a887c6ba40
* Remove unused (and sometimes broken) targets and scripts * Remove browser-specific harness code
48 lines
1.2 KiB
TypeScript
48 lines
1.2 KiB
TypeScript
// @ts-check
|
|
/**
|
|
* @param {string} message
|
|
* @returns {never}
|
|
*/
|
|
function fail(message) {
|
|
throw new Error(message);
|
|
}
|
|
|
|
/**
|
|
* @param {number} value
|
|
*/
|
|
function base64FormatEncode(value) {
|
|
return value < 0 ? fail("Invalid value") :
|
|
value < 26 ? 0x41 /*A*/ + value :
|
|
value < 52 ? 0x61 /*a*/ + value - 26 :
|
|
value < 62 ? 0x30 /*0*/ + value - 52 :
|
|
value === 62 ? 0x2B /*+*/ :
|
|
value === 63 ? 0x2F /*/*/ :
|
|
fail("Invalid value");
|
|
}
|
|
|
|
/**
|
|
* @param {number} value
|
|
*/
|
|
function base64VLQFormatEncode(value) {
|
|
if (value < 0) {
|
|
value = ((-value) << 1) + 1;
|
|
}
|
|
else {
|
|
value = value << 1;
|
|
}
|
|
|
|
// Encode 5 bits at a time starting from least significant bits
|
|
let result = "";
|
|
do {
|
|
let currentDigit = value & 31; // 11111
|
|
value = value >> 5;
|
|
if (value > 0) {
|
|
// There are still more digits to decode, set the msb (6th bit)
|
|
currentDigit = currentDigit | 32;
|
|
}
|
|
result += String.fromCharCode(base64FormatEncode(currentDigit));
|
|
} while (value > 0);
|
|
|
|
return result;
|
|
}
|
|
exports.base64VLQFormatEncode = base64VLQFormatEncode; |