PAGE_SIZE := 4096
MAX_ALLOC := 0xFF

alloc := fn($Expr: type, bytes: int): ^Expr {
	pages := (1 + bytes) / PAGE_SIZE
	if pages <= MAX_ALLOC {
		return @bitcast(@inline(request_page, pages))
	}
	ptr := @inline(request_page, 0xFF)
	remaining := pages - MAX_ALLOC
	loop if remaining <= 0 break else {
		if remaining < MAX_ALLOC {
			request_page(remaining)
		} else {
			request_page(MAX_ALLOC)
		}
		remaining -= MAX_ALLOC
	}
	return @bitcast(ptr)
}

request_page := fn(page_count: u8): ^u8 {
	msg := "\{00}\{01}xxxxxxxx\0"
	msg_page_count := msg + 1;
	*msg_page_count = page_count
	return @eca(3, 2, msg, 12)
}

release_page := fn(ptr: ^u8, page_count: u8): void {
	msg := "\{01}\{00}xxxxxxxx\0"

	msg_page_count := msg + 1;
	*msg_page_count = page_count

	msg_ptr := @as(^^u8, @bitcast(msg + 2));
	*msg_ptr = ptr

	return @eca(3, 2, msg, 12)
}

OutbMsg := packed struct {a: u8, b: u8, addr: u16, value: u8}
InbMsg := packed struct {a: u8, b: u8, addr: u16}
OutlMsg := packed struct {a: u8, b: u8, addr: u16, value: u32}
InlMsg := packed struct {a: u8, b: u8, addr: u16}

outb := fn(addr: u16, value: u8): void {
	return @eca(3, 3, &OutbMsg.(1, 0, addr, value), @sizeof(OutbMsg))
}

inb := fn(addr: u16): u8 {
	return @eca(3, 3, &InbMsg.(0, 0, addr), @sizeof(InbMsg))
}

outl := fn(addr: u16, value: u32): void {
	return @eca(3, 3, &OutlMsg.(1, 2, addr, value), @sizeof(OutlMsg))
}

inl := fn(addr: u16): u32 {
	return @eca(3, 3, &InlMsg.(0, 2, addr), @sizeof(InlMsg))
}

CopyMsg := packed struct {a: u8, count: uint, src: uint, dest: ^u8}
copy := fn($Expr: type, src: ^Expr, dest: ^Expr, count: uint): void {
	return @eca(3, 2, &CopyMsg.(4, count * @sizeof(Expr), @bitcast(src), @bitcast(dest)), @sizeof(CopyMsg))
}

SetMsg := packed struct {a: u8, count: uint, size: uint, src: ^u8, dest: ^u8}
set := fn($Expr: type, src: ^Expr, dest: ^Expr, count: uint): void {
	return @eca(3, 2, &SetMsg.(5, count, @sizeof(Expr), @bitcast(src), @bitcast(dest)), @sizeof(SetMsg))
}