C PROGRAM TO DISPLAY TYPE OF A FILE

Hi Friends,

This is my C program to check the type of a file in UNIX system. Before going to program, have a look on what actually a 'type' means in UNIX system. A file may be one of the  following types :

1. Regular File  : It may be either a text file or a binary file.
2. Directory File : These are the files that can store other files (like file folder we use) so that users can organise their files into some hierarchical manner.!!)
3. Character Device File : It refers to a physical device that transmits data in a character-based manner. (like printer, modems, consoles),
4. Block Device File : Similar to character device file, but it can transmit a block  of data at a time.
5. FIFO FILE : A special pipe device file which furnishes a temporary buffer for 2 or more processes to communicate (by writing to / reading data from buffer).

Note: A single device can have both block and character device files representing them for different access methods.Consider F be a character device file on its creation. But F can be used by a hard disk to bulk/ non-blocking data transfer between a process and the disk.

         Here is the complete program. . .

TYPECHECK.C 

 /*
PROGRAM NAME: TYPECHECK.C
AIM : TO READ A FILE NAME AND DISPLAY IT'S TYPE
DATE : 07/31/2011
*/

  #include<stdio.h>                                                                           
  #include<sys/stat.h>                                          
                                                                             
  main ()
 {   
    char file_name[20];
    struct stat p;
    printf("\nEnter filename :  ");
    scanf("%s",file_name);
    stat(file_name,&p);
    printf("\a\n%s is a ",file_name); 
    if(S_ISREG(p.st_mode))
    printf("regular file");
     else if(S_ISDIR(p.st_mode))
     printf("directory file");

     else if(S_ISCHR(p.st_mode))
     printf("character file");
     else if(S_ISBLK(p.st_mode))
     printf("block file");
      else if(S_ISFIFO(p.st_mode))
      printf("FIFO file");
      else
      printf("Unknown type file or not found..!!");
      getch();
     

 }                   



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C PROGRAM TO IMPLEMENT MACRO PROCESSOR

 Here is my C program implementing a Macro Processor. We know that Macro is a single line abbreviation for a group of statements. We should define that sentence - cluster before using them in actual program. Macro processor will analyse the program and on encountering  macro variable, it will replace that 'Macro invocation' to corresponding Macro definition. It should also take care the number  and position of arguments used in Macro invocation.

ALGORITHM

MACROPROCESSOR

• EXPANDING=FALSE.
• Read each line and call GETLINE() and PROCESSLINE() until END encounters.

PROCESSLINE ( )

• If OPCODE is a macroname then EXPAND ( ).
• Else if OPCODE is MACRO ,then DEFINE ( ).
• Else write line to expanded file as such.

DEFINE( )

• Enter Macro name into NMATAB.
• Enter macro prototype into DEFTAB.
• Set LEVEL=1.
• Substitute parameters with positional notations and enter to DEFTAB.
• If OPCODE=MACRO, LEVEL++;
• If OPCODE=MEND, LEVEL--;
• Continue this until LEVEL=0
• Store beginning and end of definition as pointers within NAMTAB

EXPAND ( )

• EXPANDING = TRUE
• Set up arguments from macro invocation in ARGTAB.
• Write macro invocation statement to expanded file  as a comment line.
• Call GETLINE() and PROCESSLINE() till macro definition ends.
• Set EXPANDING=FALSE.

GETLINE ( )

• If EXPANDING is TRUE, read from DEFTAB (data structure where macro body is stored) and substitute arguments for positional notations.
• If  EXPANDING is FALSE , read next line from input file.

MACROPROCESSOR.C

 /*

PROGRAM NAME:MACRO.C

AIM: TO IMPLEMENT MACRO PROCESSOR.

