This commit is contained in:
Danila Fedorin 2018-09-19 17:51:12 -07:00
parent d40ea2a8ae
commit bc798f11fe
1 changed files with 49 additions and 7 deletions

View File

@ -1,22 +1,64 @@
# chalk
TODO: Write a description here
Chalk is a basic compiler from a toy language into CHIP-8 bytecode.
It supports some higher-level constructs like looks and if-statements,
and has some higher-level functions for drawing numbers and sprites.
## Installation
TODO: Write installation instructions here
To compile chalk, simply run
crystal build --release src/
## Usage
### Syntax
Chalk has minimal syntax. All code goes into functions, which are declared as follows:
fun function(param, another_param): return_type {
TODO: Write usage instructions here
All parameters are assumed to be of type `u8`, an unsigned byte.
The return type can be either `u8` or `u0`, the latter being the same as `void` in C.
Users can declare variables using the `var` keyword:
var name = 5;
Assigning to existing variables is performed as such:
name = 6;
It's possible to call another function, which uses the CHIP-8 stack. This stack
is used exclusively for function calls, and may not exceed 12, as per the specifications
of the CHIP-8 virtual machine.
var result = double(name);
Additionally, to ensure that user-defined variables stored
in registers are not modified, chalk uses its own custom stack, placed at the end of the program.
This stack is accessed by modifying a stack pointer register, which holds the offset from the beginning of the stack. Because CHIP-8 registers can only hold up 8-bit unsinged numbers, the stack is therefore limited to 254 items.
## Development
If statements take "truthy" values to be those that have a nonzero value. As such,
`if (0) {}` will never run, while `while(5) {}` will never terminate. Input can be awaited
using the `get_key` function, which returns the number of the next key pressed.
TODO: Write development instructions here
Sprites can be declared using a quasi-visual syntax:
sprite dum [
` x x `
` x x `
` x x `
` `
`x x`
` xxxxxx `
These sprites can then be used in calls to `draw_sprite(sprite, x, y)`.
## Contributing
1. Fork it (<>)
1. Fork it (<>)
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Add some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
@ -24,4 +66,4 @@ TODO: Write development instructions here
## Contributors
- [your-github-user]( Danila Fedorin - creator, maintainer
- [DanilaFe]( Danila Fedorin - creator, maintainer