kmwebnet/OpenSK
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add format helpers for new store

Browse Source
This commit is contained in:
Julien Cretin
2020-09-30 10:34:35 +02:00
parent ea7ee9f1f9
commit d0ad46b868
3 changed files with 1255 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

907
libraries/persistent_store/src/format.rs Normal file
View File

@@ -0,0 +1,907 @@
// Copyright 2019-2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// TODO(ia0): Remove when the module is used.
#![allow(dead_code)]
use crate::bitfield::*;
use crate::{Storage, StorageIndex, StoreError, StoreResult};
use alloc::vec::Vec;
use core::cmp::min;
use core::convert::TryFrom;
type WORD = u32;
/// Size of a word in bytes.
const WORD_SIZE: usize = core::mem::size_of::<WORD>();
/// Maximum size of a page in bytes.
const MAX_PAGE_SIZE: usize = 4096;
/// Maximum number of erase cycles.
const MAX_CYCLE: usize = 65535;
/// Maximum page index.
///
/// Thus the maximum number of pages in one more than this number.
const MAX_PAGE: usize = 63;
/// Maximum number of keys.
const MAX_KEY: usize = 4095;
/// Maximum length in bytes of a user payload.
const MAX_VALUE_LEN: usize = 1023;
/// Maximum number of updates per transaction.
const MAX_UPDATES: usize = 31;
/// Maximum number of words per virtual page.
const MAX_VIRT_PAGE_SIZE: usize = div_ceil(MAX_PAGE_SIZE, WORD_SIZE) - CONTENT_WORD;
/// Word with all bits set to one.
const ERASED_WORD: u32 = 0xffffffff;
/// Helpers for a given storage configuration.
#[derive(Clone, Debug)]
pub struct Format {
/// The size in bytes of a page in the storage.
page_size: usize,
/// The number of pages in the storage.
num_pages: usize,
/// The maximum number of times a page can be erased.
max_page_erases: usize,
}
impl Format {
/// Extracts the format from a storage.
///
/// Returns `None` if the storage is not [supported].
///
/// [supported]: struct.Format.html#method.is_storage_supported
pub fn new<S: Storage>(storage: &S) -> Option<Format> {
if Format::is_storage_supported(storage) {
Some(Format {
page_size: storage.page_size(),
num_pages: storage.num_pages(),
max_page_erases: storage.max_page_erases(),
})
} else {
None
}
}
/// Returns whether a storage is supported.
///
/// A storage is supported if the following conditions hold:
/// - The size of a word is 4 bytes.
/// - The size of a word evenly divides the size of a page.
/// - A page contains at least 8 words.
/// - A page contains at most [`MAX_PAGE_SIZE`] bytes.
/// - There is at least 3 pages.
/// - There is at most [`MAX_PAGE`]` + 1` pages.
/// - A word can be written at least twice between erase cycles.
/// - A page can be erased at most [`MAX_CYCLE`] times.
///
/// [`MAX_PAGE_SIZE`]: constant.MAX_PAGE_SIZE.html
/// [`MAX_PAGE`]: constant.MAX_PAGE.html
/// [`MAX_CYCLE`]: constant.MAX_CYCLE.html
fn is_storage_supported<S: Storage>(storage: &S) -> bool {
let word_size = storage.word_size();
let page_size = storage.page_size();
let num_pages = storage.num_pages();
let max_word_writes = storage.max_word_writes();
let max_page_erases = storage.max_page_erases();
word_size == 4
&& page_size % word_size == 0
&& (8 * word_size <= page_size && page_size <= MAX_PAGE_SIZE)
&& (3 <= num_pages && num_pages <= MAX_PAGE + 1)
&& max_word_writes >= 2
&& max_page_erases <= MAX_CYCLE
}
/// The size of a word in bytes.
pub fn word_size(&self) -> usize {
WORD_SIZE
}
/// The size of a page in bytes.
///
/// We have `32 <= self.page_size() <= MAX_PAGE_SIZE`.
pub fn page_size(&self) -> usize {
self.page_size
}
/// The number of pages in the storage.
