Merge pull request #20 from Cosmo/development

Add method to read signed integers and fix typo in repo

Author: Cosmo

README.md

@@ -4,7 +4,7 @@ BinaryKit helps you to break down binary data into bits and bytes, easily access
 
 ## Access Bytes
 
-By using any `read*` method (`readByte()`, `readBytes(quantitiy:)`, `readBit()`, …), BinaryKit will increment an internal cursor (or reading offset) to the end of the requested bit or byte, so the next `read*` method can continue from there.
+By using any `read*` method (`readByte()`, `readBytes(quantity:)`, `readBit()`, …), BinaryKit will increment an internal cursor (or reading offset) to the end of the requested bit or byte, so the next `read*` method can continue from there.
 
 Any `get*` method (`getByte(index:)`, `getBytes(range:)`, `getBit(index:)`, …) will give access to binary data at any given location — without incrementing the internal cursor.
 

Sources/BinaryKit/Binary.swift

@@ -150,17 +150,17 @@ public struct Binary {
         return result
     }
 
-    /// Returns the `Int`-value of the next n-bits (`quantitiy`)
+    /// Returns the `Int`-value of the next n-bits (`quantity`)
     /// and increments the reading cursor by n-bits.
-    public mutating func readBits(_ quantitiy: Int) throws -> Int {
-        let range = (readBitCursor..<(readBitCursor + quantitiy))
+    public mutating func readBits(_ quantity: Int) throws -> Int {
+        let range = (readBitCursor..<(readBitCursor + quantity))
         let result = try getBits(range: range)
-        incrementReadCursorBy(bits: quantitiy)
+        incrementReadCursorBy(bits: quantity)
         return result
     }
 
-    public mutating func readBits(_ quantitiy: UInt8) throws -> Int {
-        return try readBits(Int(quantitiy))
+    public mutating func readBits(_ quantity: UInt8) throws -> Int {
+        return try readBits(Int(quantity))
     }
 
     /// Returns the `UInt8`-value of the next byte and
@@ -169,26 +169,26 @@ public struct Binary {
         return UInt8(try readBits(byteSize))
     }
 
-    /// Returns a `[UInt8]` of the next n-bytes (`quantitiy`) and
+    /// Returns a `[UInt8]` of the next n-bytes (`quantity`) and
     /// increments the reading cursor by n-bytes.
-    public mutating func readBytes(_ quantitiy: Int) throws -> [UInt8] {
+    public mutating func readBytes(_ quantity: Int) throws -> [UInt8] {
         // Check if the request is within bounds
-        let range = (readBitCursor..<(readBitCursor + quantitiy * byteSize))
+        let range = (readBitCursor..<(readBitCursor + quantity * byteSize))
         let storeRange = 0...(bytesStore.count * byteSize)
         guard storeRange.contains(range.endIndex) else {
             throw BinaryError.outOfBounds
         }
-        return try (0..<quantitiy).map{ _ in try readByte() }
+        return try (0..<quantity).map{ _ in try readByte() }
     }
 
-    public mutating func readBytes(_ quantitiy: UInt8) throws -> [UInt8] {
-        return try readBytes(Int(quantitiy))
+    public mutating func readBytes(_ quantity: UInt8) throws -> [UInt8] {
+        return try readBytes(Int(quantity))
     }
 
-    /// Returns a `String` of the next n-bytes (`quantitiy`) and
+    /// Returns a `String` of the next n-bytes (`quantity`) and
     /// increments the reading cursor by n-bytes.
-    public mutating func readString(quantitiyOfBytes quantitiy: Int, encoding: String.Encoding = .ascii) throws -> String {
-        guard let result = String(bytes: try self.readBytes(quantitiy), encoding: encoding) else {
+    public mutating func readString(quantityOfBytes quantity: Int, encoding: String.Encoding = .ascii) throws -> String {
+        guard let result = String(bytes: try self.readBytes(quantity), encoding: encoding) else {
             throw BinaryError.notString
         }
         return result
@@ -327,3 +327,12 @@ public struct Binary {
         bytesStore.append(contentsOf: int.bytes)
     }
 }
+
+
+extension Binary {
+    mutating func readSignedBits(_ quantity: UInt8) throws -> Int {
+        let multiplicationFactor = (try readBit() == 1) ? -1 : 1
+        let value = try readBits(quantity - 1)
+        return value * multiplicationFactor
+    }
+}

Tests/BinaryKitTests/BinaryKitTests.swift

@@ -58,7 +58,7 @@ final class BinaryKitTests: XCTestCase {
 
     func testBitsRange() {
         let bytes: [UInt8] = [0b1010_1101, 0b1010_1111]
-        var bin = Binary(bytes: bytes)
+        let bin = Binary(bytes: bytes)
 
         XCTAssertEqual(try bin.getBits(range: 0..<4), 10)
         XCTAssertEqual(try bin.getBits(range: 4..<8), 13)
@@ -179,9 +179,9 @@ final class BinaryKitTests: XCTestCase {
     func testStringAndCharacter() {
         let bytes: [UInt8] = [104, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100, 33, 0, 255, 0, 100, 0, 9]
         var bin = Binary(bytes: bytes)
-        XCTAssertEqual(try bin.readString(quantitiyOfBytes: 12), "hello, world")
+        XCTAssertEqual(try bin.readString(quantityOfBytes: 12), "hello, world")
         XCTAssertEqual(try bin.readCharacter(), "!")
-        XCTAssertThrowsError(try bin.readString(quantitiyOfBytes: 6, encoding: .nonLossyASCII))
+        XCTAssertThrowsError(try bin.readString(quantityOfBytes: 6, encoding: .nonLossyASCII))
     }
 
     // MARK: - Bool
@@ -253,7 +253,7 @@ final class BinaryKitTests: XCTestCase {
 
         XCTAssertEqual(try bin.readByte(), 7)
         XCTAssertEqual(try bin.readByte(), 128)
-        XCTAssertEqual(try bin.readString(quantitiyOfBytes: 12), "hello world!")
+        XCTAssertEqual(try bin.readString(quantityOfBytes: 12), "hello world!")
         XCTAssertEqual(try bin.readByte(), 2)
 
         XCTAssertEqual(try bin.readByte(), 255)
@@ -314,6 +314,18 @@ final class BinaryKitTests: XCTestCase {
         XCTAssertEqual(try bin.readBits(13), 0x11ff)
     }
 
+    func testSignedBits() {
+        var binary = Binary(bytes: [0xFF, 0x7F, 0x00, 0xFF, 0x77, 0xFF, 0xFF])
+        XCTAssertEqual(try binary.readSignedBits(8), -127)
+        XCTAssertEqual(try binary.readSignedBits(8), 127)
+        XCTAssertEqual(try binary.readSignedBits(8), 0)
+        XCTAssertEqual(try binary.readSignedBits(4), -7)
+        XCTAssertEqual(try binary.readSignedBits(4), -7)
+        XCTAssertEqual(try binary.readSignedBits(4), 7)
+        XCTAssertEqual(try binary.readSignedBits(4), 7)
+        XCTAssertEqual(try binary.readSignedBits(16), -32767)
+    }
+    
     // MARK: -
 
     static var allTests = [