artiq/artiq/firmware/satman/cache.rs

84 lines
2.2 KiB
Rust

use alloc::{vec, vec::Vec, string::String, collections::btree_map::BTreeMap};
use cslice::{CSlice, AsCSlice};
use core::mem::transmute;
struct Entry {
data: Vec<i32>,
slice: CSlice<'static, i32>,
borrowed: bool
}
impl core::fmt::Debug for Entry {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
f.debug_struct("Entry")
.field("data", &self.data)
.field("borrowed", &self.borrowed)
.finish()
}
}
pub struct Cache {
entries: BTreeMap<String, Entry>,
empty: CSlice<'static, i32>,
}
impl core::fmt::Debug for Cache {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
f.debug_struct("Cache")
.field("entries", &self.entries)
.finish()
}
}
impl Cache {
pub fn new() -> Cache {
let empty_vec = vec![];
let empty = unsafe {
transmute::<CSlice<'_, i32>, CSlice<'static, i32>>(empty_vec.as_c_slice())
};
Cache { entries: BTreeMap::new(), empty }
}
pub fn get(&mut self, key: &str) -> *const CSlice<'static, i32> {
match self.entries.get_mut(key) {
None => &self.empty,
Some(ref mut entry) => {
entry.borrowed = true;
&entry.slice
}
}
}
pub fn put(&mut self, key: &str, data: &[i32]) -> Result<(), ()> {
match self.entries.get_mut(key) {
None => (),
Some(ref mut entry) => {
if entry.borrowed { return Err(()) }
entry.data = Vec::from(data);
unsafe {
entry.slice = transmute::<CSlice<'_, i32>, CSlice<'static, i32>>(
entry.data.as_c_slice());
}
return Ok(())
}
}
let data = Vec::from(data);
let slice = unsafe {
transmute::<CSlice<'_, i32>, CSlice<'static, i32>>(data.as_c_slice())
};
self.entries.insert(String::from(key), Entry {
data,
slice,
borrowed: false
});
Ok(())
}
pub unsafe fn unborrow(&mut self) {
for (_key, entry) in self.entries.iter_mut() {
entry.borrowed = false;
}
}
}