# Design

## Parsing

- First we tokenize the input (syntax check)
- Then we interpret the input (semantics check)
- Then we execute the input

## Notation

- `[operation][number type]`, e.g. `divi` for divide (div) integer
- `%[register]` for addressing registers
- `$[value]` for using literals/immediate values
- `;` for end of statement (mandatory)
- `[label]:` for labels
- `#[text]` for comments: any text is ignored till a newline (`\n`) is found
- Elements must be separated by whitespace character
	- Good: `add $2 $5 %A;`
	- Bad: `add $2$5%A;`

## Examples

Divide register A by 5 and store the result in register A:
`divi %A $5 %A;`

## Reserved symbols

The following whitespace characters are used to separate symbols:
- space (` `)
- tab (`\t`)
- return carriage (`\r`)
- newline (`\n`)

The following characters are used as identifiers:
- dollar (`$`)
- percentage (`%`)
- colon (`:`)
- semicolon (`;`)
- hash (`#`)

All operands are reserved keywords and can therefore NOT be used as labels.

## Operands

- `addi` add the first to the second argument and store the result in the third argument
- `subi` subtract the first from the second argument and store the result in the third argument
- `divi` divide the first by the second argument and store the result in the third argument
- `muli` multiply the first by the second argument and store the result in the third argument
- `shli` shift left the first argument by the number of positions given by the second argument and store the result in the third argument
- `shri` shift right the first argument by the number of positions given by the second argument and store the result in the third argument
- `jmp` jump to the label given by the first argument