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UnsafeRawPointer.swift
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UnsafeRawPointer.swift
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//===--- UnsafeRawPointer.swift -------------------------------*- swift -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
/// A raw pointer for accessing
/// untyped data.
///
/// The `UnsafeRawPointer` type provides no automated memory management, no type safety,
/// and no alignment guarantees. You are responsible for handling the life
/// cycle of any memory you work with through unsafe pointers, to avoid leaks
/// or undefined behavior.
///
/// Memory that you manually manage can be either *untyped* or *bound* to a
/// specific type. You use the `UnsafeRawPointer` type to access and
/// manage raw bytes in memory, whether or not that memory has been bound to a
/// specific type.
///
/// Understanding a Pointer's Memory State
/// ======================================
///
/// The memory referenced by an `UnsafeRawPointer` instance can be in one of several
/// states. Many pointer operations must only be applied to pointers with
/// memory in a specific state---you must keep track of the state of the
/// memory you are working with and understand the changes to that state that
/// different operations perform. Memory can be untyped and uninitialized,
/// bound to a type and uninitialized, or bound to a type and initialized to a
/// value. Finally, memory that was allocated previously may have been
/// deallocated, leaving existing pointers referencing unallocated memory.
///
/// Raw, Uninitialized Memory
/// -------------------------
///
/// Raw memory that has just been allocated is in an *uninitialized, untyped*
/// state. Uninitialized memory must be initialized with values of a type
/// before it can be used with any typed operations.
///
/// To bind uninitialized memory to a type without initializing it, use the
/// `bindMemory(to:count:)` method. This method returns a typed pointer
/// for further typed access to the memory.
///
/// Typed Memory
/// ------------
///
/// Memory that has been bound to a type, whether it is initialized or
/// uninitialized, is typically accessed using typed pointers---instances of
/// `UnsafePointer` and `UnsafeMutablePointer`. Initialization, assignment,
/// and deinitialization can be performed using `UnsafeMutablePointer`
/// methods.
///
/// Memory that has been bound to a type can be rebound to a different type
/// only after it has been deinitialized or if the bound type is a *trivial
/// type*. Deinitializing typed memory does not unbind that memory's type. The
/// deinitialized memory can be reinitialized with values of the same type,
/// bound to a new type, or deallocated.
///
/// - Note: A trivial type can be copied bit for bit with no indirection or
/// reference-counting operations. Generally, native Swift types that do not
/// contain strong or weak references or other forms of indirection are
/// trivial, as are imported C structs and enumerations.
///
/// When reading from memory as raw
/// bytes when that memory is bound to a type, you must ensure that you
/// satisfy any alignment requirements.
///
/// Raw Pointer Arithmetic
/// ======================
///
/// Pointer arithmetic with raw pointers is performed at the byte level. When
/// you add to or subtract from a raw pointer, the result is a new raw pointer
/// offset by that number of bytes. The following example allocates four bytes
/// of memory and stores `0xFF` in all four bytes:
///
/// let bytesPointer = UnsafeMutableRawPointer.allocate(byteCount: 4, alignment: 4)
/// bytesPointer.storeBytes(of: 0xFFFF_FFFF, as: UInt32.self)
///
/// // Load a value from the memory referenced by 'bytesPointer'
/// let x = bytesPointer.load(as: UInt8.self) // 255
///
/// // Load a value from the last two allocated bytes
/// let offsetPointer = bytesPointer + 2
/// let y = offsetPointer.load(as: UInt16.self) // 65535
///
/// The code above stores the value `0xFFFF_FFFF` into the four newly allocated
/// bytes, and then loads the first byte as a `UInt8` instance and the third
/// and fourth bytes as a `UInt16` instance.
///
/// Always remember to deallocate any memory that you allocate yourself.
///
/// bytesPointer.deallocate()
///
/// Implicit Casting and Bridging
/// =============================
///
/// When calling a function or method with an `UnsafeRawPointer` parameter, you can pass
/// an instance of that specific pointer type, pass an instance of a
/// compatible pointer type, or use Swift's implicit bridging to pass a
/// compatible pointer.
///
/// For example, the `print(address:as:)` function in the following code sample
/// takes an `UnsafeRawPointer` instance as its first parameter:
///
/// func print<T>(address p: UnsafeRawPointer, as type: T.Type) {
/// let value = p.load(as: type)
/// print(value)
/// }
///
/// As is typical in Swift, you can call the `print(address:as:)` function with
/// an `UnsafeRawPointer` instance. This example passes `rawPointer` as the initial
/// parameter.
///
/// // 'rawPointer' points to memory initialized with `Int` values.
/// let rawPointer: UnsafeRawPointer = ...
/// print(address: rawPointer, as: Int.self)
/// // Prints "42"
///
/// Because typed pointers can be implicitly cast to raw pointers when passed
/// as a parameter, you can also call `print(address:as:)` with any mutable or
/// immutable typed pointer instance.
