使用C语言实现BITMAP的调度算法的实例

BITMAP调度算法是一种常用的内存管理算法，用于管理分配和释放内存块。下面是一个使用C语言实现BITMAP调度算法的示例代码：

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

#define MAX_BLOCKS 1024
#define BLOCK_SIZE 4096

typedef struct {
    unsigned char* bitmap;
    unsigned char* memory;
} BitmapScheduler;

BitmapScheduler* createScheduler() {
    BitmapScheduler* scheduler = (BitmapScheduler*)malloc(sizeof(BitmapScheduler));
    scheduler->bitmap = (unsigned char*)calloc(MAX_BLOCKS / 8, sizeof(unsigned char));
    scheduler->memory = (unsigned char*)malloc(MAX_BLOCKS * BLOCK_SIZE * sizeof(unsigned char));
    return scheduler;
}

void destroyScheduler(BitmapScheduler* scheduler) {
    free(scheduler->bitmap);
    free(scheduler->memory);
    free(scheduler);
}

void* allocateBlock(BitmapScheduler* scheduler) {
    for (int i = 0; i < MAX_BLOCKS; i++) {
        int byteIndex = i / 8;
        int bitIndex = i % 8;

        if ((scheduler->bitmap[byteIndex] & (1 << bitIndex)) == 0) {
            scheduler->bitmap[byteIndex] |= (1 << bitIndex);
            return scheduler->memory + (i * BLOCK_SIZE);
        }
    }

    return NULL;
}

void freeBlock(BitmapScheduler* scheduler, void* block) {
    int blockIndex = ((unsigned char*)block - scheduler->memory) / BLOCK_SIZE;
    int byteIndex = blockIndex / 8;
    int bitIndex = blockIndex % 8;

    scheduler->bitmap[byteIndex] &= ~(1 << bitIndex);
}

void printBitmap(BitmapScheduler* scheduler) {
    printf("Bitmap:\n");
    for (int i = 0; i < MAX_BLOCKS; i++) {
        int byteIndex = i / 8;
        int bitIndex = i % 8;

        bool allocated = (scheduler->bitmap[byteIndex] & (1 << bitIndex)) != 0;
        printf("%d ", allocated);

        if ((i + 1) % 32 == 0) {
            printf("\n");
        }
    }
}

int main() {
    BitmapScheduler* scheduler = createScheduler();

    // 分配内存块
    void* block1 = allocateBlock(scheduler);
    void* block2 = allocateBlock(scheduler);
    void* block3 = allocateBlock(scheduler);

    // 释放内存块
    freeBlock(scheduler, block2);

    // 打印位图
    printBitmap(scheduler);

    destroyScheduler(scheduler);

    return 0;
}

这个示例代码实现了BITMAP调度算法的内存分配和释放功能。通过`allocateBlock`函数可以分配一个内存块，通过`freeBlock`函数可以释放一个内存块。`printBitmap`函数用于打印当前的位图情况。

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