Copyright (C) 2016-2021 Luca Saiu
Written by Luca Saiu

This file is part of Jitter.

Jitter is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Jitter is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Jitter.  If not, see <http://www.gnu.org/licenses/>.


About Jitter
============
Jitter is a software automatically building a portable, very efficient language
virtual machine with performance close to native code, starting from a
relatively high-level specification provided by the user.

The VM state may include registers, stacks or a combination of both along with
any runtime structure defined by user code; whenever possible the generator
attempts to map such state data structures into hardware machine registers.

The specification contains some C code associated to every VM instruction; the
generator takes care of combining such small blocks of C into a whole body of
code with low---usually zero---dispatching and branching overhead.
The generated code includes a simple C API to dynamically emit and execute VM
code, and a self-contained driver program for running VM routines from text
files.

The generated C code is heavily conditionalized and can be configured to run
using different dispatching techniques, of varying sophistication; the most
efficient dispatching techniques rely on some architecture-specific---but not
VM-specific---assembly support already included in this software; every
dispatching model but one also relies on GNU C extensions.

As a fallback case, in the interest of portability, one dispatching technique is
provided, switch dispatching, requiring nothing more than standard C.

Configuration parameters are transparent with respect to the VM semantics and
even the C API: a VM routine will always behave in the same way independently
from the dispatching technique and other configuration parameters, the only
observable difference being execution speed.

[FIXME: talk about optional features for VMs such as overflow checking and
garbage collection]


Online resources
================
The Jitter home page is http://ageinghacker.net/projects/jitter .
A public git repository is available at the URL http://git.ageinghacker.net/jitter .

Discussions about Jitter, which spawned off as a sub-project of GNU epsilon, are
always considered on topic on the GNU epsilon mailing list.  See
https://lists.gnu.org/mailman/listinfo/epsilon-devel .


About the author
================
Jitter was written by Luca Saiu.  His personal web site, whcih includes contact
information, is http://ageinghacker.net .