1 |
|
2 | function decodeUTF8(uint8array) {
|
3 | const out = [];
|
4 | const input = uint8array;
|
5 | let i = 0;
|
6 | const length = uint8array.length;
|
7 |
|
8 | while (i < length) {
|
9 | if (input[i] < 0x80) {
|
10 | out.push(String.fromCharCode(input[i]));
|
11 | ++i;
|
12 | continue;
|
13 | } else if (input[i] < 0xC0) {
|
14 |
|
15 | } else if (input[i] < 0xE0) {
|
16 | if (checkContinuation(input, i, 1)) {
|
17 | const ucs4 = (input[i] & 0x1F) << 6 | (input[i + 1] & 0x3F);
|
18 | if (ucs4 >= 0x80) {
|
19 | out.push(String.fromCharCode(ucs4 & 0xFFFF));
|
20 | i += 2;
|
21 | continue;
|
22 | }
|
23 | }
|
24 | } else if (input[i] < 0xF0) {
|
25 | if (checkContinuation(input, i, 2)) {
|
26 | const ucs4 = (input[i] & 0xF) << 12 | (input[i + 1] & 0x3F) << 6 | input[i + 2] & 0x3F;
|
27 | if (ucs4 >= 0x800 && (ucs4 & 0xF800) !== 0xD800) {
|
28 | out.push(String.fromCharCode(ucs4 & 0xFFFF));
|
29 | i += 3;
|
30 | continue;
|
31 | }
|
32 | }
|
33 | } else if (input[i] < 0xF8) {
|
34 | if (checkContinuation(input, i, 3)) {
|
35 | let ucs4 = (input[i] & 0x7) << 18 | (input[i + 1] & 0x3F) << 12 |
|
36 | (input[i + 2] & 0x3F) << 6 | (input[i + 3] & 0x3F);
|
37 | if (ucs4 > 0x10000 && ucs4 < 0x110000) {
|
38 | ucs4 -= 0x10000;
|
39 | out.push(String.fromCharCode((ucs4 >>> 10) | 0xD800));
|
40 | out.push(String.fromCharCode((ucs4 & 0x3FF) | 0xDC00));
|
41 | i += 4;
|
42 | continue;
|
43 | }
|
44 | }
|
45 | }
|
46 | out.push(String.fromCharCode(0xFFFD));
|
47 | ++i;
|
48 | }
|
49 |
|
50 | return out.join('');
|
51 | }
|
52 |
|
53 | function checkContinuation(uint8array, start, checkLength) {
|
54 | let array = uint8array;
|
55 | if (start + checkLength < array.length) {
|
56 | while (checkLength--) {
|
57 | if ((array[++start] & 0xC0) !== 0x80)
|
58 | return false;
|
59 | }
|
60 | return true;
|
61 | } else {
|
62 | return false;
|
63 | }
|
64 | }
|
65 | export default decodeUTF8; |
\ | No newline at end of file |