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chore: import upstream snapshot with attribution
2026-07-13 12:25:30 +08:00

79 lines
2.5 KiB
Swift

//===----------------------------------------------------------------------===//
// Copyright © 2025-2026 Apple Inc. and the Containerization project authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//===----------------------------------------------------------------------===//
import CoreFoundation
// takes a pointer and converts its contents to native endian bytes
public func withUnsafeLittleEndianBytes<T, Result>(of value: T, body: (UnsafeRawBufferPointer) throws -> Result)
rethrows -> Result
{
switch Endian {
case .little:
return try withUnsafeBytes(of: value) { bytes in
try body(bytes)
}
case .big:
return try withUnsafeBytes(of: value) { buffer in
let reversedBuffer = Array(buffer.reversed())
return try reversedBuffer.withUnsafeBytes { buf in
try body(buf)
}
}
}
}
public func withUnsafeLittleEndianBuffer<T>(
of value: UnsafeRawBufferPointer, body: (UnsafeRawBufferPointer) throws -> T
) rethrows -> T {
switch Endian {
case .little:
return try body(value)
case .big:
let reversed = Array(value.reversed())
return try reversed.withUnsafeBytes { buf in
try body(buf)
}
}
}
extension UnsafeRawBufferPointer {
// loads littleEndian raw data, converts it native endian format and calls UnsafeRawBufferPointer.load
public func loadLittleEndian<T>(as type: T.Type) -> T {
switch Endian {
case .little:
return self.load(as: T.self)
case .big:
let buffer = Array(self.reversed())
return buffer.withUnsafeBytes { ptr in
ptr.load(as: T.self)
}
}
}
}
public enum Endianness {
case little
case big
}
// returns current endianness
public var Endian: Endianness {
var value: UInt32 = 0x0102_0304
return withUnsafeBytes(of: &value) { buffer in
buffer.first == 0x04 ? .little : .big
}
}