From f1ecd26c8b52e112712b0039ee087095f559287b Mon Sep 17 00:00:00 2001
From: lizhanhui <lizhanhui@gmail.com>
Date: Sat, 18 Nov 2023 20:50:33 +0800
Subject: [PATCH] fix #49 consider effect refin with arbitary seed/initial
 value

Signed-off-by: lizhanhui <lizhanhui@gmail.com>
---
 Cargo.toml    |  1 +
 src/hasher.rs | 22 ++++++++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 36e49aa..66c29a1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,6 +19,7 @@ build = "build.rs"
 [dev-dependencies]
 rand = { version ="0.8", features=["alloc", "getrandom"] }
 criterion = "0.4"
+crc = "3.0.1"
 
 [build-dependencies]
 rustc_version = "0.4"
diff --git a/src/hasher.rs b/src/hasher.rs
index ab11777..edc2c5a 100644
--- a/src/hasher.rs
+++ b/src/hasher.rs
@@ -13,11 +13,13 @@ pub struct Crc32cHasher {
 }
 
 impl Crc32cHasher {
-    /// Create the [Hasher] pre-loaded with a particular checksum.
+    /// Create the [Hasher] pre-loaded with an arbitrary seed value.
     ///
     /// Use the [Default::default()] constructor for a clean start.
     pub fn new(initial: u32) -> Self {
-        Self { checksum: initial }
+        Self {
+            checksum: !initial.reverse_bits(),
+        }
     }
 }
 
@@ -45,4 +47,20 @@ mod tests {
         hasher.write(TEST_STRING);
         assert_eq!(hasher.finish(), CHECKSUM as u64);
     }
+
+    #[test]
+    fn test_with_initial_value() {
+        let seed = 123u32;
+        let buffer = b"123456789";
+        let mut hasher = Crc32cHasher::new(seed);
+        hasher.write(buffer);
+        let crc1 = hasher.finish() as u32;
+
+        let castagnoli = crc::Crc::<u32>::new(&crc::CRC_32_ISCSI);
+        let mut digest = castagnoli.digest_with_initial(seed);
+        digest.update(buffer);
+        let crc2 = digest.finalize();
+
+        assert_eq!(crc1, crc2);
+    }
 }