From fffa7454d6fbc90de033a1a0c15794c440536426 Mon Sep 17 00:00:00 2001
From: Eli Bendersky <eliben@gmail.com>
Date: Mon, 28 Jun 2021 11:31:47 -0700
Subject: [PATCH] Fix sta decoding issue

---
 package.json     |  2 +-
 src/assembler.js |  2 +-
 test/test.js     | 19 +++++++++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/package.json b/package.json
index 0ccd88b..e155ffd 100644
--- a/package.json
+++ b/package.json
@@ -17,6 +17,6 @@
   },
   "homepage": "https://github.com/eliben/js-8080-sim#readme",
   "devDependencies": {
-    "mocha": "^8.0.1"
+    "mocha": "^8.4.0"
   }
 }
diff --git a/src/assembler.js b/src/assembler.js
index d905c96..afaa2f7 100644
--- a/src/assembler.js
+++ b/src/assembler.js
@@ -386,7 +386,7 @@ class Assembler {
       }
       case 'sta': {
         this._expectArgsCount(sl, 1);
-        let num = this._argImmOrLabel(sl, sl.args[1], curAddr);
+        let num = this._argImmOrLabel(sl, sl.args[0], curAddr);
         // 16-bit immediates encoded litte-endian.
         return [0b00110010, num & 0xff, (num >> 8) & 0xff];
       }
diff --git a/test/test.js b/test/test.js
index 2e995e7..3e24aee 100644
--- a/test/test.js
+++ b/test/test.js
@@ -283,6 +283,25 @@ describe('sim', () => {
     assert.equal(state.a, 33);
   });
 
+  it('lda-sta', () => {
+    let [state, mem] = runProg(`
+      lda myArray
+      mov c, a
+      mvi a, 99
+      sta myArray
+
+      mvi a, 0
+      lda myArray
+      hlt
+    myArray:
+      db 33
+    `);
+
+    assert.ok(state.halted);
+    assert.equal(state.c, 33);
+    assert.equal(state.a, 99);
+  });
+
   it('array-dw', () => {
     let [state, mem, labelToAddr] = runProg(`
       hlt