Playground enhancements

playground/src/base64.ts

@@ -0,0 +1,45 @@
+// tables
+const i2c = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+const c2i: Record<string, number> = {};
+i2c.split("").forEach((c, i) => (c2i[c] = i));
+
+export function b64encode(data: Uint8Array): string {
+  let rval = "";
+  let i = 0;
+  while (i < data.length) {
+    let v = data[i++];
+    // aaaaaa aa
+    rval += i2c[v >> 2];
+    // aabbbb bbbb
+    v = ((v & 3) << 8) | data[i++];
+    rval += i2c[v >> 4];
+    if (i > data.length) break;
+    // bbbbcc cccccc
+    v = ((v & 15) << 8) | data[i++];
+    rval += i2c[v >> 6];
+    if (i > data.length) break;
+    // cccccc
+    rval += i2c[v & 63];
+  }
+  return rval;
+}
+
+export function b64decode(s: string) {
+  let i = 0;
+  let arr: number[] = [];
+  while (i < s.length) {
+    // aaaaaabb bbbb
+    let acc = (c2i[s[i++]] << 6) | c2i[s[i++]];
+    arr.push(acc >> 4);
+    if (i >= s.length) break;
+    // bbbbcccc cc
+    acc = ((acc & 15) << 6) | c2i[s[i++]];
+    arr.push(acc >> 2);
+    if (i >= s.length) break;
+    // ccdddddd
+    acc = ((acc & 3) << 6) | c2i[s[i++]];
+    arr.push(acc);
+    if (i >= s.length) break;
+  }
+  return Uint8Array.from(arr);
+}