动态内存管理代码，求评价
由于嵌入式平台需求，自己写了个内存管理程序，可以动态分配和回收内存，求各位看官对该算法的评价。
#include "stdio.h"unsigned int free_tmp[1024*1024*2/4]={0};//申请空间头结构struct new_head{ unsigned int new_size; //申请空间块总大小 unsigned int magic; //合法性校验，值为（~new_size）};//空闲空间头结构struct free_head{ unsigned int free_size; //空闲块总大小 struct free_head * next; //下一个空闲块指针 unsigned int magic; //合法性校验，值为 （next+~free_size）};struct free_head *global_first_pFreeHead; //全局 地址最低的空闲块//初始化动态内存块int free_init(void* start_add,unsigned int size){ global_first_pFreeHead = (struct free_head *)start_add; global_first_pFreeHead->next=NULL; global_first_pFreeHead->free_size=size; global_first_pFreeHead->magic=(unsigned int)global_first_pFreeHead->next+~global_first_pFreeHead->free_size; return 0;}//申请内存void * new_n(unsigned int new_size){ struct free_head * p_free=NULL; //链表遍历指针 struct free_head * tmp=NULL; //暂存指针 struct new_head * new_tmp; //申请内存头指针 new_size=(((new_size-1)>>2)<<2)+4; //使申请字节数为4的倍数 for(p_free=global_first_pFreeHead;p_free!=NULL;p_free=p_free->next) //查找空闲块链表中符合要求的最小块 { /// for debug if(p_free->magic!=(unsigned int)p_free->next+~p_free->free_size) //检查空闲内存头合法性 { printf("堆栈检查错误！堆栈被破坏！\r\n"); return NULL; } if(p_free->free_size>=(new_size+sizeof(struct new_head))) { if(tmp==NULL || tmp->free_size>p_free->free_size) { tmp = p_free; } } } if(tmp!=NULL) //从该空闲块中剥离申请空间 { struct free_head * store_tmp; p_free=tmp; store_tmp=p_free; p_free=(struct free_head *)(((char *)p_free)+new_size+sizeof(struct new_head)); p_free->free_size=store_tmp->free_size-(new_size+sizeof(struct new_head)); p_free->next=store_tmp->next; p_free->magic=(unsigned int)p_free->next+~p_free->free_size; if(store_tmp==global_first_pFreeHead) { global_first_pFreeHead=p_free; } } else return NULL; // 将剥离的空间初始化，并返回可用空间指针 new_tmp=(struct new_head *)tmp; new_tmp->new_size=new_size+sizeof(struct new_head); new_tmp->magic=~(new_tmp->new_size); return ((char *)new_tmp)+sizeof(struct new_head);}//释放空间void free_n(void *p){ struct new_head * p_tmp; // struct free_head * p_new; // struct free_head * p_free; //链表遍历指针 unsigned int bytes_num; //记录释放空间大小 p_tmp=(struct new_head *)((char *)p - sizeof(struct new_head)); //指向申请内存头 if(p_tmp->new_size!=~p_tmp->magic) //检查内存头合法性 { printf("wrong pointer to be free is detected! free failed!"); return; } bytes_num=p_tmp->new_size;//记录释放空间大小 p_new=(struct free_head *)p_tmp; //将该内存块变为空闲块 p_new->free_size=bytes_num; for(p_free=global_first_pFreeHead;;) //将释放区域插入链表中 { /// for debug if(p_free->magic!=(unsigned int)p_free->next+~p_free->free_size) //检查空闲内存头合法性 { printf("堆栈检查错误！堆栈被破坏！\r\n"); return; } if(p_free==global_first_pFreeHead && p_free>p_new) //插入链表首位置 { global_first_pFreeHead=p_new; p_new->next=p_free; break; } if(p_free < p_new && p_free->next > p_new) //插入链表中间位置 { p_new->next=p_free->next; p_free->next=p_new; p_free->magic=(unsigned int)p_free->next+~p_free->free_size; break; } if(p_free->next==NULL) //插入链表末尾 { p_free->next=p_new; p_free->magic=(unsigned int)p_free->next+~p_free->free_size; p_new->next=NULL; break; } else { p_free=p_free->next; } } p_new->magic=(unsigned int)p_new->next+~p_new->free_size; for(p_free=global_first_pFreeHead;p_free!=NULL;p_free=p_free->next) //组合连续链表 { int flag1,flag2=NULL; do { flag1=NULL; if(p_free == (struct free_head *)((char *)p_free->next - p_free->free_size)) //判断连续性 { p_free->free_size = p_free->free_size + p_free->next->free_size;//必须先设置大小，然后再设置链表指针 p_free->next = p_free->next->next; flag1=!NULL; flag2=!NULL; } }while(flag1); if(flag2) p_free->magic=(unsigned int)p_free->next+~p_free->free_size; }}int _tmain(int argc, _TCHAR* argv[]){ unsigned int i=0; printf("%d %u",sizeof(int),i-1); free_init(free_tmp,1024*1024*2); int * p0=(int *)new_n(sizeof(int)); *p0=0x12345678; //free_n(p0); int *p1=(int *)new_n(sizeof(int)); *p1=0x77777777; //free_n(p0); int *p2=(int *)new_n(sizeof(int)*1); p2[0]=0x12341234; //p2[1]=0x66668888; int * p3=(int *)new_n(sizeof(int)*1); p3[0]=0x11111111; //p3[1]=0x22222222; //p3[2]=0x33333333; free_n(p0); free_n(p2); free_n(p3); free_n(p1); return 0;}