import { nativeEncoder, nativeDecoder } from './platform.js'
import { encodeAscii, decodeAscii } from './latin1.js'
// See https://datatracker.ietf.org/doc/html/rfc4648
const BASE64 = [...'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/']
const BASE64URL = [...'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_']
const BASE64_HELPERS = {}
const BASE64URL_HELPERS = {}
export const E_CHAR = 'Invalid character in base64 input'
export const E_PADDING = 'Invalid base64 padding'
export const E_LENGTH = 'Invalid base64 length'
export const E_LAST = 'Invalid last chunk'
// We construct output by concatenating chars, this seems to be fine enough on modern JS engines
// Expects a checked Uint8Array
export function toBase64(arr, isURL, padding) {
const fullChunks = (arr.length / 3) | 0
const fullChunksBytes = fullChunks * 3
let o = ''
let i = 0
const alphabet = isURL ? BASE64URL : BASE64
const helpers = isURL ? BASE64URL_HELPERS : BASE64_HELPERS
if (!helpers.pairs) {
helpers.pairs = []
if (nativeDecoder) {
// Lazy to save memory in case if this is not needed
helpers.codepairs = new Uint16Array(64 * 64)
const u16 = helpers.codepairs
const u8 = new Uint8Array(u16.buffer, u16.byteOffset, u16.byteLength) // write as 1-byte to ignore BE/LE difference
for (let i = 0; i < 64; i++) {
const ic = alphabet[i].charCodeAt(0)
for (let j = 0; j < 64; j++) u8[(i << 7) | (j << 1)] = u8[(j << 7) | ((i << 1) + 1)] = ic
}
} else {
const p = helpers.pairs
for (let i = 0; i < 64; i++) {
for (let j = 0; j < 64; j++) p.push(`${alphabet[i]}${alphabet[j]}`)
}
}
}
const { pairs, codepairs } = helpers
// Fast path for complete blocks
// This whole loop can be commented out, the algorithm won't change, it's just an optimization of the next loop
if (nativeDecoder) {
const oa = new Uint16Array(fullChunks * 2)
let j = 0
for (const last = arr.length - 11; i < last; i += 12, j += 8) {
const x0 = arr[i]
const x1 = arr[i + 1]
const x2 = arr[i + 2]
const x3 = arr[i + 3]
const x4 = arr[i + 4]
const x5 = arr[i + 5]
const x6 = arr[i + 6]
const x7 = arr[i + 7]
const x8 = arr[i + 8]
const x9 = arr[i + 9]
const x10 = arr[i + 10]
const x11 = arr[i + 11]
oa[j] = codepairs[(x0 << 4) | (x1 >> 4)]
oa[j + 1] = codepairs[((x1 & 0x0f) << 8) | x2]
oa[j + 2] = codepairs[(x3 << 4) | (x4 >> 4)]
oa[j + 3] = codepairs[((x4 & 0x0f) << 8) | x5]
oa[j + 4] = codepairs[(x6 << 4) | (x7 >> 4)]
oa[j + 5] = codepairs[((x7 & 0x0f) << 8) | x8]
oa[j + 6] = codepairs[(x9 << 4) | (x10 >> 4)]
oa[j + 7] = codepairs[((x10 & 0x0f) << 8) | x11]
}
// i < last here is equivalent to i < fullChunksBytes
for (const last = arr.length - 2; i < last; i += 3, j += 2) {
const a = arr[i]
const b = arr[i + 1]
const c = arr[i + 2]
oa[j] = codepairs[(a << 4) | (b >> 4)]
oa[j + 1] = codepairs[((b & 0x0f) << 8) | c]
}
o = decodeAscii(oa)
} else {
// This can be optimized by ~25% with templates on Hermes, but this codepath is not called on Hermes, it uses btoa
// Check git history for templates version
for (; i < fullChunksBytes; i += 3) {
