bfmap.c

操作系统课程设计 有进程同步问题 内存管理 设备管理

/***************************************************************************
 *   Copyright (C) 2004 by root                                            *
 *   root@simplymepis                                                      *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#define MAPSIZE 100

struct map  //存储资源表结构
{
    /*  char *m_size;
    char *m_addr;
    */
    int m_addr;
    int m_size;

};

struct map map[MAPSIZE];   //存储资源表

int BF_malloc(struct map *mp,int size)  //存储分配函数
{
    register int a,s;
    register struct map *bp,*bpp;

    for(bp = mp; bp->m_size; bp++)
    {
        if (bp->m_size >= size)
        {
            a = bp->m_addr;
            s = bp->m_size;
            for(bpp = bp; bpp->m_size; bpp++)//find the best fit
            {
                if(bpp->m_size >= size && bpp->m_size < s)
                {
                    a = bpp->m_addr;
                    s = bpp->m_size;
                    bp = bpp;
                }
            }
            bp->m_addr += size;
            if ((bp->m_size -=size) == 0)
                do
                {
                    bp++;
                    (bp-1)->m_addr = bp->m_addr;
                }
                while((bp-1)->m_size = bp->m_size);
            return(a);
        }
    }
    return(-1);
}

void mfree(struct map *mp,int aa,int size)  //存储释放函数
{
    register struct map *bp;
    register int t;
    register int a;

    a = aa;
    for(bp = mp; bp->m_addr<=a && bp->m_size != 0; bp++)
        ;
    if(bp>mp && (bp-1)->m_addr+(bp-1)->m_size==a)
    {   //与前合并
        (bp-1)->m_size += size;
        if (a+size == bp->m_addr)
        {   //前后合并
            (bp-1)->m_size += bp->m_size;
            while (bp->m_size)
            {
                bp++;
                (bp-1)->m_addr = bp->m_addr;
                (bp-1)->m_size = bp->m_size;
            }
        }
    }
    else
    {
        if (a+size == bp->m_addr && bp->m_size)
        {   //与后合并
            bp->m_addr -= size;
            bp->m_size += size;
        }
        else if (size)
            do
            {    //无合并
                t = bp->m_addr;
                bp->m_addr = a;
                a = t;
                t = bp->m_size;
                bp->m_size = size;
                bp++;
            }
            while (size = t);
    }
}

void init()
{
    struct map *bp;
    int addr,size;
    int i=0;
    bp=map;
    printf("Please input starting addr and total size:");
    scanf("%d,%d",&addr,&size);
    bp->m_addr=addr;
    bp->m_size=size;
    (++bp)->m_size=0;  //表尾
}

void show_map()
{
    int i=0;
    system("clear"); //调用清屏命令
    struct map *bp;
    bp=map;
    printf("\nCurrent memory map...\n");
    printf("Address\t\tSize\n");
    while(bp->m_size!=0)
    {
        printf("<%d\t\t%d>\n",bp->m_addr,bp->m_size);
	bp++;
    }
    printf("\n");
}

main()
{
    int a,s;
    int c;
    int i;
    init();
    do
    {
        //显示存储分配表
        show_map();
        printf("Please input, 1 for request,2 for release, 0 for exit:");
        scanf("%d",&c);
        switch(c)
        {
        case 1:
            printf("Please input size:");
            scanf("%d", &s);
            if((a=BF_malloc(map,s))==-1)    //call malloc
                printf("request can't be satisfied\n");
            else
                printf("alloc memory at address:%d,size:%d\n",a,s);
            break;
        case 2:
            printf("Please input addr and size:");
            scanf("%d,%d",&a,&s);
            mfree(map,a,s);
            break;
        case 0:
            exit(0);
        }
    }
    while(1);
}