web: load/save/delete plots

1 files changed, 18 insertions, 0 deletions

diff --git a/web/utils.js b/web/utils.js
index d7cf657..53f49ab 100644
--- a/web/utils.js
+++ b/web/utils.js
@@ -32,3 +32,21 @@ export const range = (a, b=null) => {
 
 // return a Promise that resolves in n seconds
 export const sleep = (n) => new Promise(res => setTimeout(res, n*1000));
+
+// hash an ArrayBuffer
+export const hash = (data, seed = 0) => {
+  let h1 = 0xdeadbeef ^ seed;
+  let h2 = 0x41c6ce57 ^ seed;
+
+  data = new Uint8Array(data);
+  for (const byte of data) {
+    h1 = Math.imul(h1 ^ byte, 2654435761);
+    h2 = Math.imul(h2 ^ byte, 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);
+  return 4294967296 * (2097151 & h2) + (h1 >>> 0);
+};