C语言实现分页式存储系统位示图管理：多进程内存分配与错误处理

```c #include <stdio.h> #include <stdbool.h> #define BLOCKS 64 // 总共的块数 // 模拟位示图，0 表示未分配，1 表示已分配 int bitmap[BLOCKS] = {0}; // 已经被占用的块号 int occupied_blocks[] = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19}; int occupied_count = sizeof(occupied_blocks) / sizeof(occupied_blocks[0]); // 标记已占用的块 void mark_occupied() { for (int i = 0; i < occupied_count; i++) { bitmap[occupied_blocks[i]] = 1; } } // 分配内存块 int allocate_blocks(int process_id, int blocks_needed) { int start_block = -1; int consecutive_blocks = 0; for (int i = 0; i < BLOCKS; i++) { if (bitmap[i] == 0) { if (start_block == -1) { start_block = i; } consecutive_blocks++; if (consecutive_blocks == blocks_needed) { // 找到了足够的连续块 for (int j = start_block; j < start_block + blocks_needed; j++) { bitmap[j] = 1; } return start_block; } } else { start_block = -1; consecutive_blocks = 0; } } // 没有足够的连续块 return -1; } // 主函数 int main() { int requests[4]; int process_id, page_number; // 初始化位示图 mark_occupied(); // 读取四个进程的请求 for (int i = 0; i < 4; i++) { scanf("%d", &requests[i]); } // 读取进程编号和页号 scanf("%d %d", &process_id, &page_number); // 检查进程编号是否有效 if (process_id < 1 || process_id > 4) { printf("error\n"); return 0; } // 检查页号是否合理 if (page_number < 0 || page_number >= 54) { printf("error\n"); return 0; } // 计算进程需要的总块数 int blocks_needed = requests[process_id - 1]; // 分配内存块 int start_block = allocate_blocks(process_id, blocks_needed); if (start_block == -1) { // 没有足够的连续块 printf("wait\n"); } else { // 计算页号对应的块号 int block_number = start_block + page_number; if (block_number < start_block || block_number >= start_block + blocks_needed) { printf("error\n"); } else { printf("%d\n", block_number); } } return 0; } ``` 需要注意的逻辑点： 1. 边界检查：确保进程编号和页号在合理范围内。 2. 连续块分配：在位示图中找到足够多的连续空闲块。 3. 错误处理：当没有足够的连续块时，进程需要等待。 ######[AI写代码神器 | 740点数解答 | 2024-12-02 10:42:06]