///
/// Notation: `N`. We have `3 <= N <= MAX_PAGE + 1`.
pub fn num_pages(&self) -> usize {
self.num_pages
}
/// The maximum page index.
///
/// We have `2 <= self.max_page() <= MAX_PAGE`.
pub fn max_page(&self) -> usize {
self.num_pages - 1
}
/// The maximum number of times a page can be erased.
///
/// Notation: `E`. We have `E <= MAX_CYCLE`.
pub fn max_page_erases(&self) -> usize {
self.max_page_erases
}
/// The maximum key.
pub fn max_key(&self) -> usize {
MAX_KEY
}
/// The maximum number of updates per transaction.
pub fn max_updates(&self) -> usize {
MAX_UPDATES
}
/// The size of a virtual page in words.
///
/// A virtual page is stored in a physical page after the page header.
///
/// Notation: `Q`. We have `6 <= Q <= MAX_VIRT_PAGE_SIZE`.
pub fn virt_page_size(&self) -> usize {
self.page_size() / self.word_size() - CONTENT_WORD
}
/// The maximum length in bytes of a user payload.
///
/// We have `20 <= self.max_value_len() <= MAX_VALUE_LEN`.
pub fn max_value_len(&self) -> usize {
min(
(self.virt_page_size() - 1) * self.word_size(),
MAX_VALUE_LEN,
)
}
/// The maximum prefix length in words.
///
/// A prefix is the first words of a virtual page that belong to the last entry of the previous
/// virtual page. This happens because entries may overlap up to 2 virtual pages.
///
/// Notation: `M`. We have `5 <= M < Q`.
pub fn max_prefix_len(&self) -> usize {
self.bytes_to_words(self.max_value_len())
}
/// The total virtual capacity in words.
///
/// Notation: `V`. We have `V = (N - 1) * (Q - 1) - M`.
pub fn virt_size(&self) -> usize {
(self.num_pages() - 1) * (self.virt_page_size() - 1) - self.max_prefix_len()
}
/// The total user capacity in words.
///
/// Notation: `C`. We have `C = V - N = (N - 1) * (Q - 2) - M - 1`.
pub fn total_capacity(&self) -> usize {
// From the virtual capacity, we reserve N - 1 words for `Erase` entries and 1 word for a
// `Clear` entry.
self.virt_size() - self.num_pages()
}
/// The total virtual lifetime in words.
///
/// Notation: `L`. We have `L = (E * N + N - 1) * Q`.
pub fn total_lifetime(&self) -> Position {
Position::new(self, self.max_page_erases(), self.num_pages() - 1, 0)
}
/// Returns the word position of the first entry of a page.
///
/// The init info of the page must be provided to know where the first entry of the page
/// starts.
pub fn page_head(&self, init: InitInfo, page: usize) -> Position {
Position::new(self, init.cycle, page, init.prefix)
}
/// Returns the storage index of the init info of a page.
pub fn index_init(&self, page: usize) -> StorageIndex {
let byte = INIT_WORD * self.word_size();
StorageIndex { page, byte }
}
/// Parses the init info of a page from its storage representation.
pub fn parse_init(&self, word: &[u8]) -> StoreResult<WordState<InitInfo>> {
let word = slice_to_word(word);
Ok(if word == ERASED_WORD {
WordState::Erased
} else if WORD_CHECKSUM.get(word)? != 0 {
WordState::Partial
} else {
let cycle = INIT_CYCLE.get(word);
let prefix = INIT_PREFIX.get(word);
if cycle > self.max_page_erases() || prefix > self.max_prefix_len() {
return Err(StoreError::InvalidStorage);
}
WordState::Valid(InitInfo { cycle, prefix })
})
}
/// Builds the storage representation of an init info.
pub fn build_init(&self, init: InitInfo) -> [u8; WORD_SIZE] {
let mut word = ERASED_WORD;
INIT_CYCLE.set(&mut word, init.cycle);
INIT_PREFIX.set(&mut word, init.prefix);
WORD_CHECKSUM.set(&mut word, 0);
word.to_ne_bytes()
}
/// Returns the storage index of the compact info of a page.
