1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
import Foundation
@usableFromInline
internal func char(forNibble value: UInt8) -> CChar {
switch value {
case 0 ..< 10:
return CChar(UInt8(ascii: "0") + value)
default:
precondition(value < 16)
return CChar(UInt8(ascii: "a") + value - 10)
}
}
@usableFromInline
internal func nibble(forHexChar char: UInt8) -> UInt8? {
switch char {
case UInt8(ascii: "0")...UInt8(ascii: "9"):
return char - UInt8(ascii: "0")
case UInt8(ascii: "a")...UInt8(ascii: "f"):
return 10 + char - UInt8(ascii: "a")
case UInt8(ascii: "A")...UInt8(ascii: "F"):
return 10 + char - UInt8(ascii: "a")
default:
return nil
}
}
@inlinable
public func hexEncode<T: Collection>(_ bytes: T) -> [CChar] where T.Element == UInt8, T.Index == Int {
var output = [CChar](repeating: 0, count: Int(bytes.count) * 2)
for (i, byte) in bytes.enumerated() {
output[i*2 + 0] = char(forNibble: (byte >> 4) & 0xF)
output[i*2 + 1] = char(forNibble: (byte >> 0) & 0xF)
}
return output
}
@inlinable
public func hexEncode<T: Collection>(_ bytes: T) -> String where T.Element == UInt8, T.Index == Int {
let chars = hexEncode(bytes) as [CChar]
return String(tsc_fromUTF8: chars.map{ UInt8($0) })
}
extension String {
/// Decode the string as a sequence of hex bytes (with no leading 0x prefix).
@inlinable
public func tsc_hexDecode() -> [UInt8]? {
let utf8 = self.utf8
let count = utf8.count
let byteCount = count / 2
if count != byteCount * 2 { return nil }
var result = [UInt8](repeating: 0, count: byteCount)
var seq = utf8.makeIterator()
for i in 0 ..< byteCount {
guard let hi = nibble(forHexChar: seq.next()!) else { return nil }
guard let lo = nibble(forHexChar: seq.next()!) else { return nil }
result[i] = (hi << 4) | lo
}
return result
}
}
|
