From 842f4a85693b418af81560738aa3136ac500d9b1 Mon Sep 17 00:00:00 2001 From: Valentin Popov Date: Tue, 10 Feb 2026 08:38:58 +0000 Subject: Implement LZSS decompression with optional XOR decryption - Added `lzss_decompress_simple` function for LZSS decompression in `lzss.rs`. - Introduced `XorState` struct and `xor_stream` function for XOR decryption in `xor.rs`. - Updated `mod.rs` to include new LZSS and XOR modules. - Refactored `parse_library` function in `parse.rs` to utilize the new XOR decryption functionality. - Cleaned up and organized code in `lib.rs` by removing redundant functions and structures. - Added tests for new functionality in `tests.rs`. --- crates/rsli/src/compress/xor.rs | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 crates/rsli/src/compress/xor.rs (limited to 'crates/rsli/src/compress/xor.rs') diff --git a/crates/rsli/src/compress/xor.rs b/crates/rsli/src/compress/xor.rs new file mode 100644 index 0000000..c4c3d7d --- /dev/null +++ b/crates/rsli/src/compress/xor.rs @@ -0,0 +1,29 @@ +/// XOR cipher state for RsLi format +pub struct XorState { + lo: u8, + hi: u8, +} + +impl XorState { + /// Create new XOR state from 16-bit key + pub fn new(key16: u16) -> Self { + Self { + lo: (key16 & 0xFF) as u8, + hi: ((key16 >> 8) & 0xFF) as u8, + } + } + + /// Decrypt a single byte and update state + pub fn decrypt_byte(&mut self, encrypted: u8) -> u8 { + self.lo = self.hi ^ self.lo.wrapping_shl(1); + let decrypted = encrypted ^ self.lo; + self.hi = self.lo ^ (self.hi >> 1); + decrypted + } +} + +/// Decrypt entire buffer with XOR stream cipher +pub fn xor_stream(data: &[u8], key16: u16) -> Vec { + let mut state = XorState::new(key16); + data.iter().map(|&b| state.decrypt_byte(b)).collect() +} -- cgit v1.2.3