tree a161bfdaaf62da3df7e3e33fd732e5bb13b71420
parent e9a95cea30e2e53d90dbfdc2497bd36a9e73700d
author Johnathan Van Why <jrvanwhy@google.com> 1594680488 -0700
committer Johnathan Van Why <jrvanwhy@google.com> 1595024742 -0700

Add the `Syscalls` trait to `libtock_platform`.

`Syscalls` is a trait representing Tock's system call API. It will be implemented by both `libtock_runtime` (included by TBF binaries) and `libtock_fake` (included by unit tests). It will allow us to replace the real Tock kernel with a fake Tock kernel for testing purposes.

`Syscalls` is designed to introduce no overhead over the system call assembly logic. For `allow`, `command`, and `subscribe`, it is based on Tock's `Driver` trait. A higher-level interface over Tock's system calls, for use by `libtock_core` and client code, will be introduced in a later PR.