FIFO页面置换算法

本文以序列长度20的{ 7,0,1,2,0,3,0,4,2,3,0,3,2,1,2,0,1,7,0,1};以及页面4；为例；

#include <stdio.h>

#define InitPysiBlocks 4
#define MaxPages 20
int PysicalBlocks[InitPysiBlocks] = { -1,-1,-1,-1 };
int PageSequence[MaxPages] = { 7,0,1,2,0,3,0,4,2,3,0,3,2,1,2,0,1,7,0,1};

void FIFO(int py[],int pg[])
{
    int i,q,j,table[InitPysiBlocks][MaxPages];
    char flag,f[MaxPages];
    for (i = 0; i < MaxPages; i++)
    {
        q = 0;
        while(pg[i] != py[q] && q != InitPysiBlocks)
            q++;
        if(q == InitPysiBlocks)
            flag = '*';
        else
            flag = ' ';
        if(flag == '*')
        {
            for (j = InitPysiBlocks - 1; j > 0; j--)
                py[j] = py[j - 1];
            py[0] = pg[i];
        }
        for (j = 0; j < InitPysiBlocks; j++)
            table[j][i] = py[j];
        f[i] = flag;
    }
    printf("输出结果为下表(-1代表为空,*代表有缺页)：
");
    for(i = 0; i < InitPysiBlocks; i++)
    {
        for(j = 0; j < MaxPages; j++)
            printf("%3d",table[i][j]);
        printf("
");
    }
    for(i = 0; i < MaxPages; i++)
        printf("%3c",f[i]);
    printf("
");
}

void main()
{
    FIFO(PysicalBlocks,PageSequence);
}

结果：