Add Checksum protocol and simplify CRC verification

Sources/CRC+Verify.swift

@@ -9,29 +9,32 @@ import Foundation
 
 public struct VerificationError<Value: FixedWidthInteger>: Error, CustomStringConvertible {
 
+    // MARK: Stored Properties
+
     public let actualValue: Value
     public let expectedValue: Value
 
-    public init(actual: Value, expected: Value) {
-        self.actualValue = actual
-        self.expectedValue = expected
-    }
+    // MARK: Computed Properties
 
     public var description: String {
         "\(String(describing: Self.self))(expected: 0x\(expectedValue.hex), actual: 0x\(actualValue.hex))"
     }
 
+    // MARK: Initialization
+
+    internal init(actual: Value, expected: Value) {
+        self.actualValue = actual
+        self.expectedValue = expected
+    }
+
 }
 
-extension CRC {
+extension Checksum {
 
-    public func verify<S: Sequence<UInt8>>(_ expectedValue: Value, for bytes: S) throws {
-        let actualValue = calculate(for: bytes)
-        guard expectedValue == actualValue else {
-            throw VerificationError(
-                actual: actualValue,
-                expected: expectedValue
-            )
+    public func verify<S: Sequence<UInt8>>(_ expectedValue: Value, for data: S) throws {
+        let actualValue = calculate(for: data)
+        guard actualValue == expectedValue else {
+            throw VerificationError(actual: actualValue, expected: expectedValue)
         }
     }
 
@@ -50,21 +53,3 @@ extension CRCCalculator {
     }
 
 }
-
-extension FixedWidthInteger {
-
-    internal var hex: String {
-        withUnsafeBytes(of: bigEndian) { $0.hex }
-    }
-
-}
-
-extension Sequence<UInt8> {
-
-    internal var hex: String {
-        self
-            .map { String(format: "%02hhX", $0) }
-            .joined()
-    }
-
-}

Sources/CRC.swift

@@ -6,7 +6,7 @@
 
 import Foundation
 
-public struct CRC<Value: FixedWidthInteger> {
+public struct CRC<Value: FixedWidthInteger>: Checksum {
 
     // MARK: Stored Properties
 

Sources/CRC32.swift

@@ -17,7 +17,6 @@ extension CRC32 {
     public static let posix = Self(polynomial: 0x04C11DB7, xorOut: 0xFFFFFFFF)
     public static let sata = Self(polynomial: 0x04C11DB7, initialValue: 0x52325032)
     public static let xfer = Self(polynomial: 0x000000AF)
-
     public static let c = Self(polynomial: 0x1EDC6F41, initialValue: 0xFFFFFFFF, reflected: true, xorOut: 0xFFFFFFFF)
     public static let d = Self(polynomial: 0xA833982B, initialValue: 0xFFFFFFFF, reflected: true, xorOut: 0xFFFFFFFF)
     public static let q = Self(polynomial: 0x814141AB)

Sources/Checksum.swift

@@ -0,0 +1,14 @@
+//
+//  File.swift
+//  
+//
+//  Created by Paul Kraft on 26.07.23.
+//
+
+import Foundation
+
+public protocol Checksum {
+    associatedtype Value: FixedWidthInteger
+
+    func calculate<S: Sequence<UInt8>>(for data: S) -> Value
+}

Sources/Hex.swift

@@ -0,0 +1,26 @@
+//
+//  File.swift
+//  
+//
+//  Created by Paul Kraft on 26.07.23.
+//
+
+import Foundation
+
+extension FixedWidthInteger {
+
+    internal var hex: String {
+        withUnsafeBytes(of: bigEndian) { $0.hex }
+    }
+
+}
+
+extension Sequence<UInt8> {
+
+    internal var hex: String {
+        self
+            .map { String(format: "%02hhX", $0) }
+            .joined()
+    }
+
+}