diff --git a/Cargo.lock b/Cargo.lock
index 5659237..bc2a637 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -68,12 +68,6 @@ dependencies = [
  "windows-sys 0.59.0",
 ]
 
-[[package]]
-name = "anyhow"
-version = "1.0.95"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"
-
 [[package]]
 name = "assert_cmd"
 version = "2.0.16"
@@ -229,21 +223,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "crc"
-version = "3.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "69e6e4d7b33a94f0991c26729976b10ebde1d34c3ee82408fb536164fa10d636"
-dependencies = [
- "crc-catalog",
-]
-
-[[package]]
-name = "crc-catalog"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "19d374276b40fb8bbdee95aef7c7fa6b5316ec764510eb64b8dd0e2ed0d7e7f5"
-
 [[package]]
 name = "crc32fast"
 version = "1.4.2"
@@ -416,12 +395,6 @@ version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
-[[package]]
-name = "hex-literal"
-version = "0.4.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6fe2267d4ed49bc07b63801559be28c718ea06c4738b7a03c94df7386d2cde46"
-
 [[package]]
 name = "icu_collections"
 version = "1.5.0"
@@ -659,13 +632,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"
 
 [[package]]
-name = "lzma-rs"
-version = "0.3.0"
+name = "lz4_flex"
+version = "0.11.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "297e814c836ae64db86b36cf2a557ba54368d03f6afcd7d947c266692f71115e"
+checksum = "75761162ae2b0e580d7e7c390558127e5f01b4194debd6221fd8c207fc80e3f5"
 dependencies = [
- "byteorder",
- "crc",
+ "twox-hash",
 ]
 
 [[package]]
@@ -689,15 +661,6 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "830b246a0e5f20af87141b25c173cd1b609bd7779a4617d6ec582abaf90870f3"
 
-[[package]]
-name = "object"
-version = "0.36.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "62948e14d923ea95ea2c7c86c71013138b66525b86bdc08d2dcc262bdb497b87"
-dependencies = [
- "memchr",
-]
-
 [[package]]
 name = "once_cell"
 version = "1.20.2"
@@ -708,15 +671,10 @@ checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
 name = "oodle_loader"
 version = "0.2.2"
 dependencies = [
- "anyhow",
  "hex",
- "hex-literal",
- "libc",
  "libloading",
- "lzma-rs",
- "object",
- "seq-macro",
- "sha1",
+ "sha2",
+ "thiserror",
  "ureq",
 ]
 
@@ -835,6 +793,8 @@ dependencies = [
  "base64",
  "byteorder",
  "flate2",
+ "hex",
+ "lz4_flex",
  "oodle_loader",
  "paste",
  "sha1",
@@ -941,12 +901,6 @@ dependencies = [
  "winapi-util",
 ]
 
-[[package]]
-name = "seq-macro"
-version = "0.3.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a3f0bf26fd526d2a95683cd0f87bf103b8539e2ca1ef48ce002d67aad59aa0b4"
-
 [[package]]
 name = "serde"
 version = "1.0.217"
@@ -1013,6 +967,12 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a8f112729512f8e442d81f95a8a7ddf2b7c6b8a1a6f509a95864142b30cab2d3"
 
+[[package]]
+name = "static_assertions"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
+
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -1119,6 +1079,16 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "twox-hash"
+version = "1.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97fee6b57c6a41524a810daee9286c02d7752c4253064d0b05472833a438f675"
+dependencies = [
+ "cfg-if",
+ "static_assertions",
+]
+
 [[package]]
 name = "typenum"
 version = "1.17.0"
diff --git a/oodle_loader/Cargo.toml b/oodle_loader/Cargo.toml
index 7e57ccd..c5255eb 100644
--- a/oodle_loader/Cargo.toml
+++ b/oodle_loader/Cargo.toml
@@ -6,18 +6,9 @@ license.workspace = true
 version.workspace = true
 edition.workspace = true
 
-[target.'cfg(windows)'.dependencies]
-libloading = "0.8"
-
-[target.'cfg(unix)'.dependencies]
-object = { version = "0.36.7", default-features = false, features = ["std", "read"] }
-libc = "0.2.169"
-seq-macro = "0.3.5"
-
 [dependencies]
-sha1 = { workspace = true }
+libloading = "0.8"
 ureq = "2.12"
-hex-literal = "0.4"
 hex = { workspace = true }
-anyhow = "1.0.95"
-lzma-rs = "0.3.0"
+sha2 = "0.10.8"
+thiserror = "2.0.11"
diff --git a/oodle_loader/src/lib.rs b/oodle_loader/src/lib.rs
index 2803770..0bfbca9 100644
--- a/oodle_loader/src/lib.rs
+++ b/oodle_loader/src/lib.rs
@@ -1,405 +1,323 @@
-use anyhow::{anyhow, Context, Result};
+use std::{io::Read, sync::OnceLock};
 
-use std::sync::OnceLock;
+type Result<T, E = Error> = std::result::Result<T, E>;
 
-type OodleDecompress = fn(comp_buf: &[u8], raw_buf: &mut [u8]) -> i32;
+pub use oodle_lz::{CompressionLevel, Compressor};
 
-#[allow(non_camel_case_types)]
-type OodleLZ_Decompress = unsafe extern "win64" fn(
-    compBuf: *const u8,
-    compBufSize: usize,
-    rawBuf: *mut u8,
-    rawLen: usize,
-    fuzzSafe: u32,
-    checkCRC: u32,
-    verbosity: u32,
-    decBufBase: u64,
-    decBufSize: usize,
-    fpCallback: u64,
-    callbackUserData: u64,
-    decoderMemory: *mut u8,
-    decoderMemorySize: usize,
-    threadPhase: u32,
-) -> i32;
+mod oodle_lz {
+    #[derive(Debug, Clone, Copy)]
+    #[repr(i32)]
+    pub enum Compressor {
+        /// None = memcpy, pass through uncompressed bytes
+        None = 3,
 
-pub fn decompress() -> Result<OodleDecompress, Box<dyn std::error::Error>> {
-    #[cfg(windows)]
-    return Ok(windows_oodle::decompress_wrapper_windows);
-    #[cfg(unix)]
-    return Ok(linux_oodle::oodle_loader_linux());
+        /// Fast decompression and high compression ratios, amazing!
+        Kraken = 8,
+        /// Leviathan = Kraken's big brother with higher compression, slightly slower decompression.
+        Leviathan = 13,
+        /// Mermaid is between Kraken & Selkie - crazy fast, still decent compression.
+        Mermaid = 9,
+        /// Selkie is a super-fast relative of Mermaid.  For maximum decode speed.
+        Selkie = 11,
+        /// Hydra, the many-headed beast = Leviathan, Kraken, Mermaid, or Selkie (see $OodleLZ_About_Hydra)
+        Hydra = 12,
+    }
+
+    #[derive(Debug, Clone, Copy)]
+    #[repr(i32)]
+    pub enum CompressionLevel {
+        /// don't compress, just copy raw bytes
+        None = 0,
+        /// super fast mode, lower compression ratio
+        SuperFast = 1,
+        /// fastest LZ mode with still decent compression ratio
+        VeryFast = 2,
+        /// fast - good for daily use
+        Fast = 3,
+        /// standard medium speed LZ mode
+        Normal = 4,
+
+        /// optimal parse level 1 (faster optimal encoder)
+        Optimal1 = 5,
+        /// optimal parse level 2 (recommended baseline optimal encoder)
+        Optimal2 = 6,
+        /// optimal parse level 3 (slower optimal encoder)
+        Optimal3 = 7,
+        /// optimal parse level 4 (very slow optimal encoder)
+        Optimal4 = 8,
+        /// optimal parse level 5 (don't care about encode speed, maximum compression)
+        Optimal5 = 9,
+
+        /// faster than SuperFast, less compression
+        HyperFast1 = -1,
+        /// faster than HyperFast1, less compression
+        HyperFast2 = -2,
+        /// faster than HyperFast2, less compression
+        HyperFast3 = -3,
+        /// fastest, less compression
+        HyperFast4 = -4,
+    }
+
+    pub type Compress = unsafe extern "system" fn(
+        compressor: Compressor,
+        rawBuf: *const u8,
+        rawLen: usize,
+        compBuf: *mut u8,
+        level: CompressionLevel,
+        pOptions: *const (),
+        dictionaryBase: *const (),
+        lrm: *const (),
+        scratchMem: *mut u8,
+        scratchSize: usize,
+    ) -> isize;
+
+    pub type Decompress = unsafe extern "system" fn(
+        compBuf: *const u8,
+        compBufSize: usize,
+        rawBuf: *mut u8,
+        rawLen: usize,
+        fuzzSafe: u32,
+        checkCRC: u32,
+        verbosity: u32,
+        decBufBase: u64,
+        decBufSize: usize,
+        fpCallback: u64,
+        callbackUserData: u64,
+        decoderMemory: *mut u8,
+        decoderMemorySize: usize,
+        threadPhase: u32,
+    ) -> isize;
+
+    pub type GetCompressedBufferSizeNeeded =
+        unsafe extern "system" fn(compressor: Compressor, rawSize: usize) -> usize;
+
+    pub type SetPrintf = unsafe extern "system" fn(printf: *const ());
 }
 