INPUT : "INPUT.TXT"

OUTPUT: "EXPANDED.TXT"

DATE: 07/28/2011

*/

#include<stdio.h>

#include<string.h>

void GETLINE();

void PROCESSLINE();

void DEFINE();

void EXPAND();

 FILE *expanded;

 FILE *input;

 char label[10],opcode[10],operand[25];

 char line[20];

 int namcount=0, defcount=0;

 int EXPANDING;

 int curr;

 struct namtab

 {

 char name[10];

 int start,end;

}mynamtab[15];

     

 struct deftab

 {

        char macroline[25];

  }mydeftab[25];

struct argtab

{

       char arg[3][9];

 }myargtab;

///MACRO MAIN

int main()

{

    EXPANDING=0;

    input =fopen("input.txt","r");                          

 expanded=fopen("expanded.txt","w");

GETLINE();

 

     while(strcmp(opcode,"END")!=0)

{  

     PROCESSLINE();

       GETLINE();

 }

              fprintf(expanded,"%s",line);

      getch();

     return 1;

  }

                            

//   GETLINE

     void GETLINE()

     {    char word1[10],word2[10],word3[10],buff[10];

int count=0,i,j=0;

if(EXPANDING)strcpy(line,mydeftab[curr++].macroline);

 else fgets(line,20,input);

        opcode[0]='\0';label[0]='\0';operand[0]='\0';word1[0]='\0';word2[0]='\0';word3[0]='\0';

        

                      for(i=0;line[i]!='\0';i++)

                      {

                                        

                                                if(line[i]!=' ')

                                                buff[j++]=line[i];

                    

                                                 else

                      {

                                                   

                      buff[j]='\0';

                 

                   

                      strcpy(word3,word2);

                      strcpy(word2,word1);

                       strcpy(word1,buff);

                     j=0;count++;

                      }

                    

                    

                      }

                       buff[j-1]='\0';

                      strcpy(word3,word2);

                      strcpy(word2,word1);

                       strcpy(word1,buff);

                   

   

      switch(count)

                       {

                                    case 0:strcpy(opcode,word1);break;

                                    case 1:{strcpy(opcode,word2);strcpy(operand,word1);}break;

                                    case 2:{strcpy(label,word3);strcpy(opcode,word2);strcpy(operand,word1);}break;

                       }

                   

                     

                       }

                   

//     PROCESSLINE

                       void PROCESSLINE()

                       {

                            int i;

                        for(    i=0;i<namcount;i++)

                      

                                if(!strcmp(opcode,mynamtab[i].name))

                                {

                                                               

                                                                  EXPAND();return;

                                                          

                                                        

                                                             

                                                                  }

                                                           

                                                               { 

                                                                  if(!strcmp(opcode,"MACRO"))

                                                                

                                                                 DEFINE();

                                                               

                                                                 else fprintf(expanded,"%s",line);

                                                                   }

                                                                   }

   

   

     void DEFINE()

     {

          int LEVEL,i=0,j=0,k=0;

       char param[5][9];

       char s[3];

      strcpy(s,"123");

 

          strcpy(mynamtab[namcount].name,label);

          mynamtab[namcount].start=defcount;

          strcpy(mydeftab[defcount].macroline,line);

      

       

          while(operand[i]!='\0')

          {

                                if(operand[i]!=',')

                                param[j][k++]=operand[i];

                                else

                                {

                                    param[j++][k]='\0';

                                

                                    k=0;

                                    }

                              

                               i++;

                                }

                                param[j][k]='\0';

                             

        

          LEVEL=1;

     

        while(LEVEL>0)

          {

                   

            GETLINE();

           

              if(operand[0]!='\0')

             {

            for(i=0;i<3;i++)

            {

            if(!strcmp(operand,param[i]))

            {

            operand[0]='?';

            operand[1]=s[i];

            operand[2]='\0';

             }

             }

             }

           if(!strcmp(opcode,"MACRO"))

            LEVEL++;

           else if(!strcmp(opcode,"MEND"))

            LEVEL--;

            strcpy(mydeftab[defcount].macroline,opcode);

            if(operand[0]!='\0')

            {

            strcat(mydeftab[defcount].macroline," ");

            strcat(mydeftab[defcount].macroline,operand);

            strcat(mydeftab[defcount].macroline,"\n");

