switch from base64 to z85

pre-compute charset array

fix z85 implementation

Author: edde746

src/base64.js

@@ -1,4 +1,4 @@
-import { decode64 } from './base64.js';
+import { decode85 } from './z85.js';
 import {
 	HOLE,
 	NAN,
@@ -102,31 +102,26 @@ export function unflatten(parsed, revivers) {
 						}
 						break;
 
-          case "Int8Array":
-          case "Uint8Array":
-          case "Uint8ClampedArray":
-          case "Int16Array":
-          case "Uint16Array":
-          case "Int32Array":
-          case "Uint32Array":
-          case "Float32Array":
-          case "Float64Array":
-          case "BigInt64Array":
-          case "BigUint64Array": {
-            const TypedArrayConstructor = globalThis[type];
-            const base64 = value[1];
-            const arraybuffer = decode64(base64);
-            const typedArray = new TypedArrayConstructor(arraybuffer);
-            hydrated[index] = typedArray;
-            break;
-          }
-
-          case "ArrayBuffer": {
-            const base64 = value[1];
-            const arraybuffer = decode64(base64);
-            hydrated[index] = arraybuffer;
-            break;
-          }
+					case "Int8Array":
+					case "Uint8Array":
+					case "Uint8ClampedArray":
+					case "Int16Array":
+					case "Uint16Array":
+					case "Int32Array":
+					case "Uint32Array":
+					case "Float32Array":
+					case "Float64Array":
+					case "BigInt64Array":
+					case "BigUint64Array": {
+						const TypedArrayConstructor = globalThis[type];
+						hydrated[index] = new TypedArrayConstructor(decode85(value[1]));
+						break;
+					}
+
+					case "ArrayBuffer": {
+						hydrated[index] = decode85(value[1]);
+						break;
+					}
 
 					default:
 						throw new Error(`Unknown type ${type}`);

src/parse.js

@@ -15,7 +15,7 @@ import {
 	POSITIVE_INFINITY,
 	UNDEFINED
 } from './constants.js';
-import { encode64 } from './base64.js';
+import { encode85 } from './z85.js';
 
 /**
  * Turn a value into a JSON string that can be parsed with `devalue.parse`
@@ -153,20 +153,18 @@ export function stringify(value, reducers) {
 				case "BigUint64Array": {
 					/** @type {import("./types.js").TypedArray} */
 					const typedArray = thing;
-					const base64 = encode64(typedArray.buffer);
-					str = '["' + type + '","' + base64 + '"]';
+					str = '["' + type + '","' + encode85(typedArray.buffer) + '"]';
 					break;
 				}
-					
+
 				case "ArrayBuffer": {
 					/** @type {ArrayBuffer} */
 					const arraybuffer = thing;
-					const base64 = encode64(arraybuffer);
-					
-					str = `["ArrayBuffer","${base64}"]`;
+
+					str = `["ArrayBuffer","${encode85(arraybuffer)}"]`;
 					break;
 				}
-				
+
 				default:
 					if (!is_plain_object(thing)) {
 						throw new DevalueError(

src/stringify.js

@@ -0,0 +1,57 @@
+const ENCODE = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-:+=^!/*?&<>()[]{}@%$#";
+const DECODE = [-1, 68, -1, 84, 83, 82, 72, -1, 75, 76, 70, 65, -1, 63, 62, 69, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 64, -1, 73, 66, 74, 71, 81, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 77, -1, 78, 67, -1, -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 79, -1, 80, -1, -1];
+const POW_85 = [0, 1, 85, 7225, 614125, 52200625];
+const POW_256 = [1, 256, 65536, 16777216];
+
+/**
+ * Encodes binary data into a Z85 string.
+ * @param {ArrayBuffer} data - The binary data to encode
+ * @returns {string} The Z85 encoded string
+ */
+function encode85(data) {
+  const dv = new DataView(data);
+  const length = dv.byteLength;
+  const padding = (4 - (length % 4)) % 4;
+
+  let result = '', value = 0;
+  for (let i = 0; i < length + padding; ++i) {
+    const isPadding = i >= length;
+    value = value * 256 + (isPadding ? 0 : dv.getUint8(i));
+    if ((i + 1) % 4 === 0) {
+      for (let j = 5; j > 0; --j) {
+        if (isPadding && j <= padding)
+          continue;
+
+        result += ENCODE[Math.floor(value / POW_85[j]) % 85];
+      }
+      value = 0;
+    }
+  }
+
+  return result;
+};
+
+/**
+ * Decodes a Z85 string into binary data.
+ * @param {string} string - The Z85 encoded string
+ * @returns {ArrayBuffer} The decoded binary data
+ */
+function decode85(string) {
+  const remainder = string.length % 5;
+  const padding = 5 - (remainder === 0 ? 5 : remainder);
+  string = string.padEnd(string.length + padding, ENCODE[ENCODE.length - 1]);
+  const length = string.length;
+
+  let buffer = new Uint8Array((length * 4 / 5) - padding);
+  let value = 0, char = 0, byte = 0;
+  for (let i = 0; i < length; ++i) {
+    value = value * 85 + DECODE[string.charCodeAt(char++) - 32];
+    if (char % 5 !== 0) continue;
+
+    for (let j = 3; j >= 0; --j)
+      buffer[byte++] = Math.floor(value / POW_256[j]) % 256;
+    value = 0;
+  }
+
+  return buffer.buffer;
+}

src/z85.js

@@ -164,13 +164,13 @@ const fixtures = {
 			name: 'Uint8Array',
 			value: new Uint8Array([1, 2, 3]),
 			js: 'new Uint8Array([1,2,3])',
-			json: '[["Uint8Array","AQID"]]'
+			json: '[["Uint8Array","0rJu"]]'
 		},
 		{
 			name: 'ArrayBuffer',
 			value: new Uint8Array([1, 2, 3]).buffer,
 			js: 'new Uint8Array([1,2,3]).buffer',
-			json: '[["ArrayBuffer","AQID"]]'
+			json: '[["ArrayBuffer","0rJu"]]'
 		}
 	],