-fn call_decompress(comp_buf: &[u8], raw_buf: &mut [u8], decompress: OodleLZ_Decompress) -> i32 {
-    unsafe {
-        decompress(
-            comp_buf.as_ptr(),
-            comp_buf.len(),
-            raw_buf.as_mut_ptr(),
-            raw_buf.len(),
-            1,
-            1,
-            0,
-            0,
-            0,
-            0,
-            0,
-            std::ptr::null_mut(),
-            0,
-            3,
-        )
+static OODLE_VERSION: &str = "2.9.10";
+static OODLE_BASE_URL: &str = "https://github.com/WorkingRobot/OodleUE/raw/refs/heads/main/Engine/Source/Programs/Shared/EpicGames.Oodle/Sdk/";
+
+struct OodlePlatform {
+    path: &'static str,
+    name: &'static str,
+    hash: &'static str,
+}
+
+#[cfg(target_os = "linux")]
+static OODLE_PLATFORM: OodlePlatform = OodlePlatform {
+    path: "linux/lib",
+    name: "liboo2corelinux64.so.9",
+    hash: "ed7e98f70be1254a80644efd3ae442ff61f854a2fe9debb0b978b95289884e9c",
+};
+
+#[cfg(target_os = "macos")]
+static OODLE_PLATFORM: OodlePlatform = OodlePlatform {
+    path: "mac/lib",
+    name: "liboo2coremac64.2.9.10.dylib",
+    hash: "b09af35f6b84a61e2b6488495c7927e1cef789b969128fa1c845e51a475ec501",
+};
+
+#[cfg(windows)]
+static OODLE_PLATFORM: OodlePlatform = OodlePlatform {
+    path: "win/redist",
+    name: "oo2core_9_win64.dll",
+    hash: "6f5d41a7892ea6b2db420f2458dad2f84a63901c9a93ce9497337b16c195f457",
+};
+
+fn url() -> String {
+    format!(
+        "{OODLE_BASE_URL}/{}/{}/{}",
+        OODLE_VERSION, OODLE_PLATFORM.path, OODLE_PLATFORM.name
+    )
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("Oodle lib hash mismatch expected: {expected} got {found}")]
+    HashMismatch { expected: String, found: String },
+    #[error("Oodle compression failed")]
+    CompressionFailed,
+    #[error("Oodle initialization failed previously")]
+    InitializationFailed,
+    #[error("IO error {0:?}")]
+    Io(#[from] std::io::Error),
+    #[error("ureq error {0:?}")]
+    Ureq(Box<ureq::Error>),
+    #[error("Oodle libloading error {0:?}")]
+    LibLoading(#[from] libloading::Error),
+}
+impl From<ureq::Error> for Error {
+    fn from(value: ureq::Error) -> Self {
+        Self::Ureq(value.into())
     }
 }
 
-static OODLE_HASH: [u8; 20] = hex_literal::hex!("4bcc73614cb8fd2b0bce8d0f91ee5f3202d9d624");
-static OODLE_DLL_NAME: &str = "oo2core_9_win64.dll";
+fn check_hash(buffer: &[u8]) -> Result<()> {
+    use sha2::{Digest, Sha256};
+
+    let mut hasher = Sha256::new();
+    hasher.update(buffer);
+    let hash = hex::encode(hasher.finalize());
+    if hash != OODLE_PLATFORM.hash {
+        return Err(Error::HashMismatch {
+            expected: OODLE_PLATFORM.hash.into(),
+            found: hash,
+        });
+    }
+
+    Ok(())
+}
 
 fn fetch_oodle() -> Result<std::path::PathBuf> {
-    use sha1::{Digest, Sha1};
-
-    let oodle_path = std::env::current_exe()?.with_file_name(OODLE_DLL_NAME);
-
+    let oodle_path = std::env::current_exe()?.with_file_name(OODLE_PLATFORM.name);
     if !oodle_path.exists() {
-        let mut compressed = vec![];
-        ureq::get("https://origin.warframe.com/origin/50F7040A/index.txt.lzma")
+        let mut buffer = vec![];
+        ureq::get(&url())
             .call()?
             .into_reader()
-            .read_to_end(&mut compressed)?;
-
-        let mut decompressed = vec![];
-        lzma_rs::lzma_decompress(&mut std::io::Cursor::new(compressed), &mut decompressed).unwrap();
-        let index = String::from_utf8(decompressed)?;
-        let line = index
-            .lines()
-            .find(|l| l.contains(OODLE_DLL_NAME))
-            .with_context(|| format!("{OODLE_DLL_NAME} not found in index"))?;
-        let path = line.split_once(',').context("failed to parse index")?.0;
-
-        let mut compressed = vec![];
-        ureq::get(&format!("https://content.warframe.com{path}"))
-            .call()?
-            .into_reader()
-            .read_to_end(&mut compressed)?;
-
-        let mut decompressed = vec![];
-        lzma_rs::lzma_decompress(&mut std::io::Cursor::new(compressed), &mut decompressed).unwrap();
-
-        std::fs::write(&oodle_path, decompressed)?;
+            .read_to_end(&mut buffer)?;
+        check_hash(&buffer)?;
+        std::fs::write(&oodle_path, buffer)?;
     }
-
-    let mut hasher = Sha1::new();
-    hasher.update(std::fs::read(&oodle_path)?);
-    let hash = hasher.finalize();
-    (hash[..] == OODLE_HASH).then_some(()).ok_or_else(|| {
-        anyhow!(
-            "oodle hash mismatch expected: {} got: {} ",
-            hex::encode(OODLE_HASH),
-            hex::encode(hash)
-        )
-    })?;
-
+    // don't check existing file to allow user to substitute other versions
+    // check_hash(&std::fs::read(&oodle_path)?)?;
     Ok(oodle_path)
 }
 
-#[cfg(windows)]
-mod windows_oodle {
-    use super::*;
+pub struct Oodle {
+    _library: libloading::Library,
+    compress: oodle_lz::Compress,
+    decompress: oodle_lz::Decompress,
+    get_compressed_buffer_size_needed: oodle_lz::GetCompressedBufferSizeNeeded,
+    set_printf: oodle_lz::SetPrintf,
+}
+impl Oodle {
+    fn new(lib: libloading::Library) -> Result<Self> {
+        unsafe {
+            let res = Oodle {
+                compress: *lib.get(b"OodleLZ_Compress")?,
+                decompress: *lib.get(b"OodleLZ_Decompress")?,
+                get_compressed_buffer_size_needed: *lib
+                    .get(b"OodleLZ_GetCompressedBufferSizeNeeded")?,
+                set_printf: *lib.get(b"OodleCore_Plugins_SetPrintf")?,
+                _library: lib,
+            };
+            (res.set_printf)(std::ptr::null()); // silence oodle logging
+            Ok(res)
+        }
+    }
+    pub fn compress(
+        &self,
+        input: &[u8],
+        compressor: Compressor,
+        compression_level: CompressionLevel,
+    ) -> Result<Vec<u8>> {
+        unsafe {
+            let buffer_size = self.get_compressed_buffer_size_needed(compressor, input.len());
+            let mut buffer = vec![0; buffer_size];
 
