mkhd.cpp

Jazmyn is a 32-bit, protected mode, multitasking OS which runs on i386 & above CPU`s. Its complete

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<iostream>
#include<fstream>

#define TOTSEC  20160
#define IMGSZ   TOTSEC*512
#define PARTSEC (TOTSEC - 63)
#define FATENT  (PARTSEC/8)
#define EOC     0x0FFFFFFF

#define FAIL(file)  do{\
printf("read failed :%s\n",file);\
exit(0);\
}while(0)

typedef unsigned char byte;
typedef unsigned short ushort;
typedef unsigned int uint;

typedef struct
{
        byte	dir_name[11];
        byte	dir_attr;
        byte	dir_NTres;
        byte	crt_time_tenth;
        ushort	dir_crt_time;
        ushort	dir_crt_date;
        ushort	dir_lst_acc_date;
        ushort	dir_fst_clusHI;
        ushort	dir_wrt_time;
        ushort	dir_wrt_date;
        ushort	dir_fst_clusLO;
        uint	dir_file_size;

}fdir;

void openfile(std::ifstream &i,char *name,unsigned *sz)
{
        i.open(name,std::ios::binary);
        if(!i)
        {
                printf("%s failed\n",name);
                exit(0);
        }
        if(sz)
        {
                i.seekg(0,std::ios::end);
                *sz = i.tellg();
                printf("%s size : %d\n",name,*sz);
                i.seekg(0,std::ios::beg);
        }
}

void readfile(std::ifstream &i,char *buf,int sz)
{
        i.read(buf,sz);
        if(!i.gcount())
        {
                printf("read failed\n");
                exit(0);
        }
}

int main()
{
        char *buf = new char[IMGSZ];
        char *obuf = buf;
        if(!buf)
        {
                printf("buffer failed\n");
                exit(0);
        }
        std::ifstream i;
        unsigned s1,s2,s3,s4,s5,s6,s7;

        openfile(i,"mbr.com",&s1);
        readfile(i,buf,s1);
        i.close();
        buf += 63*512;
        uint t = (uint)buf + 32*512;
        

        openfile(i,"boot1.com",&s2);
        readfile(i,buf,s2);
        i.close();
        buf += s2;

        openfile(i,"boot2.com",&s3);
        readfile(i,buf,s3);
        i.close();
        buf += s3;

        openfile(i,"load.com",&s4);
        readfile(i,buf,s4);
        i.close();
        buf += s4;

        buf = (char*)t;

        uint fatsec = (FATENT*4)/512;
        if((FATENT*4)%512) fatsec++;

        t = (uint)buf + fatsec*512;

        uint *fat = (uint*)buf;
        fat[0] = 0xFFFFFFFF;
        fat[1] = 0xFFFFFFFF;
        int j;
        for(j=2;j<FATENT;j++)
        {
                fat[j] = 0;
        }
        buf =(char*)t; 
        fdir *dir = (fdir*)buf;
        strncpy((char*)dir->dir_name,"KER     COM",11);
        dir->dir_fst_clusHI = 0;
        dir->dir_fst_clusLO = 3;
        dir->dir_file_size = s5;

        fat[2] = EOC;

        t = (uint)buf + 4096;
        buf += sizeof(fdir);
        dir = (fdir*)buf;
        buf += sizeof(fdir);
        fdir *dirs = (fdir*)buf;

        buf = (char*)t;


        openfile(i,"ker.com",&s5);
        readfile(i,buf,s5);
        i.close();
        
        j = 3;
        for(int ks=0;ks<s5;ks+=4096)
        {
              fat[j] = j+1;
              j++;
              buf += 4096;
        }
        fat[j-1] = EOC;
        printf("kernel end clus: %d\n",j-1);        

        openfile(i,"init.com",&s6);
        readfile(i,buf,s6);
        i.close();

        strncpy((char*)dir->dir_name,"INIT    COM",11);
        dir->dir_fst_clusHI = 0;
        dir->dir_fst_clusLO = j;
        dir->dir_file_size = s6;
        

        for(int is=0;is<s6;is+=4096)
        {
                fat[j] = j+1;
                j++;
                buf += 4096;
        }
        fat[j-1] = EOC;


        openfile(i,"shell.com",&s7);
        readfile(i,buf,s7);
        i.close();

        strncpy((char*)dirs->dir_name,"SHELL   COM",11);
        dirs->dir_fst_clusHI = 0;
        dirs->dir_fst_clusLO = j;
        dirs->dir_file_size = s7;


        printf("start of shell %d\n",j);
        for(int ss=0;ss<s7;ss+=4096)
        {
                fat[j] = j+1;
                j++;
        }
        fat[j-1] = EOC;

        

        std::ofstream of("jazmyn",std::ios::trunc|std::ios::binary);
        of.write(obuf,IMGSZ);
        of.close();



        delete obuf;
        return 0;
}