start with config.rs from artiq's libboard_misoc
whitequark
commit
2d09805b42
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use core::{str, fmt};
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum Error {
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AlreadyLocked,
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SpaceExhausted,
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Truncated { offset: usize },
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InvalidSize { offset: usize, size: usize },
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MissingSeparator { offset: usize },
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Utf8Error(str::Utf8Error),
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NoFlash,
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}
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impl fmt::Display for Error {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match self {
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&Error::AlreadyLocked =>
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write!(f, "attempt at reentrant access"),
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&Error::SpaceExhausted =>
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write!(f, "space exhausted"),
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&Error::Truncated { offset }=>
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write!(f, "truncated record at offset {}", offset),
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&Error::InvalidSize { offset, size } =>
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write!(f, "invalid record size {} at offset {}", size, offset),
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&Error::MissingSeparator { offset } =>
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write!(f, "missing separator at offset {}", offset),
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&Error::Utf8Error(err) =>
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write!(f, "{}", err),
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&Error::NoFlash =>
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write!(f, "flash memory is not present"),
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}
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}
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}
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#[cfg(has_spiflash)]
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mod imp {
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use core::str;
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use byteorder::{ByteOrder, BigEndian};
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use cache;
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use spiflash;
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use super::Error;
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use core::fmt;
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use core::fmt::Write;
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struct FmtWrapper<'a> {
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buf: &'a mut [u8],
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offset: usize,
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}
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impl<'a> FmtWrapper<'a> {
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fn new(buf: &'a mut [u8]) -> Self {
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FmtWrapper {
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buf: buf,
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offset: 0,
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}
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}
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fn contents(&self) -> &[u8] {
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&self.buf[..self.offset]
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}
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}
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impl<'a> fmt::Write for FmtWrapper<'a> {
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fn write_str(&mut self, s: &str) -> fmt::Result {
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let bytes = s.as_bytes();
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let remainder = &mut self.buf[self.offset..];
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let remainder = &mut remainder[..bytes.len()];
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remainder.copy_from_slice(bytes);
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self.offset += bytes.len();
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Ok(())
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}
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}
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// One flash sector immediately before the firmware.
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const ADDR: usize = ::mem::FLASH_BOOT_ADDRESS - spiflash::SECTOR_SIZE;
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const SIZE: usize = spiflash::SECTOR_SIZE;
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mod lock {
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use core::slice;
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use core::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT};
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use super::Error;
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static LOCKED: AtomicUsize = ATOMIC_USIZE_INIT;
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pub struct Lock;
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impl Lock {
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pub fn take() -> Result<Lock, Error> {
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if LOCKED.swap(1, Ordering::SeqCst) != 0 {
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Err(Error::AlreadyLocked)
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} else {
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Ok(Lock)
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}
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}
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pub fn data(&self) -> &'static [u8] {
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unsafe { slice::from_raw_parts(super::ADDR as *const u8, super::SIZE) }
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}
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}
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impl Drop for Lock {
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fn drop(&mut self) {
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LOCKED.store(0, Ordering::SeqCst)
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}
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}
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}
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use self::lock::Lock;
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#[derive(Clone)]
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struct Iter<'a> {
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data: &'a [u8],
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offset: usize
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}
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impl<'a> Iter<'a> {
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fn new(data: &'a [u8]) -> Iter<'a> {
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Iter { data: data, offset: 0 }
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}
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}
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impl<'a> Iterator for Iter<'a> {
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type Item = Result<(&'a [u8], &'a [u8]), Error>;
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fn next(&mut self) -> Option<Self::Item> {
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let data = &self.data[self.offset..];
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if data.len() < 4 {
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// error!("offset {}: truncated record", self.offset);
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return Some(Err(Error::Truncated { offset: self.offset }))
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}
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let record_size = BigEndian::read_u32(data) as usize;
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if record_size == !0 /* all ones; erased flash */ {
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return None
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} else if record_size < 4 || record_size > data.len() {
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return Some(Err(Error::InvalidSize { offset: self.offset, size: record_size }))
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}
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let record_body = &data[4..record_size];
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match record_body.iter().position(|&x| x == 0) {
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None => {
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return Some(Err(Error::MissingSeparator { offset: self.offset }))
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}
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Some(pos) => {
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self.offset += record_size;
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let (key, zero_and_value) = record_body.split_at(pos);
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Some(Ok((key, &zero_and_value[1..])))