-    static DECOMPRESS: OnceLock<(OodleLZ_Decompress, libloading::Library)> = OnceLock::new();
+            let len = (self.compress)(
+                compressor,
+                input.as_ptr(),
+                input.len(),
+                buffer.as_mut_ptr(),
+                compression_level,
+                std::ptr::null(),
+                std::ptr::null(),
+                std::ptr::null(),
+                std::ptr::null_mut(),
+                0,
+            );
 
-    pub fn decompress_wrapper_windows(comp_buf: &[u8], raw_buf: &mut [u8]) -> i32 {
-        let decompress = DECOMPRESS.get_or_init(|| {
-            let path = fetch_oodle().context("failed to fetch oodle").unwrap();
+            if len == -1 {
+                return Err(Error::CompressionFailed);
+            }
+            buffer.truncate(len as usize);
 
-            let lib = unsafe { libloading::Library::new(path) }
-                .context("failed to load oodle")
-                .unwrap();
-
-            (*unsafe { lib.get(b"OodleLZ_Decompress") }.unwrap(), lib)
-        });
-        call_decompress(comp_buf, raw_buf, decompress.0)
+            Ok(buffer)
+        }
+    }
+    pub fn decompress(&self, input: &[u8], output: &mut [u8]) -> isize {
+        unsafe {
+            (self.decompress)(
+                input.as_ptr(),
+                input.len(),
+                output.as_mut_ptr(),
+                output.len(),
+                1,
+                1,
+                0,
+                0,
+                0,
+                0,
+                0,
+                std::ptr::null_mut(),
+                0,
+                3,
+            )
+        }
+    }
+    fn get_compressed_buffer_size_needed(
+        &self,
+        compressor: oodle_lz::Compressor,
+        raw_buffer: usize,
+    ) -> usize {
+        unsafe { (self.get_compressed_buffer_size_needed)(compressor, raw_buffer) }
     }
 }
 
-#[cfg(unix)]
-mod linux_oodle {
+static OODLE: OnceLock<Option<Oodle>> = OnceLock::new();
+
+fn load_oodle() -> Result<Oodle> {
+    let path = fetch_oodle()?;
+    unsafe {
+        let library = libloading::Library::new(path)?;
+        Oodle::new(library)
+    }
+}
+
+pub fn oodle() -> Result<&'static Oodle> {
+    let mut result = None;
+    let oodle = OODLE.get_or_init(|| match load_oodle() {
+        Err(err) => {
+            result = Some(Err(err));
+            None
+        }
+        Ok(oodle) => Some(oodle),
+    });
+    match (result, oodle) {
+        // oodle initialized so return
+        (_, Some(oodle)) => Ok(oodle),
+        // error during initialization
+        (Some(result), _) => result?,
+        // no error because initialization was tried and failed before
+        _ => Err(Error::InitializationFailed),
+    }
+}
+
+#[cfg(test)]
+mod test {
     use super::*;
 
-    use object::pe::{
-        ImageNtHeaders64, IMAGE_REL_BASED_DIR64, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ,
-        IMAGE_SCN_MEM_WRITE,
-    };
-    use object::read::pe::{ImageOptionalHeader, ImageThunkData, PeFile64};
+    #[test]
+    fn test_oodle() {
+        let oodle = oodle().unwrap();
 
-    use object::{LittleEndian as LE, Object, ObjectSection};
-    use std::collections::HashMap;
-    use std::ffi::{c_void, CStr};
+        let data = b"In tools and when compressing large inputs in one call, consider using
+        $OodleXLZ_Compress_AsyncAndWait (in the Oodle2 Ext lib) instead to get parallelism. Alternatively,
+        chop the data into small fixed size chunks (we recommend at least 256KiB, i.e. 262144 bytes) and
+        call compress on each of them, which decreases compression ratio but makes for trivial parallel
+        compression and decompression.";
 
-    #[repr(C)]
-    struct ThreadInformationBlock {
-        exception_list: *const c_void,
-        stack_base: *const c_void,
-        stack_limit: *const c_void,
-        sub_system_tib: *const c_void,
-        fiber_data: *const c_void,
-        arbitrary_user_pointer: *const c_void,
-        teb: *const c_void,
-    }
-
-    const TIB: ThreadInformationBlock = ThreadInformationBlock {
-        exception_list: std::ptr::null(),
-        stack_base: std::ptr::null(),
-        stack_limit: std::ptr::null(),
-        sub_system_tib: std::ptr::null(),
-        fiber_data: std::ptr::null(),
-        arbitrary_user_pointer: std::ptr::null(),
-        teb: std::ptr::null(),
-    };
-
-    static DECOMPRESS: OnceLock<OodleLZ_Decompress> = OnceLock::new();
-
-    fn decompress_wrapper(comp_buf: &[u8], raw_buf: &mut [u8]) -> i32 {
-        unsafe {
-            // Set GS register in calling thread
-            const ARCH_SET_GS: i32 = 0x1001;
-            libc::syscall(libc::SYS_arch_prctl, ARCH_SET_GS, &TIB);
-
-            // Call actual decompress function
-            call_decompress(comp_buf, raw_buf, *DECOMPRESS.get().unwrap())
-        }
-    }
-
-    #[allow(non_snake_case)]
-    mod imports {
-        use super::*;
-
-        pub unsafe extern "win64" fn OutputDebugStringA(string: *const std::ffi::c_char) {
-            print!("[OODLE] {}", CStr::from_ptr(string).to_string_lossy());
-        }
-        pub unsafe extern "win64" fn GetProcessHeap() -> *const c_void {
-            0x12345678 as *const c_void
-        }
-        pub unsafe extern "win64" fn HeapAlloc(
-            _heap: *const c_void,
-            flags: i32,
-            size: usize,
-        ) -> *const c_void {
-            assert_eq!(0, flags);
-            libc::malloc(size)
-        }
-        pub unsafe extern "win64" fn HeapFree(
-            _heap: *const c_void,
-            _flags: i32,
-            ptr: *mut c_void,
-        ) -> bool {
-            libc::free(ptr);
-            true
-        }
-        pub unsafe extern "win64" fn memset(
-            ptr: *mut c_void,
-            value: i32,
-            num: usize,
-        ) -> *const c_void {
-            libc::memset(ptr, value, num)
-        }
-        pub unsafe extern "win64" fn memmove(
-            destination: *mut c_void,
-            source: *const c_void,
-            num: usize,
-        ) -> *const c_void {
-            libc::memmove(destination, source, num)
-        }
-        pub unsafe extern "win64" fn memcpy(
-            destination: *mut c_void,
-            source: *const c_void,
-            num: usize,
-        ) -> *const c_void {
-            libc::memcpy(destination, source, num)
-        }
-    }
-
-    // Create some unique function pointers to use for unimplemented imports
-    const DEBUG_FNS: [*const fn(); 100] = gen_debug_fns();
-    static mut DEBUG_NAMES: [&str; 100] = [""; 100];
-    const fn gen_debug_fns() -> [*const fn(); 100] {
-        fn log<const I: usize>() {
-            unimplemented!("import {:?}", unsafe { DEBUG_NAMES[I] });
-        }
-        let mut array = [std::ptr::null(); 100];
-        seq_macro::seq!(N in 0..100 {
-            array[N] = log::<N> as *const fn();
-        });
-        array
-    }
-
-    pub fn oodle_loader_linux() -> OodleDecompress {
-        DECOMPRESS.get_or_init(|| get_decompress_inner().unwrap());
-        decompress_wrapper
-    }
-
-    fn get_decompress_inner() -> Result<OodleLZ_Decompress> {
-        fetch_oodle()?;
-        let oodle = std::env::current_exe()
-            .unwrap()
-            .with_file_name(OODLE_DLL_NAME);
-        let dll = std::fs::read(oodle)?;
-
-        let obj_file = PeFile64::parse(&*dll)?;
-
-        let size = obj_file.nt_headers().optional_header.size_of_image() as usize;
-        let header_size = obj_file.nt_headers().optional_header.size_of_headers() as usize;
-
-        let image_base = obj_file.relative_address_base() as usize;
-
-        // Create map
-        let mmap = unsafe {
-            std::slice::from_raw_parts_mut(
-                libc::mmap(
-                    std::ptr::null_mut(),
-                    size,
-                    libc::PROT_READ | libc::PROT_WRITE,
-                    libc::MAP_PRIVATE | libc::MAP_ANONYMOUS,
-                    -1,
-                    0,
-                ) as *mut u8,
-                size,
-            )
-        };
-
-        let map_base = mmap.as_ptr();
-
-        // Copy header to map
-        mmap[0..header_size].copy_from_slice(&dll[0..header_size]);
-        unsafe {
-            assert_eq!(
-                0,
-                libc::mprotect(
-                    mmap.as_mut_ptr() as *mut c_void,
-                    header_size,
-                    libc::PROT_READ
-                )
-            );
-        }
-
-        // Copy section data to map
-        for section in obj_file.sections() {
-            let address = section.address() as usize;
-            let data = section.data()?;
-            mmap[(address - image_base)..(address - image_base + data.len())]
-                .copy_from_slice(section.data()?);
-        }
-
-        // Apply relocations
-        let sections = obj_file.section_table();
-        let mut blocks = obj_file
-            .data_directories()
-            .relocation_blocks(&*dll, &sections)?
+        let buffer = oodle
+            .compress(data, Compressor::Mermaid, CompressionLevel::Optimal5)
             .unwrap();
 
