Disassembler.cpp File Reference

#include <iostream>
#include <string>
#include <vector>
#include <fstream>
#include <cmath>

Macros
#define	size_of_instruction_hex   8

Functions
string	convert_to_binary (char num)
	This function converts given character to its Binary format.
int	binary_to_decimal (int token, string binary)
	Converts the given Binary value to Decimal value.
string	sub_string (string parent, int start, int end)
	This function is used extract substring from string.
string	R_format (const string &stringBinary)
	If the given machine code represents RISC-V R-format instruction this function generates RISC-V instruction from the machine code.
string	I_format_immediate (const string &stringBinary)
	If the given machine code represents RISC-V I-format instruction this function generates RISC-V instruction from the machine code.
string	I_format_load (const string &stringBinary)
	If the given machine code represents RISC-V I-format load instruction type this function generates RISC-V instruction from the machine code.
string	S_format (const string &stringBinary)
	If the given machine code represents RISC-V S-format this function generates RISC-V instruction from the machine code.
string	B_format (string stringBinary, int inst_no, int total_instructions)
	If the given machine code represents RISC-V B-format this function generates RISC-V instruction from the machine code.
string	jal (string stringBinary, int inst_no, int total_instructions)
	If the given machine code represents RISC-V jal format this function generates RISC-V instruction from the machine code.
string	jalr (const string &stringBinary)
	If the given machine code represents RISC-V jalr format this function generates RISC-V instruction from the machine code.
string	lui (const string &stringBinary)
	If the given machine code represents RISC-V lui format this function generates RISC-V instruction from the machine code.
string	disassembler (int total_instructions, string instruction, int inst_no)
	This function conversion of given machine code to binary value is done and based on opcode the corresponding instruction type is found and is processed accordingly.
void	program ()
	This function reads machine code and each machine code is sent to disassembler() for further processing.
int	main ()
	Main function where program execution starts.

Detailed Description

This file contains the code for Disassembler of RISC-V machine code

Author

Anudeep Rao Perala

Function Documentation

B_format()

string B_format	(	string	stringBinary,
		int	inst_no,
		int	total_instructions
	)

If the given machine code represents RISC-V B-format this function generates RISC-V instruction from the machine code.

B-format instructions are: beq, bne, blt, bge, bltu, bgeu

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

RISC-V instruction

binary_to_decimal()

int binary_to_decimal	(	int	token,
		string	binary
	)

Converts the given Binary value to Decimal value.

Parameters

token	This is used to specify if the given binary value is in it's signed/ unsigned format
binary	Binary value

Returns

Decimal value

convert_to_binary()

string convert_to_binary

(

char

num

)

This function converts given character to its Binary format.

Parameters

num

Input

Returns

This function returns binary number format of the input character for concatenation

disassembler()

string disassembler	(	int	total_instructions,
		string	instruction,
		int	inst_no
	)

This function conversion of given machine code to binary value is done and based on opcode the corresponding instruction type is found and is processed accordingly.

Parameters

total_instructions	Total number of instructions given as input
instruction	This is machine code of the RISC-V instruction
inst_no	States the instruction number

Returns

Disassembled RISC-V instruction

I_format_immediate()

string I_format_immediate

(

const string &

stringBinary

)

If the given machine code represents RISC-V I-format instruction this function generates RISC-V instruction from the machine code.

I-format instructions are: addi, xori, ori, andi, slli, srli, srai

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

RISC-V instruction

I_format_load()

string I_format_load

(

const string &

stringBinary

)

If the given machine code represents RISC-V I-format load instruction type this function generates RISC-V instruction from the machine code.

I-format load instructions are: ld, lh, lw, lbu, lhu, lwu

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

RISC-V instruction

jal()

string jal	(	string	stringBinary,
		int	inst_no,
		int	total_instructions
	)

If the given machine code represents RISC-V jal format this function generates RISC-V instruction from the machine code.

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

jal RISC-V instruction

jalr()

string jalr

(

const string &

stringBinary

)

If the given machine code represents RISC-V jalr format this function generates RISC-V instruction from the machine code.

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

jalr RISC-V instruction

lui()

string lui

(

const string &

stringBinary

)

If the given machine code represents RISC-V lui format this function generates RISC-V instruction from the machine code.

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

lui RISC-V instruction

main()

int main

(

)

Main function where program execution starts.

Returns

0

program()

void program

(

)

This function reads machine code and each machine code is sent to disassembler() for further processing.

At a time single machine code is processed and corresponding RISC-V instruction is generated, labelling of jump operations is taken care in this function

Returns

R_format()

string R_format

(

const string &

stringBinary

)

If the given machine code represents RISC-V R-format instruction this function generates RISC-V instruction from the machine code.

R-format instructions are: add, sub, xor, or, and, sll, srl, sra

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

RISC-V instruction

S_format()

string S_format

(

const string &

stringBinary

)

If the given machine code represents RISC-V S-format this function generates RISC-V instruction from the machine code.

S-format instructions are: sb, sh, sw, sd

Parameters

stringBinary

RISC-V instruction machine code from which the RISCV instruction is generated

Returns

RISC-V instruction

sub_string()

string sub_string	(	string	parent,
		int	start,
		int	end
	)

This function is used extract substring from string.

Parameters

parent	Parent string from which substring is generated
start	Starting index of element in parent string
end	End index of element in parent string

Returns

Substring from parent string