//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
// C Primitive Types
//===----------------------------------------------------------------------===//

/// The C 'char' type.
///
/// This will be the same as either `CSignedChar` (in the common
/// case) or `CUnsignedChar`, depending on the platform.
public typealias CChar = Int8

/// The C 'unsigned char' type.
public typealias CUnsignedChar = UInt8

/// The C 'unsigned short' type.
public typealias CUnsignedShort = UInt16

/// The C 'unsigned int' type.
public typealias CUnsignedInt = UInt32

/// The C 'unsigned long' type.
public typealias CUnsignedLong = UInt

/// The C 'unsigned long long' type.
public typealias CUnsignedLongLong = UInt64

/// The C 'signed char' type.
public typealias CSignedChar = Int8

/// The C 'short' type.
public typealias CShort = Int16

/// The C 'int' type.
public typealias CInt = Int32

/// The C 'long' type.
#if os(Windows) && !CYGWIN && arch(x86_64)
public typealias CLong = Int32
#else
public typealias CLong = Int
#endif

/// The C 'long long' type.
#if os(Windows) && !CYGWIN && arch(x86_64)
public typealias CLongLong = Int
#else
public typealias CLongLong = Int64
#endif

/// The C 'float' type.
public typealias CFloat = Float

/// The C 'double' type.
public typealias CDouble = Double

// FIXME: long double

// FIXME: Is it actually UTF-32 on Darwin?
//
/// The C++ 'wchar_t' type.
public typealias CWideChar = UnicodeScalar

// FIXME: Swift should probably have a UTF-16 type other than UInt16.
//
/// The C++11 'char16_t' type, which has UTF-16 encoding.
public typealias CChar16 = UInt16

/// The C++11 'char32_t' type, which has UTF-32 encoding.
public typealias CChar32 = UnicodeScalar

/// The C '_Bool' and C++ 'bool' type.
public typealias CBool = Bool

/// A wrapper around an opaque C pointer.
///
/// Opaque pointers are used to represent C pointers to types that
/// cannot be represented in Swift, such as incomplete struct types.
@_fixed_layout
public struct OpaquePointer : Hashable {
  @_versioned
  internal var _rawValue: Builtin.RawPointer

  @_versioned
  @_transparent
  internal init(_ v: Builtin.RawPointer) {
    self._rawValue = v
  }

  /// Creates an `OpaquePointer` from a given address in memory.
  @_transparent
  public init?(bitPattern: Int) {
    if bitPattern == 0 { return nil }
    self._rawValue = Builtin.inttoptr_Word(bitPattern._builtinWordValue)
  }

  /// Creates an `OpaquePointer` from a given address in memory.
  @_transparent
  public init?(bitPattern: UInt) {
    if bitPattern == 0 { return nil }
    self._rawValue = Builtin.inttoptr_Word(bitPattern._builtinWordValue)
  }

  /// Converts a typed `UnsafePointer` to an opaque C pointer.
  @_transparent
  public init<T>(_ from: UnsafePointer<T>) {
    self._rawValue = from._rawValue
  }

  /// Converts a typed `UnsafePointer` to an opaque C pointer.
  ///
  /// The result is `nil` if `from` is `nil`.
  @_transparent
  public init?<T>(_ from: UnsafePointer<T>?) {
    guard let unwrapped = from else { return nil }
    self.init(unwrapped)
  }

  /// Converts a typed `UnsafeMutablePointer` to an opaque C pointer.
  @_transparent
  public init<T>(_ from: UnsafeMutablePointer<T>) {
    self._rawValue = from._rawValue
  }

  /// Converts a typed `UnsafeMutablePointer` to an opaque C pointer.
  ///
  /// The result is `nil` if `from` is `nil`.
  @_transparent
  public init?<T>(_ from: UnsafeMutablePointer<T>?) {
    guard let unwrapped = from else { return nil }
    self.init(unwrapped)
  }

  /// The pointer's hash value.
  ///
  /// The hash value is not guaranteed to be stable across different
  /// invocations of the same program.  Do not persist the hash value across
  /// program runs.
  public var hashValue: Int {
    return Int(Builtin.ptrtoint_Word(_rawValue))
  }
}

extension OpaquePointer : CustomDebugStringConvertible {
  /// A textual representation of the pointer, suitable for debugging.
  public var debugDescription: String {
    return _rawPointerToString(_rawValue)
  }
}

extension Int {
  public init(bitPattern pointer: OpaquePointer?) {
    self.init(bitPattern: UnsafeRawPointer(pointer))
  }
}

extension UInt {
  public init(bitPattern pointer: OpaquePointer?) {
    self.init(bitPattern: UnsafeRawPointer(pointer))
  }
}

extension OpaquePointer : Equatable {
  public static func == (lhs: OpaquePointer, rhs: OpaquePointer) -> Bool {
    return Bool(Builtin.cmp_eq_RawPointer(lhs._rawValue, rhs._rawValue))
  }
}

/// The corresponding Swift type to `va_list` in imported C APIs.
@_fixed_layout
public struct CVaListPointer {
  var value: UnsafeMutableRawPointer

  public // @testable
  init(_fromUnsafeMutablePointer from: UnsafeMutableRawPointer) {
    value = from
  }
}

extension CVaListPointer : CustomDebugStringConvertible {
  /// A textual representation of the pointer, suitable for debugging.
  public var debugDescription: String {
    return value.debugDescription
  }
}

func _memcpy(
  dest destination: UnsafeMutableRawPointer,
  src: UnsafeMutableRawPointer,
  size: UInt
) {
  let dest = destination._rawValue
  let src = src._rawValue
  let size = UInt64(size)._value
  Builtin.int_memcpy_RawPointer_RawPointer_Int64(
    dest, src, size,
    /*alignment:*/ Int32()._value,
    /*volatile:*/ false._value)
}

/// Copy `count` bytes of memory from `src` into `dest`.
///
/// The memory regions `source..<source + count` and
/// `dest..<dest + count` may overlap.
func _memmove(
  dest destination: UnsafeMutableRawPointer,
  src: UnsafeRawPointer,
  size: UInt
) {
  let dest = destination._rawValue
  let src = src._rawValue
  let size = UInt64(size)._value
  Builtin.int_memmove_RawPointer_RawPointer_Int64(
    dest, src, size,
    /*alignment:*/ Int32()._value,
    /*volatile:*/ false._value)
}

@available(*, unavailable, renamed: "OpaquePointer")
public struct COpaquePointer {}

extension OpaquePointer {
  @available(*, unavailable, 
    message:"use 'Unmanaged.toOpaque()' instead")
  public init<T>(bitPattern bits: Unmanaged<T>) {
    Builtin.unreachable()
  }
}