pub fn index_compact(&self, page: usize) -> StorageIndex {
let byte = COMPACT_WORD * self.word_size();
StorageIndex { page, byte }
}
/// Parses the compact info of a page from its storage representation.
pub fn parse_compact(&self, word: &[u8]) -> StoreResult<WordState<CompactInfo>> {
let word = slice_to_word(word);
Ok(if word == ERASED_WORD {
WordState::Erased
} else if WORD_CHECKSUM.get(word)? != 0 {
WordState::Partial
} else {
let tail = COMPACT_TAIL.get(word);
if tail > self.virt_size() + self.max_prefix_len() {
return Err(StoreError::InvalidStorage);
}
WordState::Valid(CompactInfo { tail })
})
}
/// Builds the storage representation of a compact info.
pub fn build_compact(&self, compact: CompactInfo) -> [u8; WORD_SIZE] {
let mut word = ERASED_WORD;
COMPACT_TAIL.set(&mut word, compact.tail);
WORD_CHECKSUM.set(&mut word, 0);
word.to_ne_bytes()
}
/// Builds the storage representation of an internal entry.
pub fn build_internal(&self, internal: Internal) -> [u8; WORD_SIZE] {
let mut word = ERASED_WORD;
match internal {
Internal::Erase { page } => {
ID_ERASE.set(&mut word);
ERASE_PAGE.set(&mut word, page);
}
Internal::Clear { min_key } => {
ID_CLEAR.set(&mut word);
CLEAR_MIN_KEY.set(&mut word, min_key);
}
Internal::Marker { count } => {
ID_MARKER.set(&mut word);
MARKER_COUNT.set(&mut word, count);
}
Internal::Remove { key } => {
ID_REMOVE.set(&mut word);
REMOVE_KEY.set(&mut word, key);
}
}
WORD_CHECKSUM.set(&mut word, 0);
word.to_ne_bytes()
}
/// Parses the first word of an entry from its storage representation.
pub fn parse_word(&self, word: &[u8]) -> StoreResult<WordState<ParsedWord>> {
let word = slice_to_word(word);
let valid = if ID_PADDING.check(word) {
ParsedWord::Padding(Padding { length: 0 })
} else if ID_HEADER.check(word) {
if HEADER_DELETED.get(word) {
let length = HEADER_LENGTH.get(word);
if length > self.max_value_len() {
return Err(StoreError::InvalidStorage);
}
let length = self.bytes_to_words(length);
ParsedWord::Padding(Padding { length })
} else {
let flipped = HEADER_FLIPPED.get(word);
let length = HEADER_LENGTH.get(word);
let key = HEADER_KEY.get(word);
let checksum = HEADER_CHECKSUM.get(word)?;
ParsedWord::Header(Header {
flipped,
length,
key,
checksum,
})
}
} else if ID_ERASE.check(word) {
let page = ERASE_PAGE.get(word);
ParsedWord::Internal(Internal::Erase { page })
} else if ID_CLEAR.check(word) {
let min_key = CLEAR_MIN_KEY.get(word);
ParsedWord::Internal(Internal::Clear { min_key })
} else if ID_MARKER.check(word) {
let count = MARKER_COUNT.get(word);
ParsedWord::Internal(Internal::Marker { count })
} else if ID_REMOVE.check(word) {
let key = REMOVE_KEY.get(word);
ParsedWord::Internal(Internal::Remove { key })
} else if word == ERASED_WORD {
return Ok(WordState::Erased);
} else {
return Ok(WordState::Partial);
};
if let ParsedWord::Internal(internal) = &valid {
if WORD_CHECKSUM.get(word)? != 0 {
return Ok(WordState::Partial);
}
let invalid = match internal {
Internal::Erase { page } => *page > self.max_page(),
Internal::Clear { min_key } => *min_key > self.max_key(),
Internal::Marker { count } => *count > MAX_UPDATES,
Internal::Remove { key } => *key > self.max_key(),
};
if invalid {
return Err(StoreError::InvalidStorage);
}
}
Ok(WordState::Valid(valid))
}
/// Builds the storage representation of a user entry.
