neicun.rar_Unsigned_memory

/* 内存管理实验程序 * 作者：朱睿 * 把一个数组模拟为内存，然后针对该块内存实现内存的分配和回收算法 */ #include <stdio.h> #define MEM_SIZE 80 char mm[MEM_SIZE]; void* mm_request(unsigned int size); int mm_release(void* pBlock); int IsFree(int unit); /*********************************************************************************************/ struct node { char* p; int memosize; int flag; struct node* next; }; typedef struct node* NODE; NODE list = NULL; /*********************************************************************************************/ //初始化链表，产生空闲内存 void mm_init() { list = (NODE)malloc( sizeof( struct node ) ); list->p = mm; list->memosize = MEM_SIZE; list->flag = 0; list->next = NULL; } /*****************链表按空闲区由小到大排序***************************************************/ void sort() { struct node *ptr1 = list; struct node *ptr2 = ptr1->next; int temp; while(ptr1!=NULL) { ptr2 = ptr1->next; while(ptr2!=NULL) { if(ptr1->memosize>ptr2->memosize) { //交换空闲区大小 temp = ptr1->memosize; ptr1->memosize = ptr2->memosize; ptr2->memosize = temp; //交换首地址 temp = ptr1->p; ptr1->p = ptr2->p; ptr2->p = temp; } ptr2 = ptr2->next; }//while ptr2 ptr1 = ptr1->next; }//while ptr1 }//End sort /*********************************************************************************************/ // 在数组mm的分配size大小的内存块，把首地址返回，如果分配失败，返回NULL void* mm_request(unsigned int size) { NODE comp ,listnode; comp = list; //找到大于或等于所需内存大小的内存空间块 while( ( comp != NULL )&&( ( comp->flag == 1 )||( comp->memosize < size ) ) ) comp = comp->next; if( comp==NULL ) return NULL; //从中划分一块出来供它用之 else if( comp->memosize > size ) { listnode = (NODE)malloc(sizeof( struct node ) ); listnode->p = comp->p + size; listnode->memosize = comp->memosize - size; listnode->flag = 0; listnode->next = comp->next; comp->memosize = size; comp->flag = 1; comp->next = listnode; return comp->p; } return NULL; } /*********************************************************************************************/ // 释放首地址为p的内存块，成功返回非0值，失败返回0 int mm_release(void* p) { NODE comp,temp; comp = list; /*若释放的内存为第一块内存，则直接将其标志为0*/ if( comp->p == (char*)p ) { comp->flag = 0; /*若它的下一个结点可以与它合并，则将其合并*/ if( comp->next->flag == 0 ) { comp->memosize = comp->memosize + comp->next->memosize; temp = comp->next; comp->next = temp->next; free( temp ); } return 1; } /*若内存块为其他结点所指的内存块，则循环去找到合符要求的内存块*/ else { while ( ( comp->next != NULL )&&( comp->next->p != (char *)p ) ) comp = comp->next; if( comp->next == NULL ) return 0; else if( comp->next->p == (char*)p ) { comp->next->flag = 0; /*需要合并下一个结点则并之，需要合并上一个结点则并之*/ if( ( comp->next->next != NULL )&&( comp->next->next->flag == 0 ) ) { comp->next->memosize = comp->next->memosize + comp->next->next->memosize; temp = comp->next->next; comp->next->next = temp->next; free( temp ); } if( comp->flag == 0 ) { comp ->memosize = comp->memosize + comp->next->memosize; temp = comp->next; comp->next = temp->next; free ( temp ); } return 1; } } return 0; } /*********************************************************************************************/ // 判断数组mm中下标为unit的单元是否被占用， 空闲返回非0，否则返回0 int IsFree(int unit) { NODE comp; char* B; comp = list; B = mm + unit ; /*循环找到单元内存所在结点结点，若结点标志为1则返回0，否则返回1*/ while( comp != NULL ) { if( ( (comp->p ) <= B )&&( ( comp->p ) + comp->memosize -1 >= B ) ) { if( comp->flag == 0 ) return 1; else return 0; } comp = comp->next; } return 0; } /*********************************************************************************************/ // 测试代码 #define MAX_BLOCK_SIZE 1000 #define BLOCK_COUNT 80 struct BLOCK { void* p; int size; }; void PrintMemoryUsage(void); int New(struct BLOCK *pBlocks); int Delete(struct BLOCK *pBlocks); int ranReq(); int ranRel(); int total = 0; int main(void) { struct BLOCK blocks[BLOCK_COUNT] = {0,0}; int ch = 0; int rtn = 1; int i; mm_init(); do { switch (ch) { case 'n': //do{ rtn = New(blocks); //}while(rtn==1); //去掉此处注释可以实现自动分配 break; case 'd': rtn = Delete(blocks); break; case '\n': continue; break; } if(rtn!=-1) { printf("The rate of memory use is: %f \n",((float)(total))/((float)MEM_SIZE)); PrintMemoryUsage(); printf("Input \'n\' to new, \'d\' to delete and \'q\' to quit:"); } else {printf("\nError!!!!\n"); printf("The rate of memory use is: %f \n",((float)(total))/((float)MEM_SIZE));break;} } while ((ch=getchar()) != 'q'&&rtn == 1); /* 删除所有已申请的block */ for (i=0; i<BLOCK_COUNT; i++) { if (blocks[i].p != NULL) { mm_release(blocks[i].p); } } return 0; } /* 打印memory分配情况 */ void PrintMemoryUsage(void) { int i; putchar('\n'); for (i=0; i<MEM_SIZE; i++) { if (IsFree(i)) putchar('-'); else putchar('*'); } putchar('\n'); } /* 新申请block */ int New(struct BLOCK *pBlocks) { int size=ranReq(); while (pBlocks->p != NULL) pBlocks++; pBlocks->p = mm_request(size); pBlocks->size = size; if(total+size<MEM_SIZE) { total+=size; return (pBlocks->p != NULL);} else return(-1); } /* 删除已经申请的block */ int Delete(struct BLOCK *pBlocks) { int i; for (i=0; i<BLOCK_COUNT; i++) { if (pBlocks[i].p != NULL) { printf("%d:%d\t", i, pBlocks[i].size); } } /*打印所有分配的内存情况*/ printf("\nWhich to delete:"); scanf("%d", &i); if (mm_release(pBlocks[i].p)) { pBlocks[i].p = NULL; return !0; } else return 0; } //**********************产生1—50之间的随机数************************************************* int ranReq() { int i; do{i = rand()%20;}while(i==0); //printf("%d\n", rand()%100); return i; }//End random int ranRel() { int i; do{i = rand();}while(i<0||i>=MAX_BLOCK_SIZE); printf("%d\n", i); return i; }//End random*/