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Base64Decode()

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This commit is contained in:
ReznoRMichael 2021-01-23 00:41:56 +01:00
parent 3f78f229a0
commit 4ec77f8c3a
1 changed files with 34 additions and 3 deletions
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37
js/LoadSaveFile.js
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@ -1,4 +1,7 @@
const CSHARP_HEADER = [0, 1, 0, 0, 0, 255, 255, 255, 255, 1, 0, 0, 0, 0, 0, 0, 0, 6, 1, 0, 0, 0];
const CSHARP_HEADER = [0, 1, 0, 0, 0, 255, 255, 255, 255, 1, 0, 0, 0, 0, 0, 0, 0, 6, 1, 0, 0, 0]; // 22 bytes
const BASE64_ARRAY = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=".split("").map(c => c.charCodeAt(0));
const BASE64_DECODE_TABLE = new Map(BASE64_ARRAY.map((ord, i) => [ord, i]));
function ShowFile(input) {
let inputFileObject = input.files[0];
@ -25,7 +28,6 @@ function LoadSaveFile(input) {
// 2. Decode file
// base64 Decoding (ArrayBuffer)
// AES decryption (ECB) removes pkcs7 padding (ArrayBuffer)
// Convert ArrayBuffer to string/text TextDecoder().decode(ArrayBuffer)
@ -40,7 +42,7 @@ function FileObjectToArrayBuffer() {
let inputArrayBuffer = this.result;
try {
// Uint8Array(ArrayBuffer)
// Uint8Array(ArrayBuffer) uint8_t equivalent in C
inputArrayBuffer = new Uint8Array(inputArrayBuffer);
// ArrayBuffer.slice()
@ -50,6 +52,9 @@ function FileObjectToArrayBuffer() {
// remove C# header (ArrayBuffer)
inputArrayBuffer = RemoveCSharpHeader(inputArrayBuffer);
// base64 Decoding (ArrayBuffer)
inputArrayBuffer = Base64Decode(inputArrayBuffer);
alert(`File: ${inputArrayBuffer}`);
} catch (error) {
alert(`The file cannot be read. Error: ${error}`);
@ -74,3 +79,29 @@ function RemoveCSharpHeader(buffer) {
return fixedArrayBuffer;
}
// From bloodorca https://github.com/bloodorca/hollow based on KayDeeTee https://github.com/KayDeeTee/Hollow-Knight-SaveManager
function Base64Decode(buffer) {
buffer = new Uint8Array(buffer).slice();
buffer = buffer.map(v => BASE64_DECODE_TABLE.get(v))
{
let p = buffer.indexOf(64);
buffer = buffer.subarray(0, p != -1 ? p : buffer.length);
}
let output = new Uint8Array(3 * buffer.length / 4);
let continuous = Math.floor(buffer.length / 4) * 4;
for (let i = 0; i < continuous; i += 4) {
let k = 3 * i / 4;
output[k] = buffer[i] << 2 | buffer[i + 1] >> 4;
output[k + 1] = (buffer[i + 1] & 0x0F) << 4 | buffer[i + 2] >> 2;
output[k + 2] = (buffer[i + 2] & 0x03) << 6 | buffer[i + 3];
}
if (buffer[continuous] != undefined) {
let k = 3 * continuous / 4;
output[k] = buffer[continuous] << 2 | buffer[continuous + 1] >> 4;
if (buffer[continuous + 2] != undefined) {
output[k + 1] = (buffer[continuous + 1] & 0x0F) << 4 | buffer[continuous + 2] >> 2;
}
}
return output;
}