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}
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}
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}
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}
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pub fn read<F: FnOnce(Result<&[u8], Error>) -> R, R>(key: &str, f: F) -> R {
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f(Lock::take().and_then(|lock| {
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let mut iter = Iter::new(lock.data());
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let mut value = &[][..];
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while let Some(result) = iter.next() {
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let (record_key, record_value) = result?;
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if key.as_bytes() == record_key {
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// last write wins
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value = record_value
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}
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}
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Ok(value)
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}))
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}
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pub fn read_str<F: FnOnce(Result<&str, Error>) -> R, R>(key: &str, f: F) -> R {
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read(key, |result| {
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f(result.and_then(|value| str::from_utf8(value).map_err(Error::Utf8Error)))
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})
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}
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unsafe fn append_at(data: &[u8], mut offset: usize,
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key: &[u8], value: &[u8]) -> Result<usize, Error> {
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let record_size = 4 + key.len() + 1 + value.len();
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if offset + record_size > data.len() {
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return Err(Error::SpaceExhausted)
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}
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let mut record_size_bytes = [0u8; 4];
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BigEndian::write_u32(&mut record_size_bytes[..], record_size as u32);
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{
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let mut write = |payload| {
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spiflash::write(data.as_ptr().offset(offset as isize) as usize, payload);
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offset += payload.len();
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};
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write(&record_size_bytes[..]);
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write(key);
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write(&[0]);
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write(value);
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cache::flush_l2_cache();
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}
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Ok(offset)
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}
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fn compact() -> Result<(), Error> {
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let lock = Lock::take()?;
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let data = lock.data();
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static mut OLD_DATA: [u8; SIZE] = [0; SIZE];
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let old_data = unsafe {
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OLD_DATA.copy_from_slice(data);
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&OLD_DATA[..]
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};
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unsafe { spiflash::erase_sector(data.as_ptr() as usize) };
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// This is worst-case quadratic, but we're limited by a small SPI flash sector size,
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// so it does not really matter.
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let mut offset = 0;
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let mut iter = Iter::new(old_data);
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'iter: while let Some(result) = iter.next() {
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let (key, mut value) = result?;
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if value.is_empty() {
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// This is a removed entry, ignore it.
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continue
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}
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let mut next_iter = iter.clone();
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while let Some(next_result) = next_iter.next() {
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let (next_key, _) = next_result?;
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if key == next_key {
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// There's another entry that overwrites this one, ignore this one.
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continue 'iter
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}
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}
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offset = unsafe { append_at(data, offset, key, value)? };
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}
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Ok(())
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}
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fn append(key: &str, value: &[u8]) -> Result<(), Error> {
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let lock = Lock::take()?;
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let data = lock.data();
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let free_offset = {
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let mut iter = Iter::new(data);
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while let Some(result) = iter.next() {
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let _ = result?;
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}
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iter.offset
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};
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unsafe { append_at(data, free_offset, key.as_bytes(), value)? };
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Ok(())
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}
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pub fn write(key: &str, value: &[u8]) -> Result<(), Error> {
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match append(key, value) {
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Err(Error::SpaceExhausted) => {
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compact()?;
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append(key, value)
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}
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res => res
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}
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}
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pub fn write_int(key: &str, value: u32) -> Result<(), Error> {
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let mut buf = [0; 16];
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let mut wrapper = FmtWrapper::new(&mut buf);
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write!(&mut wrapper, "{}", value).unwrap();
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write(key, wrapper.contents())
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}
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pub fn remove(key: &str) -> Result<(), Error> {
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write(key, &[])
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}
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pub fn erase() -> Result<(), Error> {
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let lock = Lock::take()?;
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let data = lock.data();
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unsafe { spiflash::erase_sector(data.as_ptr() as usize) };
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cache::flush_l2_cache();
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Ok(())
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}
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}
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#[cfg(not(has_spiflash))]
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mod imp {
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use super::Error;
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pub fn read<F: FnOnce(Result<&[u8], Error>) -> R, R>(_key: &str, f: F) -> R {
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f(Err(Error::NoFlash))
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}
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pub fn read_str<F: FnOnce(Result<&str, Error>) -> R, R>(_key: &str, f: F) -> R {
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f(Err(Error::NoFlash))
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}
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pub fn write(_key: &str, _value: &[u8]) -> Result<(), Error> {
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Err(Error::NoFlash)
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}
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pub fn remove(_key: &str) -> Result<(), Error> {
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Err(Error::NoFlash)
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}
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pub fn erase() -> Result<(), Error> {
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Err(Error::NoFlash)
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}
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}
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pub use self::imp::*;
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