-        while let Some(block) = blocks.next()? {
-            let block_address = block.virtual_address();
-            let block_data = sections.pe_data_at(&*dll, block_address).map(object::Bytes);
-            for reloc in block {
-                let offset = (reloc.virtual_address - block_address) as usize;
-                match reloc.typ {
-                    IMAGE_REL_BASED_DIR64 => {
-                        let addend = block_data
-                            .and_then(|data| data.read_at::<object::U64Bytes<LE>>(offset).ok())
-                            .map(|addend| addend.get(LE));
-                        if let Some(addend) = addend {
-                            mmap[reloc.virtual_address as usize
-                                ..reloc.virtual_address as usize + 8]
-                                .copy_from_slice(&u64::to_le_bytes(
-                                    addend - image_base as u64 + map_base as u64,
-                                ));
-                        }
-                    }
-                    _ => unimplemented!(),
-                }
-            }
-        }
+        dbg!((data.len(), buffer.len()));
 
-        // Fix up imports
-        let import_table = obj_file.import_table()?.unwrap();
-        let mut import_descs = import_table.descriptors()?;
+        let mut uncomp = vec![0; data.len()];
+        oodle.decompress(&buffer, &mut uncomp);
 
-        let mut i = 0;
-        while let Some(import_desc) = import_descs.next()? {
-            let mut thunks = import_table.thunks(import_desc.original_first_thunk.get(LE))?;
-
-            let mut address = import_desc.first_thunk.get(LE) as usize;
-            while let Some(thunk) = thunks.next::<ImageNtHeaders64>()? {
-                let (_hint, name) = import_table.hint_name(thunk.address())?;
-                let name = String::from_utf8_lossy(name).to_string();
-
-                use imports::*;
-
-                let fn_addr = match name.as_str() {
-                    "OutputDebugStringA" => OutputDebugStringA as usize,
-                    "GetProcessHeap" => GetProcessHeap as usize,
-                    "HeapAlloc" => HeapAlloc as usize,
-                    "HeapFree" => HeapFree as usize,
-                    "memset" => memset as usize,
-                    "memcpy" => memcpy as usize,
-                    "memmove" => memmove as usize,
-                    _ => {
-                        unsafe { DEBUG_NAMES[i] = name.leak() }
-                        let a = DEBUG_FNS[i] as usize;
-                        i += 1;
-                        a
-                    }
-                };
-
-                mmap[address..address + 8].copy_from_slice(&usize::to_le_bytes(fn_addr));
-
-                address += 8;
-            }
-        }
-
-        // Build export table
-        let mut exports = HashMap::new();
-        for export in obj_file.exports()? {
-            let name = String::from_utf8_lossy(export.name());
-            let address = export.address() - image_base as u64 + map_base as u64;
-            exports.insert(name, address as *const c_void);
-        }
-
-        // Fix section permissions
-        for section in obj_file.sections() {
-            let address = section.address() as usize;
-            let data = section.data()?;
-            let size = data.len();
-
-            let mut permissions = 0;
-
-            let flags = match section.flags() {
-                object::SectionFlags::Coff { characteristics } => characteristics,
-                _ => unreachable!(),
-            };
-
-            if 0 != flags & IMAGE_SCN_MEM_READ {
-                permissions |= libc::PROT_READ;
-            }
-            if 0 != flags & IMAGE_SCN_MEM_WRITE {
-                permissions |= libc::PROT_WRITE;
-            }
-            if 0 != flags & IMAGE_SCN_MEM_EXECUTE {
-                permissions |= libc::PROT_EXEC;
-            }
-
-            unsafe {
-                assert_eq!(
-                    0,
-                    libc::mprotect(
-                        mmap.as_mut_ptr().add(address - image_base) as *mut c_void,
-                        size,
-                        permissions
-                    )
-                );
-            }
-        }
-
-        Ok(unsafe {
-            std::mem::transmute::<*const c_void, OodleLZ_Decompress>(exports["OodleLZ_Decompress"])
-        })
+        assert_eq!(data[..], uncomp[..]);
     }
 }
diff --git a/repak/Cargo.toml b/repak/Cargo.toml
index 8c83e46..f9461a4 100644
--- a/repak/Cargo.toml
+++ b/repak/Cargo.toml
@@ -9,11 +9,8 @@ keywords.workspace = true
 
 [features]
 default = ["compression", "encryption"]
-compression = ["dep:flate2", "dep:zstd"]
-oodle = []
-oodle_loader = ["dep:oodle_loader"]
-oodle_explicit = ["oodle"]
-oodle_implicit_dynamic = ["dep:oodle_loader", "oodle"]
+compression = ["dep:flate2", "dep:zstd", "dep:lz4_flex"]
+oodle = ["dep:oodle_loader", "compression"]
 encryption = ["dep:aes"]
 wuthering-waves = []
 
@@ -22,10 +19,12 @@ byteorder = "1.5"
 aes = { workspace = true, optional = true }
 flate2 = { version = "1.0", optional = true }
 zstd = { version = "0.13", optional = true }
+lz4_flex = { version = "0.11.3", optional = true }
 oodle_loader = { path = "../oodle_loader", optional = true}
 thiserror = "2.0"
 sha1 = { workspace = true }
 strum = { workspace = true }
+hex.workspace = true
 