///
/// let intPointer: UnsafePointer<Int> = ...
/// print(address: intPointer, as: Int.self)
/// // Prints "42"
///
/// let mutableIntPointer = UnsafeMutablePointer(mutating: intPointer)
/// print(address: mutableIntPointer, as: Int.self)
/// // Prints "42"
///
/// Alternatively, you can use Swift's *implicit bridging* to pass a pointer to
/// an instance or to the elements of an array. Use inout syntax to implicitly
/// create a pointer to an instance of any type. The following example uses
/// implicit bridging to pass a pointer to `value` when calling
/// `print(address:as:)`:
///
/// var value: Int = 23
/// print(address: &value, as: Int.self)
/// // Prints "23"
///
/// An immutable pointer to the elements of an array is implicitly created when
/// you pass the array as an argument. This example uses implicit bridging to
/// pass a pointer to the elements of `numbers` when calling
/// `print(address:as:)`.
///
/// let numbers = [5, 10, 15, 20]
/// print(address: numbers, as: Int.self)
/// // Prints "5"
///
/// You can also use inout syntax to pass a mutable pointer to the elements of
/// an array. Because `print(address:as:)` requires an immutable pointer,
/// although this is syntactically valid, it isn't necessary.
///
/// var mutableNumbers = numbers
/// print(address: &mutableNumbers, as: Int.self)
///
/// - Important: The pointer created through implicit bridging of an instance
/// or of an array's elements is only valid during the execution of the
/// called function. Escaping the pointer to use after the execution of the
/// function is undefined behavior. In particular, do not use implicit
/// bridging when calling an `UnsafeRawPointer` initializer.
///
/// var number = 5
/// let numberPointer = UnsafeRawPointer(&number)
/// // Accessing 'numberPointer' is undefined behavior.
@frozen
public struct UnsafeRawPointer: _Pointer {
public typealias Pointee = UInt8
/// The underlying raw pointer.
/// Implements conformance to the public protocol `_Pointer`.
public let _rawValue: Builtin.RawPointer
/// Creates a new raw pointer from a builtin raw pointer.
@_transparent
public init(_ _rawValue: Builtin.RawPointer) {
self._rawValue = _rawValue
}
/// Creates a new raw pointer from the given typed pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The typed pointer to convert.
@_transparent
public init<T>(_ other: UnsafePointer<T>) {
_rawValue = other._rawValue
}
/// Creates a new raw pointer from the given typed pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The typed pointer to convert. If `other` is `nil`, the
/// result is `nil`.
@_transparent
public init?<T>(_ other: UnsafePointer<T>?) {
guard let unwrapped = other else { return nil }
_rawValue = unwrapped._rawValue
}
/// Creates a new raw pointer from the given mutable raw pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The mutable raw pointer to convert.
@_transparent
public init(_ other: UnsafeMutableRawPointer) {
_rawValue = other._rawValue
}
/// Creates a new raw pointer from the given mutable raw pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The mutable raw pointer to convert. If `other` is
/// `nil`, the result is `nil`.
@_transparent
public init?(_ other: UnsafeMutableRawPointer?) {
guard let unwrapped = other else { return nil }
_rawValue = unwrapped._rawValue
}
/// Creates a new raw pointer from the given typed pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The typed pointer to convert.
@_transparent
public init<T>(_ other: UnsafeMutablePointer<T>) {
_rawValue = other._rawValue
}
/// Creates a new raw pointer from the given typed pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The typed pointer to convert. If `other` is `nil`, the
/// result is `nil`.
@_transparent
public init?<T>(_ other: UnsafeMutablePointer<T>?) {
guard let unwrapped = other else { return nil }
_rawValue = unwrapped._rawValue
}
/// Deallocates the previously allocated memory block referenced by this pointer.
///
/// The memory to be deallocated must be uninitialized or initialized to a
/// trivial type.
@inlinable
public func deallocate() {
// Passing zero alignment to the runtime forces "aligned
// deallocation". Since allocation via `UnsafeMutable[Raw][Buffer]Pointer`
// always uses the "aligned allocation" path, this ensures that the
// runtime's allocation and deallocation paths are compatible.
Builtin.deallocRaw(_rawValue, (-1)._builtinWordValue, (0)._builtinWordValue)
}
/// Binds the memory to the specified type and returns a typed pointer to the
/// bound memory.
///
/// Use the `bindMemory(to:capacity:)` method to bind the memory referenced
/// by this pointer to the type `T`. The memory must be uninitialized or
/// initialized to a type that is layout compatible with `T`. If the memory
/// is uninitialized, it is still uninitialized after being bound to `T`.
///
/// In this example, 100 bytes of raw memory are allocated for the pointer
/// `bytesPointer`, and then the first four bytes are bound to the `Int8`
/// type.
