Compilation & Output
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
Tests
We strongly encourage you to work all together on a set of tests
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. The goal of this project is to create an interpreter for Monty ByteCodes files.
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:
julien@ubuntu:~/monty$ cat -e bytecodes/000.m
push 0$
push 1$
push 2$
push 3$
pall $
push 4$
push 5 $
push 6 $
pall$
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:
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$
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 statusEXIT_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 statusEXIT_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 statusEXIT_FAILURE
where 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 statusEXIT_FAILURE
- You have to use
malloc
andfree
and are not allowed to use any other function fromman malloc
(realloc, calloc, …)
Tasks
0. push, pall
Implement the push and pall opcodes.
-
The push opcode
-
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 messageL<line_number>: usage: push integer
, followed by a new line, and exit with the statusEXIT_FAILURE
where is the line number in the file -
You won’t have to deal with overflows. Use the
atoi
function -
The pall opcode
-
The opcode
pall
prints all the values on the stack, starting from the top of the stack. -
Usage
pall
-
Format: see example
-
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 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 statusEXIT_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 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 stac
k, followed by a new line, and exit with the statusEXIT_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 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 statusEXIT_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 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 statusEXIT_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 nop opcode
-
The opcode
nop
doesn’t do anything. -
Usage:
nop