cksum: Use crc_fast::Digest on the fly to improve performances

Author: RenjiSann

src/uucore/src/lib/features/checksum.rs

@@ -1155,7 +1155,7 @@ where
 
 pub fn digest_reader<T: Read>(
     digest: &mut Box<dyn Digest>,
-    reader: &mut BufReader<T>,
+    reader: &mut T,
     binary: bool,
     output_bits: usize,
 ) -> io::Result<(String, usize)> {

src/uucore/src/lib/features/sum.rs

@@ -138,51 +138,48 @@ impl Digest for Sm3 {
     }
 }
 
-pub struct Crc {
-    state: u32,
-    size: usize,
-    // Store data for SIMD processing
-    data_buffer: Vec<u8>,
+pub struct Crc(crc_fast::Digest);
+
+impl Crc {
+    /// POSIX cksum SIMD configuration for crc-fast
+    /// This uses SIMD instructions (PCLMULQDQ) for fast CRC computation
+    fn get_posix_cksum_params() -> crc_fast::CrcParams {
+        crc_fast::CrcParams::new(
+            "CRC-32/CKSUM", // Name
+            32,             // Width
+            0x04c11db7,     // Polynomial
+            0x00000000,     // Initial CRC value: 0 (not 0xffffffff)
+            false,          // No input reflection (refin)
+            0xffffffff,     // XOR output with 0xffffffff (xorout)
+            0,              // Check value (not used)
+        )
+    }
 }
 
 impl Digest for Crc {
     fn new() -> Self {
-        Self {
-            state: 0,
-            size: 0,
-            data_buffer: Vec::with_capacity(8192),
-        }
+        Self(crc_fast::Digest::new_with_params(
+            Self::get_posix_cksum_params(),
+        ))
     }
 
     fn hash_update(&mut self, input: &[u8]) {
-        self.size += input.len();
-        // Store data for SIMD processing
-        self.data_buffer.extend_from_slice(input);
+        self.0.update(input);
     }
 
     fn hash_finalize(&mut self, out: &mut [u8]) {
-        // Add the size bytes to the data buffer
-        let mut sz = self.size;
-        while sz != 0 {
-            self.data_buffer.push(sz as u8);
-            sz >>= 8;
-        }
-
-        // Use SIMD-accelerated CRC computation
-        self.state = checksum_with_params(get_posix_cksum_params(), &self.data_buffer) as u32;
-        out.copy_from_slice(&self.state.to_ne_bytes());
+        let xout = self.0.finalize();
+        out.copy_from_slice(&xout.to_ne_bytes());
     }
 
     fn result_str(&mut self) -> String {
-        let mut _out: Vec<u8> = vec![0; 4];
-        self.hash_finalize(&mut _out);
-        format!("{}", self.state)
+        let mut out: [u8; 8] = [0; 8];
+        self.hash_finalize(&mut out);
+        u64::from_ne_bytes(out).to_string()
     }
 
     fn reset(&mut self) {
-        self.state = 0;
-        self.size = 0;
-        self.data_buffer.clear();
+        self.0.reset();
     }
 
     fn output_bits(&self) -> usize {