///
/// let count = 4
/// let bytesPointer = UnsafeMutableRawPointer.allocate(
/// bytes: 100,
/// alignedTo: MemoryLayout<Int8>.alignment)
/// let int8Pointer = bytesPointer.bindMemory(to: Int8.self, capacity: count)
///
/// After calling `bindMemory(to:capacity:)`, the first four bytes of the
/// memory referenced by `bytesPointer` are bound to the `Int8` type, though
/// they remain uninitialized. The remainder of the allocated region is
/// unbound raw memory. All 100 bytes of memory must eventually be
/// deallocated.
///
/// - Warning: A memory location may only be bound to one type at a time. The
/// behavior of accessing memory as a type unrelated to its bound type is
/// undefined.
///
/// - Parameters:
/// - type: The type `T` to bind the memory to.
/// - count: The amount of memory to bind to type `T`, counted as instances
/// of `T`.
/// - Returns: A typed pointer to the newly bound memory. The memory in this
/// region is bound to `T`, but has not been modified in any other way.
/// The number of bytes in this region is
/// `count * MemoryLayout<T>.stride`.
@_transparent
@discardableResult
public func bindMemory<T>(
to type: T.Type, capacity count: Int
) -> UnsafePointer<T> {
Builtin.bindMemory(_rawValue, count._builtinWordValue, type)
return UnsafePointer<T>(_rawValue)
}
/// Returns a typed pointer to the memory referenced by this pointer,
/// assuming that the memory is already bound to the specified type.
///
/// Use this method when you have a raw pointer to memory that has *already*
/// been bound to the specified type. The memory starting at this pointer
/// must be bound to the type `T`. Accessing memory through the returned
/// pointer is undefined if the memory has not been bound to `T`. To bind
/// memory to `T`, use `bindMemory(to:capacity:)` instead of this method.
///
/// - Parameter to: The type `T` that the memory has already been bound to.
/// - Returns: A typed pointer to the same memory as this raw pointer.
@_transparent
public func assumingMemoryBound<T>(to: T.Type) -> UnsafePointer<T> {
return UnsafePointer<T>(_rawValue)
}
/// Returns a new instance of the given type, constructed from the raw memory
/// at the specified offset.
///
/// The memory at this pointer plus `offset` must be properly aligned for
/// accessing `T` and initialized to `T` or another type that is layout
/// compatible with `T`.
///
/// - Parameters:
/// - offset: The offset from this pointer, in bytes. `offset` must be
/// nonnegative. The default is zero.
/// - type: The type of the instance to create.
/// - Returns: A new instance of type `T`, read from the raw bytes at
/// `offset`. The returned instance is memory-managed and unassociated
/// with the value in the memory referenced by this pointer.
@inlinable
public func load<T>(fromByteOffset offset: Int = 0, as type: T.Type) -> T {
_debugPrecondition(0 == (UInt(bitPattern: self + offset)
& (UInt(MemoryLayout<T>.alignment) - 1)),
"load from misaligned raw pointer")
return Builtin.loadRaw((self + offset)._rawValue)
}
}
extension UnsafeRawPointer: Strideable {
// custom version for raw pointers
@_transparent
public func advanced(by n: Int) -> UnsafeRawPointer {
return UnsafeRawPointer(Builtin.gepRaw_Word(_rawValue, n._builtinWordValue))
}
}
/// A raw pointer for accessing and manipulating
/// untyped data.
///
/// The `UnsafeMutableRawPointer` type provides no automated memory management, no type safety,
/// and no alignment guarantees. You are responsible for handling the life
/// cycle of any memory you work with through unsafe pointers, to avoid leaks
/// or undefined behavior.
///
/// Memory that you manually manage can be either *untyped* or *bound* to a
/// specific type. You use the `UnsafeMutableRawPointer` type to access and
/// manage raw bytes in memory, whether or not that memory has been bound to a
/// specific type.
///
/// Understanding a Pointer's Memory State
/// ======================================
///
/// The memory referenced by an `UnsafeMutableRawPointer` instance can be in one of several
/// states. Many pointer operations must only be applied to pointers with
/// memory in a specific state---you must keep track of the state of the
/// memory you are working with and understand the changes to that state that
/// different operations perform. Memory can be untyped and uninitialized,
/// bound to a type and uninitialized, or bound to a type and initialized to a
/// value. Finally, memory that was allocated previously may have been
/// deallocated, leaving existing pointers referencing unallocated memory.
///
/// Raw, Uninitialized Memory
/// -------------------------
///
/// Raw memory that has just been allocated is in an *uninitialized, untyped*
/// state. Uninitialized memory must be initialized with values of a type
/// before it can be used with any typed operations.
