jorgezafra94 / monty

:abc: Interpreter of Monty ByteCode files

Monty

monty is an interpreter of Monty ByteCodes files, which is a scripting language just like Python.

About the Monty language

This is a language that contains specific instructions to manipulate data information (stacks or queues), where each instruction (called opcode) is sended per line. Files which contains Monty byte codes usually have the .m extension.

Example (file.m):

$ cat file.m
# Pushing element to the stack
push 0
push 1
push 2
# Printing all elements
pall
push 3
push 4
pop
# Rotating the stack to the bottom
rotr
pall
rotl
# Setting FIFO
queue
push 5
# Setting LIFO
stack
push 5
$

Technologies

• Interpreter was written with C language
• C files are compiled using gcc 4.8.4
• C files are written according to the C90 standard
• Tested on Ubuntu 14.04 LTS

Usage

To compile all files:

$ gcc -Wall -Werror -Wextra -pedantic *.c -o monty
$

The synopsis of the interpreter is the following:

$ ./monty [filename]
$

To run the interpreter:

$ ./monty file.m
2
1
0
0
3
2
1
$

Features

Opcodes

monty executes the following opcodes:

Opcode	Description
push	Pushes an element to the stack
pall	Prints all the values on the stack
pint	Prints the value at the top of the stack
pop	Removes the top element of the stack
swap	Swaps the top two elements of the stack
queue	Sets the format of the data to a queue (FIFO)
stack	Sets the format of the data to a stack (LIFO)
nop	Doesn't do anything
add	Adds the top two elements of the stack
sub	Subtracts the top element of the stack from the second top element of the stack
mul	Multiplies the second top element of the stack with the top element of the stack
div	Divides the second top element of the stack by the top element of the stack
mod	Computes the rest of the division of the second top element of the stack by the top element of the stack
pchar	Prints the char at the top of the stack
pstr	Prints the string starting at the top of the stack
rotl	Rotates the stack to the top
rotr	Rotates the stack to the bottom

Comments, indicated with #, are not executed by the interpreter.

When a nonextistent opcode is passed, the interpreter prints an error message and stops:

$ cat errorfile.m
push 1
pint
pcx
$ ./monty errorfile.m
1
L3: unknown instruction pcx

Return value

When there is no errors, monty returns 0. Otherwise, returns 1

Authors

• Jorge Zafra: Twitter - GitHub
• Luis Chaparro: Twitter - GitHub

monty's Issues

Task 15. stack, queue

Implement the stack and queue opcodes.

• The opcode stack sets the format of the data to a stack (LIFO). This is the default behavior of the program.

• The opcode queue sets the format of the data to a queue (FIFO).

• The top of the stack becomes the front of the queue

• The front of the queue becomes the top of the stack

Task 3. Swap

Implement the swap opcode.

• The opcode swap swaps the top two elements of the stack.

• less than two elements print error and exit status EXIT_FAILURE

Task 6. sub

Implement the sub opcode.

• sub works

• error when stack contains less than two elements.

Task 11. pchar

Implement the pchar opcode.

• The integer stored at the top of the stack is treated as the ascii value of the character to be printed

• If the value is not in the ascii table (man ascii) print the error message and exit status EXIT_FAILURE

• If the stack is empty, print the error message and exit status EXIT_FAILURE

Task 12. pstr

Implement the pstr opcode: prints the string starting at the top of the stack.

• pstr works

Error when:

• stack is over

• the value of the element is 0

• the value of the element is not in the ascii table

Task 10. comments

Implement comments to the interpreter:

• comments work

Task 2. pop

Implement the pop opcode.

• pop works

• error with pop (print message)

Task 19. Multiplication level up

Multiply two digits given by the user.

• Read the two digits from stdin, multiply them, and print the result, followed by a new line

Task 9. mod

Implement the mod opcode.
The opcode mod computes the rest of the division of the second top element of the stack by the top element of the stack.

• If the stack contains less than two elements, print the error message and exit status EXIT_FAILURE

• The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
  - The top element of the stack contains the result
  - The stack is one element shorter

• If the top element of the stack is 0, print the error message and exit status EXIT_FAILURE

Task 5. nop

Implement the nop opcode.

• The opcode nop doesn’t do anything.

Task 14. rotr

Implement the rotr opcode.

• rotr works

• rotr never fails

Task 1. Pint

Implement the pint opcode.

• The opcode pint prints the value at the top of the stack, followed by a new line.

• If the stack is empty, print the error message, and exit status EXIT_FAILURE

Task 18. Multiplication

Multiply two digits given by the user.

• Read the two digits from stdin, multiply them and print the result

• The result of the multiplication will be one digit-long

Task 7. div

Implement the div opcode.

The opcode div divides the second top element of the stack by the top element of the stack.

• If the stack contains less than two elements, print the error message and exit status EXIT_FAILURE

• The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
  - The top element of the stack contains the result
  - The stack is one element shorter

• if the top element of the stack is 0, print the error message and exit with EXIT_FAILURE

Task 16. Holberton

Write a BF script that prints Holberton

• Files are stored inside bf sub directory

Task 8. mul

Implement the mul opcode.

• mul works

• error when stack contains less than two elements

• exit with the status EXIT_FAILURE when there is an error

Task 4. add

Implement the add opcode.

• add works

• error when stack contains less than two elements.

Task 17. Add two digits

Add two digits given by the user.

• Read the two digits from stdin, add them, and print the result

• The total of the two digits with be one digit-long (<10)

Task 13. rotl

The opcode rotl rotates the stack to the top.

• The top element of the stack becomes the last one, and the second top element of the stack becomes the first one

• rotl never fails

Task 0. push, pall

Implement the push and pall opcodes:

• push

• pall