Replace crc crate with simpler implementation

The package is kept as a dev-dependency to prevent regressions though!

Cargo.toml

@@ -25,15 +25,14 @@ libunshield = "1.4"
 walkdir = "2"
 hmac-sha512 = "1"
 criterion = "0.4"
+# used for testing our jamcrc implementation
+crc = "3"
 
 [features]
 retail_game_testing = []
 patch_testing = []
 
 [dependencies]
-# used for jamcrc implementation, should eventually move away from it
-crc = "3"
-
 # amazing binary parsing/writing library
 binrw = "0.10"
 

src/crc.rs

@@ -0,0 +1,63 @@
+pub struct JAMCRC {
+    table: [u32; 256]
+}
+
+impl JAMCRC {
+    pub(crate) const fn new() -> Self {
+        let mut table: [u32; 256] = [0u32; 256];
+
+        let polynomial: u32 = 0xEDB88320;
+        let mut i = 0;
+        while i < table.len() {
+            let mut c: u32 = i as u32;
+            let mut j = 0;
+            while j < 8 {
+                if (c & 1u32) == 1u32 {
+                    c = polynomial ^ (c >> 1);
+                } else {
+                    c >>= 1;
+                }
+                j += 1;
+            }
+
+            table[i] = c;
+            i += 1;
+        }
+
+        Self {
+            table
+        }
+    }
+
+    pub(crate) fn checksum(&self, bytes: &[u8]) -> u32 {
+        let mut c : u32 = 0xFFFFFFFF;
+        for byte in bytes {
+            c = self.table[((c ^ *byte as u32) & 0xFF) as usize] ^ (c >> 8);
+        }
+
+        !(c ^ 0xFFFFFFFF)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::fiin::FileInfo;
+    use std::fs::read;
+    use std::path::PathBuf;
+
+    #[test]
+    fn basic_parsing() {
+        use crc::{Crc, CRC_32_JAMCRC};
+        use std::io::{Read, Seek, SeekFrom};
+
+        const JAMCR: Crc<u32> = Crc::<u32>::new(&CRC_32_JAMCRC);
+
+        let bytes : [u8; 9] = [1, 1, 2, 4, 5, 6, 12, 12, 12];
+
+        const crc : JAMCRC = JAMCRC::new();
+
+        assert_eq!(JAMCR.checksum(&bytes),
+            crc.checksum(&bytes))
+    }
+}

src/lib.rs

@@ -67,3 +67,5 @@ pub mod tex;
 
 /// Reading material files (MTRL)
 pub mod mtrl;
+
+mod crc;

src/sqpack.rs

@@ -1,10 +1,10 @@
 use crate::compression::no_header_decompress;
 use crate::dat::{BlockHeader, CompressionMode};
 use binrw::BinRead;
-use crc::{Crc, CRC_32_JAMCRC};
 use std::io::{Read, Seek, SeekFrom};
+use crate::crc::JAMCRC;
 
-const JAMCRC: Crc<u32> = Crc::<u32>::new(&CRC_32_JAMCRC);
+const CRC : JAMCRC = JAMCRC::new();
 
 /// Calculates a hash for `index` files from a game path.
 pub fn calculate_hash(path: &str) -> u64 {
@@ -14,8 +14,8 @@ pub fn calculate_hash(path: &str) -> u64 {
 
     let (directory, filename) = lowercase.split_at(pos);
 
-    let directory_crc = JAMCRC.checksum(directory.as_bytes());
+    let directory_crc = CRC.checksum(directory.as_bytes());
-    let filename_crc = JAMCRC.checksum(filename[1..filename.len()].as_bytes());
+    let filename_crc = CRC.checksum(filename[1..filename.len()].as_bytes());
 
     (directory_crc as u64) << 32 | (filename_crc as u64)
 }