///
/// You can use methods like `initializeMemory(as:from:)` and
/// `moveInitializeMemory(as:from:count:)` to bind raw memory to a type and
/// initialize it with a value or series of values. To bind uninitialized
/// memory to a type without initializing it, use the `bindMemory(to:count:)`
/// method. These methods all return typed pointers for further typed access
/// to the memory.
///
/// Typed Memory
/// ------------
///
/// Memory that has been bound to a type, whether it is initialized or
/// uninitialized, is typically accessed using typed pointers---instances of
/// `UnsafePointer` and `UnsafeMutablePointer`. Initialization, assignment,
/// and deinitialization can be performed using `UnsafeMutablePointer`
/// methods.
///
/// Memory that has been bound to a type can be rebound to a different type
/// only after it has been deinitialized or if the bound type is a *trivial
/// type*. Deinitializing typed memory does not unbind that memory's type. The
/// deinitialized memory can be reinitialized with values of the same type,
/// bound to a new type, or deallocated.
///
/// - Note: A trivial type can be copied bit for bit with no indirection or
/// reference-counting operations. Generally, native Swift types that do not
/// contain strong or weak references or other forms of indirection are
/// trivial, as are imported C structs and enumerations.
///
/// When reading from or writing to memory as raw
/// bytes when that memory is bound to a type, you must ensure that you
/// satisfy any alignment requirements.
/// Writing to typed memory as raw bytes must only be performed when the bound
/// type is a trivial type.
///
/// Raw Pointer Arithmetic
/// ======================
///
/// Pointer arithmetic with raw pointers is performed at the byte level. When
/// you add to or subtract from a raw pointer, the result is a new raw pointer
/// offset by that number of bytes. The following example allocates four bytes
/// of memory and stores `0xFF` in all four bytes:
///
/// let bytesPointer = UnsafeMutableRawPointer.allocate(byteCount: 4, alignment: 1)
/// bytesPointer.storeBytes(of: 0xFFFF_FFFF, as: UInt32.self)
///
/// // Load a value from the memory referenced by 'bytesPointer'
/// let x = bytesPointer.load(as: UInt8.self) // 255
///
/// // Load a value from the last two allocated bytes
/// let offsetPointer = bytesPointer + 2
/// let y = offsetPointer.load(as: UInt16.self) // 65535
///
/// The code above stores the value `0xFFFF_FFFF` into the four newly allocated
/// bytes, and then loads the first byte as a `UInt8` instance and the third
/// and fourth bytes as a `UInt16` instance.
///
/// Always remember to deallocate any memory that you allocate yourself.
///
/// bytesPointer.deallocate()
///
/// Implicit Casting and Bridging
/// =============================
///
/// When calling a function or method with an `UnsafeMutableRawPointer` parameter, you can pass
/// an instance of that specific pointer type, pass an instance of a
/// compatible pointer type, or use Swift's implicit bridging to pass a
/// compatible pointer.
///
/// For example, the `print(address:as:)` function in the following code sample
/// takes an `UnsafeMutableRawPointer` instance as its first parameter:
///
/// func print<T>(address p: UnsafeMutableRawPointer, as type: T.Type) {
/// let value = p.load(as: type)
/// print(value)
/// }
///
/// As is typical in Swift, you can call the `print(address:as:)` function with
/// an `UnsafeMutableRawPointer` instance. This example passes `rawPointer` as the initial
/// parameter.
///
/// // 'rawPointer' points to memory initialized with `Int` values.
/// let rawPointer: UnsafeMutableRawPointer = ...
/// print(address: rawPointer, as: Int.self)
/// // Prints "42"
///
/// Because typed pointers can be implicitly cast to raw pointers when passed
/// as a parameter, you can also call `print(address:as:)` with any mutable
/// typed pointer instance.
///
/// let intPointer: UnsafeMutablePointer<Int> = ...
/// print(address: intPointer, as: Int.self)
/// // Prints "42"
///
/// Alternatively, you can use Swift's *implicit bridging* to pass a pointer to
/// an instance or to the elements of an array. Use inout syntax to implicitly
/// create a pointer to an instance of any type. The following example uses
/// implicit bridging to pass a pointer to `value` when calling
/// `print(address:as:)`:
///
/// var value: Int = 23
/// print(address: &value, as: Int.self)
/// // Prints "23"
///
/// A mutable pointer to the elements of an array is implicitly created when
/// you pass the array using inout syntax. This example uses implicit bridging
/// to pass a pointer to the elements of `numbers` when calling
/// `print(address:as:)`.
///
/// var numbers = [5, 10, 15, 20]
/// print(address: &numbers, as: Int.self)
/// // Prints "5"
///
/// - Important: The pointer created through implicit bridging of an instance
/// or of an array's elements is only valid during the execution of the
/// called function. Escaping the pointer to use after the execution of the
/// function is undefined behavior. In particular, do not use implicit
/// bridging when calling an `UnsafeMutableRawPointer` initializer.