            }

            strcat(mydeftab[defcount++].macroline,"\n");

                        }

                        mynamtab[namcount++].end=defcount;

                   

                    

                        }

                      

         

//Expand
        

    void EXPAND()

                        {

                             int i,end=0,j=0,k=0;

                             EXPANDING=1;

                             int arg=0;

                      

                         fprintf(expanded,"//%s",line);

                             for(i=0;i<namcount;i++)

                             {

                             if(!strcmp(opcode,mynamtab[i].name))

                             {

                                                             

                             curr=mynamtab[i].start;

                             end=mynamtab[i].end;

                          

                           

                                   while(operand[i]!='\0')

                                {

                                if(operand[i]!=',')

                                myargtab.arg[j][k++]=operand[i];

                                else

                                {

                                    myargtab.arg[j++][k]='\n';

                                

                                    k=0;

                                    }

                              

                               i++;

                                }                              

                                 myargtab.arg[j][k]='\n';

                           

                        

                             }

                             }

                           

                             while(curr<(end-1))

                             {

                                              GETLINE();

                           if(operand[0]=='?')

                                         

                          strcpy(operand,myargtab.arg[operand[1]-'0'-1]);

                           fprintf(expanded,"%s %s %s",label,opcode,operand);

                        

                             }

                             EXPANDING=0;

                           

                           

                         }



/*************************************************************************************/


  Let us have a look on what will be the output of the program for a sample input.


input.txt



COPY START 1000

RDBUFF MACRO P,Q,R
CLEAR A
CLEAR S
CLEAR X
+LDT #4096
TD P
JEQ *-3
RD P
STCH Q
JLT *-19
LDA R
COMP #0
STX R
MEND

//main program





FIRST STL RETADR
RDBUFF F1,BUFF1,L1
CLEAR X
RDBUFF F2,BUFF2,L2
RDBUFF F3,BUFF3,L3
JLT *-19
STA
END



The output produced will be,

expanded.txt

COPY START 1000
//main program
FIRST STL RETADR
//RDBUFF F1,BUFF1,L1
 CLEAR A
 CLEAR S
 CLEAR X
 +LDT #4096
 TD F1
 JEQ *-3
 RD F1
 STCH BUFF1
 JLT *-19
 LDA L1
 COMP #0
 STX L1
CLEAR X
//RDBUFF F2,BUFF2,L2
 CLEAR A
 CLEAR S
 CLEAR X
 +LDT #4096
 TD F2
 JEQ *-3
 RD F2
 STCH BUFF2
 JLT *-19
 LDA L2
 COMP #0
 STX L2
//RDBUFF F3,BUFF3,L3
 CLEAR A
 CLEAR S
 CLEAR X
 +LDT #4096
 TD F3
 JEQ *-3
 RD F3
 STCH BUFF3
 JLT *-19
 LDA L3
 COMP #0
 STX L3
JLT *-19
STA
END

        

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To Read Student Details and Make Rank List

Here is a simple C program that can be used to input students details. The program can store the details into a file and from that file it can make a rank list which can be written to another file.!! On reading the aim it is obvious that actual file handling may not be in same manner. But this program surely introduce you how Actual file 'read ' and 'write' occurs. Here we go..

STUDENT.C

/*

*PROGRAM NAME:STUDENT.C

*AIM : TO READ STUDENT DETAILS AND MAKE PROGRESS REPORT IN A FILE

*OUTPUT FILE: STUDENT.TXT , PROGRESS. TXT

*DATE: 07/30/2011

*/

#include<stdio.h>
#include<fcntl.h>
struct student
{
       int roll_no,total;
       char Name[10];
        }
       buff,stud[20];
      
