Project Name

0x19. C - Stacks, Queues - LIFO, FIFO

Author Details
Requirements
Authorized functions and macros
Project Description
Compilation
The Monty Language
Tasks
Known Bugs
Collaborate

Author Details

Wendy Munyasi - [email protected]

Requirements

Allowed editors: vi, vim, emacs.
All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89.
Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl.
All your files should end with a new line.
You allowed to use a maximum of one global variable.
No more than 5 functions per file.
You are allowed to use the C standard library.
The prototypes of all your functions should be included in your header file called monty.h.
All your header files should be include guarded.

Project Description

Learn about what do LIFO and FIFO mean? What is a stack, and when to use it. What is a queue, and when to use it. What are the common implementations of stacks and queues. What are the most common use cases of stacks and queues. What is the proper way to use global variables. The goal of this project is to create an interpreter for Monty ByteCodes files.

More Info

Data structures

Please use the following data structures for this project.

/**
 * struct stack_s - doubly linked list representation of a stack (or queue)
 * @n: integer
 * @prev: points to the previous element of the stack (or queue)
 * @next: points to the next element of the stack (or queue)
 *
 * Description: doubly linked list node structure
 * for stack, queues, LIFO, FIFO
 */
typedef struct stack_s
{
		int n;
		struct stack_s *prev;
		struct stack_s *next;
} stack_t;

/**
 * struct instruction_s - opcode and its function
 * @opcode: the opcode
 * @f: function to handle the opcode
 *
 * Description: opcode and its function
 * for stack, queues, LIFO, FIFO
 */
typedef struct instruction_s
{
		char *opcode;
		void (*f)(stack_t **stack, unsigned int line_number);
} instruction_t;

Compilation

Your code will be compiled this way.

$ gcc -Wall -Werror -Wextra -pedantic -std=c89 *.c -o monty

Any output must be printed on stdout.
Any error message must be printed on stderr.
- Here is a link to a GitHub repository that could help you making sure your errors are printed on stderr.

The Monty language

Monty 0.98 is a scripting language that is first compiled into Monty byte codes (Just like Python). It relies on a unique stack, with specific instructions to manipulate it.

Monty byte code files

Files containing Monty byte codes usually have the .m extension. Most of the industry uses this standard but it is not required by the specification of the language. There is not more than one instruction per line. There can be any number of spaces before or after the opcode and its argument. Monty byte code files can contain blank lines (empty or made of spaces only, and any additional text after the opcode or its required argument is not taken into account:

julien@ubuntu:~/monty$ cat -e bytecodes/001.m
push 0 Push 0 onto the stack$
push 1 Push 1 onto the stack$
$
push 2$
  push 3$
				   pall    $
$
$
						   $
push 4$
$
	push 5    $
	  push    6        $
$
pall This is the end of our program. Monty is awesome!$
julien@ubuntu:~/monty$
``
Monty byte code files can contain blank lines (empty or made of spaces only, and any additional text after the opcode or its required argument is not taken into account:

The monty program

Usage: monty file where file is the path to the file containing Monty byte code.
If the user does not give any file or more than one argument to your program, print the error message USAGE: monty file, followed by a new line, and exit with the status EXIT_FAILURE.
If, for any reason, it’s not possible to open the file, print the error message Error: Can't open file <file>, followed by a new line, and exit with the status EXIT_FAILURE where <file> is the name of the file.
If the file contains an invalid instruction, print the error message L<line_number>: unknown instruction <opcode>, followed by a new line, and exit with the status EXIT_FAILURE where <line_number> is the line number where the instruction appears. Line numbers always start at 1.
The monty program runs the bytecodes line by line and stop if either:
- it executed properly every line of the file,
- it finds an error in the file,
- an error occured.
If you can’t malloc anymore, print the error message Error: malloc failed, followed by a new line, and exit with status EXIT_FAILURE.
You have to use malloc and free and are not allowed to use any other function from man malloc (realloc, calloc, …).

Tasks

0. push, pall

Implement the push and pall opcodes.

The opcode push pushes an element to the stack.

Usage: push <int> where <int> is an integer.
If <int> is not an integer or if there is no argument given to push, print the error message L<line_number>: usage: push integer, followed by a new line, and exit with the status EXIT_FAILURE where <line_number> is the line number in the file.
You won’t have to deal with overflows. Use the atoi function.

The opcode pall prints all the values on the stack, starting from the top of the stack.

Usage pall and if the stack is empty, don’t print anything.

julien@ubuntu:~/monty$ cat -e bytecodes/00.m
push 1$
push 2$
push 3$
pall$
julien@ubuntu:~/monty$ ./monty bytecodes/00.m
3
2
1
julien@ubuntu:~/monty$

1. pint

Implement the pint opcode.

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

Usage: pint
If the stack is empty, print the error message L<line_number>: can't pint, stack empty, followed by a new line, and exit with the status EXIT_FAILURE.

julien@ubuntu:~/monty$ cat bytecodes/06.m 
push 1
pint
push 2
pint
push 3
pint
julien@ubuntu:~/monty$ ./monty bytecodes/06.m 
1
2
3
julien@ubuntu:~/monty$

2. pop

Implement the pop opcode.

The opcode pop removes the top element of the stack.

Usage: pop
If the stack is empty, print the error message L<line_number>: can't pop an empty stack, followed by a new line, and exit with the status EXIT_FAILURE.

julien@ubuntu:~/monty$ cat bytecodes/07.m 
push 1
push 2
push 3
pall
pop
pall
pop
pall
pop
pall
julien@ubuntu:~/monty$ ./monty bytecodes/07.m 
3
2
1
2
1
1
julien@ubuntu:~/monty$

3. swap

Implement the swap opcode.