///
/// var number = 5
/// let numberPointer = UnsafeMutableRawPointer(&number)
/// // Accessing 'numberPointer' is undefined behavior.
@frozen
public struct UnsafeMutableRawPointer: _Pointer {
public typealias Pointee = UInt8
/// The underlying raw pointer.
/// Implements conformance to the public protocol `_Pointer`.
public let _rawValue: Builtin.RawPointer
/// Creates a new raw pointer from a builtin raw pointer.
@_transparent
public init(_ _rawValue: Builtin.RawPointer) {
self._rawValue = _rawValue
}
/// Creates a new raw pointer from the given typed pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeMutableRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The typed pointer to convert.
@_transparent
public init<T>(_ other: UnsafeMutablePointer<T>) {
_rawValue = other._rawValue
}
/// Creates a new raw pointer from the given typed pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeMutableRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The typed pointer to convert. If `other` is `nil`, the
/// result is `nil`.
@_transparent
public init?<T>(_ other: UnsafeMutablePointer<T>?) {
guard let unwrapped = other else { return nil }
_rawValue = unwrapped._rawValue
}
/// Creates a new mutable raw pointer from the given immutable raw pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeMutableRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The immutable raw pointer to convert.
@_transparent
public init(mutating other: UnsafeRawPointer) {
_rawValue = other._rawValue
}
/// Creates a new mutable raw pointer from the given immutable raw pointer.
///
/// Use this initializer to explicitly convert `other` to an `UnsafeMutableRawPointer`
/// instance. This initializer creates a new pointer to the same address as
/// `other` and performs no allocation or copying.
///
/// - Parameter other: The immutable raw pointer to convert. If `other` is
/// `nil`, the result is `nil`.
@_transparent
public init?(mutating other: UnsafeRawPointer?) {
guard let unwrapped = other else { return nil }
_rawValue = unwrapped._rawValue
}
/// Allocates uninitialized memory with the specified size and alignment.
///
/// You are in charge of managing the allocated memory. Be sure to deallocate
/// any memory that you manually allocate.
///
/// The allocated memory is not bound to any specific type and must be bound
/// before performing any typed operations. If you are using the memory for
/// a specific type, allocate memory using the
/// `UnsafeMutablePointer.allocate(capacity:)` static method instead.
///
/// - Parameters:
/// - byteCount: The number of bytes to allocate. `byteCount` must not be negative.
/// - alignment: The alignment of the new region of allocated memory, in
/// bytes.
/// - Returns: A pointer to a newly allocated region of memory. The memory is
/// allocated, but not initialized.
@inlinable
public static func allocate(
byteCount: Int, alignment: Int
) -> UnsafeMutableRawPointer {
// For any alignment <= _minAllocationAlignment, force alignment = 0.
// This forces the runtime's "aligned" allocation path so that
// deallocation does not require the original alignment.
//
// The runtime guarantees:
//
// align == 0 || align > _minAllocationAlignment:
// Runtime uses "aligned allocation".
//
// 0 < align <= _minAllocationAlignment:
// Runtime may use either malloc or "aligned allocation".
var alignment = alignment
if alignment <= _minAllocationAlignment() {
alignment = 0
}
return UnsafeMutableRawPointer(Builtin.allocRaw(
byteCount._builtinWordValue, alignment._builtinWordValue))
}
/// Deallocates the previously allocated memory block referenced by this pointer.
///
/// The memory to be deallocated must be uninitialized or initialized to a
/// trivial type.
@inlinable
public func deallocate() {
// Passing zero alignment to the runtime forces "aligned
// deallocation". Since allocation via `UnsafeMutable[Raw][Buffer]Pointer`
// always uses the "aligned allocation" path, this ensures that the
// runtime's allocation and deallocation paths are compatible.
Builtin.deallocRaw(_rawValue, (-1)._builtinWordValue, (0)._builtinWordValue)
}
/// Binds the memory to the specified type and returns a typed pointer to the
/// bound memory.
///
/// Use the `bindMemory(to:capacity:)` method to bind the memory referenced
/// by this pointer to the type `T`. The memory must be uninitialized or
/// initialized to a type that is layout compatible with `T`. If the memory
/// is uninitialized, it is still uninitialized after being bound to `T`.
///
/// In this example, 100 bytes of raw memory are allocated for the pointer
/// `bytesPointer`, and then the first four bytes are bound to the `Int8`
/// type.
///
/// let count = 4
/// let bytesPointer = UnsafeMutableRawPointer.allocate(
/// bytes: 100,
/// alignedTo: MemoryLayout<Int8>.alignment)
/// let int8Pointer = bytesPointer.bindMemory(to: Int8.self, capacity: count)
///
/// After calling `bindMemory(to:capacity:)`, the first four bytes of the
/// memory referenced by `bytesPointer` are bound to the `Int8` type, though
/// they remain uninitialized. The remainder of the allocated region is
/// unbound raw memory. All 100 bytes of memory must eventually be
/// deallocated.