       int main()
       {

           int count,i,j;
           int fd=open("STUDENT.TXT",O_WRONLY|O_APPEND);  //open 'student.txt' to write unsorted student-details
           printf("Enter the no. of students..");
           scanf("%d",&count);
           for( i=0;i<count;printf("\n"))
           {
           printf("Student %d\n",++i);
           printf("Roll no : ");
           scanf("%d",&buff.roll_no);
           printf("Name : ");
           scanf("%s",buff.Name);
           printf("Total Marks : ");
           scanf("%d",&buff.total);
           write(fd,&buff,sizeof(buff));  //Store each data in a "buffer" structure and append to 'student.txt'..
           }                                            
            close(fd);
            
             fd=open("STUDENT.TXT",O_RDONLY);
            int fd2=open("PROGRESS.TXT",O_WRONLY);
            count=0;
            while(read(fd,&buff,sizeof(buff))>0)  //Open 'student.txt' in read mode and copy data to structure-array..
                 stud[count++]=buff;
                
               for(i=0;i<count;i++)                //Sort the details in structure array
               for(j=0;j< count-i-1;j++)
               if(stud[j].total<stud[j+1].total)
               {
                buff=stud[j];
                stud[j]=stud[j+1];
                stud[j+1]=buff;
                }
               for(i=0;i<count;i++)
               write(fd2,&stud[i],sizeof(stud[i]));//Write back the sorted details to 'progress.txt'..
               close(fd2);
               close(fd);
               fd2=open("PROGRESS.TXT",O_RDONLY); //Open 'progress.txt' file to read and display ranklist 
               printf("\n\tPROGRESS REPORT\n\t_______________\n\n\n RANK\t NAME \tROLLNO\tMARKS\n\n");
               i=0;
               while(read(fd2,&buff,sizeof(buff))>0)
               printf("\n (%d)\t%s\t%d\t%d",++i,buff.Name,buff.roll_no,buff.total);
               getch();
                           }

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Display the Contents of a Directory

    Here is a simple program to open and display the contents of a directory.

                                             

 DIRECTORY.C

/*

PROGRAM NAME:DIRECTORY.C

AIM:TO DISPLAY THE CONTENTS OF A DIRCTORY

DATE:07/30/2011

*/

#include<stdio.h>

#include<dirent.h>

main()

{

char dirname[10];

DIR *ptr;

struct dirent *dir;

printf("Enter the directory Name..");

scanf("%s",dirname);

ptr=opendir(dirname);

printf("\nContents in %s are..\n",dirname);

while((dir=readdir(ptr))!=NULL)

printf("%s\n",dir->d_name);

getch();

closedir(ptr);

}

Note

• System calls for directory operations are included in the header file <dirent.h>.
• opendir: Opens afile directory.
• closedir: Closes a directory.
• readdir : Reads the next record from file.
• rewinddir: Sets file pointer to the beginning of file.

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IMPLEMENTATION OF TWO PASS ASSEMBLER IN C

Hi friends,

Here I'm posting a complete C program to implement a two pass assembler. A 2-pass assembler is a program that accepts an assembly language program as input and produces its machine language equivalent along with the information for the loader. The assembling of source program to object code requires to accomplish following functions.

• Convert mnemonic opcodes to their machine language equivalent.(e.g, LDA to 00)
• Convert symbolic operands to their equivalent machine address   (eg, LOOP to 2045)
• Allocate necessary memory.
• Convert data constants to internal machine equivalents.
• Write the object program and assembly listing.    

                      A two pass assembler do these functions in two passes ,i.e., two times the input programs will be scanned/processed.

 PASS 1

1. Assign addresses to all statements in the program.
2. Addresses of symbolic labels are stored.
3. Some assemble directives will be processed.

PASS 2

1. Translate opcodes and symbolic operands.
2. Generate data values defined by BYTE,WORD etc.
3. Assemble directives will be processed.
4. Write the object program and assembly listing.

  The following C program take assembly program saved in "input.txt" and in pass 1 write intermediate code to "inter.txt". After pass - 2 Object program will be written to "output.txt".