 [dev-dependencies]
 base64 = { workspace = true }
diff --git a/repak/src/data.rs b/repak/src/data.rs
new file mode 100644
index 0000000..37a3cac
--- /dev/null
+++ b/repak/src/data.rs
@@ -0,0 +1,222 @@
+use std::io::Write;
+
+use crate::{
+    entry::{Block, Entry},
+    Compression, Error, Hash, Version, VersionMajor,
+};
+
+type Result<T, E = Error> = std::result::Result<T, E>;
+
+pub struct PartialEntry<D: AsRef<[u8]>> {
+    compression: Option<Compression>,
+    compressed_size: u64,
+    uncompressed_size: u64,
+    compression_block_size: u32,
+    data: PartialEntryData<D>,
+    hash: Hash,
+}
+pub(crate) struct PartialBlock {
+    uncompressed_size: usize,
+    data: Vec<u8>,
+}
+pub(crate) enum PartialEntryData<D> {
+    Slice(D),
+    Blocks(Vec<PartialBlock>),
+}
+
+#[cfg(feature = "compression")]
+fn get_compression_slot(
+    version: Version,
+    compression_slots: &mut Vec<Option<Compression>>,
+    compression: Compression,
+) -> Result<u32> {
+    let slot = compression_slots
+        .iter()
+        .enumerate()
+        .find(|(_, s)| **s == Some(compression));
+    Ok(if let Some((i, _)) = slot {
+        // existing found
+        i
+    } else {
+        if version.version_major() < VersionMajor::FNameBasedCompression {
+            return Err(Error::Other(format!(
+                "cannot use {compression:?} prior to FNameBasedCompression (pak version 8)"
+            )));
+        }
+
+        // find empty slot
+        if let Some((i, empty_slot)) = compression_slots
+            .iter_mut()
+            .enumerate()
+            .find(|(_, s)| s.is_none())
+        {
+            // empty found, set it to used compression type
+            *empty_slot = Some(compression);
+            i
+        } else {
+            // no empty slot found, add a new one
+            compression_slots.push(Some(compression));
+            compression_slots.len() - 1
+        }
+    } as u32)
+}
+
+impl<D: AsRef<[u8]>> PartialEntry<D> {
+    pub(crate) fn build_entry(
+        &self,
+        version: Version,
+        #[allow(unused)] compression_slots: &mut Vec<Option<Compression>>,
+        file_offset: u64,
+    ) -> Result<Entry> {
+        #[cfg(feature = "compression")]
+        let compression_slot = self
+            .compression
+            .map(|c| get_compression_slot(version, compression_slots, c))
+            .transpose()?;
+        #[cfg(not(feature = "compression"))]
+        let compression_slot = None;
+
+        let blocks = match &self.data {
+            PartialEntryData::Slice(_) => None,
+            PartialEntryData::Blocks(blocks) => {
+                let entry_size =
+                    Entry::get_serialized_size(version, compression_slot, blocks.len() as u32);
+
+                let mut offset = entry_size;
+                if version.version_major() < VersionMajor::RelativeChunkOffsets {
+                    offset += file_offset;
+                };
+
+                Some(
+                    blocks
+                        .iter()
+                        .map(|block| {
+                            let start = offset;
+                            offset += block.data.len() as u64;
+                            let end = offset;
+                            Block { start, end }
+                        })
+                        .collect(),
+                )
+            }
+        };
+
+        Ok(Entry {
+            offset: file_offset,
+            compressed: self.compressed_size,
+            uncompressed: self.uncompressed_size,
+            compression_slot,
+            timestamp: None,
+            hash: Some(self.hash),
+            blocks,
+            flags: 0,
+            compression_block_size: self.compression_block_size,
+        })
+    }
+    pub(crate) fn write_data<S: Write>(&self, stream: &mut S) -> Result<()> {
+        match &self.data {
+            PartialEntryData::Slice(data) => {
+                stream.write_all(data.as_ref())?;
+            }
+            PartialEntryData::Blocks(blocks) => {
+                for block in blocks {
+                    stream.write_all(&block.data)?;
+                }
+            }
+        }
+        Ok(())
+    }
+}
+
+pub(crate) fn build_partial_entry<D>(
+    allowed_compression: &[Compression],
+    data: D,
+) -> Result<PartialEntry<D>>
+where
+    D: AsRef<[u8]>,
+{
+    // TODO hash needs to be post-compression/encryption
+    use sha1::{Digest, Sha1};
+    let mut hasher = Sha1::new();
+
+    // TODO possibly select best compression based on some criteria instead of picking first
+    let compression = allowed_compression.first().cloned();
+    let uncompressed_size = data.as_ref().len() as u64;
+    let compression_block_size;
+
+    let (data, compressed_size) = match compression {
+        #[cfg(not(feature = "compression"))]
+        Some(_) => {
+            unreachable!("should not be able to reach this point without compression feature")
+        }
+        #[cfg(feature = "compression")]
+        Some(compression) => {
+            // https://github.com/EpicGames/UnrealEngine/commit/3aad0ff7976be1073005dca2c1282af548b45d89
+            // Block size must fit into flags field or it may cause unreadable paks for earlier Unreal Engine versions
+            compression_block_size = 0x3e << 11; // max possible block size
+            let mut compressed_size = 0;
+            let mut blocks = vec![];
+            for chunk in data.as_ref().chunks(compression_block_size as usize) {
+                let data = compress(compression, chunk)?;
+                compressed_size += data.len() as u64;
+                hasher.update(&data);
+                blocks.push(PartialBlock {
+                    uncompressed_size: chunk.len(),
+                    data,
+                })
+            }
+
+            (PartialEntryData::Blocks(blocks), compressed_size)
+        }
+        None => {
+            compression_block_size = 0;
+            hasher.update(data.as_ref());
+            (PartialEntryData::Slice(data), uncompressed_size)
+        }
+    };
+
+    Ok(PartialEntry {
+        compression,
+        compressed_size,
+        uncompressed_size,
+        compression_block_size,
+        data,
+        hash: Hash(hasher.finalize().into()),
+    })
+}
+
+#[cfg(feature = "compression")]
+fn compress(compression: Compression, data: &[u8]) -> Result<Vec<u8>> {
+    use std::io::Write;
+
+    let compressed = match compression {
+        Compression::Zlib => {
+            let mut compress =
+                flate2::write::ZlibEncoder::new(Vec::new(), flate2::Compression::fast());
+            compress.write_all(data.as_ref())?;
+            compress.finish()?
+        }
+        Compression::Gzip => {
+            let mut compress =
+                flate2::write::GzEncoder::new(Vec::new(), flate2::Compression::fast());
+            compress.write_all(data.as_ref())?;
+            compress.finish()?
+        }
+        Compression::Zstd => zstd::stream::encode_all(data, 0)?,
+        Compression::LZ4 => lz4_flex::block::compress(data),
+        Compression::Oodle => {
+            #[cfg(not(feature = "oodle"))]
+            return Err(super::Error::Oodle);
+            #[cfg(feature = "oodle")]
+            {
+                oodle_loader::oodle().unwrap().compress(
+                    data.as_ref(),
+                    oodle_loader::Compressor::Mermaid,
+                    oodle_loader::CompressionLevel::Normal,
+                )?
+            }
+        }
+    };
+
+    Ok(compressed)
+}
diff --git a/repak/src/entry.rs b/repak/src/entry.rs
index 517493d..88e6c6b 100644
--- a/repak/src/entry.rs
+++ b/repak/src/entry.rs
@@ -2,7 +2,7 @@ use std::io;
 
 use byteorder::{LE, ReadBytesExt, WriteBytesExt};
 
-use crate::{Error, reader, writer};
+use crate::{data::build_partial_entry, reader, writer, Error, Hash};
 
 use super::{Compression, ext::BoolExt, ext::ReadExt, Version, VersionMajor};
 
