Relocation loader using C

IMPLEMENTATION OF RELOCATION LOADER

AIM

To implement relocation loader using C.

ALGORITHM

1.Enter new starting location to which object has ti be relocated.

2.Read the content of the input file as strings one at a time in an array input.

3.Transfer the string read in array input into another array output until it is incremented.

4.Move consecutive next 3 strings into array “output”.

5.Cover current location bit associated with each text record to binary form.

6.Make necessary changes in corresponding words of object code and store the updated object code into array “output”.

7.Move object code for which corresponding  relocation bit is not set directly to the array “output” from array “input” without any change.

8.Repeat step 2 to 8 until end record is encountered.

9.If the object code is in character form ,convert into internal hexadecimal representation.

10.Move object code to specified location in memory

11.Write starting LOCCTR value of block of object code and the corresponding internal hexadecimal representative to the output files.

Absolute loader

IMPLEMENTATION OF ABSOLUTE LOADER

AIM

To implement absolute loader using C.

ALGORITHM

1.Read loader record and filter the starting location and other details.

2.Read the first text record.

3.If the object code is in character form convert it into internal hexadecimal representation.

4.Move object code to specified location in memory.

5.Write starting location couter value of block of object code and corresponding internal hexadecimal representation to the output file.

6.Read next record from the input file.

7.Close all opened files and exit.

PROGRAM:

#include<stdio.h>

C-program for implementing a macro processor.

IMPLEMENTATION OF MACRO PROCESSOR

AIM

To write a C-program for implementing a macro processor.

ALGORITHM

1.Get the state from input file.

2.From the line read,check if opcode is directive “MACRO” if so then number of macro “n” must be incremented.

3.Repeat step 1 and 2 until end of file is encountered.

4.Open “n” number of files in write mode.These files will later hold body of “n” macro respectively.

5.Rewind the input file pointer.

6.If opcode is “MACRO”

7.Enter macro name present in operand file field into array names “m”.

8.Write line to expanded output file.

9.Enter lines in body of each macro into corresponding files already opened in file.

10.Write body of each macro to be expanded output file also until “END” is reached.

11.Else if OPCODE is “CALL” the line must be a macro invocation statement so the macro body is retrieved from the corresponding file.

12.Write all the remaining lines directly to expanded lines.

PROGRAM:

#include<stdio.h>

single pass assembler using C

IMPLEMENTATION OF SINGLE PASS ASSEMBLER

AIM

To implement single pass assembler using C.

ALGORITHM

1.Read first line from the intermediate file.

2.Check to see if the opcode from the first line read is “START”.If so then write label,opcode and operand field values of corresponding statement directly to final output files.

3.Start the following processing for other lines in intermediate file if it is not a comment line until an “END” statement is reached.

4.Start writing labels LOCCTR opcode and operand fields of corresponding statements to the output file along with the object code.The object code is found by assembling each statement opcode machine equivalent with the label address.

5.If there is no symbol or label in the operand field , then the operand address is assigned as zero and it is assembled with object code of instruction.

6.If OPCODE is BYTE,WORD,RESB etc are convert constants to object code close operand file and exit.

PASS2_OF_2_PASS_ASSEMBLER

IMPLEMENTATION OF PASS-2 OF 2-PASS ASSEMBLER

AIM

To write a C-program to implement pass-2  assembler.

ALGORITHM

1.Read first line from the intermediate file.

2.Check to see if the opcode from the first line read is “START”.If so then write label,opcode and operand field values of corresponding statement directly to final output files.

3.Start the following processing for other lines in intermediate file if it is not a comment line until an “END” statement is reached.

4.Start writing labels LOCCTR opcode and operand fields of corresponding statements to the output file along with the object code.The object code is found by assembling each statement opcode machine equivalent with the label address.

5.If there is no symbol or label in the operand field , then the operand address is assigned as zero and it is assembled with object code of instruction.

6.If OPCODE is BYTE,WORD,RESB etc are convert constants to object code close operand file and exit.

PROGRAM:

#include<stdio.h>

PASS1_OF_2_PASS_ASSEMBLER

IMPLEMENTATION OF PASS-1 OF TWO PASS ASSEMBLER

AIM

To write a C-program to implement pass-1 assembler ie object code.

ALGORITHM

1.Read first line from the input file.

2.Check to see if the opcode from the first line read is “START”.If so then write label opcode and            operand field values of corresponding statement directly to find output files.

3.Start the following processing for other lines in input file if it is not a comment line until an “END” statement is reached.

4.Start writing label LOCCTR opcode and operand fields of corresponding statement to the output file along with object code.The object code is found by assembling each statement opcode machine equivalent with label address.

5.If there is no symbol or label in the operand field,then the operand address is assigned as zero and it is assembled with object code of instruction.

6.Ip OPCODE is BYTE,WORD,RESB etc are convert constants to object code.close operand file and exit.

PROGRAM:

#include<stdio.h>

SYMBOL TABLE

SYMBOL TABLE

AIM

To write a program in C to implement symbol table.

ALGORITHM

1.Create a structure having member variable and values

2.Display the option and get choice from the user

3.I f choice 1 call create()

4.If choice 2 call insert()

5.If choice 3 call modify()

6.If choice 4 call search()

7.If choice 5 call display()

8.Exit

9.create()

                Do till less than 3

                Get input from the user for variables and values

10.insert()

                Get number of records to insert.

                a.Do till i is less than sum of I and number of records to insert.

                b.Get input for symbol name and value

11.modify()

                Get record or symbol name to modify

                If it is equal to  any symbol name then print “record found”

                Else print “record not found”

                Get the value for corresponding symbol name

12.search()

                Get the symbol name to modify

If it is present in table then print “record found”

Else print “record not found”

Get the value for corresponding symbol name

13.display()

                Do till k is less than tottal number of records.

                Print the symbil name and values.