 KiB
C
101 lines
3.4 KiB
C
#include <VM/Heap.h>
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#include <VM/PMM.h>
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#include <VM/VMM.h>
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#include <Lib/String.h>
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#include <OS/Panic.h>
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static VMHeapBlockHeader* sVMHeapListHead = nullptr;
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static void CombineForward(VMHeapBlockHeader* current) {
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if (!current->next || !current->next->isFree) return;
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current->size += sizeof(VMHeapBlockHeader) + current->next->size;
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current->next = current->next->next;
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if (current->next) current->next->previous = current;
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}
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void HeapInitialize() {
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Address heapStart = kKernelHeapStart;
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for (UInt64 i = 0; i < kHeapSizePages; i++) {
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Address physical = (Address)PMMAllocatePage();
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if (!physical) OSPanic("OOM during heap init");
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Address virtual = heapStart + (i * kVMPageSize);
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VMMMapPage(gVMKernelL0Table, physical, virtual, kPTENormalMem | kPTEAccessRW | kPTEPrivNX | kPTEUserNX);
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}
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sVMHeapListHead = (VMHeapBlockHeader*)heapStart;
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sVMHeapListHead->magic = kHeapBlockHeaderMagic;
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sVMHeapListHead->size = (kHeapSizePages * kVMPageSize) - sizeof(VMHeapBlockHeader);
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sVMHeapListHead->isFree = true;
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sVMHeapListHead->next = nullptr;
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sVMHeapListHead->previous = nullptr;
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}
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Pointer HeapAllocate(Size size) {
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if (size == 0) return nullptr;
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Size alignedSize = (size + 15) & ~15;
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VMHeapBlockHeader* current = sVMHeapListHead;
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while (current) {
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if (current->isFree && current->size >= alignedSize) {
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if (current->size > alignedSize + sizeof(VMHeapBlockHeader) + 16) {
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VMHeapBlockHeader* new_block = (VMHeapBlockHeader*)((Address)current + sizeof(VMHeapBlockHeader) + alignedSize);
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new_block->size = current->size - alignedSize - sizeof(VMHeapBlockHeader);
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new_block->isFree = true;
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new_block->next = current->next;
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new_block->previous = current;
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new_block->magic = kHeapBlockHeaderMagic;
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if (current->next) current->next->previous = new_block;
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current->next = new_block;
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current->size = alignedSize;
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}
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current->isFree = false;
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return (Pointer)((Address)current + sizeof(VMHeapBlockHeader));
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}
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current = current->next;
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}
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return nullptr;
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}
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void HeapFree(Pointer pointer) {
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if (!pointer) return;
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VMHeapBlockHeader* current = (VMHeapBlockHeader*)((Address)pointer - sizeof(VMHeapBlockHeader));
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if (current->magic != kHeapBlockHeaderMagic) return;
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current->isFree = true;
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if (current->next && current->next->isFree) CombineForward(current);
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if (current->previous && current->previous->isFree) CombineForward(current->previous);
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}
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Pointer HeapResize(Pointer pointer, Size newSize) {
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if (!pointer) return HeapAllocate(newSize);
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if (newSize == 0) {
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HeapFree(pointer);
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return nullptr;
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}
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Size alignedSize = (newSize + 15) & ~15;
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VMHeapBlockHeader* current = (VMHeapBlockHeader*)((Address)pointer - sizeof(VMHeapBlockHeader));
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if (current->size >= alignedSize) {
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return pointer;
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}
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if (current->next && current->next->isFree &&
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(current->size + sizeof(VMHeapBlockHeader) + current->next->size) >= alignedSize) {
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CombineForward(current);
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return pointer;
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}
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Pointer newPointer = HeapAllocate(newSize);
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if (newPointer) {
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MemoryCopy(newPointer, pointer, current->size);
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HeapFree(pointer);
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}
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return newPointer;
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} |