go get github.com/Marahin/yaaibig
Then yaaibig should be available in your PATH, assuming you have Go folders set up correctly.
You can try tinkering with provided examples.
This is an interpreter for a very basic, simplified "assembly" dialect. It does not comply with any standards, although it bases on some of the most popular instructions.
This was made purely for fun.
- a real Assembly,
- efficient way to write code,
- a compiler,
- production ready.
I wanted to see how an interpreter for a simple language can be done in Go, assuming not so sophisticated instructions. Assembly was a perfect choice as it follows a very straightforward syntax and instructions.
What I also love about assembly is how primitive the code has to be, due to the limitations. This way it was also so easy to implement & test the instructions, as - for instance - the Fibonacci or Factorial program consists of three most common used operators (mov, mul, add, jnz).
Also thanks to this being in Golang, it can easily be used for various other purposes, such as:
- deploying to Lambda, making a lightning talk about it <wink wink>,
- explaining how the basics of Assembly work; sample programs
Following descriptions are purely for the convenience of having same understanding of yaaibig's internals.
INSTRUCTION is a single line of code, exactly how the programmer perceives it. It can contain code, it can be empty, or it can contain comment.
Current INSTRUCTION is stored in instruction REGISTER (see REGISTRY section).
REGISTRY is a cell which can contain VALUE. Registers are identified by a single character (A-Z). Registers identified by lower case characters should be considered as internal, that means those can be used for interpreter's purposes.
Currently, only following registers are reserved:
i- INSTRUCTION registry, which contains current INSTRUCTION index,m- memory registry, to which some operands write
Above registers SHOULD be considered as internal, but it it not enforced. User is still able to read, write and change values of internal registers.
For example, changing the INSTRUCTION registry value will change which INSTRUCTION will be executed next.
In current implementation VALUE is either an int or a string.
Currently, only the DEBUG_FLAG is a handled flag. It has to be passed BEFORE the file path.
$ ./yaaibig -debug examples/factorial.gasm
It adds lots of verbosity to the program.
mov takes two arguments (ARG1, ARG2).
ARG1 is a REGISTRY, and ARG2 can be either REGISTRY or VALUE.
If ARG2 is a REGISTRY, then value of REGISTRY ARG1 will be set to value of ARG2 REGISTRY.
If ARG2 is a VALUE, then value of REGISTRY ARG1 will be set to ARG2.
mul takes two arguments (ARG1, ARG2). It has a common implementation like imul in the real assembly dialects.
For registers, it will evaluate ARG1 and ARG2, as values stored in given registry.
Then it executes ARG1*ARG2 and stores the result in memory REGISTRY.
add takes two arguments (ARG1, ARG2).
For registers, it will evaluate ARG1 and ARG2, as values stored in given registry.
Then it executes ARG1+ARG2 and stores the result in memory REGISTRY.
jnz takes one argument (ARG).
ARG has to be an integer value. If memory REGISTRY (m) is non-zero, then INSTRUCTION REGISTRY will change to ARG (effectively changing the next instruction to be executed).
jmp takes one argument (ARG).
ARG has to be an integer value. INSTRUCTION REGISTRY will change to ARG (effectively changing the next instruction to be executed). It is basically the same thing as jnz but without the zeroed memory condition.
ret takes one argument (ARG).
If ARG is a REGISTRY, then it will be evaluated to contained value.
If ARG is a VALUE, then the program will exit with a status code equal to ARG.
int takes one argument (ARG).
ARG is a INTERRUPT identifier that points to a particular operation.
See INTERRUPTS below for more detailed explanation on each INTERRUPT identifier.
_MEMDUMP takes no arguments.
It will display all changed REGISTERs with their values.
_INSTRUCTION_DUMP takes no arguments.
It will display all INSTRUCTIONs (including comments, empty lines) with corresponding line (INSTRUCTION) indexes.
This interrupt signal will print out any VALUE, stored in MEMORY, to standard output.