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Add utility functions for hashing and integrate into cache management

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This commit is contained in:
Michael Green 2025-11-20 13:10:41 +11:00
parent 2a6d65f8a5
commit 77a3ff935d
4 changed files with 60 additions and 40 deletions
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1
data/loader.js
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@ -4,6 +4,7 @@
"nipplejs.js",
"shaders.js",
"storage.js",
"utils.js",
"cache.js",
"gamepad.js",
"GameManager.js",

13
data/src/cache.js
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@ -20,6 +20,8 @@ class EJS_Cache {
this.minAgeMins = Math.max(60, maxAgeMins * 0.1); // Minimum 1 hour, or 10% of max age
this.debug = debug;
this.utils = new EJS_UTILS();
if (this.debug) {
console.log("Initialized EJS_Cache with settings:", {
enabled: this.enabled,
@ -33,6 +35,17 @@ class EJS_Cache {
}
}
/**
* Generates a cache key for the given data array.
* @param {Uint8Array} dataArray
* @returns {string} The generated cache key.
*/
generateCacheKey(dataArray) {
let hash = this.utils.simpleHash(dataArray);
const compressionCacheKey = "Obj-" + hash + "-" + dataArray.length;
return compressionCacheKey;
}
/**
* Retrieves an item from the cache.
* @param {*} key - The unique key identifying the cached item.

44
data/src/emulator.js
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@ -209,6 +209,7 @@ class EmulatorJS {
this.checkForUpdates();
}
this.netplayEnabled = true;
this.utils = new EJS_UTILS();
this.config = config;
this.config.buttonOpts = this.buildButtonOptions(this.config.buttonOpts);
this.config.settingsLanguage = window.EJS_settingsLanguage || false;
@ -579,11 +580,7 @@ class EmulatorJS {
// Generate cache key based on data hash
const hashStartTime = performance.now();
const dataArray = new Uint8Array(data);
let hash = 0;
for (let i = 0; i < dataArray.length; i++) {
hash = ((hash << 5) - hash + dataArray[i]) & 0xffffffff;
}
const cacheKey = `compression_${hash}_${dataArray.length}`;
const cacheKey = this.storageCache.generateCacheKey(dataArray);
const hashTime = performance.now() - hashStartTime;
// Check if decompressed content is in cache
@ -763,16 +760,6 @@ class EmulatorJS {
});
}
// Helper function to generate cache key for core data
const generateCoreDataCacheKey = (data) => {
const dataArray = new Uint8Array(data);
let hash = 0;
for (let i = 0; i < dataArray.length; i++) {
hash = ((hash << 5) - hash + dataArray[i]) & 0xffffffff;
}
return "compression_" + hash + "_" + dataArray.length;
};
// Helper function to check if cached core is expired
const isCoreExpired = (cachedItem) => {
if (!cachedItem) return true;
@ -842,11 +829,7 @@ class EmulatorJS {
if (quickDownload && quickDownload.data) {
// Generate cache key the same way checkCompression does
const dataArray = new Uint8Array(quickDownload.data);
let hash = 0;
for (let i = 0; i < dataArray.length; i++) {
hash = ((hash << 5) - hash + dataArray[i]) & 0xffffffff;
}
const compressionCacheKey = `compression_${hash}_${dataArray.length}`;
const compressionCacheKey = this.storageCache.generateCacheKey(dataArray);
const cachedDecompression = await this.storageCache.get(compressionCacheKey);
if (cachedDecompression && cachedDecompression.files && cachedDecompression.files.length > 0) {
@ -7452,28 +7435,9 @@ class EmulatorJS {
}
enableSaveUpdateEvent() {
// https://stackoverflow.com/questions/7616461
// Modified to accept a buffer instead of a string and return hex instead of an int
async function cyrb53(charBuffer, seed = 0) {
let h1 = 0xdeadbeef ^ seed, h2 = 0x41c6ce57 ^ seed;
for(let i = 0, ch; i < charBuffer.length; i++) {
ch = charBuffer[i];
h1 = Math.imul(h1 ^ ch, 2654435761);
h2 = Math.imul(h2 ^ ch, 1597334677);
}
h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507);
h1 ^= Math.imul(h2 ^ (h2 >>> 13), 3266489909);
h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507);
h2 ^= Math.imul(h1 ^ (h1 >>> 13), 3266489909);
// Cyrb53 is a 53-bit hash; we need 14 hex characters to represent it, and the first char will
// always be 0 or 1 (since it is only 1 bit)
return (4294967296 * (2097151 & h2) + (h1 >>> 0)).toString(16).padStart(14, "0");
};
function withGameSaveHash(saveFile, callback) {
if (saveFile) {
cyrb53(saveFile).then(digest => callback(digest, saveFile));
this.utils.cyrb53(saveFile).then(digest => callback(digest, saveFile));
} else {
console.warn("Save file not found when attempting to hash");
callback(null, null);

42
data/src/utils.js Normal file
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@ -0,0 +1,42 @@
/**
* EJS Utility Functions
*/
class EJS_UTILS {
/**
* Computes a simple hash of the given data array.
* @param {Uint8Array} dataArray
* @returns {number} The computed hash.
*/
simpleHash(dataArray) {
let hash = 0;
for (let i = 0; i < dataArray.length; i++) {
hash = ((hash << 5) - hash + dataArray[i]) & 0xffffffff;
}
return hash;
}
/**
* Cyrb53 hash function adapted for buffers.
* @param {*} charBuffer
* @param {*} seed
* @returns {string} Hexadecimal representation of the hash.
*/
async cyrb53(charBuffer, seed = 0) {
// https://stackoverflow.com/questions/7616461
// Modified to accept a buffer instead of a string and return hex instead of an int
let h1 = 0xdeadbeef ^ seed, h2 = 0x41c6ce57 ^ seed;
for(let i = 0, ch; i < charBuffer.length; i++) {
ch = charBuffer[i];
h1 = Math.imul(h1 ^ ch, 2654435761);
h2 = Math.imul(h2 ^ ch, 1597334677);
}
h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507);
h1 ^= Math.imul(h2 ^ (h2 >>> 13), 3266489909);
h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507);
h2 ^= Math.imul(h1 ^ (h1 >>> 13), 3266489909);
// Cyrb53 is a 53-bit hash; we need 14 hex characters to represent it, and the first char will
// always be 0 or 1 (since it is only 1 bit)
return (4294967296 * (2097151 & h2) + (h1 >>> 0)).toString(16).padStart(14, "0");
};
}