artiq/artiq/firmware/libboard/config.rs

266 lines
7.5 KiB
Rust

use core::{str, fmt};
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Error {
AlreadyLocked,
SpaceExhausted,
Truncated { offset: usize },
InvalidSize { offset: usize, size: usize },
MissingSeparator { offset: usize },
Utf8Error(str::Utf8Error)
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
&Error::AlreadyLocked =>
write!(f, "attempt at reentrant access"),
&Error::SpaceExhausted =>
write!(f, "space exhausted"),
&Error::Truncated { offset }=>
write!(f, "truncated record at offset {}", offset),
&Error::InvalidSize { offset, size } =>
write!(f, "invalid record size {} at offset {}", size, offset),
&Error::MissingSeparator { offset } =>
write!(f, "missing separator at offset {}", offset),
&Error::Utf8Error(err) =>
write!(f, "{}", err)
}
}
}
#[cfg(has_spiflash)]
mod imp {
use core::str;
use byteorder::{ByteOrder, BigEndian};
use cache;
use spiflash;
use super::Error;
// One flash sector immediately before the firmware.
const ADDR: usize = ::mem::FLASH_BOOT_ADDRESS - spiflash::SECTOR_SIZE;
const SIZE: usize = spiflash::SECTOR_SIZE;
mod lock {
use core::slice;
use core::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT};
use super::Error;
static LOCKED: AtomicUsize = ATOMIC_USIZE_INIT;
pub struct Lock;
impl Lock {
pub fn take() -> Result<Lock, Error> {
if LOCKED.swap(1, Ordering::SeqCst) != 0 {
Err(Error::AlreadyLocked)
} else {
Ok(Lock)
}
}
pub fn data(&self) -> &'static [u8] {
unsafe { slice::from_raw_parts(super::ADDR as *const u8, super::SIZE) }
}
}
impl Drop for Lock {
fn drop(&mut self) {
LOCKED.store(0, Ordering::SeqCst)
}
}
}
use self::lock::Lock;
#[derive(Clone)]
struct Iter<'a> {
data: &'a [u8],
offset: usize
}
impl<'a> Iter<'a> {
fn new(data: &'a [u8]) -> Iter<'a> {
Iter { data: data, offset: 0 }
}
}
impl<'a> Iterator for Iter<'a> {
type Item = Result<(&'a [u8], &'a [u8]), Error>;
fn next(&mut self) -> Option<Self::Item> {
let data = &self.data[self.offset..];
if data.len() < 4 {
// error!("offset {}: truncated record", self.offset);
return Some(Err(Error::Truncated { offset: self.offset }))
}
let record_size = BigEndian::read_u32(data) as usize;
if record_size == !0 /* all ones; erased flash */ {
return None
} else if record_size < 4 || record_size > data.len() {
return Some(Err(Error::InvalidSize { offset: self.offset, size: record_size }))
}
let record_body = &data[4..record_size];
match record_body.iter().position(|&x| x == 0) {
None => {
return Some(Err(Error::MissingSeparator { offset: self.offset }))
}
Some(pos) => {
self.offset += record_size;
let (key, zero_and_value) = record_body.split_at(pos);
Some(Ok((key, &zero_and_value[1..])))
}
}
}
}
pub fn read<F: FnOnce(Result<&[u8], Error>) -> R, R>(key: &str, f: F) -> R {
f(Lock::take().and_then(|lock| {
let mut iter = Iter::new(lock.data());
let mut value = &[][..];
while let Some(result) = iter.next() {
let (record_key, record_value) = result?;
if key.as_bytes() == record_key {
// last write wins
value = record_value
}
}
Ok(value)
}))
}
pub fn read_str<F: FnOnce(Result<&str, Error>) -> R, R>(key: &str, f: F) -> R {
read(key, |result| {
f(result.and_then(|value| str::from_utf8(value).map_err(Error::Utf8Error)))
})
}
unsafe fn append_at(data: &[u8], mut offset: usize,
key: &[u8], value: &[u8]) -> Result<usize, Error> {
let record_size = 4 + key.len() + 1 + value.len();
if offset + record_size > data.len() {
return Err(Error::SpaceExhausted)
}
let mut record_size_bytes = [0u8; 4];
BigEndian::write_u32(&mut record_size_bytes[..], record_size as u32);
{
let mut write = |payload| {
spiflash::write(data.as_ptr().offset(offset as isize) as usize, payload);
offset += payload.len();
};
write(&record_size_bytes[..]);
write(key);
write(&[0]);
write(value);
cache::flush_l2_cache();
}
Ok(offset)
}
fn compact() -> Result<(), Error> {
let lock = Lock::take()?;
let data = lock.data();
static mut OLD_DATA: [u8; SIZE] = [0; SIZE];
let old_data = unsafe {
OLD_DATA.copy_from_slice(data);
&OLD_DATA[..]
};
unsafe { spiflash::erase_sector(data.as_ptr() as usize) };
// This is worst-case quadratic, but we're limited by a small SPI flash sector size,
// so it does not really matter.
let mut offset = 0;
let mut iter = Iter::new(old_data);
while let Some(result) = iter.next() {
let (key, mut value) = result?;
let mut next_iter = iter.clone();
while let Some(next_result) = next_iter.next() {
let (next_key, next_value) = next_result?;
if key == next_key {
value = next_value
}
}
offset = unsafe { append_at(data, offset, key, value)? };
}
Ok(())
}
fn append(key: &str, value: &[u8]) -> Result<(), Error> {
let lock = Lock::take()?;
let data = lock.data();
let free_offset = {
let mut iter = Iter::new(data);
while let Some(result) = iter.next() {
let _ = result?;
}
iter.offset
};
unsafe { append_at(data, free_offset, key.as_bytes(), value)? };
Ok(())
}
pub fn write(key: &str, value: &[u8]) -> Result<(), Error> {
match append(key, value) {
Err(Error::SpaceExhausted) => {
compact()?;
append(key, value)
}
res => res
}
}
pub fn remove(key: &str) -> Result<(), Error> {
write(key, &[])
}
pub fn erase() -> Result<(), Error> {
let lock = Lock::take()?;
let data = lock.data();
unsafe { spiflash::erase_sector(data.as_ptr() as usize) };
cache::flush_l2_cache();
Ok(())
}
}
#[cfg(not(has_spiflash))]
mod imp {
pub fn read<F: FnOnce(Result<&[u8], Error>) -> R, R>(_key: &str, f: F) -> R {
f(Err(()))
}
pub fn read_str<F: FnOnce(Result<&str, Error>) -> R, R>(_key: &str, f: F) -> R {
f(Err(()))
}
pub fn write(_key: &str, _value: &[u8]) -> Result<(), Error> {
Err(())
}
pub fn remove(_key: &str) -> Result<(), Error> {
Err(())
}
pub fn erase() -> Result<(), Error> {
Err(())
}
}
pub use self::imp::*;