pub fn build_user(&self, key: usize, value: &[u8]) -> Vec<u8> {
let length = value.len();
let word_size = self.word_size();
let footer = self.bytes_to_words(length);
let mut result = vec![0xff; (1 + footer) * word_size];
result[word_size..][..length].copy_from_slice(value);
let mut word = ERASED_WORD;
ID_HEADER.set(&mut word);
if footer > 0 && is_erased(&result[footer * word_size..]) {
HEADER_FLIPPED.set(&mut word);
*result.last_mut().unwrap() = 0x7f;
}
HEADER_LENGTH.set(&mut word, length);
HEADER_KEY.set(&mut word, key);
HEADER_CHECKSUM.set(&mut word, count_zeros(&result[footer * word_size..]));
result[..word_size].copy_from_slice(&word.to_ne_bytes());
result
}
/// Sets the padding bit in the first word of a user entry.
///
/// The word is taken as a slice for convenience.
///
/// # Panics
///
/// Panics if `slice.len() != WORD_SIZE`.
pub fn set_padding(&self, slice: &mut [u8]) {
let mut word = slice_to_word(slice);
ID_PADDING.set(&mut word);
slice.copy_from_slice(&word.to_ne_bytes());
}
/// Sets the deleted bit in the first word of a user entry.
///
/// The word is taken as a slice for convenience.
///
/// # Panics
///
/// Panics if `slice.len() != WORD_SIZE`.
pub fn set_deleted(&self, slice: &mut [u8]) {
let mut word = slice_to_word(slice);
HEADER_DELETED.set(&mut word);
slice.copy_from_slice(&word.to_ne_bytes());
}
/// Returns the minimum number of words to represent a given number of bytes.
pub fn bytes_to_words(&self, bytes: usize) -> usize {
div_ceil(bytes, self.word_size())
}
}
/// The word index of the init info in a page.
const INIT_WORD: usize = 0;
/// The word index of the compact info in a page.
const COMPACT_WORD: usize = 1;
/// The word index of the content of a page.
const CONTENT_WORD: usize = 2;
/// The checksum for a single word.
///
/// It needs 5 bits to store numbers between 0 and 27.
const WORD_CHECKSUM: Checksum = Checksum {
field: Field { pos: 27, len: 5 },
};
// The fields of the init info of a page.
bitfield! {
/// The number of times the page has been erased.
INIT_CYCLE: Field <= MAX_CYCLE,
/// The word index of the first entry in this virtual page.
INIT_PREFIX: Field <= div_ceil(MAX_VALUE_LEN, WORD_SIZE),
#[cfg(test)]
LEN_INIT: Length,
}
// The fields of the compact info of a page.
bitfield! {
/// The distance in words between head and tail at compaction.
///
/// In particular, compaction copies non-deleted user entries from the head to the tail as long
/// as entries span the page to be compacted.
COMPACT_TAIL: Field <= MAX_VIRT_PAGE_SIZE * MAX_PAGE,
#[cfg(test)]
LEN_COMPACT: Length,
}
// Overview of the first word of the different kind of entries:
//
// 0123456789abcdef0123456789abcdef
// padding 0
// header 10..............................
// erase 11000...........
// clear 11001.................
// marker 11010..........
// remove 11011.................
//
// NOTE: We could pad the internal entries to the right.
// The fields of a padding entry.
bitfield! {
/// The identifier for padding entries.
ID_PADDING: ConstField = [0],
}
// The fields of a user entry.
bitfield! {
/// The identifier for user entries.
ID_HEADER: ConstField = [1 0],
/// Whether the user entry is deleted.
HEADER_DELETED: Bit,
/// Whether the last bit of the user data is flipped.
HEADER_FLIPPED: Bit,
/// The length in bytes of the user data.
// NOTE: It is possible to support values of length 1024 by having a separate kind of entries
// when the value is empty. We could then subtract one from the length here.
HEADER_LENGTH: Field <= MAX_VALUE_LEN,
/// The key of the user entry.