///
/// - Warning: A memory location may only be bound to one type at a time. The
/// behavior of accessing memory as a type unrelated to its bound type is
/// undefined.
///
/// - Parameters:
/// - type: The type `T` to bind the memory to.
/// - count: The amount of memory to bind to type `T`, counted as instances
/// of `T`.
/// - Returns: A typed pointer to the newly bound memory. The memory in this
/// region is bound to `T`, but has not been modified in any other way.
/// The number of bytes in this region is
/// `count * MemoryLayout<T>.stride`.
@_transparent
@discardableResult
public func bindMemory<T>(
to type: T.Type, capacity count: Int
) -> UnsafeMutablePointer<T> {
Builtin.bindMemory(_rawValue, count._builtinWordValue, type)
return UnsafeMutablePointer<T>(_rawValue)
}
/// Returns a typed pointer to the memory referenced by this pointer,
/// assuming that the memory is already bound to the specified type.
///
/// Use this method when you have a raw pointer to memory that has *already*
/// been bound to the specified type. The memory starting at this pointer
/// must be bound to the type `T`. Accessing memory through the returned
/// pointer is undefined if the memory has not been bound to `T`. To bind
/// memory to `T`, use `bindMemory(to:capacity:)` instead of this method.
///
/// - Parameter to: The type `T` that the memory has already been bound to.
/// - Returns: A typed pointer to the same memory as this raw pointer.
@_transparent
public func assumingMemoryBound<T>(to: T.Type) -> UnsafeMutablePointer<T> {
return UnsafeMutablePointer<T>(_rawValue)
}
/// Initializes the memory referenced by this pointer with the given value,
/// binds the memory to the value's type, and returns a typed pointer to the
/// initialized memory.
///
/// The memory referenced by this pointer must be uninitialized or
/// initialized to a trivial type, and must be properly aligned for
/// accessing `T`.
///
/// The following example allocates enough raw memory to hold four instances
/// of `Int8`, and then uses the `initializeMemory(as:repeating:count:)` method
/// to initialize the allocated memory.
///
/// let count = 4
/// let bytesPointer = UnsafeMutableRawPointer.allocate(
/// byteCount: count * MemoryLayout<Int8>.stride,
/// alignment: MemoryLayout<Int8>.alignment)
/// let int8Pointer = myBytes.initializeMemory(
/// as: Int8.self, repeating: 0, count: count)
///
/// // After using 'int8Pointer':
/// int8Pointer.deallocate()
///
/// After calling this method on a raw pointer `p`, the region starting at
/// `self` and continuing up to `p + count * MemoryLayout<T>.stride` is bound
/// to type `T` and initialized. If `T` is a nontrivial type, you must
/// eventually deinitialize or move from the values in this region to avoid leaks.
///
/// - Parameters:
/// - type: The type to bind this memory to.
/// - repeatedValue: The instance to copy into memory.
/// - count: The number of copies of `value` to copy into memory. `count`
/// must not be negative.
/// - Returns: A typed pointer to the memory referenced by this raw pointer.
@inlinable
@discardableResult
public func initializeMemory<T>(
as type: T.Type, repeating repeatedValue: T, count: Int
) -> UnsafeMutablePointer<T> {
_debugPrecondition(count >= 0,
"UnsafeMutableRawPointer.initializeMemory: negative count")
Builtin.bindMemory(_rawValue, count._builtinWordValue, type)
var nextPtr = self
for _ in 0..<count {
Builtin.initialize(repeatedValue, nextPtr._rawValue)
nextPtr += MemoryLayout<T>.stride
}
return UnsafeMutablePointer(_rawValue)
}
/// Initializes the memory referenced by this pointer with the values
/// starting at the given pointer, binds the memory to the values' type, and
/// returns a typed pointer to the initialized memory.
///
/// The memory referenced by this pointer must be uninitialized or
/// initialized to a trivial type, and must be properly aligned for
/// accessing `T`.
///
/// The following example allocates enough raw memory to hold four instances
/// of `Int8`, and then uses the `initializeMemory(as:from:count:)` method
/// to initialize the allocated memory.
