可变式分区实验c语言

实现可变大小分区分配方式的C语言代码如下：

#include <stdio.h>
#include <stdlib.h>

#define MAX_MEM_SIZE 1024 // 内存大小
#define MIN_MEM_SIZE 32 // 最小分区大小
#define MAX_BLOCKS 32 // 最多分区数

int mem_size = MAX_MEM_SIZE; // 实际内存大小
int block_count = 0; // 分区数
int block_size[MAX_BLOCKS]; // 分区大小
int block_start[MAX_BLOCKS]; // 分区起始地址
int block_used[MAX_BLOCKS]; // 分区是否被使用

void init() {
    int i;
    for (i = 0; i < MAX_BLOCKS; i++) {
        block_used[i] = 0;
    }
    block_count = 1;
    block_size[0] = mem_size;
    block_start[0] = 0;
    block_used[0] = 0;
}

void split_block(int index, int size) {
    int i;
    for (i = block_count - 1; i >= index; i--) {
        block_size[i + 1] = block_size[i];
        block_start[i + 1] = block_start[i];
        block_used[i + 1] = block_used[i];
    }
    block_count++;
    block_size[index] = size;
    block_start[index] = block_start[index - 1] + block_size[index - 1];
    block_used[index] = 0;
    block_size[index - 1] -= size;
}

int allocate(int size) {
    int i;
    for (i = 0; i < block_count; i++) {
        if (block_used[i] == 0 && block_size[i] >= size) {
            if (block_size[i] > size + MIN_MEM_SIZE) {
                split_block(i + 1, size);
            }
            block_used[i] = 1;
            return block_start[i];
        }
    }
    return -1;
}

void deallocate(int start) {
    int i;
    for (i = 0; i < block_count; i++) {
        if (block_start[i] == start) {
            block_used[i] = 0;
            if (i != 0 && block_used[i-1] == 0) {
                block_size[i-1] += block_size[i];
                block_count--;
                for (; i < block_count; i++) {
                    block_size[i] = block_size[i+1];
                    block_start[i] = block_start[i+1];
                    block_used[i] = block_used[i+1];
                }
            }
            if (i != block_count-1 && block_used[i+1] == 0) {
                block_size[i] += block_size[i+1];
                block_count--;
                for (; i < block_count; i++) {
                    block_size[i+1] = block_size[i+2];
                    block_start[i+1] = block_start[i+2];
                    block_used[i+1] = block_used[i+2];
                }
            }
            break;
        }
    }
}

void display() {
    int i;
    printf("Memory Map:\n");
    for (i = 0; i < block_count; i++) {
        printf("Block %d: [%d-%d] %d bytes %s\n", i, block_start[i], block_start[i]+block_size[i]-1, block_size[i], block_used[i]?"(used)":"(free)");
    }
}

int main() {
    int choice, size, start;
    init();
    do {
        printf("\n1. Allocate memory\n2. Deallocate memory\n3. Display memory map\n4. Exit\nEnter your choice: ");
        scanf("%d", &choice);
        switch(choice) {
            case 1:
                printf("Enter size: ");
                scanf("%d", &size);
                start = allocate(size);
                if (start == -1) {
                    printf("Memory allocation failed!\n");
                } else {
                    printf("Memory allocated at address %d\n", start);
                }
                break;
            case 2:
                printf("Enter start address: ");
                scanf("%d", &start);
                deallocate(start);
                break;
            case 3:
                display();
                break;
            case 4:
                exit(0);
            default:
                printf("Invalid choice!\n");
        }
    } while (1);
    return 0;
}

这段代码实现了可变大小分区分配方式的内存管理。其中，`init()`函数用于初始化内存分区，`allocate(int size)`函数用于分配指定大小的内存块，`deallocate(int start)`函数用于释放指定起始地址的内存块，`display()`函数用于显示内存分区状态。在主函数中，通过菜单选项来选择不同的操作。