HEADER_KEY: Field <= MAX_KEY,
/// The checksum of the user entry.
///
/// This counts the number of bits set to zero in both the first and last words of the user
/// entry, except in the checksum itself. So it needs 6 bits to store numbers between 0 and 58.
// NOTE: It may be possible to save one bit by storing:
// - the footer checksum (as a field) if the value is not empty
// - the header checksum (as a checksum) if the value is empty
HEADER_CHECKSUM: Checksum <= 58,
#[cfg(test)]
LEN_HEADER: Length,
}
// The fields of an erase entry.
bitfield! {
/// The identifier for erase entries.
ID_ERASE: ConstField = [1 1 0 0 0],
/// The page to be erased.
ERASE_PAGE: Field <= MAX_PAGE,
#[cfg(test)]
LEN_ERASE: Length,
}
// The fields of a clear entry.
bitfield! {
/// The identifier for clear entries.
ID_CLEAR: ConstField = [1 1 0 0 1],
/// The minimum key to be cleared.
///
/// All entries with a key below this limit are not cleared. All other entries are deleted.
CLEAR_MIN_KEY: Field <= MAX_KEY,
#[cfg(test)]
LEN_CLEAR: Length,
}
// The fields of a marker entry.
bitfield! {
/// The identifier for marker entries.
ID_MARKER: ConstField = [1 1 0 1 0],
/// The number of updates in this transaction.
///
/// The update entries follow this marker entry.
MARKER_COUNT: Field <= MAX_UPDATES,
#[cfg(test)]
LEN_MARKER: Length,
}
// The fields of a remove entry.
bitfield! {
/// The identifier for remove entries.
ID_REMOVE: ConstField = [1 1 0 1 1],
/// The key of the user entry to be removed.
REMOVE_KEY: Field <= MAX_KEY,
#[cfg(test)]
LEN_REMOVE: Length,
}
/// The position of a word in the virtual storage.
///
/// With the notations defined in `Format`, let:
/// - `w` a virtual word offset in a page which is between `0` and `Q - 1`
/// - `p` a page offset which is between `0` and `N - 1`
/// - `c` the number of erase cycles of a page which is between `0` and `E`
///
/// Then the position of a word is `(c*N + p)*Q + w`. This position monotonically increases and
/// represents the consumed lifetime of the storage.
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct Position(usize);
impl core::ops::Add<usize> for Position {
type Output = Position;
fn add(self, delta: usize) -> Position {
Position(self.0 + delta)
}
}
impl core::ops::Sub<Position> for Position {
type Output = usize;
fn sub(self, base: Position) -> usize {
self.0 - base.0
}
}
impl core::ops::AddAssign<usize> for Position {
fn add_assign(&mut self, delta: usize) {
self.0 += delta;
}
}
impl Position {
/// Create a word position given its coordinates.
///
/// The coordinates of a word are:
/// - Its word index in its page.
/// - Its page index in the storage.
/// - The number of times that page was erased.
pub fn new(format: &Format, cycle: usize, page: usize, word: usize) -> Position {
Position((cycle * format.num_pages() + page) * format.virt_page_size() + word)
}
/// Accesses the underlying position as a natural number.
pub fn get(self) -> usize {
self.0
}
/// Returns the associated storage index.
pub fn index(self, format: &Format) -> StorageIndex {
let page = self.page(format);
let word = CONTENT_WORD + self.word(format);
let byte = word * format.word_size();
StorageIndex { page, byte }
}
/// Returns the beginning of the current virtual page.
pub fn page_begin(self, format: &Format) -> Position {
let virt_page_size = format.virt_page_size();
Position((self.0 / virt_page_size) * virt_page_size)
}
/// Returns the beginning of the next virtual page.
pub fn next_page(self, format: &Format) -> Position {
let virt_page_size = format.virt_page_size();
Position((self.0 / virt_page_size + 1) * virt_page_size)
}
/// Returns the number of times the current page was erased.
pub fn cycle(self, format: &Format) -> usize {
(self.0 / format.virt_page_size()) / format.num_pages()
}
/// Returns the current page index.
pub fn page(self, format: &Format) -> usize {
(self.0 / format.virt_page_size()) % format.num_pages()
}
/// Returns the current word index in the page.
pub fn word(self, format: &Format) -> usize {
self.0 % format.virt_page_size()
}
}
/// Possible states of some storage representation as a word.
pub enum WordState<T> {
/// The word is still erased.
