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nod-rs
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Export LaggedFibonacci & add more helper methods

This commit is contained in:
Luke Street 2024-10-18 00:04:11 -06:00
parent e0d735dd39
commit 32e08f9543
3 changed files with 145 additions and 21 deletions
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19
nod/src/io/block.rs
View File

@ -1,5 +1,4 @@
use std::{
cmp::min,
fs, io,
io::{Read, Seek},
path::Path,
@ -375,23 +374,19 @@ fn generate_junk(
partition: Option<&PartitionInfo>,
disc_header: &DiscHeader,
) {
let (mut pos, mut offset) = if partition.is_some() {
let (pos, offset) = if partition.is_some() {
(sector as u64 * SECTOR_DATA_SIZE as u64, HASHES_SIZE)
} else {
(sector as u64 * SECTOR_SIZE as u64, 0)
};
out[..offset].fill(0);
while offset < SECTOR_SIZE {
// The LFG spans a single sector of the decrypted data,
// so we may need to initialize it multiple times
let mut lfg = LaggedFibonacci::default();
lfg.init_with_seed(*array_ref![disc_header.game_id, 0, 4], disc_header.disc_num, pos);
let sector_end = (pos + SECTOR_SIZE as u64) & !(SECTOR_SIZE as u64 - 1);
let len = min(SECTOR_SIZE - offset, (sector_end - pos) as usize);
lfg.fill(&mut out[offset..offset + len]);
pos += len as u64;
offset += len;
}
lfg.fill_sector_chunked(
&mut out[offset..],
*array_ref![disc_header.game_id, 0, 4],
disc_header.disc_num,
pos,
);
}
fn rebuild_hash_block(out: &mut [u8; SECTOR_SIZE], part_sector: u32, partition: &PartitionInfo) {

1
nod/src/lib.rs
View File

@ -73,6 +73,7 @@ pub use io::{
block::{DiscStream, PartitionInfo},
Compression, DiscMeta, Format, KeyBytes, MagicBytes,
};
pub use util::lfg::LaggedFibonacci;
mod disc;
mod io;

