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import Foundation
enum Endianness {
case big
case little
}
extension Data {
init(_ val: UInt8) {
self.init()
self.appendUInt8(val)
}
init(_ val: UInt16) {
self.init()
self.appendUInt16(val)
}
init(_ val: UInt32) {
self.init()
self.appendUInt32(val)
}
func readUInt8(at offset: Int) -> UInt8? {
guard offset >= 0, offset + 1 <= self.count else {
return nil
}
return self[offset]
}
func readUInt16(at offset: Int) -> UInt16? {
guard offset >= 0, offset + 2 <= self.count else {
return nil
}
return (UInt16(self[offset]) << 8) + UInt16(self[offset + 1])
}
func readUInt32(at offset: Int) -> UInt32? {
guard offset >= 0, offset + 4 <= self.count else {
return nil
}
return (UInt32(self[offset]) << 24) + (UInt32(self[offset + 1]) << 16) + (UInt32(self[offset + 2]) << 8) + UInt32(self[offset + 3])
}
func readData(at offset: Int, length: Int) -> Data? {
guard offset >= 0, offset + length <= self.count else {
return nil
}
return self.subdata(in: offset..<(offset + length))
}
func readString(at offset: Int, length: Int, encoding: String.Encoding) -> String? {
return String(data: self[offset..<(offset + length)], encoding: encoding)
}
mutating func appendUInt8(_ value: UInt8, endianness: Endianness = .big) {
var val = endianness == .big ? value.bigEndian : value.littleEndian
append(&val, count: MemoryLayout<UInt8>.size)
}
mutating func appendUInt16(_ value: UInt16, endianness: Endianness = .big) {
var val = endianness == .big ? value.bigEndian : value.littleEndian
Swift.withUnsafeBytes(of: &val) { buffer in
append(buffer.bindMemory(to: UInt8.self))
}
// append(&val, count: MemoryLayout<UInt16>.size)
}
mutating func appendUInt32(_ value: UInt32, endianness: Endianness = .big) {
var val = endianness == .big ? value.bigEndian : value.littleEndian
Swift.withUnsafeBytes(of: &val) { buffer in
append(buffer.bindMemory(to: UInt8.self))
}
// append(&val, count: MemoryLayout<UInt32>.size)
}
}
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