ableos-framebuffer/hblang/README.md

# HERE SHALL THE DOCUMENTATION RESIDE

## Enforced Political Views

- worse is better
- less is more
- embrace `unsafe {}`
- adhere `macro_rules!`
- pessimization == death (put in `std::pin::Pin` and left with hungry crabs)
- importing external dependencies == death (`fn(dependencies) -> ExecutionStrategy`)
- above sell not be disputed, discussed, or questioned

## What hblang is

Holey-Bytes-Language (hblang for short) (*.hb) is the only true language targeting hbvm byte code. hblang is low level, manually managed, and procedural. Its rumored to be better then writing hbasm and you should probably use it for complex applications.

## What hblang isnt't

hblang knows what it isn't, because it knows what it is, hblang computes this by sub...

## Examples

Examples are also used in tests. To add an example that runs during testing add:
<pre>
#### &lt;name&gt
```hb
&lt;example&gt
```
</pre>
and also:
```rs
<name> => README;
```
to the `run_tests` macro at the bottom of the `src/codegen.rs`.

### Tour Examples

Following examples incrementally introduce language features and syntax.

#### main_fn
```hb
main := fn(): int {
	return 1;
}
```

#### arithmetic
```hb
main := fn(): int {
	return 10 - 20 / 2 + 4 * (2 + 2) - 4 * 4 + 1;
}
```

#### functions
```hb
main := fn(): int {
	return add_one(10) + add_two(20);
}

add_two := fn(x: int): int {
	return x + 2;
}

add_one := fn(x: int): int {
	return x + 1;
}
```

#### if_statements
```hb
main := fn(): int {
	return fib(10);
}

fib := fn(x: int): int {
	if x <= 2 {
		return 1;
	} else {
		return fib(x - 1) + fib(x - 2);
	}
}
```

#### variables
```hb
main := fn(): int {
	a := 1;
	b := 2;
	a = a + 1;
	return a - b;
}
```

#### loops
```hb
main := fn(): int {
	return fib(10);
}

fib := fn(n: int): int {
	a := 0;
	b := 1;
	loop {
		if n == 0 break;
		c := a + b;
		a = b;
		b = c;
		n -= 1;

		stack_reclamation_edge_case := 0;

		continue;
	}
	return a;
}
```

#### pointers
```hb
main := fn(): int {
	a := 1;
	b := &a;
	modify(b);
	drop(a);
	stack_reclamation_edge_case := 0;
	return *b - 2;
}

modify := fn(a: ^int): void {
	*a = 2;
	return;
}

drop := fn(a: int): void {
	return;
}
```

#### structs
```hb
Ty := struct {
	a: int,
	b: int,
}

Ty2 := struct {
	ty: Ty,
	c: int,
}

main := fn(): int {
	finst := Ty2.{ ty: Ty.{ a: 4, b: 1 }, c: 3 };
	inst := odher_pass(finst);
	if inst.c == 3 {
		return pass(&inst.ty);
	}
	return 0;
}

pass := fn(t: ^Ty): int {
	return t.a - t.b;
}

odher_pass := fn(t: Ty2): Ty2 {
	return t;
}
```

#### struct_operators
```hb
Point := struct {
	x: int,
	y: int,
}

Rect := struct {
	a: Point,
	b: Point,
}

main := fn(): int {
	a := Point.(1, 2);
	b := Point.(3, 4);

	d := Rect.(a + b, b - a);
	d2 := Rect.(Point.(0, 0) - b, a);
	d2 = d2 + d;

	c := d2.a + d2.b;
	return c.x + c.y;
}
```

#### global_variables
```hb
global_var := 10;

complex_global_var := fib(global_var) - 5;

fib := fn(n: int): int {
	if 2 > n {
		return n;
	}
	return fib(n - 1) + fib(n - 2);
}

main := fn(): int {
	return complex_global_var;
}
```
note: values of global variables are evaluated at compile time

#### directives
```hb
Type := struct {
	brah: int,
	blah: int,
}

main := fn(): int {
	byte := @as(u8, 10);
	same_type_as_byte := @as(@TypeOf(byte), 30);
	wide_uint := @as(u32, 40);
	truncated_uint := @as(u8, @intcast(wide_uint));
	size_of_Type_in_bytes := @sizeof(Type);
	align_of_Type_in_bytes := @alignof(Type);
	hardcoded_pointer := @as(^u8, @bitcast(10));
	ecall_that_returns_int := @eca(int, 1, Type.(10, 20), 5, 6);
	return 0;
}
```