@@ -12,7 +12,7 @@ pub(crate) enum EntryLocation {
     Index,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Default, Clone)]
 pub(crate) struct Block {
     pub start: u64,
     pub end: u64,
@@ -57,7 +57,7 @@ pub(crate) struct Entry {
     pub uncompressed: u64,
     pub compression_slot: Option<u32>,
     pub timestamp: Option<u64>,
-    pub hash: Option<[u8; 20]>,
+    pub hash: Option<Hash>,
     pub blocks: Option<Vec<Block>>,
     pub flags: u8,
     pub compression_block_size: u32,
@@ -105,127 +105,13 @@ impl Entry {
         version: Version,
         compression_slots: &mut Vec<Option<Compression>>,
         allowed_compression: &[Compression],
-        data: impl AsRef<[u8]>,
-    ) -> Result<Self, super::Error> {
-        // TODO hash needs to be post-compression
-        use sha1::{Digest, Sha1};
-        let mut hasher = Sha1::new();
-        hasher.update(&data);
-
-        let offset = writer.stream_position()?;
-        let len = data.as_ref().len() as u64;
-
-        // TODO possibly select best compression based on some criteria instead of picking first
-        let compression = allowed_compression.first().cloned();
-
-        let compression_slot = if let Some(compression) = compression {
-            // find existing
-            let slot = compression_slots
-                .iter()
-                .enumerate()
-                .find(|(_, s)| **s == Some(compression));
-            Some(if let Some((i, _)) = slot {
-                // existing found
-                i
-            } else {
-                if version.version_major() < VersionMajor::FNameBasedCompression {
-                    return Err(Error::Other(format!(
-                        "cannot use {compression:?} prior to FNameBasedCompression (pak version 8)"
-                    )));
-                }
-
-                // find empty slot
-                if let Some((i, empty_slot)) = compression_slots
-                    .iter_mut()
-                    .enumerate()
-                    .find(|(_, s)| s.is_none())
-                {
-                    // empty found, set it to used compression type
-                    *empty_slot = Some(compression);
-                    i
-                } else {
-                    // no empty slot found, add a new one
-                    compression_slots.push(Some(compression));
-                    compression_slots.len() - 1
-                }
-            } as u32)
-        } else {
-            None
-        };
-
-        let (blocks, compressed) = match compression {
-            #[cfg(not(feature = "compression"))]
-            Some(_) => {
-                unreachable!("should not be able to reach this point without compression feature")
-            }
-            #[cfg(feature = "compression")]
-            Some(compression) => {
-                use std::io::Write;
-
-                let entry_size = Entry::get_serialized_size(version, compression_slot, 1);
-                let data_offset = offset + entry_size;
-
-                let compressed = match compression {
-                    Compression::Zlib => {
-                        let mut compress = flate2::write::ZlibEncoder::new(
-                            Vec::new(),
-                            flate2::Compression::fast(),
-                        );
-                        compress.write_all(data.as_ref())?;
-                        compress.finish()?
-                    }
-                    Compression::Gzip => {
-                        let mut compress =
-                            flate2::write::GzEncoder::new(Vec::new(), flate2::Compression::fast());
-                        compress.write_all(data.as_ref())?;
-                        compress.finish()?
-                    }
-                    Compression::Zstd => zstd::stream::encode_all(data.as_ref(), 0)?,
-                    Compression::Oodle => {
-                        return Err(Error::Other("writing Oodle compression unsupported".into()))
-                    }
-                };
-
-                let compute_offset = |index: usize| -> u64 {
-                    match version.version_major() >= VersionMajor::RelativeChunkOffsets {
-                        true => index as u64 + (data_offset - offset),
-                        false => index as u64 + data_offset,
-                    }
-                };
-
-                let blocks = vec![Block {
-                    start: compute_offset(0),
-                    end: compute_offset(compressed.len()),
-                }];
-
-                (Some(blocks), Some(compressed))
-            }
-            None => (None, None),
-        };
-
-        let entry = super::entry::Entry {
-            offset,
-            compressed: compressed
-                .as_ref()
-                .map(|c: &Vec<u8>| c.len() as u64)
-                .unwrap_or(len),
-            uncompressed: len,
-            compression_slot,
-            timestamp: None,
-            hash: Some(hasher.finalize().into()),
-            blocks,
-            flags: 0,
-            compression_block_size: compressed.as_ref().map(|_| len as u32).unwrap_or_default(),
-        };
-
-        entry.write(writer, version, EntryLocation::Data)?;
-
-        if let Some(compressed) = compressed {
-            writer.write_all(&compressed)?;
-        } else {
-            writer.write_all(data.as_ref())?;
-        }
-
+        data: &[u8],
+    ) -> Result<Self, Error> {
+        let partial_entry = build_partial_entry(allowed_compression, data)?;
+        let stream_position = writer.stream_position()?;
+        let entry = partial_entry.build_entry(version, compression_slots, stream_position)?;
+        entry.write(writer, version, crate::entry::EntryLocation::Data)?;
+        partial_entry.write_data(writer)?;
         Ok(entry)
     }
 
@@ -245,7 +131,7 @@ impl Entry {
             n => Some(n - 1),
         };
         let timestamp = (ver == VersionMajor::Initial).then_try(|| reader.read_u64::<LE>())?;
-        let hash = Some(reader.read_guid()?);
+        let hash = Some(Hash(reader.read_guid()?));
         let blocks = (ver >= VersionMajor::CompressionEncryption && compression.is_some())
             .then_try(|| reader.read_array(Block::read))?;
         let flags = (ver >= VersionMajor::CompressionEncryption)
@@ -289,7 +175,7 @@ impl Entry {
             writer.write_u64::<LE>(self.timestamp.unwrap_or_default())?;
         }
         if let Some(hash) = self.hash {
-            writer.write_all(&hash)?;
+            writer.write_all(&hash.0)?;
         } else {
             panic!("hash missing");
         }
@@ -391,6 +277,11 @@ impl Entry {
         let is_uncompressed_size_32_bit_safe = self.uncompressed <= u32::MAX as u64;
         let is_offset_32_bit_safe = self.offset <= u32::MAX as u64;
 
+        assert!(
+            compression_blocks_count < 0x10_000,
+            "compression blocks count fits in 16 bits"
+        );
+
         let flags = (compression_block_size)
             | (compression_blocks_count << 6)
             | ((self.is_encrypted() as u32) << 22)
@@ -436,7 +327,6 @@ impl Entry {
         version: Version,
         compression: &[Option<Compression>],
         #[allow(unused)] key: &super::Key,
-        #[allow(unused)] oodle: &super::Oodle,
         buf: &mut W,
     ) -> Result<(), super::Error> {
         reader.seek(io::SeekFrom::Start(self.offset))?;
@@ -464,7 +354,7 @@ impl Entry {
             }
         }
 
-        #[cfg(any(feature = "compression", feature = "oodle"))]
+        #[cfg(feature = "compression")]
         let ranges = {
             let offset = |index: u64| -> usize {
                 (match version.version_major() >= VersionMajor::RelativeChunkOffsets {
@@ -494,56 +384,52 @@ impl Entry {
 
         match self.compression_slot.and_then(|c| compression[c as usize]) {
             None => buf.write_all(&data)?,
-            #[cfg(feature = "compression")]
-            Some(Compression::Zlib) => decompress!(flate2::read::ZlibDecoder<&[u8]>),
-            #[cfg(feature = "compression")]
-            Some(Compression::Gzip) => decompress!(flate2::read::GzDecoder<&[u8]>),
-            #[cfg(feature = "compression")]
-            Some(Compression::Zstd) => {
-                for range in ranges {
-                    io::copy(&mut zstd::stream::read::Decoder::new(&data[range])?, buf)?;
-                }
-            }
-            #[cfg(feature = "oodle")]
-            Some(Compression::Oodle) => {
-                let oodle = match oodle {
-                    crate::Oodle::Some(getter) => getter().map_err(|_| super::Error::OodleFailed),
-                    crate::Oodle::None => Err(super::Error::OodleFailed),
-                }?;
-                let mut decompressed = vec![0; self.uncompressed as usize];
-
-                let mut compress_offset = 0;
-                let mut decompress_offset = 0;
-                let block_count = ranges.len();
-                for range in ranges {
-                    let decomp = if block_count == 1 {
-                        self.uncompressed as usize
-                    } else {
-                        (self.compression_block_size as usize)
-                            .min(self.uncompressed as usize - compress_offset)
-                    };
-                    let buffer = &mut data[range];
-                    let out = oodle(
-                        buffer,
-                        &mut decompressed[decompress_offset..decompress_offset + decomp],
-                    );
-                    if out == 0 {
-                        return Err(super::Error::DecompressionFailed(Compression::Oodle));
-                    }
-                    compress_offset += self.compression_block_size as usize;
-                    decompress_offset += out as usize;
-                }
-
-                debug_assert_eq!(
-                    decompress_offset, self.uncompressed as usize,
-                    "Oodle decompression length mismatch"
-                );
-                buf.write_all(&decompressed)?;
-            }
-            #[cfg(not(feature = "oodle"))]
-            Some(Compression::Oodle) => return Err(super::Error::Oodle),
             #[cfg(not(feature = "compression"))]
             _ => return Err(super::Error::Compression),
+            #[cfg(feature = "compression")]
+            Some(comp) => {
+                let chunk_size = if ranges.len() == 1 {
+                    self.uncompressed as usize
+                } else {
+                    self.compression_block_size as usize
+                };
+
+                match comp {
+                    Compression::Zlib => decompress!(flate2::read::ZlibDecoder<&[u8]>),
+                    Compression::Gzip => decompress!(flate2::read::GzDecoder<&[u8]>),
+                    Compression::Zstd => {
+                        for range in ranges {
+                            io::copy(&mut zstd::stream::read::Decoder::new(&data[range])?, buf)?;
+                        }
+                    }
+                    Compression::LZ4 => {
+                        let mut decompressed = vec![0; self.uncompressed as usize];
+                        for (decomp_chunk, comp_range) in
+                            decompressed.chunks_mut(chunk_size).zip(ranges)
+                        {
+                            lz4_flex::block::decompress_into(&data[comp_range], decomp_chunk)
+                                .map_err(|_| Error::DecompressionFailed(Compression::LZ4))?;
+                        }
+                        buf.write_all(&decompressed)?;
+                    }
+                    #[cfg(feature = "oodle")]
+                    Compression::Oodle => {
+                        let mut decompressed = vec![0; self.uncompressed as usize];
+                        for (decomp_chunk, comp_range) in
+                            decompressed.chunks_mut(chunk_size).zip(ranges)
+                        {
+                            let out =
+                                oodle_loader::oodle()?.decompress(&data[comp_range], decomp_chunk);
+                            if out == 0 {
+                                return Err(Error::DecompressionFailed(Compression::Oodle));
+                            }
+                        }
+                        buf.write_all(&decompressed)?;
+                    }
+                    #[cfg(not(feature = "oodle"))]
+                    Compression::Oodle => return Err(super::Error::Oodle),
+                }
+            }
         }
         buf.flush()?;
         Ok(())
diff --git a/repak/src/error.rs b/repak/src/error.rs
index b60bc92..363dc86 100644
--- a/repak/src/error.rs
+++ b/repak/src/error.rs
@@ -42,8 +42,9 @@ pub enum Error {
     #[error("found magic of {:#x} instead of {:#x}", .0, super::MAGIC)]
     Magic(u32),
 