const a = arr[i]
const b = arr[i + 1]
const c = arr[i + 2]
o += pairs[(a << 4) | (b >> 4)]
o += pairs[((b & 0x0f) << 8) | c]
}
}
// If we have something left, process it with a full algo
let carry = 0
let shift = 2 // First byte needs to be shifted by 2 to get 6 bits
const length = arr.length
for (; i < length; i++) {
const x = arr[i]
o += alphabet[carry | (x >> shift)] // shift >= 2, so this fits
if (shift === 6) {
shift = 0
o += alphabet[x & 0x3f]
}
carry = (x << (6 - shift)) & 0x3f
shift += 2 // Each byte prints 6 bits and leaves 2 bits
}
if (shift !== 2) o += alphabet[carry] // shift 2 means we have no carry left
if (padding) o += ['', '==', '='][length - fullChunksBytes]
return o
}
// TODO: can this be optimized? This only affects non-Hermes barebone engines though
const mapSize = nativeEncoder ? 128 : 65_536 // we have to store 64 KiB map or recheck everything if we can't decode to byte array
export function fromBase64(str, isURL) {
let inputLength = str.length
while (str[inputLength - 1] === '=') inputLength--
const paddingLength = str.length - inputLength
const tailLength = inputLength % 4
const mainLength = inputLength - tailLength // multiples of 4
if (tailLength === 1) throw new SyntaxError(E_LENGTH)
if (paddingLength > 3 || (paddingLength !== 0 && str.length % 4 !== 0)) {
throw new SyntaxError(E_PADDING)
}
const alphabet = isURL ? BASE64URL : BASE64
const helpers = isURL ? BASE64URL_HELPERS : BASE64_HELPERS
if (!helpers.fromMap) {
helpers.fromMap = new Int8Array(mapSize).fill(-1) // no regex input validation here, so we map all other bytes to -1 and recheck sign
alphabet.forEach((c, i) => (helpers.fromMap[c.charCodeAt(0)] = i))
}
const m = helpers.fromMap
const arr = new Uint8Array(Math.floor((inputLength * 3) / 4))
let at = 0
let i = 0
if (nativeEncoder) {
const codes = encodeAscii(str, E_CHAR)
for (; i < mainLength; i += 4) {
const c0 = codes[i]
const c1 = codes[i + 1]
const c2 = codes[i + 2]
const c3 = codes[i + 3]
const a = (m[c0] << 18) | (m[c1] << 12) | (m[c2] << 6) | m[c3]
if (a < 0) throw new SyntaxError(E_CHAR)
arr[at] = a >> 16
arr[at + 1] = (a >> 8) & 0xff
arr[at + 2] = a & 0xff
at += 3
}
} else {
for (; i < mainLength; i += 4) {
const c0 = str.charCodeAt(i)
const c1 = str.charCodeAt(i + 1)
const c2 = str.charCodeAt(i + 2)
const c3 = str.charCodeAt(i + 3)
const a = (m[c0] << 18) | (m[c1] << 12) | (m[c2] << 6) | m[c3]
if (a < 0) throw new SyntaxError(E_CHAR)
arr[at] = a >> 16
arr[at + 1] = (a >> 8) & 0xff
arr[at + 2] = a & 0xff
at += 3
}
}
// Can be 0, 2 or 3, verified by padding checks already
if (tailLength < 2) return arr // 0
const ab = (m[str.charCodeAt(i++)] << 6) | m[str.charCodeAt(i++)]
if (ab < 0) throw new SyntaxError(E_CHAR)
arr[at++] = ab >> 4
if (tailLength < 3) {
if (ab & 0xf) throw new SyntaxError(E_LAST)
return arr // 2
}
const c = m[str.charCodeAt(i++)]
if (c < 0) throw new SyntaxError(E_CHAR)
arr[at++] = ((ab << 4) & 0xff) | (c >> 2)
if (c & 0x3) throw new SyntaxError(E_LAST)
return arr // 3
}