- `@TypeOf(<expr>)`: results into literal type of whatever the type of `<expr>` is, `<expr>` is not included in final binary
- `@as(<ty>, <expr>)`: hint to the compiler that  `@TypeOf(<expr>) == <ty>`
- `@intcast(<expr>)`: needs to be used when conversion of `@TypeOf(<expr>)` would loose precision (widening of integers is implicit)
- `@sizeof(<ty>), @alignof(<ty>)`: I think explaining this would insult your intelligence
- `@bitcast(<expr>)`: tell compiler to assume `@TypeOf(<expr>)` is whatever is inferred, so long as size and alignment did not change
- `@eca(<ty>, <expr>...)`: invoke `eca` instruction, where `<ty>` is the type this will return and `<expr>...` are arguments passed to the call

### Incomplete Examples

#### generic_types
```hb
MALLOC_SYS_CALL := 69
FREE_SYS_CALL := 96

malloc := fn(size: uint, align: uint): ^void
	return @eca(^void, MALLOC_SYS_CALL, size, align);

free := fn(ptr: ^void, size: uint, align: uint): void
	return @eca(void, FREE_SYS_CALL, ptr, size, align);

Vec := fn($Elem: type): type {
	return struct {
		data: ^Elem,
		len: uint,
		cap: uint,
	};
}

new := fn($Elem: type): Vec(Elem) return Vec(Elem).{ data: @bitcast(0), len: 0, cap: 0 };

deinit := fn($Elem: type, vec: ^Vec(Elem)): void {
	free(@bitcast(vec.data), vec.len * @sizeof(Elem), @alignof(Elem));
	*vec = new(Elem);
}

push := fn($Elem: type, vec: ^Vec(Elem), value: Elem): ^Elem {
	if vec.len == vec.cap {
		if vec.cap == 0 {
			vec.cap = 1;
		} else {
			vec.cap *= 2;
		}

		new_alloc := @as(^Elem, @bitcast(malloc(vec.cap * @sizeof(Elem), @alignof(Elem))));
		if @as(uint, @bitcast(new_alloc)) == 0 return @bitcast(0);

		src_cursor := vec.data;
		dst_cursor := new_alloc;
		end := vec.data + vec.len;
		
		loop if src_cursor == end break else {
			*dst_cursor = *src_cursor;
			src_cursor += 1;
			dst_cursor += 1;
		}

		free(@bitcast(vec.data), vec.len * @sizeof(Elem), @alignof(Elem));
		vec.data = new_alloc;
	}

	slot := vec.data + vec.len;
	*slot = value;
	vec.len += 1;
	return slot;
}

main := fn(): int {
	vec := new(int);
	push(int, &vec, 69);
	return *vec.data;
}
```

#### generic_functions
```hb
add := fn($T: type, a: T, b: T): T return a + b;

main := fn(): int {
	return add(u32, 2, 2) - add(int, 1, 3);
}
```

#### fb_driver
```hb
arm_fb_ptr := fn(): int return 100;
x86_fb_ptr := fn(): int return 100;


check_platform := fn(): int {
    return x86_fb_ptr();
}

set_pixel := fn(x: int, y: int, width: int): int {
    pix_offset := y * width + x;

    return 0;
}

main := fn(): int {
    fb_ptr := check_platform();
    width := 100;
    height := 30;
    x:= 0;
    y:= 0;

    loop {
        if x <= height + 1 {
            set_pixel(x,y,width);
            x = x + 1;
        } else {
            set_pixel(x,y,width);
            x = 0;
            y = y + 1;
        }
        if y == width {
            break;
        }
    }
    return 0;
}
```

### Purely Testing Examples

#### different_types
```hb

Color := struct {
	r: u8,
	g: u8,
	b: u8,
	a: u8,
}

Point := struct {
	x: u32,
	y: u32,
}

Pixel := struct {
	color: Color,
	point: Point,
}

main := fn(): int {
	pixel := Pixel.{
		color: Color.{
			r: 255,
			g: 0,
			b: 0,
			a: 255,
		},
		point: Point.{
			x: 0,
			y: 2,
		},
	};

	if *(&pixel.point.x + 1) != 2 {
		return 0;
	}

	if *(&pixel.point.y - 1) != 0 {
		return 64;
	}

	return pixel.point.x + pixel.point.y + pixel.color.r
		+ pixel.color.g + pixel.color.b + pixel.color.a;
}
```