Erased,
/// The word is partially written.
Partial,
/// Holds the decoded version of a valid word.
Valid(T),
}
/// Information for an initialized page.
pub struct InitInfo {
/// The number of times this page has been erased.
pub cycle: usize,
/// The word index of the first entry in this virtual page.
pub prefix: usize,
}
/// Information for a page being compacted.
pub struct CompactInfo {
/// The distance in words between head and tail at compaction.
pub tail: usize,
}
/// The first word of an entry.
#[derive(Debug)]
pub enum ParsedWord {
/// Padding entry.
Padding(Padding),
/// Header of a user entry.
Header(Header),
/// Internal entry.
Internal(Internal),
}
/// Padding entry.
#[derive(Debug)]
pub struct Padding {
/// The number of following padding words after the first word of the padding entry.
pub length: usize,
}
/// Header of a user entry.
#[derive(Debug)]
pub struct Header {
/// Whether the last bit of the user data is flipped.
pub flipped: bool,
/// The length in bytes of the user data.
pub length: usize,
/// The key of the user entry.
pub key: usize,
/// The checksum of the user entry.
pub checksum: usize,
}
impl Header {
/// Checks the validity of a user entry.
///
/// If the user entry has no payload, the `footer` must be set to `None`. Otherwise it should be
/// the last word of the entry.
pub fn check(&self, footer: Option<&[u8]>) -> bool {
footer.map_or(0, |x| count_zeros(x)) == self.checksum
}
}
/// Internal entry.
#[derive(Debug)]
pub enum Internal {
/// Indicates that a page should be erased.
Erase {
/// The page to be erased.
page: usize,
},
/// Indicates that user entries with high key should be deleted.
Clear {
/// The minimum key a user entry should have to be deleted.
min_key: usize,
},
/// Marks the start of a transaction.
///
/// The marker is followed by a given number of updates, which are either user entries or remove
/// entries.
Marker {
/// The number of updates in the transaction.
count: usize,
},
/// Indicates that a user entry should be removed.
///
/// This is only useful (and valid) as part of a transaction, since removing a single entry is
/// already atomic.
Remove {
/// The key of the user entry to be removed.
key: usize,
},
}
/// Returns whether a slice has all bits equal to one.
pub fn is_erased(slice: &[u8]) -> bool {
slice.iter().all(|&x| x == 0xff)
}
/// Converts a word slice into a word.
///
/// # Panics
///
/// Panics if `word.len() != WORD_SIZE`.
fn slice_to_word(word: &[u8]) -> WORD {
u32::from_ne_bytes(<[u8; WORD_SIZE]>::try_from(word).unwrap())
}
/// Divides then takes ceiling.
///
/// Returns `ceil(x / m)` with mathematical notations.
pub const fn div_ceil(x: usize, m: usize) -> usize {
(x + m - 1) / m
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn size_of_format() {
assert_eq!(std::mem::size_of::<Format>(), 24);
}
#[test]
fn checksum_ok() {
let Field { pos, len } = WORD_CHECKSUM.field;
// There is enough bits to represents the number of zeros preceding the checksum.
assert_eq!(len, num_bits(pos));
// The checksum is the last field of a word.
assert_eq!(pos + len, 8 * WORD_SIZE);
// The data of words using the checksum don't overlap the checksum.