-    #[error("pointer to OodleLZ_Decompress was not provided")]
-    OodleFailed,
+    #[cfg(feature = "oodle")]
+    #[error("Oodle loader error: {0}")]
+    OodleFailed(#[from] oodle_loader::Error),
 
     #[error("No entry found at {0}")]
     MissingEntry(String),
diff --git a/repak/src/footer.rs b/repak/src/footer.rs
index 0bc35d5..7e3c1c4 100644
--- a/repak/src/footer.rs
+++ b/repak/src/footer.rs
@@ -1,4 +1,7 @@
-use crate::ext::{BoolExt, WriteExt};
+use crate::{
+    ext::{BoolExt, WriteExt},
+    Hash,
+};
 
 use super::{ext::ReadExt, Compression, Version, VersionMajor};
 use byteorder::{ReadBytesExt, WriteBytesExt, LE};
@@ -13,7 +16,7 @@ pub struct Footer {
     pub version_major: VersionMajor,
     pub index_offset: u64,
     pub index_size: u64,
-    pub hash: [u8; 20],
+    pub hash: Hash,
     pub frozen: bool,
     pub compression: Vec<Option<Compression>>,
 }
@@ -29,7 +32,7 @@ impl Footer {
             VersionMajor::from_repr(reader.read_u32::<LE>()?).unwrap_or(version.version_major());
         let index_offset = reader.read_u64::<LE>()?;
         let index_size = reader.read_u64::<LE>()?;
-        let hash = reader.read_guid()?;
+        let hash = Hash(reader.read_guid()?);
         let frozen = version.version_major() == VersionMajor::FrozenIndex && reader.read_bool()?;
         let compression = {
             let mut compression = Vec::with_capacity(match version {
@@ -91,7 +94,7 @@ impl Footer {
         writer.write_u32::<LE>(self.version_major as u32)?;
         writer.write_u64::<LE>(self.index_offset)?;
         writer.write_u64::<LE>(self.index_size)?;
-        writer.write_all(&self.hash)?;
+        writer.write_all(&self.hash.0)?;
         if self.version_major == VersionMajor::FrozenIndex {
             writer.write_bool(self.frozen)?;
         }
diff --git a/repak/src/lib.rs b/repak/src/lib.rs
index 6b93f9d..56a1591 100644
--- a/repak/src/lib.rs
+++ b/repak/src/lib.rs
@@ -1,4 +1,5 @@
 #![allow(dead_code)]
+mod data;
 mod entry;
 mod error;
 mod ext;
@@ -7,19 +8,10 @@ mod pak;
 mod reader;
 mod writer;
 
-pub use {error::*, pak::*};
+pub use {data::PartialEntry, error::*, pak::*};
 
 pub const MAGIC: u32 = 0x5A6F12E1;
 
-#[cfg(feature = "oodle")]
-mod oodle {
-    pub type OodleGetter = fn() -> Result<OodleDecompress, Box<dyn std::error::Error>>;
-    pub type OodleDecompress = fn(comp_buf: &[u8], raw_buf: &mut [u8]) -> i32;
-}
-
-#[cfg(feature = "oodle_loader")]
-pub use oodle_loader;
-
 #[derive(
     Clone,
     Copy,
@@ -135,6 +127,7 @@ pub enum Compression {
     Gzip,
     Oodle,
     Zstd,
+    LZ4,
 }
 
 #[allow(clippy::large_enum_variant)]
@@ -152,11 +145,3 @@ impl From<aes::Aes256> for Key {
         Self::Some(value)
     }
 }
-
-#[derive(Debug, Default)]
-pub(crate) enum Oodle {
-    #[cfg(feature = "oodle")]
-    Some(oodle::OodleGetter),
-    #[default]
-    None,
-}
diff --git a/repak/src/pak.rs b/repak/src/pak.rs
index f570527..bd352e2 100644
--- a/repak/src/pak.rs
+++ b/repak/src/pak.rs
@@ -1,5 +1,6 @@
+use crate::data::build_partial_entry;
 use crate::entry::Entry;
-use crate::Compression;
+use crate::{Compression, Error, PartialEntry};
 
 use super::ext::{ReadExt, WriteExt};
 use super::{Version, VersionMajor};
@@ -7,10 +8,17 @@ use byteorder::{ReadBytesExt, WriteBytesExt, LE};
 use std::collections::BTreeMap;
 use std::io::{self, Read, Seek, Write};
 
+#[derive(Default, Clone, Copy)]
+pub(crate) struct Hash(pub(crate) [u8; 20]);
+impl std::fmt::Debug for Hash {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Hash({})", hex::encode(self.0))
+    }
+}
+
 #[derive(Debug)]
 pub struct PakBuilder {
     key: super::Key,
-    oodle: super::Oodle,
     allowed_compression: Vec<Compression>,
 }
 
@@ -24,10 +32,6 @@ impl PakBuilder {
     pub fn new() -> Self {
         Self {
             key: Default::default(),
-            #[cfg(not(feature = "oodle_implicit_dynamic"))]
-            oodle: super::Oodle::None,
-            #[cfg(feature = "oodle_implicit_dynamic")]
-            oodle: super::Oodle::Some(oodle_loader::decompress),
             allowed_compression: Default::default(),
         }
     }
@@ -36,25 +40,20 @@ impl PakBuilder {
         self.key = super::Key::Some(key);
         self
     }
-    #[cfg(feature = "oodle_explicit")]
-    pub fn oodle(mut self, oodle_getter: super::oodle::OodleGetter) -> Self {
-        self.oodle = super::Oodle::Some(oodle_getter);
-        self
-    }
     #[cfg(feature = "compression")]
     pub fn compression(mut self, compression: impl IntoIterator<Item = Compression>) -> Self {
         self.allowed_compression = compression.into_iter().collect();
         self
     }
     pub fn reader<R: Read + Seek>(self, reader: &mut R) -> Result<PakReader, super::Error> {
-        PakReader::new_any_inner(reader, self.key, self.oodle)
+        PakReader::new_any_inner(reader, self.key)
     }
     pub fn reader_with_version<R: Read + Seek>(
         self,
         reader: &mut R,
         version: super::Version,
     ) -> Result<PakReader, super::Error> {
-        PakReader::new_inner(reader, version, self.key, self.oodle)
+        PakReader::new_inner(reader, version, self.key)
     }
     pub fn writer<W: Write + Seek>(
         self,
@@ -78,7 +77,6 @@ impl PakBuilder {
 pub struct PakReader {
     pak: Pak,
     key: super::Key,
-    oodle: super::Oodle,
 }
 
 #[derive(Debug)]
@@ -144,8 +142,8 @@ impl Index {
         self.entries
     }
 
-    fn add_entry(&mut self, path: &str, entry: super::entry::Entry) {
-        self.entries.insert(path.to_string(), entry);
+    fn add_entry(&mut self, path: String, entry: super::entry::Entry) {
+        self.entries.insert(path, entry);
     }
 }
 