144
nod/src/util/lfg.rs
View File

@ -1,4 +1,8 @@
use std::{cmp::min, io, io::Read};
use std::{
cmp::min,
io,
io::{Read, Write},
};
use zerocopy::{transmute_ref, IntoBytes};
@ -8,7 +12,7 @@ pub const LFG_K: usize = 521;
pub const LFG_J: usize = 32;
pub const SEED_SIZE: usize = 17;
/// Lagged Fibonacci generator for Wii partition junk data.
/// Lagged Fibonacci generator for GC / Wii partition junk data.
///
/// References (license CC0-1.0):
/// https://github.com/dolphin-emu/dolphin/blob/a0f555648c27ec0c928f6b1e1fcad5e2d7c4d0c4/docs/WiaAndRvz.md
@ -19,6 +23,7 @@ pub struct LaggedFibonacci {
}
impl Default for LaggedFibonacci {
#[inline]
fn default() -> Self { Self { buffer: [0u32; LFG_K], position: 0 } }
}
@ -38,12 +43,16 @@ impl LaggedFibonacci {
}
}
pub fn init_with_seed(&mut self, init: [u8; 4], disc_num: u8, partition_offset: u64) {
/// Initializes the LFG with the standard seed for a given disc ID, disc number, and sector.
/// The partition offset is used to determine the sector and how many bytes to skip within the
/// sector.
#[allow(clippy::missing_inline_in_public_items)]
pub fn init_with_seed(&mut self, disc_id: [u8; 4], disc_num: u8, partition_offset: u64) {
let seed = u32::from_be_bytes([
init[2],
init[1],
init[3].wrapping_add(init[2]),
init[0].wrapping_add(init[1]),
disc_id[2],
disc_id[1],
disc_id[3].wrapping_add(disc_id[2]),
disc_id[0].wrapping_add(disc_id[1]),
]) ^ disc_num as u32;
let sector = (partition_offset / SECTOR_SIZE as u64) as u32;
let sector_offset = partition_offset % SECTOR_SIZE as u64;
@ -62,6 +71,9 @@ impl LaggedFibonacci {
self.skip(sector_offset as usize);
}
/// Initializes the LFG with the seed read from a reader. The seed is assumed to be big-endian.
/// This is used for rebuilding junk data in WIA/RVZ files.
#[allow(clippy::missing_inline_in_public_items)]
pub fn init_with_reader<R>(&mut self, reader: &mut R) -> io::Result<()>
where R: Read + ?Sized {
reader.read_exact(self.buffer[..SEED_SIZE].as_mut_bytes())?;
@ -73,7 +85,8 @@ impl LaggedFibonacci {
Ok(())
}
pub fn forward(&mut self) {
/// Advances the LFG by one step.
fn forward(&mut self) {
for i in 0..LFG_J {
self.buffer[i] ^= self.buffer[i + LFG_K - LFG_J];
}
@ -82,6 +95,8 @@ impl LaggedFibonacci {
}
}
/// Skips `n` bytes of junk data.
#[allow(clippy::missing_inline_in_public_items)]
pub fn skip(&mut self, n: usize) {
self.position += n;
while self.position >= LFG_K * 4 {
@ -90,6 +105,8 @@ impl LaggedFibonacci {
}
}
/// Fills the buffer with junk data.
#[allow(clippy::missing_inline_in_public_items)]
pub fn fill(&mut self, mut buf: &mut [u8]) {
while !buf.is_empty() {
let len = min(buf.len(), LFG_K * 4 - self.position);
@ -103,6 +120,68 @@ impl LaggedFibonacci {
}
}
}
/// Writes junk data to the output stream.
#[allow(clippy::missing_inline_in_public_items)]
pub fn write<W>(&mut self, w: &mut W, mut len: u64) -> io::Result<()>
where W: Write + ?Sized {
while len > 0 {
let write_len = min(len, LFG_K as u64 * 4 - self.position as u64) as usize;
let bytes: &[u8; LFG_K * 4] = transmute_ref!(&self.buffer);
w.write_all(&bytes[self.position..self.position + write_len])?;
self.position += write_len;
len -= write_len as u64;
if self.position == LFG_K * 4 {
self.forward();
self.position = 0;
}
}
Ok(())
}
/// The junk data on GC / Wii discs is reinitialized every 32KB. This functions handles the
/// wrapping logic and reinitializes the LFG at sector boundaries.
#[allow(clippy::missing_inline_in_public_items)]
pub fn fill_sector_chunked(
&mut self,
mut buf: &mut [u8],
disc_id: [u8; 4],
disc_num: u8,
mut partition_offset: u64,
) {
while !buf.is_empty() {
self.init_with_seed(disc_id, disc_num, partition_offset);
let len =
(SECTOR_SIZE - (partition_offset % SECTOR_SIZE as u64) as usize).min(buf.len());
self.fill(&mut buf[..len]);
buf = &mut buf[len..];
partition_offset += len as u64;
}
}
/// The junk data on GC / Wii discs is reinitialized every 32KB. This functions handles the
/// wrapping logic and reinitializes the LFG at sector boundaries.
#[allow(clippy::missing_inline_in_public_items)]
pub fn write_sector_chunked<W>(
&mut self,
w: &mut W,
mut len: u64,
disc_id: [u8; 4],
disc_num: u8,
mut partition_offset: u64,
) -> io::Result<()>
where
W: Write + ?Sized,
{
while len > 0 {
self.init_with_seed(disc_id, disc_num, partition_offset);
let write_len = (SECTOR_SIZE as u64 - (partition_offset % SECTOR_SIZE as u64)).min(len);
self.write(w, write_len)?;
len -= write_len;
partition_offset += write_len;
}
Ok(())
}
}
#[cfg(test)]
@ -132,4 +211,53 @@ mod tests {
0xEA, 0xD0
]);
}
#[test]
fn test_init_with_seed_3() {
let mut lfg = LaggedFibonacci::default();
lfg.init_with_seed([0x47, 0x50, 0x49, 0x45], 0, 0x322904);
let mut buf = [0u8; 16];
lfg.fill(&mut buf);
assert_eq!(buf, [
0x97, 0xD8, 0x23, 0x0B, 0x12, 0xAA, 0x20, 0x45, 0xC2, 0xBD, 0x71, 0x8C, 0x30, 0x32,
0xC5, 0x2F
]);
}
#[test]
fn test_write() {
let mut lfg = LaggedFibonacci::default();
lfg.init_with_seed([0x47, 0x50, 0x49, 0x45], 0, 0x322904);
let mut buf = [0u8; 16];
lfg.write(&mut buf.as_mut_slice(), 16).unwrap();
assert_eq!(buf, [
0x97, 0xD8, 0x23, 0x0B, 0x12, 0xAA, 0x20, 0x45, 0xC2, 0xBD, 0x71, 0x8C, 0x30, 0x32,
0xC5, 0x2F
]);
}
#[test]
fn test_fill_sector_chunked() {
let mut lfg = LaggedFibonacci::default();
let mut buf = [0u8; 32];
lfg.fill_sector_chunked(&mut buf, [0x47, 0x4D, 0x38, 0x45], 0, 0x27FF0);
assert_eq!(buf, [
0xAD, 0x6F, 0x21, 0xBE, 0x05, 0x57, 0x10, 0xED, 0xEA, 0xB0, 0x8E, 0xFD, 0x91, 0x58,
0xA2, 0x0E, 0xDC, 0x0D, 0x59, 0xC0, 0x02, 0x98, 0xA5, 0x00, 0x39, 0x5B, 0x68, 0xA6,
0x5D, 0x53, 0x2D, 0xB6
]);
}
#[test]
fn test_write_sector_chunked() {
let mut lfg = LaggedFibonacci::default();
let mut buf = [0u8; 32];
lfg.write_sector_chunked(&mut buf.as_mut_slice(), 32, [0x47, 0x4D, 0x38, 0x45], 0, 0x27FF0)
.unwrap();
assert_eq!(buf, [
0xAD, 0x6F, 0x21, 0xBE, 0x05, 0x57, 0x10, 0xED, 0xEA, 0xB0, 0x8E, 0xFD, 0x91, 0x58,
0xA2, 0x0E, 0xDC, 0x0D, 0x59, 0xC0, 0x02, 0x98, 0xA5, 0x00, 0x39, 0x5B, 0x68, 0xA6,
0x5D, 0x53, 0x2D, 0xB6
]);
}
}