///
/// let count = 4
/// let bytesPointer = UnsafeMutableRawPointer.allocate(
/// bytes: count * MemoryLayout<Int8>.stride,
/// alignedTo: MemoryLayout<Int8>.alignment)
/// let values: [Int8] = [1, 2, 3, 4]
/// let int8Pointer = values.withUnsafeBufferPointer { buffer in
/// return bytesPointer.initializeMemory(as: Int8.self,
/// from: buffer.baseAddress!,
/// count: buffer.count)
/// }
/// // int8Pointer.pointee == 1
/// // (int8Pointer + 3).pointee == 4
///
/// // After using 'int8Pointer':
/// int8Pointer.deallocate(count)
///
/// After calling this method on a raw pointer `p`, the region starting at
/// `p` and continuing up to `p + count * MemoryLayout<T>.stride` is bound
/// to type `T` and initialized. If `T` is a nontrivial type, you must
/// eventually deinitialize or move from the values in this region to avoid
/// leaks. The instances in the region `source..<(source + count)` are
/// unaffected.
///
/// - Parameters:
/// - type: The type to bind this memory to.
/// - source: A pointer to the values to copy. The memory in the region
/// `source..<(source + count)` must be initialized to type `T` and must
/// not overlap the destination region.
/// - count: The number of copies of `value` to copy into memory. `count`
/// must not be negative.
/// - Returns: A typed pointer to the memory referenced by this raw pointer.
@inlinable
@discardableResult
public func initializeMemory<T>(
as type: T.Type, from source: UnsafePointer<T>, count: Int
) -> UnsafeMutablePointer<T> {
_debugPrecondition(
count >= 0,
"UnsafeMutableRawPointer.initializeMemory with negative count")
_debugPrecondition(
(UnsafeRawPointer(self + count * MemoryLayout<T>.stride)
<= UnsafeRawPointer(source))
|| UnsafeRawPointer(source + count) <= UnsafeRawPointer(self),
"UnsafeMutableRawPointer.initializeMemory overlapping range")
Builtin.bindMemory(_rawValue, count._builtinWordValue, type)
Builtin.copyArray(
T.self, self._rawValue, source._rawValue, count._builtinWordValue)
// This builtin is equivalent to:
// for i in 0..<count {
// (self.assumingMemoryBound(to: T.self) + i).initialize(to: source[i])
// }
return UnsafeMutablePointer(_rawValue)
}
/// Initializes the memory referenced by this pointer with the values
/// starting at the given pointer, binds the memory to the values' type,
/// deinitializes the source memory, and returns a typed pointer to the
/// newly initialized memory.
///
/// The memory referenced by this pointer must be uninitialized or
/// initialized to a trivial type, and must be properly aligned for
/// accessing `T`.
///
/// The memory in the region `source..<(source + count)` may overlap with the
/// destination region. The `moveInitializeMemory(as:from:count:)` method
/// automatically performs a forward or backward copy of all instances from
/// the source region to their destination.
///
/// After calling this method on a raw pointer `p`, the region starting at
/// `p` and continuing up to `p + count * MemoryLayout<T>.stride` is bound
/// to type `T` and initialized. If `T` is a nontrivial type, you must
/// eventually deinitialize or move from the values in this region to avoid
/// leaks. Any memory in the region `source..<(source + count)` that does
/// not overlap with the destination region is returned to an uninitialized
/// state.
///
/// - Parameters:
/// - type: The type to bind this memory to.
/// - source: A pointer to the values to copy. The memory in the region
/// `source..<(source + count)` must be initialized to type `T`.
/// - count: The number of copies of `value` to copy into memory. `count`
/// must not be negative.
/// - Returns: A typed pointer to the memory referenced by this raw pointer.
@inlinable
@discardableResult
public func moveInitializeMemory<T>(
as type: T.Type, from source: UnsafeMutablePointer<T>, count: Int
) -> UnsafeMutablePointer<T> {
_debugPrecondition(
count >= 0,
"UnsafeMutableRawPointer.moveInitializeMemory with negative count")
Builtin.bindMemory(_rawValue, count._builtinWordValue, type)
if self < UnsafeMutableRawPointer(source)
|| self >= UnsafeMutableRawPointer(source + count) {
// initialize forward from a disjoint or following overlapping range.
Builtin.takeArrayFrontToBack(
T.self, self._rawValue, source._rawValue, count._builtinWordValue)
// This builtin is equivalent to:
// for i in 0..<count {
// (self.assumingMemoryBound(to: T.self) + i)
// .initialize(to: (source + i).move())
// }
}
else {
// initialize backward from a non-following overlapping range.
Builtin.takeArrayBackToFront(
T.self, self._rawValue, source._rawValue, count._builtinWordValue)
// This builtin is equivalent to:
// var src = source + count
// var dst = self.assumingMemoryBound(to: T.self) + count
// while dst != self {
// (--dst).initialize(to: (--src).move())
// }
}
return UnsafeMutablePointer(_rawValue)
}
/// Returns a new instance of the given type, constructed from the raw memory
/// at the specified offset.
///
/// The memory at this pointer plus `offset` must be properly aligned for
/// accessing `T` and initialized to `T` or another type that is layout
/// compatible with `T`.
