71 lines
2.4 KiB
TypeScript
71 lines
2.4 KiB
TypeScript
|
export function str2ab8(str) {
|
||
|
|
const buf = new ArrayBuffer(str.length);
|
||
|
|
const bufView = new Uint8Array(buf);
|
||
|
|
for (let i = 0, strLen = str.length; i < strLen; i++) {
|
||
|
|
bufView[i] = str.charCodeAt(i);
|
||
|
|
}
|
||
|
|
return buf;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* FIXME Dont use atob, because it sucks for non UTF-8 tings */
|
||
|
|
export function arrayBufferBase64(base64: string) {
|
||
|
|
base64 = atob(base64);
|
||
|
|
const buf = new ArrayBuffer(base64.length);
|
||
|
|
const bufView = new Uint8Array(buf);
|
||
|
|
for (let i = 0, strLen = base64.length; i < strLen; i++) {
|
||
|
|
bufView[i] = base64.charCodeAt(i);
|
||
|
|
}
|
||
|
|
return buf;
|
||
|
|
}
|
||
|
|
|
||
|
|
export function base64_encode_ab(source: ArrayBufferLike) {
|
||
|
|
const encodings = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
|
||
|
|
let base64 = "";
|
||
|
|
|
||
|
|
const bytes = new Uint8Array(source);
|
||
|
|
const byte_length = bytes.byteLength;
|
||
|
|
const byte_reminder = byte_length % 3;
|
||
|
|
const main_length = byte_length - byte_reminder;
|
||
|
|
|
||
|
|
let a, b, c, d;
|
||
|
|
let chunk;
|
||
|
|
|
||
|
|
// Main loop deals with bytes in chunks of 3
|
||
|
|
for (let i = 0; i < main_length; i = i + 3) {
|
||
|
|
// Combine the three bytes into a single integer
|
||
|
|
chunk = (bytes[i] << 16) | (bytes[i + 1] << 8) | bytes[i + 2];
|
||
|
|
|
||
|
|
// Use bitmasks to extract 6-bit segments from the triplet
|
||
|
|
a = (chunk & 16515072) >> 18; // 16515072 = (2^6 - 1) << 18
|
||
|
|
b = (chunk & 258048) >> 12; // 258048 = (2^6 - 1) << 12
|
||
|
|
c = (chunk & 4032) >> 6; // 4032 = (2^6 - 1) << 6
|
||
|
|
d = (chunk & 63) >> 0; // 63 = (2^6 - 1) << 0
|
||
|
|
|
||
|
|
// Convert the raw binary segments to the appropriate ASCII encoding
|
||
|
|
base64 += encodings[a] + encodings[b] + encodings[c] + encodings[d];
|
||
|
|
}
|
||
|
|
|
||
|
|
// Deal with the remaining bytes and padding
|
||
|
|
if (byte_reminder == 1) {
|
||
|
|
chunk = bytes[main_length];
|
||
|
|
|
||
|
|
a = (chunk & 252) >> 2; // 252 = (2^6 - 1) << 2
|
||
|
|
|
||
|
|
// Set the 4 least significant bits to zero
|
||
|
|
b = (chunk & 3) << 4; // 3 = 2^2 - 1
|
||
|
|
|
||
|
|
base64 += encodings[a] + encodings[b] + '==';
|
||
|
|
} else if (byte_reminder == 2) {
|
||
|
|
chunk = (bytes[main_length] << 8) | bytes[main_length + 1];
|
||
|
|
|
||
|
|
a = (chunk & 64512) >> 10; // 64512 = (2^6 - 1) << 10
|
||
|
|
b = (chunk & 1008) >> 4; // 1008 = (2^6 - 1) << 4
|
||
|
|
|
||
|
|
// Set the 2 least significant bits to zero
|
||
|
|
c = (chunk & 15) << 2; // 15 = 2^4 - 1
|
||
|
|
|
||
|
|
base64 += encodings[a] + encodings[b] + encodings[c] + '=';
|
||
|
|
}
|
||
|
|
|
||
|
|
return base64
|
||
|
|
}
|