                                                          ASSEMBLER.C

/*
PROGRAM NAME: ASSEMBLER.C
AIM: TO IMPLEMENT A TWO-PASS ASSEMBLER
INPUT: "input.txt"
OUTPUT: "inter.txt" , "output.txt"
DATE: 08/09/2011
*/


 #include<stdio.h>
#include<string.h>
void chk_label();
void chk_opcode();
void READ_LINE();
struct optab
{
    char   code[10],objcode[10];
}myoptab[3]={
                   {"LDA","00"},
                   {"JMP","01"},
                   {"STA","02"}
             };
                  
                  
struct symtab{
                    char symbol[10];
                    int addr;
              }mysymtab[10];
                   
int startaddr,locctr,symcount=0,length;
char line[20],label[8],opcode[8],operand[8],programname[10];
                   
//                void PASS1()
                  {
                       FILE *input,*inter;                                  
                       input=fopen("input.txt","r");                            
                       inter=fopen("inter.txt","w");
                        printf("LOCATION LABEL\tOPERAND\tOPCODE\n");
                        printf("_____________________________________");                      
                        fgets(line,20,input);
                     
                      READ_LINE();
                     
                     if(!strcmp(opcode,"START"))
                      {
                     
                       startaddr=atoi(operand);
                       locctr=startaddr;                    
                      strcpy(programname,label);
                      
                           fprintf(inter,"%s",line);
                       fgets(line,20,input);
                       }
                      else
                      {
                          programname[0]='\0';
                          startaddr=0;
                          locctr=0;
                      }
                         printf("\n %d\t %s\t%s\t %s",locctr,label,opcode,operand); 
                         
                           while(strcmp(line,"END")!=0)
                          {
                  
                                   READ_LINE();
                                   printf("\n %d\t %s \t%s\t %s",locctr,label,opcode,operand);
                                   if(label[0]!='\0')chk_label();
                                   chk_opcode();
                                   fprintf(inter,"%s %s %s\n",label,opcode,operand);
                                   fgets(line,20,input);
                          }
                         
                   printf("\n %d\t\t%s",locctr,line);
                   fprintf(inter,"%s",line);
 
                    fclose(inter);
                    fclose(input);
                      }
//=====================================================================================================================================                     
          void PASS2()
          {
                FILE *inter,*output;
                char record[30],part[6],value[5];
                int currtxtlen=0,foundopcode,foundoperand,chk,operandaddr,recaddr=0;
                inter=fopen("inter.txt","r");
                output=fopen("output.txt","w");
                fgets(line,20,inter);
              
                READ_LINE();
                if(!strcmp(opcode,"START")) fgets(line,20,inter);
               printf("\n\nCorresponding Object code is..\n");
               printf("\nH^ %s ^ %d ^ %d ",programname,startaddr,length);
               fprintf(output,"\nH^ %s ^ %d ^ %d ",programname,startaddr,length);
               recaddr=startaddr; record[0]='\0';
               while(strcmp(line,"END")!=0)
                          {
                                             operandaddr=foundoperand=foundopcode=0;
                                             value[0]=part[0]= '\0';
                                             READ_LINE();
           for(chk=0;chk<3;chk++)
             {
               if(!strcmp(opcode,myoptab[chk].code))
               {                                    
               foundopcode=1;
               strcpy(part,myoptab[chk].objcode);
            
             if(operand[0]!='\0')
             {
             for(chk=0;chk<symcount;chk++)
                                  
             if(!strcmp(mysymtab[chk].symbol,operand))
             {
             itoa(mysymtab[chk].addr,value,10);
             strcat(part,value);
             foundoperand=1;
             }
              if(!foundoperand)strcat(part,"err");
              }
              }
              }
               if(!foundopcode)
               {
                               if(strcmp(opcode,"BYTE")==0 || strcmp(opcode,"WORD")||strcmp(opcode,"RESB"))
                               {strcat(part,operand);
                              }}
               if((currtxtlen+strlen(part))<=8)
               {
                strcat(record,"^");
                strcat(record,part);
               
                currtxtlen+=strlen(part);
               }
                else
                {
                 printf("\nT^ %d ^%d %s",recaddr,currtxtlen,record);
                 fprintf(output,"\nT^ %d ^%d %s",recaddr,currtxtlen,record);
                 recaddr+=currtxtlen;
                 currtxtlen=strlen(part);
                 strcpy(record,part);
               
