Absrtact_VM

AbstractVM is a machine that uses a stack to compute simple arithmetic expressions. These arithmetic expressions are provided to the machine as basic assembly programs.

Example

As an example is still better that all the possible explanations in the world, this is an example of an assembly program that your machine will be able to compute:

;-------------
; exemple.avm -
;-------------
push int32(42)
push int32(33)
add
push float(44.55)
mul
push double(42.42)
push int32(42)
dump
pop
assert double(42.42)
exit

Description

As for any assembly language, the language of AbstractVM is composed of a series of instructions, with one instruction per line. However, AbstractVM’s assembly language has a limited type system, which is a major difference from other real world assembly languages.

• Comments: Comments start with a ’;’ and finish with a newline. A comment can be either at the start of a line, or after an instruction.

push v:

Pushes the value v at the top of the stack. The value v must have one of the following form:

int8(n) : Creates an 8-bit integer with value n.
int16(n) : Creates a 16-bit integer with value n.
int32(n) : Creates a 32-bit integer with value n.
float(z) : Creates a float with value z.
double(z) : Creates a double with value z.

pop:

Unstacks the value from the top of the stack. If the stack is empty, the program execution must stop with an error.

dump:

Displays each value of the stack, from the most recent one to the oldest one WITHOUT CHANGING the stack. Each value is separated from the next one by a newline.

assert v:

Asserts that the value at the top of the stack is equal to the one passed as parameter for this instruction. If it is not the case, the program execution must stop with an error. The value v has the same form that those passed as parameters to the instruction push.

add:

Unstacks the first two values on the stack, adds them together and stacks the result. If the number of values on the stack is strictly inferior to 2, the program execution must stop with an error.

sub:

Unstacks the first two values on the stack, subtracts them, then stacks the result. If the number of values on the stack is strictly inferior to 2, the program execution must stop with an error.

mul:

Unstacks the first two values on the stack, multiplies them, then stacks the result. If the number of values on the stack is strictly inferior to 2, the program execution must stop with an error.