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#![allow(dead_code)]
const CONFIGURABLE_SYNCHRONIZER_THRESHOLD: u32 = 10;
pub trait Synchronizer: Send {
fn declare_response(&mut self) -> u32;
fn is_permitted(&self, id: u32) -> bool;
fn permission_for_response(&mut self, id: u32) -> bool;
}
#[derive(Debug, Default)]
pub struct FifoSynchronizer {
declared_responses: u32,
next_to_grant: u32,
}
impl Synchronizer for FifoSynchronizer {
fn declare_response(&mut self) -> u32 {
let result = self.declared_responses;
self.declared_responses = self.declared_responses.overflowing_add(1).0;
result
}
fn is_permitted(&self, id: u32) -> bool {
id == self.next_to_grant
}
fn permission_for_response(&mut self, id: u32) -> bool {
if id == self.next_to_grant {
self.next_to_grant = self.next_to_grant.overflowing_add(1).0;
true
} else {
false
}
}
}
#[derive(Debug, Default)]
pub struct NoopSynchronizer {
declared_responses: u32,
}
impl Synchronizer for NoopSynchronizer {
fn declare_response(&mut self) -> u32 {
let result = self.declared_responses;
self.declared_responses = self.declared_responses.overflowing_add(1).0;
result
}
fn is_permitted(&self, _id: u32) -> bool {
true
}
fn permission_for_response(&mut self, _id: u32) -> bool {
true
}
}
#[derive(Debug)]
struct ThresholdSynchronizer {
inner: FifoSynchronizer,
to_grant_min: u32,
to_grant_max: u32,
}
impl ThresholdSynchronizer {
fn new(declared: u32, threshold: u32) -> Self {
ThresholdSynchronizer {
inner: FifoSynchronizer {
declared_responses: declared,
next_to_grant: declared,
},
to_grant_min: declared.overflowing_sub(threshold).0,
to_grant_max: declared,
}
}
fn within_threshold(&self, id: u32) -> bool {
if self.to_grant_min <= self.to_grant_max {
self.to_grant_min <= id && id < self.to_grant_max
} else {
self.to_grant_min <= id || id < self.to_grant_max
}
}
}
impl Synchronizer for ThresholdSynchronizer {
fn declare_response(&mut self) -> u32 {
self.inner.declare_response()
}
fn is_permitted(&self, id: u32) -> bool {
self.inner.is_permitted(id) || self.within_threshold(id)
}
fn permission_for_response(&mut self, id: u32) -> bool {
self.inner.permission_for_response(id) || self.within_threshold(id)
}
}
#[derive(Debug)]
enum InnerSynchronizer {
Noop(NoopSynchronizer),
Threshold(ThresholdSynchronizer),
}
impl InnerSynchronizer {
pub fn new(sync: bool) -> Self {
if sync {
InnerSynchronizer::Threshold(ThresholdSynchronizer::new(0, 0))
} else {
InnerSynchronizer::Noop(NoopSynchronizer::default())
}
}
}
#[derive(Debug)]
pub struct ConfigurableSynchronizer {
inner: InnerSynchronizer,
}
impl Default for ConfigurableSynchronizer {
fn default() -> Self {
ConfigurableSynchronizer::new(false)
}
}
impl ConfigurableSynchronizer {
pub fn new(sync: bool) -> Self {
ConfigurableSynchronizer {
inner: InnerSynchronizer::new(sync),
}
}
pub fn change_sync_policy(&mut self, sync: bool) {
let new_inner = match self.inner {
InnerSynchronizer::Threshold(ref s) if !sync => {
InnerSynchronizer::Noop(NoopSynchronizer {
declared_responses: s.inner.declared_responses,
})
},
InnerSynchronizer::Noop(ref s) if sync => {
let threshold = ThresholdSynchronizer::new(
s.declared_responses,
CONFIGURABLE_SYNCHRONIZER_THRESHOLD,
);
InnerSynchronizer::Threshold(threshold)
},
_ => return (),
};
self.inner = new_inner;
}
}
impl Synchronizer for ConfigurableSynchronizer {
fn declare_response(&mut self) -> u32 {
match self.inner {
InnerSynchronizer::Noop(ref mut s) => s.declare_response(),
InnerSynchronizer::Threshold(ref mut s) => s.declare_response(),
}
}
fn is_permitted(&self, id: u32) -> bool {
match self.inner {
InnerSynchronizer::Noop(ref s) => s.is_permitted(id),
InnerSynchronizer::Threshold(ref s) => s.is_permitted(id),
}
}
fn permission_for_response(&mut self, id: u32) -> bool {
match self.inner {
InnerSynchronizer::Threshold(ref mut s) => s.permission_for_response(id),
InnerSynchronizer::Noop(ref mut s) => s.permission_for_response(id),
}
}
}
#[cfg(test)]
mod tests {
use super::{
Synchronizer, FifoSynchronizer, NoopSynchronizer, ConfigurableSynchronizer, ThresholdSynchronizer
};
#[test]
fn test_fifo_synchronizer() {
let mut s = FifoSynchronizer::default();
let id0 = s.declare_response();
let id1 = s.declare_response();
let id2 = s.declare_response();
assert!(!s.permission_for_response(id1));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id0));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id1));
assert!(s.permission_for_response(id2));
}
#[test]
fn test_noop_synchronizer() {
let mut s = NoopSynchronizer::default();
let id0 = s.declare_response();
let id1 = s.declare_response();
let id2 = s.declare_response();
assert!(s.permission_for_response(id1));
assert!(s.permission_for_response(id2));
assert!(s.permission_for_response(id0));
}
#[test]
fn test_threshold_synchronizer() {
let mut s = ThresholdSynchronizer::new(2, 2);
let id0 = s.declare_response();
let id1 = s.declare_response();
let id2 = s.declare_response();
assert!(!s.permission_for_response(id1));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id0));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id1));
assert!(s.permission_for_response(id2));
assert!(s.permission_for_response(1));
assert!(s.permission_for_response(0));
assert!(!s.permission_for_response(2));
}
#[test]
fn test_configurable_synchronizer() {
let mut s = ConfigurableSynchronizer::new(true);
let id0 = s.declare_response();
let id1 = s.declare_response();
let id2 = s.declare_response();
assert!(!s.permission_for_response(id1));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id0));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id1));
assert!(s.permission_for_response(id2));
s.change_sync_policy(false);
let id0 = s.declare_response();
let id1 = s.declare_response();
let id2 = s.declare_response();
assert!(s.permission_for_response(id1));
assert!(s.permission_for_response(id2));
assert!(s.permission_for_response(id0));
let d0 = s.declare_response();
let d1 = s.declare_response();
s.change_sync_policy(true);
let id0 = s.declare_response();
let id1 = s.declare_response();
let id2 = s.declare_response();
assert!(!s.permission_for_response(id1));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id0));
assert!(!s.permission_for_response(id2));
assert!(s.permission_for_response(id1));
assert!(s.permission_for_response(id2));
assert!(s.permission_for_response(d1));
assert!(s.permission_for_response(d0));
}
}