              
              
                }
          fgets(line,20,inter);
                }  
                      printf("\nT^ %d ^%d %s",recaddr,currtxtlen,record);
                      fprintf(output,"\nT^ %d ^%d %s",recaddr,currtxtlen,record);
                      printf("\nE^ %d\n",startaddr);
                      fprintf(output,"\nE^ %d\n",startaddr);
                      fclose(inter);
                      fclose(output);
       }          
//=================================================
 
       void READ_LINE()
       {
            char buff[8],word1[8],word2[8],word3[8];
            int i,j=0,count=0;
             label[0]=opcode[0]=operand[0]=word1[0]=word2[0]=word3[0]='\0';
                 for(i=0;line[i]!='\0';i++)
                      {
                   if(line[i]!=' ')buff[j++]=line[i];
                   else
                      {
                     buff[j]='\0';
                     strcpy(word3,word2);strcpy(word2,word1);strcpy(word1,buff);
                     j=0;count++;
                      }
                      }
                      buff[j-1]='\0';
                      strcpy(word3,word2);
                      strcpy(word2,word1);
                      strcpy(word1,buff);
                    switch(count)
                       {
                                    case 0:strcpy(opcode,word1);break;
                                    case 1:{strcpy(opcode,word2);strcpy(operand,word1);}break;
                                    case 2:{strcpy(label,word3);strcpy(opcode,word2);strcpy(operand,word1);}break;
                       }
                       }
//======================================================
            void chk_label()
                  {
                       int k,dupsym=0;
                     for(k=0;k<symcount;k++)
                     if(!strcmp(label,mysymtab[k].symbol))
                     {
                                                          mysymtab[k].addr=-1;
                                                          dupsym=1;
                                                          break;
                                                          }
               if(!dupsym)
               {
               strcpy(mysymtab[symcount].symbol,label);
               mysymtab[symcount++].addr=locctr;
                }
                }
//  =====================================================     
  void chk_opcode()
         {
                      
          int k=0,found=0;
          for(k=0;k<3;k++)
         
                   
                          if(!strcmp(opcode,myoptab[k].code))
                          {
                                                          
                                                     locctr+=3;
                                                  
                                                     found=1;
                                                     break;            
                           }
              if(!found)
              {
                        if(!strcmp( opcode,"WORD")) locctr+=3;
                        else if (!strcmp(opcode,"RESW"))locctr+=(3*atoi(operand));
                        else if(!strcmp(opcode,"RESB"))locctr+=atoi(operand);
               }
    }
            
//==================================================
  int main()
                    {
                    
                   
                        PASS1();
                        length=locctr-startaddr;
                        PASS2();                                              
                        getch();
                    }    

/*

Do not forget to create "input.txt","inter.txt" and "output.txt" prior to run this program. For sake of simplicity, only a few opcodes are included in this program. So for better results try to include input programs with these opcodes.

Here is one sample program (of course, it has no logic..)

input.txt

MYPGM START 1000
STA
LOOP1 JMP LOOP2
LDA
LOOP2 JMP LOOP1
RESB 04
LDA
STA
JMP LOOP1
END

inter.txt

MYPGM START 1000
STA
LOOP1 JMP LOOP2
LDA
LOOP2 JMP LOOP1
RESB 04
LDA
STA
JMP LOOP1
END

 output.txt

H^ MYPGM ^ 1000 ^ 25
T^ 1000 ^8 ^02^011009
T^ 1008 ^8 00^011003
T^ 1016 ^6 04^00^02
T^ 1022 ^6 011003
E^ 1000

                                                    Happy programming..!!!!!!!

*/

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