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-rw-r--r--libs/base-x/ts_src/index.ts161
1 files changed, 161 insertions, 0 deletions
diff --git a/libs/base-x/ts_src/index.ts b/libs/base-x/ts_src/index.ts
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1// base-x encoding / decoding
2// Copyright (c) 2018 base-x contributors
3// Copyright (c) 2014-2018 The Bitcoin Core developers (base58.cpp)
4// Distributed under the MIT software license, see the accompanying
5// file LICENSE or http://www.opensource.org/licenses/mit-license.php.
6
7// @ts-ignore
8const _Buffer = require('safe-buffer').Buffer;
9
10function base (ALPHABET: string): base.BaseConverter {
11 if (ALPHABET.length >= 255) throw new TypeError('Alphabet too long')
12
13 const BASE_MAP = new Uint8Array(256)
14 BASE_MAP.fill(255)
15
16 for (let i = 0; i < ALPHABET.length; i++) {
17 const x = ALPHABET.charAt(i)
18 const xc = x.charCodeAt(0)
19
20 if (BASE_MAP[xc] !== 255) throw new TypeError(x + ' is ambiguous')
21 BASE_MAP[xc] = i
22 }
23
24 const BASE = ALPHABET.length
25 const LEADER = ALPHABET.charAt(0)
26 const FACTOR = Math.log(BASE) / Math.log(256) // log(BASE) / log(256), rounded up
27 const iFACTOR = Math.log(256) / Math.log(BASE) // log(256) / log(BASE), rounded up
28
29 function encode (source: Buffer): string {
30 if (!_Buffer.isBuffer(source)) throw new TypeError('Expected Buffer')
31 if (source.length === 0) return ''
32
33 // Skip & count leading zeroes.
34 let zeroes = 0
35 let length = 0
36 let pbegin = 0
37 const pend = source.length
38
39 while (pbegin !== pend && source[pbegin] === 0) {
40 pbegin++
41 zeroes++
42 }
43
44 // Allocate enough space in big-endian base58 representation.
45 const size = ((pend - pbegin) * iFACTOR + 1) >>> 0
46 const b58 = new Uint8Array(size)
47
48 // Process the bytes.
49 while (pbegin !== pend) {
50 let carry = source[pbegin]
51
52 // Apply "b58 = b58 * 256 + ch".
53 let i = 0
54 for (let it1 = size - 1; (carry !== 0 || i < length) && (it1 !== -1); it1--, i++) {
55 carry += (256 * b58[it1]) >>> 0
56 b58[it1] = (carry % BASE) >>> 0
57 carry = (carry / BASE) >>> 0
58 }
59
60 if (carry !== 0) throw new Error('Non-zero carry')
61 length = i
62 pbegin++
63 }
64
65 // Skip leading zeroes in base58 result.
66 let it2 = size - length
67 while (it2 !== size && b58[it2] === 0) {
68 it2++
69 }
70
71 // Translate the result into a string.
72 let str = LEADER.repeat(zeroes)
73 for (; it2 < size; ++it2) str += ALPHABET.charAt(b58[it2])
74
75 return str
76 }
77
78 function decodeUnsafe (source: string): Buffer | undefined {
79 if (typeof source !== 'string') throw new TypeError('Expected String')
80 if (source.length === 0) return _Buffer.alloc(0)
81
82 let psz = 0
83
84 // Skip leading spaces.
85 if (source[psz] === ' ') return
86
87 // Skip and count leading '1's.
88 let zeroes = 0
89 let length = 0
90 while (source[psz] === LEADER) {
91 zeroes++
92 psz++
93 }
94
95 // Allocate enough space in big-endian base256 representation.
96 const size = (((source.length - psz) * FACTOR) + 1) >>> 0 // log(58) / log(256), rounded up.
97 const b256 = new Uint8Array(size)
98
99 // Process the characters.
100 while (source[psz]) {
101 // Decode character
102 let carry = BASE_MAP[source.charCodeAt(psz)]
103
104 // Invalid character
105 if (carry === 255) return
106
107 let i = 0
108 for (let it3 = size - 1; (carry !== 0 || i < length) && (it3 !== -1); it3--, i++) {
109 carry += (BASE * b256[it3]) >>> 0
110 b256[it3] = (carry % 256) >>> 0
111 carry = (carry / 256) >>> 0
112 }
113
114 if (carry !== 0) throw new Error('Non-zero carry')
115 length = i
116 psz++
117 }
118
119 // Skip trailing spaces.
120 if (source[psz] === ' ') return
121
122 // Skip leading zeroes in b256.
123 let it4 = size - length
124 while (it4 !== size && b256[it4] === 0) {
125 it4++
126 }
127
128 const vch = _Buffer.allocUnsafe(zeroes + (size - it4))
129 vch.fill(0x00, 0, zeroes)
130
131 let j = zeroes
132 while (it4 !== size) {
133 vch[j++] = b256[it4++]
134 }
135
136 return vch
137 }
138
139 function decode (string: string): Buffer {
140 const buffer = decodeUnsafe(string)
141 if (buffer) return buffer
142
143 throw new Error('Non-base' + BASE + ' character')
144 }
145
146 return {
147 encode: encode,
148 decodeUnsafe: decodeUnsafe,
149 decode: decode
150 }
151}
152
153export = base;
154
155declare namespace base {
156 interface BaseConverter {
157 encode(buffer: Buffer): string;
158 decodeUnsafe(string: string): Buffer | undefined;
159 decode(string: string): Buffer;
160 }
161}