apple2js/js/base64.ts
2020-11-25 17:28:37 -08:00

122 lines
3.7 KiB
TypeScript

import { memory } from './types';
const B64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
/** Encode an array of bytes in base64. */
export function base64_encode(data: memory) {
// Twacked by Will Scullin to handle arrays of 'bytes'
// http://kevin.vanzonneveld.net
// + original by: Tyler Akins (http://rumkin.com)
// + improved by: Bayron Guevara
// + improved by: Thunder.m
// + improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// + bugfixed by: Pellentesque Malesuada
// + improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// - depends on: utf8_encode
// * example 1: base64_encode('Kevin van Zonneveld');
// * returns 1: 'S2V2aW4gdmFuIFpvbm5ldmVsZA=='
// mozilla has this native
// - but breaks in 2.0.0.12!
//if (typeof this.window['atob'] == 'function') {
// return atob(data);
//}
let o1, o2, o3, h1, h2, h3, h4, bits, i = 0, ac = 0, enc='';
const tmp_arr = [];
if (!data) {
return data;
}
do { // pack three octets into four hexets
o1 = data[i++];
o2 = data[i++];
o3 = data[i++];
bits = o1<<16 | o2<<8 | o3;
h1 = bits>>18 & 0x3f;
h2 = bits>>12 & 0x3f;
h3 = bits>>6 & 0x3f;
h4 = bits & 0x3f;
// use hexets to index into b64, and append result to encoded string
tmp_arr[ac++] = B64.charAt(h1) + B64.charAt(h2) + B64.charAt(h3) + B64.charAt(h4);
} while (i < data.length);
enc = tmp_arr.join('');
switch (data.length % 3) {
case 1:
enc = enc.slice(0, -2) + '==';
break;
case 2:
enc = enc.slice(0, -1) + '=';
break;
}
return enc;
}
/** Returns undefined if the input is null or undefined. */
export function base64_decode(data: null | undefined): undefined;
/** Returns an array of bytes from the given base64-encoded string. */
export function base64_decode(data: string): memory;
/** Returns an array of bytes from the given base64-encoded string. */
export function base64_decode(data: string | null | undefined): memory | undefined {
// Twacked by Will Scullin to handle arrays of 'bytes'
// http://kevin.vanzonneveld.net
// + original by: Tyler Akins (http://rumkin.com)
// + improved by: Thunder.m
// + input by: Aman Gupta
// + improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// + bugfixed by: Onno Marsman
// + bugfixed by: Pellentesque Malesuada
// + improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// + input by: Brett Zamir (http://brett-zamir.me)
// + bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// - depends on: utf8_decode
// * example 1: base64_decode('S2V2aW4gdmFuIFpvbm5ldmVsZA==');
// * returns 1: 'Kevin van Zonneveld'
// mozilla has this native
// - but breaks in 2.0.0.12!
//if (typeof this.window['btoa'] == 'function') {
// return btoa(data);
//}
let o1, o2, o3, h1, h2, h3, h4, bits, i = 0, ac = 0;
const tmp_arr = [];
if (!data) {
return undefined;
}
do { // unpack four hexets into three octets using index points in B64
h1 = B64.indexOf(data.charAt(i++));
h2 = B64.indexOf(data.charAt(i++));
h3 = B64.indexOf(data.charAt(i++));
h4 = B64.indexOf(data.charAt(i++));
bits = h1<<18 | h2<<12 | h3<<6 | h4;
o1 = bits>>16 & 0xff;
o2 = bits>>8 & 0xff;
o3 = bits & 0xff;
tmp_arr[ac++] = o1;
if (h3 != 64) {
tmp_arr[ac++] = o2;
}
if (h4 != 64) {
tmp_arr[ac++] = o3;
}
} while (i < data.length);
return tmp_arr;
}