ReactOS系统中平衡二叉树。给定地址超导其所属区块MmFindRegion()

系列文章目录

PMM_REGION NTAPI MmFindRegion(
PVOID BaseAddress,
PLIST_ENTRY RegionListHead,
PVOID Address,
PVOID* RegionBaseAddress
);

宏函数
//给定地址找到其中所属区块

#define CONTAINING_RECORD(address,type,field) ((type FAR *\
    (PCHAR)(address)-(PCHAR)(&((type *)0)->field)))获取外层数据结构的指针
    ```
@[TOC](文章目录)

---

# MmFindRegion()
```c
//给定地址超导其所属区块
PMM_REGION NTAPI 
MmFindRegion(PVOID BaseAddress, PLIST_ENTRY RegionListHead,
    PVOID Address, PVOID * RegionBaseAddress)
{
    PLIST_ENTRY current_entry;
    PMM_REGION current;
    PVOID StartAddress = BaseAddress;//搜索的起点
    current_entry = RegionListHead->Flink;//获得第一个MM REGION区块指针
    while (current_entry != RegionListHead)//遍历一个MEMORY AREA即某个区间的区块双向链表
    {
        //curren获得该指向该结构的首地址
        current = CONTAINING_RECORD(current entry, MM REGION, RegionListEntry);
        //若目标地址在(StartAddress ~startAddress+current->Length)说明找到了该地址所在区块
        if (StartAddress <= Address &&
            ((char*)StartAddresS + current->Length) > (char*)Address) {//找到了
            if (RegionBaseAddress != NULL)
                *RegionBaseAddress = StartAddress;//将区块开始地址给RegionBaseAddress返回return(current);//返回该区块的结构信息
            currententry = current_entry->Flink://下一个区块StartAddress =(PVOID)((ULONG PTR)StartAddress + current->Length);
            return(NULL);
        }
        current_entry = current_entry->Flink;//下一个区块
        StartAddress = (PVOID)((ULONG_PTR)StartAddress + current->Length);
    }
    return (NULL);
}
c