From 1105daaad0d20271bd34233ba6768a3f78c285d3 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Sat, 14 Mar 2026 18:48:11 +0000
Subject: [PATCH] Add support for extended opcodes

---
 asm.js | 42 ++++++++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/asm.js b/asm.js
index 103f493..5099352 100644
--- a/asm.js
+++ b/asm.js
@@ -712,7 +712,7 @@ export class Assembler {
 
     action_append(action) {
         const code = action.opcode != undefined
-              ? [ action.opcode ]
+              ? [ action.opcode ].flat()
               : this.leb128(action.literal);
         this.funcs[this.current_func].body.push(...code);
     }
@@ -799,7 +799,7 @@ export class Assembler {
         const data = this.data.at(-1).data;
         const value = action.value != null
               ? action.value
-              : this.le_bytes(this.lookup_def(action.symbol), action.size);
+              : this.le(this.lookup_def(action.symbol), action.size);
         data.push(...value);
         this.pos.addr += action.size;
     }
@@ -871,17 +871,33 @@ export class Assembler {
         return this.defs[symbol];
     }
 
-    le_bytes(value, count) {
+    le(value, count) {
         let bytes = []
-        while (value != 0 && bytes.length < count) {
+        while (value != 0) {
             bytes.push(value & 0xff);
             value >>= 8;
         }
-        while (bytes.length < count)
-            bytes.push(0);
+        if (count != undefined) {
+            while (bytes.length < count)
+                bytes.push(0);
+        }
         return bytes;
     }
 
+    leb128(x) {
+        const orig = x;
+        const bytes = [];
+        while (true) {
+            const b = x & 0x7f;
+            x >>= 7;
+            if (x == 0 && (b & 0x40) == 0 || x == -1 && (b & 0x40) != 0) {
+                bytes.push(b);
+                return bytes;
+            }
+            bytes.push(b | 0x80);
+        }
+    }
+
     wasm_section_type() {
         const funcs = Object.values(this.funcs);
         if (funcs.length == 0) return null;
@@ -1022,18 +1038,4 @@ export class Assembler {
         else
             return [ flags, init ];
     }
-
-    leb128(x) {
-        const orig = x;
-        const bytes = [];
-        while (true) {
-            const b = x & 0x7f;
-            x >>= 7;
-            if (x == 0 && (b & 0x40) == 0 || x == -1 && (b & 0x40) != 0) {
-                bytes.push(b);
-                return bytes;
-            }
-            bytes.push(b | 0x80);
-        }
-    }
 }