141 lines
3.6 KiB
C++
141 lines
3.6 KiB
C++
#include "Kernel\Sys.h"
|
||
#include "Interrupt.h"
|
||
|
||
#include "Heap.h"
|
||
#include "TTime.h"
|
||
|
||
#define MEMORY_ALIGN 4
|
||
|
||
// 当前堆
|
||
Heap* Heap::Current = nullptr;
|
||
|
||
/*
|
||
堆分配原理：
|
||
1，使用内存块，记录当前块已使用大小以及下一块地址，形成内存块链表
|
||
2，每个内存块剩余空间是下一块指针减去当前块指针再减去已用大小
|
||
3，初始化第一个内存块，已使用0
|
||
4，申请内存时，从第一块开始找空余空间大于等于目标大小的内存块，割下来作为链表新节点
|
||
5，释放内存时，找到所在块，然后当前块上一块的Next指针直接指向当前块的下一块地址，移除当前节点
|
||
*/
|
||
|
||
/******************************** MemoryBlock ********************************/
|
||
// 内存块。大小和下一块地址
|
||
typedef struct MemoryBlock_
|
||
{
|
||
uint Used;
|
||
struct MemoryBlock_* Next;
|
||
} MemoryBlock;
|
||
|
||
/******************************** Heap ********************************/
|
||
Heap::Heap(uint addr, int size)
|
||
{
|
||
Current = this;
|
||
|
||
// 地址对齐
|
||
uint end = addr + size;
|
||
addr = (addr + MEMORY_ALIGN - 1) & (~(MEMORY_ALIGN - 1));
|
||
end = end & (~(MEMORY_ALIGN - 1));
|
||
|
||
Address = addr;
|
||
Size = end - addr;
|
||
|
||
// 第一块内存块
|
||
auto mb = (MemoryBlock*)addr;
|
||
mb->Used = sizeof(MemoryBlock);
|
||
mb->Next = (MemoryBlock*)(end - sizeof(MemoryBlock));
|
||
mb->Next->Used = sizeof(MemoryBlock);
|
||
mb->Next->Next = nullptr;
|
||
|
||
_Used = sizeof(MemoryBlock) << 1;
|
||
_Count = 0;
|
||
|
||
// 记录第一个有空闲内存的块，减少内存分配时的查找次数
|
||
_First = mb;
|
||
|
||
debug_printf("Heap::Init(%p, %d) Free=%d \r\n", Address, Size, FreeSize());
|
||
}
|
||
|
||
int Heap::Used() const { return _Used; }
|
||
int Heap::Count() const { return _Count; }
|
||
int Heap::FreeSize() const { return Size - _Used; }
|
||
|
||
void* Heap::Alloc(int size)
|
||
{
|
||
// 要申请的内存大小需要对齐
|
||
size = (size+MEMORY_ALIGN-1) & (~(MEMORY_ALIGN-1));
|
||
|
||
if(size > Size - _Used)
|
||
{
|
||
debug_printf("Heap::Alloc %d > %d 失败！ \r\n", size, Size - _Used);
|
||
return nullptr;
|
||
}
|
||
|
||
#if DEBUG
|
||
// 检查头部完整性
|
||
auto head = (MemoryBlock*)Address;
|
||
assert(head->Used <= (uint)Size && (uint)head + head->Used <= (uint)head->Next, "堆头被破坏！");
|
||
assert(_Used <= Size, "Heap::Used异常！");
|
||
#endif
|
||
|
||
void* ret = nullptr;
|
||
int need = size + sizeof(MemoryBlock);
|
||
|
||
SmartIRQ irq;
|
||
for(auto mcb=(MemoryBlock*)_First; mcb->Next!=nullptr; mcb=mcb->Next)
|
||
{
|
||
// 找到一块满足大小的内存块。计算当前块剩余长度
|
||
int free = (int)mcb->Next - (int)mcb - mcb->Used;
|
||
if(free >= need)
|
||
{
|
||
// 割一块出来
|
||
auto tmp = (MemoryBlock*)((uint)mcb + mcb->Used);
|
||
tmp->Next = mcb->Next;
|
||
tmp->Used = need;
|
||
mcb->Next = tmp;
|
||
|
||
// 记录第一个有空闲内存的块，减少内存分配时的查找次数
|
||
_First = tmp;
|
||
|
||
ret = (void*)((uint)(tmp+1));
|
||
|
||
_Used += need;
|
||
_Count++;
|
||
|
||
//debug_printf("Heap::Alloc (%p, %d) First=%p Used=%d Count=%d \r\n", ret, need, _First, _Used, _Count);
|
||
|
||
break;
|
||
}
|
||
}
|
||
|
||
if(!ret) debug_printf("Heap::Alloc %d 失败！\r\n", size);
|
||
|
||
return ret;
|
||
}
|
||
|
||
void Heap::Free(void* ptr)
|
||
{
|
||
auto prev = (MemoryBlock*)Address;
|
||
auto cur = (MemoryBlock*)ptr - 1;
|
||
|
||
SmartIRQ irq;
|
||
for(auto mcb=prev->Next; mcb->Next!=nullptr; mcb=mcb->Next)
|
||
{
|
||
// 找到内存块
|
||
if(mcb == cur)
|
||
{
|
||
_Used -= cur->Used;
|
||
_Count--;
|
||
|
||
// 前面有空闲位置
|
||
if(cur <= _First) _First = prev;
|
||
|
||
//debug_printf("Heap::Free (%p, %d) First=%p Used=%d Count=%d \r\n", ptr, cur->Used, _First, _Used, _Count);
|
||
|
||
prev->Next = cur->Next;
|
||
|
||
break;
|
||
}
|
||
prev = mcb;
|
||
}
|
||
}
|