@@ -166,14 +164,13 @@ impl PakReader {
     fn new_any_inner<R: Read + Seek>(
         reader: &mut R,
         key: super::Key,
-        oodle: super::Oodle,
     ) -> Result<Self, super::Error> {
         use std::fmt::Write;
         let mut log = "\n".to_owned();
 
         for ver in Version::iter() {
             match Pak::read(&mut *reader, ver, &key) {
-                Ok(pak) => return Ok(Self { pak, key, oodle }),
+                Ok(pak) => return Ok(Self { pak, key }),
                 Err(err) => writeln!(log, "trying version {} failed: {}", ver, err)?,
             }
         }
@@ -184,9 +181,8 @@ impl PakReader {
         reader: &mut R,
         version: super::Version,
         key: super::Key,
-        oodle: super::Oodle,
     ) -> Result<Self, super::Error> {
-        Pak::read(reader, version, &key).map(|pak| Self { pak, key, oodle })
+        Pak::read(reader, version, &key).map(|pak| Self { pak, key })
     }
 
     pub fn version(&self) -> super::Version {
@@ -227,7 +223,6 @@ impl PakReader {
                 self.pak.version,
                 &self.pak.compression,
                 &self.key,
-                &self.oodle,
                 writer,
             ),
             None => Err(super::Error::MissingEntry(path.to_owned())),
@@ -273,27 +268,91 @@ impl<W: Write + Seek> PakWriter<W> {
         self.writer
     }
 
-    pub fn write_file(&mut self, path: &str, data: impl AsRef<[u8]>) -> Result<(), super::Error> {
+    pub fn write_file(
+        &mut self,
+        path: &str,
+        allow_compress: bool,
+        data: impl AsRef<[u8]>,
+    ) -> Result<(), super::Error> {
         self.pak.index.add_entry(
-            path,
+            path.to_string(),
             Entry::write_file(
                 &mut self.writer,
                 self.pak.version,
                 &mut self.pak.compression,
-                &self.allowed_compression,
-                data,
+                if allow_compress {
+                    &self.allowed_compression
+                } else {
+                    &[]
+                },
+                data.as_ref(),
             )?,
         );
 
         Ok(())
     }
 
+    pub fn entry_builder(&self) -> EntryBuilder {
+        EntryBuilder {
+            allowed_compression: self.allowed_compression.clone(),
+        }
+    }
+
+    pub fn write_entry<D: AsRef<[u8]>>(
+        &mut self,
+        path: String,
+        partial_entry: PartialEntry<D>,
+    ) -> Result<(), Error> {
+        let stream_position = self.writer.stream_position()?;
+
+        let entry = partial_entry.build_entry(
+            self.pak.version,
+            &mut self.pak.compression,
+            stream_position,
+        )?;
+
+        entry.write(
+            &mut self.writer,
+            self.pak.version,
+            crate::entry::EntryLocation::Data,
+        )?;
+
+        self.pak.index.add_entry(path, entry);
+        partial_entry.write_data(&mut self.writer)?;
+
+        Ok(())
+    }
     pub fn write_index(mut self) -> Result<W, super::Error> {
         self.pak.write(&mut self.writer, &self.key)?;
         Ok(self.writer)
     }
 }
 
+struct Data<'d>(Box<dyn AsRef<[u8]> + Send + Sync + 'd>);
+impl AsRef<[u8]> for Data<'_> {
+    fn as_ref(&self) -> &[u8] {
+        self.0.as_ref().as_ref()
+    }
+}
+
+#[derive(Clone)]
+pub struct EntryBuilder {
+    allowed_compression: Vec<Compression>,
+}
+impl EntryBuilder {
+    /// Builds an entry in memory (compressed if requested) which must be written out later
+    pub fn build_entry<D: AsRef<[u8]> + Send + Sync>(
+        &self,
+        compress: bool,
+        data: D,
+    ) -> Result<PartialEntry<D>, Error> {
+        let compression = compress
+            .then_some(self.allowed_compression.as_slice())
+            .unwrap_or_default();
+        build_partial_entry(compression, data)
+    }
+}
+
 impl Pak {
     fn read<R: Read + Seek>(
         reader: &mut R,
@@ -541,12 +600,12 @@ impl Pak {
             index_writer.write_u32::<LE>(1)?; // we have path hash index
             index_writer.write_u64::<LE>(path_hash_index_offset)?;
             index_writer.write_u64::<LE>(phi_buf.len() as u64)?; // path hash index size
-            index_writer.write_all(&hash(&phi_buf))?;
+            index_writer.write_all(&hash(&phi_buf).0)?;
 
             index_writer.write_u32::<LE>(1)?; // we have full directory index
             index_writer.write_u64::<LE>(full_directory_index_offset)?;
             index_writer.write_u64::<LE>(fdi_buf.len() as u64)?; // path hash index size
-            index_writer.write_all(&hash(&fdi_buf))?;
+            index_writer.write_all(&hash(&fdi_buf).0)?;
 
             index_writer.write_u32::<LE>(encoded_entries.len() as u32)?;
             index_writer.write_all(&encoded_entries)?;
@@ -584,11 +643,11 @@ impl Pak {
     }
 }
 
-fn hash(data: &[u8]) -> [u8; 20] {
+fn hash(data: &[u8]) -> Hash {
     use sha1::{Digest, Sha1};
     let mut hasher = Sha1::new();
     hasher.update(data);
-    hasher.finalize().into()
+    Hash(hasher.finalize().into())
 }
 
 fn generate_path_hash_index<W: Write>(
diff --git a/repak/tests/test.rs b/repak/tests/test.rs
index 5c63f8c..e951c02 100644
--- a/repak/tests/test.rs
+++ b/repak/tests/test.rs
@@ -185,7 +185,7 @@ fn test_write(_version: repak::Version, _file_name: &str, bytes: &[u8]) {
 
     for path in pak_reader.files() {
         let data = pak_reader.get(&path, &mut reader).unwrap();
-        pak_writer.write_file(&path, data).unwrap();
+        pak_writer.write_file(&path, false, data).unwrap();
     }
 
     assert!(pak_writer.write_index().unwrap().into_inner() == reader.into_inner());
diff --git a/repak_cli/Cargo.toml b/repak_cli/Cargo.toml
index 7397c92..2de9afb 100644
--- a/repak_cli/Cargo.toml
+++ b/repak_cli/Cargo.toml
@@ -19,7 +19,7 @@ path = "src/main.rs"
 
 [features]
 default = ["oodle"]
-oodle = ["repak/oodle_implicit_dynamic"]
+oodle = ["repak/oodle"]
 
 [dependencies]
 repak = { path = "../repak" }
diff --git a/repak_cli/src/main.rs b/repak_cli/src/main.rs
index 1c13b51..7b83063 100644
--- a/repak_cli/src/main.rs
+++ b/repak_cli/src/main.rs
@@ -487,7 +487,7 @@ fn pack(args: ActionPack) -> Result<(), repak::Error> {
     use indicatif::ProgressIterator;
 
     let iter = paths.iter();
-    let (log, mut iter) = if !args.quiet {
+    let (log, iter) = if !args.quiet {
         let iter =
             iter.progress_with_style(indicatif::ProgressStyle::with_template(STYLE).unwrap());
         (
@@ -498,17 +498,39 @@ fn pack(args: ActionPack) -> Result<(), repak::Error> {
         (Output::Stdout, itertools::Either::Right(iter))
     };
     let log = log.clone();
-    iter.try_for_each(|p| {
-        let rel = &p
-            .strip_prefix(input_path)
-            .expect("file not in input directory")
-            .to_slash()
-            .expect("failed to convert to slash path");
-        if args.verbose {
-            log.println(format!("packing {}", &rel));
+
+    let mut result = None;
+    let result_ref = &mut result;
+    rayon::in_place_scope(|scope| -> Result<(), repak::Error> {
+        let (tx, rx) = std::sync::mpsc::sync_channel(0);
+        let entry_builder = pak.entry_builder();
+
+        scope.spawn(move |_| {
+            *result_ref = Some(
+                iter.par_bridge()
+                    .try_for_each(|p| -> Result<(), repak::Error> {
+                        let rel = &p
+                            .strip_prefix(input_path)
+                            .expect("file not in input directory")
+                            .to_slash()
+                            .expect("failed to convert to slash path");
+                        if args.verbose {
+                            log.println(format!("packing {}", &rel));
+                        }
+                        let entry = entry_builder.build_entry(true, std::fs::read(p)?)?;
+
+                        tx.send((rel.to_string(), entry)).unwrap();
+                        Ok(())
+                    }),
+            );
+        });
+
+        for (path, entry) in rx {
+            pak.write_entry(path, entry)?;
         }
-        pak.write_file(rel, std::fs::read(p)?)
+        Ok(())
     })?;
+    result.unwrap()?;
 
     pak.write_index()?;