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use crate::fmt::{assert, *};
pub struct RingBuffer<'a> {
buf: &'a mut [u8],
start: usize,
end: usize,
empty: bool,
}
impl<'a> RingBuffer<'a> {
pub fn new(buf: &'a mut [u8]) -> Self {
Self {
buf,
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;
}
fn wrap(&self, n: usize) -> usize {
assert!(n <= self.buf.len());
if n == self.buf.len() {
0
} else {
n
}
}
}
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