Add Crc::digest_with_initial

src/crc128.rs

@@ -54,13 +54,17 @@ impl Crc<u128> {
     }
 
     pub const fn digest(&self) -> Digest<u128> {
-        Digest::new(self)
+        let initial = self.init();
+        Digest::new(self, initial)
+    }
+
+    pub const fn digest_with_initial(&self, initial: u128) -> Digest<u128> {
+        Digest::new(self, initial)
     }
 }
 
 impl<'a> Digest<'a, u128> {
-    const fn new(crc: &'a Crc<u128>) -> Self {
-        let value = crc.init();
+    const fn new(crc: &'a Crc<u128>, value: u128) -> Self {
         Digest { crc, value }
     }
 

src/crc16.rs

@@ -54,13 +54,17 @@ impl Crc<u16> {
     }
 
     pub const fn digest(&self) -> Digest<u16> {
-        Digest::new(self)
+        let initial = self.init();
+        Digest::new(self, initial)
+    }
+
+    pub const fn digest_with_initial(&self, initial: u16) -> Digest<u16> {
+        Digest::new(self, initial)
     }
 }
 
 impl<'a> Digest<'a, u16> {
-    const fn new(crc: &'a Crc<u16>) -> Self {
-        let value = crc.init();
+    const fn new(crc: &'a Crc<u16>, value: u16) -> Self {
         Digest { crc, value }
     }
 

src/crc32.rs

@@ -54,13 +54,17 @@ impl Crc<u32> {
     }
 
     pub const fn digest(&self) -> Digest<u32> {
-        Digest::new(self)
+        let initial = self.init();
+        Digest::new(self, initial)
+    }
+
+    pub const fn digest_with_initial(&self, initial: u32) -> Digest<u32> {
+        Digest::new(self, initial)
     }
 }
 
 impl<'a> Digest<'a, u32> {
-    const fn new(crc: &'a Crc<u32>) -> Self {
-        let value = crc.init();
+    const fn new(crc: &'a Crc<u32>, value: u32) -> Self {
         Digest { crc, value }
     }
 

src/crc64.rs

@@ -54,13 +54,17 @@ impl Crc<u64> {
     }
 
     pub const fn digest(&self) -> Digest<u64> {
-        Digest::new(self)
+        let initial = self.init();
+        Digest::new(self, initial)
+    }
+
+    pub const fn digest_with_initial(&self, initial: u64) -> Digest<u64> {
+        Digest::new(self, initial)
     }
 }
 
 impl<'a> Digest<'a, u64> {
-    const fn new(crc: &'a Crc<u64>) -> Self {
-        let value = crc.init();
+    const fn new(crc: &'a Crc<u64>, value: u64) -> Self {
         Digest { crc, value }
     }
 

src/crc8.rs

@@ -47,13 +47,17 @@ impl Crc<u8> {
     }
 
     pub const fn digest(&self) -> Digest<u8> {
-        Digest::new(self)
+        let initial = self.init();
+        Digest::new(self, initial)
+    }
+
+    pub const fn digest_with_initial(&self, initial: u8) -> Digest<u8> {
+        Digest::new(self, initial)
     }
 }
 
 impl<'a> Digest<'a, u8> {
-    const fn new(crc: &'a Crc<u8>) -> Self {
-        let value = crc.init();
+    const fn new(crc: &'a Crc<u8>, value: u8) -> Self {
         Digest { crc, value }
     }