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

Usage: swap If the stack contains less than two elements, print the error message L<line_number>: can't swap, stack too short, followed by a new line, and exit with the status EXIT_FAILURE.

julien@ubuntu:~/monty$ cat bytecodes/09.m 
push 1
push 2
push 3
pall
swap
pall
julien@ubuntu:~/monty$ ./monty bytecodes/09.m 
3
2
1
2
3
1
julien@ubuntu:~/monty$

4. add

Implement the add opcode.

The opcode add adds the top two elements of the stack.

Usage: add
If the stack contains less than two elements, print the error message L<line_number>: can't add, stack too short, followed by a new line, and exit with the 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.

julien@ubuntu:~/monty$ cat bytecodes/12.m 
push 1
push 2
push 3
pall
add
pall

julien@ubuntu:~/monty$ ./monty bytecodes/12.m 
3
2
1
5
1
julien@ubuntu:~/monty$

5. nop

Implement the nop opcode.

The opcode nop doesn’t do anything. Usage: nop

6. sub

Implement the sub opcode.

The opcode sub subtracts the top element of the stack from the second top element of the stack.

Usage: sub
If the stack contains less than two elements, print the error message L<line_number>: can't sub, stack too short, followed by a new line, and exit with the 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.

julien@ubuntu:~/monty$ cat bytecodes/19.m 
push 1
push 2
push 10
push 3
sub
pall
julien@ubuntu:~/monty$ ./monty bytecodes/19.m 
7
2
1
julien@ubuntu:~/monty$

7. div

Implement the div opcode.

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

Usage: div
If the stack contains less than two elements, print the error message L<line_number>: can't div, stack too short, followed by a new line, and exit with the 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 L<line_number>: division by zero, followed by a new line, and exit with the status EXIT_FAILURE.

8. mul

Implement the mul opcode.

The opcode mul multiplies the second top element of the stack with the top element of the stack.

Usage: mul
If the stack contains less than two elements, print the error message L<line_number>: can't mul, stack too short, followed by a new line, and exit with the 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.

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.

Usage: mod
If the stack contains less than two elements, print the error message L<line_number>: can't mod, stack too short, followed by a new line, and exit with the 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 L<line_number>: division by zero, followed by a new line, and exit with the status EXIT_FAILURE.

10. comments

Every good language comes with the capability of commenting. When the first non-space character of a line is #, treat this line as a comment (don’t do anything).

11. pchar

Implement the pchar opcode.

The opcode pchar prints the char at the top of the stack, followed by a new line.

Usage: pchar
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 L<line_number>: can't pchar, value out of range, followed by a new line, and exit with the status EXIT_FAILURE.
If the stack is empty, print the error message L<line_number>: can't pchar, stack empty, followed by a new line, and exit with the status EXIT_FAILURE.

julien@ubuntu:~/monty$ cat bytecodes/28.m 
push 72
pchar
julien@ubuntu:~/monty$ ./monty bytecodes/28.m 
H
julien@ubuntu:~/monty$

12. pstr

Implement the pstr opcode.

The opcode pstr prints the string starting at the top of the stack, followed by a new line.

Usage: pstr
The integer stored in each element of the stack is treated as the ascii value of the character to be printed.
The string stops when either: the stack is over, the value of the element is 0 or the value of the element is not in the ascii table.
If the stack is empty, print only a new line.

julien@ubuntu:~/monty$ cat bytecodes/31.m 
push 1
push 2
push 3
push 4
push 0
push 110
push 0
push 108
push 111
push 111
push 104
push 99
push 83
pstr
julien@ubuntu:~/monty$ ./monty bytecodes/31.m 
School
julien@ubuntu:~/monty$

13. rotl

Implement the rotl opcode.

The opcode rotl rotates the stack to the top.

Usage: rotl
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.

julien@ubuntu:~/monty$ cat bytecodes/35.m 
push 1
push 2
push 3
push 4
push 5
push 6
push 7
push 8
push 9
push 0
pall
rotl
pall
julien@ubuntu:~/monty$ ./monty bytecodes/35.m 
0
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
0
julien@ubuntu:~/monty$

14. rotr

Implement the rotr opcode.

The opcode rotr rotates the stack to the bottom.

Usage: rotr
The last element of the stack becomes the first one.
rotl never fails.

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.

Usage: stack

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

Usage: queue

When switching mode:

The top of the stack becomes the front of the queue,
The front of the queue becomes the top of the stack.

julien@ubuntu:~/monty$ cat bytecodes/47.m
queue
push 1
push 2
push 3
pall
stack
push 4
push 5
push 6
pall
add
pall
queue
push 11111
add
pall
julien@ubuntu:~/monty$ ./monty bytecodes/47.m
1
2
3
6
5
4
1
2
3
11
4
1
2
3
15
1
2
3
11111
julien@ubuntu:~/monty$

16. Brainfuck

Write a Brainfuck script that prints School, followed by a new line.

All your Brainfuck files should be stored inside the bf sub directory.
You can install the bf interpreter to test your code: sudo apt-get install bf.

julien@ubuntu:~/monty/bf$ bf 1000-school.bf 
School
julien@ubuntu:~/monty/bf$

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 will be one digit-long (<10).

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 (<10).

julien@ubuntu:~/monty/bf$ bf 1002-mul.bf
24
8julien@ubuntu:~/monty/bf$

19. Multiplication level up