📅  最后修改于: 2023-12-03 15:39:53.074000             🧑  作者: Mango
在计算机系统中,动态分区是一种用于内存管理的技术,即将内存划分为多个区域,每个区域可以单独分配和释放,以提高内存利用率。当需要更多内存或释放一些内存时,操作系统会自动调整内存分区。
常见的分配算法包括:
下面是一个动态分区分配的示例代码:
#include <stdio.h>
#include <stdlib.h>
struct Node {
int start;
int size;
struct Node* next;
};
struct Node* head = NULL;
void print_list() {
struct Node* cur = head;
printf("[ ");
while (cur != NULL) {
printf("(%d,%d) ", cur->start, cur->size);
cur = cur->next;
}
printf("]\n");
}
void init_list(int mem_size) {
head = (struct Node*)malloc(sizeof(struct Node));
head->start = 0;
head->size = mem_size;
head->next = NULL;
}
void insert_node(struct Node* prev, int start, int size) {
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
new_node->start = start;
new_node->size = size;
new_node->next = prev->next;
prev->next = new_node;
}
void delete_node(struct Node* prev) {
struct Node* temp = prev->next;
prev->next = temp->next;
free(temp);
}
void allocate_mem(int size) {
struct Node* cur = head;
while (cur != NULL) {
int avail_size = cur->size;
if (!cur->next) {
avail_size = cur->size - cur->start;
} else {
avail_size = cur->next->start - cur->start - cur->size;
}
if (avail_size >= size) {
insert_node(cur, cur->start + cur->size, size);
cur->size = cur->size + size;
break;
}
cur = cur->next;
}
}
void free_mem(int start) {
struct Node* cur = head;
while (cur->next != NULL && cur->next->start != start) {
cur = cur->next;
}
cur->size = cur->size + cur->next->size;
delete_node(cur);
// Merge free memory
if (cur->next != NULL && cur->next->start == cur->start + cur->size) {
cur->size = cur->size + cur->next->size;
delete_node(cur);
}
}
int main() {
init_list(1024); // Initialize memory list with 1024 bytes
allocate_mem(256); // Allocate 256 bytes
allocate_mem(512); // Allocate another 512 bytes
free_mem(256); // Free 256 bytes from memory
allocate_mem(128); // Allocate 128 bytes
print_list(); // Print current memory list
return 0;
}
以上示例代码实现了动态分区分配和释放。使用 print_list()
函数可以打印当前的内存分区情况。