From 45b6cf40a85c475855f739cecd98845b4ede2b1e Mon Sep 17 00:00:00 2001
From: AlttiRi <16310547+AlttiRi@users.noreply.github.com>
Date: Sat, 7 Sep 2024 00:02:29 +0300
Subject: [PATCH] Use `byteOffset` and `byteLength` in `DataView` constructor
 (fixes #2)

---
 base85.js                 |  2 +-
 base85.ts                 |  2 +-
 package.json              |  2 +-
 tests/test-4-offset-ab.js | 21 +++++++++++++++++++++
 4 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 tests/test-4-offset-ab.js

diff --git a/base85.js b/base85.js
index 3aa6bae..01b7c21 100644
--- a/base85.js
+++ b/base85.js
@@ -43,7 +43,7 @@ export function encode(ui8a, charset) {
     const last5Length = remain ? remain + 1 : 0;
     const length = Math.ceil(ui8a.length * 5 / 4);
     const target = new Uint8Array(length);
-    const dw = new DataView(ui8a.buffer);
+    const dw = new DataView(ui8a.buffer, ui8a.byteOffset, ui8a.byteLength);
     const to = Math.trunc(ui8a.length / 4);
     for (let i = 0; i < to; i++) {
         let num = dw.getUint32(4 * i);
diff --git a/base85.ts b/base85.ts
index 6dc8507..50b4d50 100644
--- a/base85.ts
+++ b/base85.ts
@@ -52,7 +52,7 @@ export function encode(ui8a: Uint8Array, charset?: "ascii85" | "z85" | CharSet):
     const length = Math.ceil(ui8a.length * 5 / 4);
     const target = new Uint8Array(length);
 
-    const dw = new DataView(ui8a.buffer);
+    const dw = new DataView(ui8a.buffer, ui8a.byteOffset, ui8a.byteLength);
     const to = Math.trunc(ui8a.length / 4);
     for (let i = 0; i < to; i++) {
         let num = dw.getUint32(4 * i);
diff --git a/package.json b/package.json
index 866c709..330aa0f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@alttiri/base85",
-  "version": "1.7.6",
+  "version": "1.8.0",
   "description": "Pretty fast base85 JavaScript library",
   "homepage": "https://github.com/alttiri/base85",
   "keywords": [
diff --git a/tests/test-4-offset-ab.js b/tests/test-4-offset-ab.js
new file mode 100644
index 0000000..c05305a
--- /dev/null
+++ b/tests/test-4-offset-ab.js
@@ -0,0 +1,21 @@
+import {Tester} from "@alttiri/util-node-js";
+import {encode} from "../base85.js";
+
+const {t} = new Tester().destructible();
+
+const a = [0x00, 0x86, 0x4F, 0xD2, 0x6F, 0xB5, 0x59, 0xF7, 0x5B];
+const newA1 = new Uint8Array(a).slice(1);
+const newA2 = new Uint8Array(a).subarray(1);
+
+// console.log(newA1);
+// console.log(newA2);
+// console.log(encode(newA1));
+// console.log(encode(newA2));
+
+// Uint8Array(8) [134, 79, 210, 111, 181, 89, 247, 91]
+// HelloWorld
+
+t({
+    expect: true,
+    result: encode(newA1) === encode(newA2),
+});