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|
pub struct RingBuffer<const N: usize> {
buf: [u8; N],
start: usize,
end: usize,
empty: bool,
}
impl<const N: usize> RingBuffer<N> {
pub const fn new() -> Self {
Self {
buf: [0; N],
start: 0,
end: 0,
empty: true,
}
}
pub fn push_buf(&mut self) -> &mut [u8] {
if self.start == self.end && !self.empty {
trace!(" ringbuf: push_buf empty");
return &mut self.buf[..0];
}
let n = if self.start <= self.end {
self.buf.len() - self.end
} else {
self.start - self.end
};
trace!(" ringbuf: push_buf {:?}..{:?}", self.end, self.end + n);
&mut self.buf[self.end..self.end + n]
}
pub fn push(&mut self, n: usize) {
trace!(" ringbuf: push {:?}", n);
if n == 0 {
return;
}
self.end = self.wrap(self.end + n);
self.empty = false;
}
pub fn pop_buf(&mut self) -> &mut [u8] {
if self.empty {
trace!(" ringbuf: pop_buf empty");
return &mut self.buf[..0];
}
let n = if self.end <= self.start {
self.buf.len() - self.start
} else {
self.end - self.start
};
trace!(" ringbuf: pop_buf {:?}..{:?}", self.start, self.start + n);
&mut self.buf[self.start..self.start + n]
}
pub fn pop(&mut self, n: usize) {
trace!(" ringbuf: pop {:?}", n);
if n == 0 {
return;
}
self.start = self.wrap(self.start + n);
self.empty = self.start == self.end;
}
pub fn is_full(&self) -> bool {
self.start == self.end && !self.empty
}
pub fn is_empty(&self) -> bool {
self.empty
}
#[allow(unused)]
pub fn len(&self) -> usize {
if self.empty {
0
} else if self.start < self.end {
self.end - self.start
} else {
N + self.end - self.start
}
}
pub fn clear(&mut self) {
self.start = 0;
self.end = 0;
self.empty = true;
}
fn wrap(&self, n: usize) -> usize {
assert!(n <= self.buf.len());
if n == self.buf.len() {
0
} else {
n
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn push_pop() {
let mut rb: RingBuffer<4> = RingBuffer::new();
let buf = rb.push_buf();
assert_eq!(4, buf.len());
buf[0] = 1;
buf[1] = 2;
buf[2] = 3;
buf[3] = 4;
rb.push(4);
let buf = rb.pop_buf();
assert_eq!(4, buf.len());
assert_eq!(1, buf[0]);
rb.pop(1);
let buf = rb.pop_buf();
assert_eq!(3, buf.len());
assert_eq!(2, buf[0]);
rb.pop(1);
let buf = rb.pop_buf();
assert_eq!(2, buf.len());
assert_eq!(3, buf[0]);
rb.pop(1);
let buf = rb.pop_buf();
assert_eq!(1, buf.len());
assert_eq!(4, buf[0]);
rb.pop(1);
let buf = rb.pop_buf();
assert_eq!(0, buf.len());
let buf = rb.push_buf();
assert_eq!(4, buf.len());
}
}
|