let words = &[
&LEN_INIT,
&LEN_COMPACT,
&LEN_ERASE,
&LEN_CLEAR,
&LEN_MARKER,
&LEN_REMOVE,
];
for word in words {
assert!(word.pos < pos);
}
}
#[test]
fn init_ok() {
assert_eq!(INIT_CYCLE.pos, 0);
assert_eq!(INIT_CYCLE.len, 16);
assert_eq!(INIT_PREFIX.pos, 16);
assert_eq!(INIT_PREFIX.len, 9);
assert_eq!(LEN_INIT.pos, 25);
}
#[test]
fn compact_ok() {
assert_eq!(COMPACT_TAIL.pos, 0);
assert_eq!(COMPACT_TAIL.len, 16);
assert_eq!(LEN_COMPACT.pos, 16);
}
#[test]
fn header_ok() {
assert_eq!(ID_HEADER.field.pos, 0);
assert_eq!(ID_HEADER.field.len, 2);
assert_eq!(ID_HEADER.value, 0b01);
assert_eq!(HEADER_DELETED.pos, 2);
assert_eq!(HEADER_FLIPPED.pos, 3);
assert_eq!(HEADER_LENGTH.pos, 4);
assert_eq!(HEADER_LENGTH.len, 10);
assert_eq!(HEADER_KEY.pos, 14);
assert_eq!(HEADER_KEY.len, 12);
assert_eq!(HEADER_CHECKSUM.field.pos, 26);
assert_eq!(HEADER_CHECKSUM.field.len, 6);
assert_eq!(LEN_HEADER.pos, 32);
}
#[test]
fn erase_ok() {
assert_eq!(ID_ERASE.field.pos, 0);
assert_eq!(ID_ERASE.field.len, 5);
assert_eq!(ID_ERASE.value, 0b00011);
assert_eq!(ERASE_PAGE.pos, 5);
assert_eq!(ERASE_PAGE.len, 6);
assert_eq!(LEN_ERASE.pos, 11);
}
#[test]
fn clear_ok() {
assert_eq!(ID_CLEAR.field.pos, 0);
assert_eq!(ID_CLEAR.field.len, 5);
assert_eq!(ID_CLEAR.value, 0b10011);
assert_eq!(CLEAR_MIN_KEY.pos, 5);
assert_eq!(CLEAR_MIN_KEY.len, 12);
assert_eq!(LEN_CLEAR.pos, 17);
}
#[test]
fn marker_ok() {
assert_eq!(ID_MARKER.field.pos, 0);
assert_eq!(ID_MARKER.field.len, 5);
assert_eq!(ID_MARKER.value, 0b01011);
assert_eq!(MARKER_COUNT.pos, 5);
assert_eq!(MARKER_COUNT.len, 5);
assert_eq!(LEN_MARKER.pos, 10);
}
#[test]
fn remove_ok() {
assert_eq!(ID_REMOVE.field.pos, 0);
assert_eq!(ID_REMOVE.field.len, 5);
assert_eq!(ID_REMOVE.value, 0b11011);
assert_eq!(REMOVE_KEY.pos, 5);
assert_eq!(REMOVE_KEY.len, 12);
assert_eq!(LEN_REMOVE.pos, 17);
}
#[test]
fn is_erased_ok() {
assert!(is_erased(&[]));
assert!(is_erased(&[0xff]));
assert!(is_erased(&[0xff, 0xff]));
assert!(!is_erased(&[0x00]));
assert!(!is_erased(&[0xff, 0xfe]));
assert!(!is_erased(&[0x7f, 0xff]));
}
#[test]
fn slice_to_word_ok() {
// We write test with little-endian in mind, but use this helper function to test regardless
// of endianness.
fn test(slice: &[u8], word: u32) {
#[cfg(target_endian = "little")]
let word = word.swap_bytes();
assert_eq!(slice_to_word(slice), word);
}
test(&[0x01, 0x02, 0x03, 0x04], 0x01020304);
test(&[0xf0, 0x78, 0x3c, 0x1e], 0xf0783c1e);
}
#[test]
fn div_ceil_ok() {
assert_eq!(div_ceil(0, 1), 0);
assert_eq!(div_ceil(1, 1), 1);
assert_eq!(div_ceil(2, 1), 2);
assert_eq!(div_ceil(0, 2), 0);
assert_eq!(div_ceil(1, 2), 1);
assert_eq!(div_ceil(2, 2), 1);
assert_eq!(div_ceil(3, 2), 2);
}
}