///
/// - Parameters:
/// - offset: The offset from this pointer, in bytes. `offset` must be
/// nonnegative. The default is zero.
/// - type: The type of the instance to create.
/// - Returns: A new instance of type `T`, read from the raw bytes at
/// `offset`. The returned instance is memory-managed and unassociated
/// with the value in the memory referenced by this pointer.
@inlinable
public func load<T>(fromByteOffset offset: Int = 0, as type: T.Type) -> T {
_debugPrecondition(0 == (UInt(bitPattern: self + offset)
& (UInt(MemoryLayout<T>.alignment) - 1)),
"load from misaligned raw pointer")
return Builtin.loadRaw((self + offset)._rawValue)
}
/// Stores the given value's bytes into raw memory at the specified offset.
///
/// The type `T` to be stored must be a trivial type. The memory at this
/// pointer plus `offset` must be properly aligned for accessing `T`. The
/// memory must also be uninitialized, initialized to `T`, or initialized to
/// another trivial type that is layout compatible with `T`.
///
/// After calling `storeBytes(of:toByteOffset:as:)`, the memory is
/// initialized to the raw bytes of `value`. If the memory is bound to a
/// type `U` that is layout compatible with `T`, then it contains a value of
/// type `U`. Calling `storeBytes(of:toByteOffset:as:)` does not change the
/// bound type of the memory.
///
/// - Note: A trivial type can be copied with just a bit-for-bit copy without
/// any indirection or reference-counting operations. Generally, native
/// Swift types that do not contain strong or weak references or other
/// forms of indirection are trivial, as are imported C structs and enums.
///
/// If you need to store a copy of a nontrivial value into memory, or to
/// store a value into memory that contains a nontrivial value, you cannot
/// use the `storeBytes(of:toByteOffset:as:)` method. Instead, you must know
/// the type of value previously in memory and initialize or assign the
/// memory. For example, to replace a value stored in a raw pointer `p`,
/// where `U` is the current type and `T` is the new type, use a typed
/// pointer to access and deinitialize the current value before initializing
/// the memory with a new value.
///
/// let typedPointer = p.bindMemory(to: U.self, capacity: 1)
/// typedPointer.deinitialize(count: 1)
/// p.initializeMemory(as: T.self, to: newValue)
///
/// - Parameters:
/// - value: The value to store as raw bytes.
/// - offset: The offset from this pointer, in bytes. `offset` must be
/// nonnegative. The default is zero.
/// - type: The type of `value`.
@inlinable
public func storeBytes<T>(
of value: T, toByteOffset offset: Int = 0, as type: T.Type
) {
_debugPrecondition(0 == (UInt(bitPattern: self + offset)
& (UInt(MemoryLayout<T>.alignment) - 1)),
"storeBytes to misaligned raw pointer")
var temp = value
withUnsafeMutablePointer(to: &temp) { source in
let rawSrc = UnsafeMutableRawPointer(source)._rawValue
// FIXME: to be replaced by _memcpy when conversions are implemented.
Builtin.int_memcpy_RawPointer_RawPointer_Int64(
(self + offset)._rawValue, rawSrc, UInt64(MemoryLayout<T>.size)._value,
/*volatile:*/ false._value)
}
}
/// Copies the specified number of bytes from the given raw pointer's memory
/// into this pointer's memory.
///
/// If the `byteCount` bytes of memory referenced by this pointer are bound to
/// a type `T`, then `T` must be a trivial type, this pointer and `source`
/// must be properly aligned for accessing `T`, and `byteCount` must be a
/// multiple of `MemoryLayout<T>.stride`.
///
/// The memory in the region `source..<(source + byteCount)` may overlap with
/// the memory referenced by this pointer.
///
/// After calling `copyMemory(from:byteCount:)`, the `byteCount` bytes of
/// memory referenced by this pointer are initialized to raw bytes. If the
/// memory is bound to type `T`, then it contains values of type `T`.
///
/// - Parameters:
/// - source: A pointer to the memory to copy bytes from. The memory in the
/// region `source..<(source + byteCount)` must be initialized to a
/// trivial type.
/// - byteCount: The number of bytes to copy. `byteCount` must not be negative.
@inlinable
public func copyMemory(from source: UnsafeRawPointer, byteCount: Int) {
_debugPrecondition(
byteCount >= 0, "UnsafeMutableRawPointer.copyMemory with negative count")
_memmove(dest: self, src: source, size: UInt(byteCount))
}
}
extension UnsafeMutableRawPointer: Strideable {
// custom version for raw pointers
@_transparent
public func advanced(by n: Int) -> UnsafeMutableRawPointer {
return UnsafeMutableRawPointer(Builtin.gepRaw_Word(_rawValue, n._builtinWordValue))
}
}
extension OpaquePointer {
@_transparent
public init(_ from: UnsafeMutableRawPointer) {