From 5d5576c07789f7b8e3b56dfa67664ac016c91965 Mon Sep 17 00:00:00 2001
From: minjaesong <alswo9628@gmail.com>
Date: Sat, 20 Dec 2025 11:17:50 +0900
Subject: [PATCH] fix: mmio-based readKey() having delayed event because of
 race condition

---
 .../src/net/torvald/tsvm/VMJSR223Delegate.kt  | 20 +++++++------------
 .../net/torvald/tsvm/peripheral/IOSpace.kt    | 14 ++++++++-----
 2 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/tsvm_core/src/net/torvald/tsvm/VMJSR223Delegate.kt b/tsvm_core/src/net/torvald/tsvm/VMJSR223Delegate.kt
index 9341a5b..e55ec4a 100644
--- a/tsvm_core/src/net/torvald/tsvm/VMJSR223Delegate.kt
+++ b/tsvm_core/src/net/torvald/tsvm/VMJSR223Delegate.kt
@@ -208,25 +208,19 @@ class VMJSR223Delegate(private val vm: VM) {
      * ^A-^Z: 1 through 26
      */
     fun readKey(): Int {
-        val inputStream = vm.getInputStream()
-        var key: Int = inputStream.read()
-        inputStream.close()
-        return key
-
-        // impl that doesn't rely on InputStream
-        // fixme it's causing event-wise delay
-        /*vm.getIO().let {
-            it.mmio_write(38, 1)
+        // MMIO-based implementation that can be replicated by JS via MMIO read/writes
+        vm.getIO().let {
+            it.mmio_write(38, 1) // Set keyboardInputRequested = true (also clears buffer)
 
             vm.isIdle.set(true)
-            while (it.mmio_read(49L) == 0.toByte()) {
+            while (it.mmio_read(49L) == 0.toByte()) { // Wait for keyPushed flag
                 Thread.sleep(6L)
             }
             vm.isIdle.set(false)
 
-            it.mmio_write(38, 0)
-            return it.mmio_read(37L)!!.toUint()
-        }*/
+            it.mmio_write(38, 0) // Clear keyboardInputRequested
+            return it.mmio_read(37L)!!.toUint()  // Read and remove key from buffer
+        }
     }
 
     /**
diff --git a/tsvm_core/src/net/torvald/tsvm/peripheral/IOSpace.kt b/tsvm_core/src/net/torvald/tsvm/peripheral/IOSpace.kt
index 3e2ca8b..0a220c1 100644
--- a/tsvm_core/src/net/torvald/tsvm/peripheral/IOSpace.kt
+++ b/tsvm_core/src/net/torvald/tsvm/peripheral/IOSpace.kt
@@ -99,7 +99,11 @@ class IOSpace(val vm: VM) : PeriBase("io"), InputProcessor {
             in 32..33 -> (mouseX.toInt() shr (adi - 32).times(8)).toByte()
             in 34..35 -> (mouseY.toInt() shr (adi - 34).times(8)).toByte()
             36L -> mouseDown.toInt().toByte()
-            37L -> keyboardBuffer.removeTail() ?: -1
+            37L -> {
+                val key = keyboardBuffer.removeTail() ?: -1
+                keyPushed = !keyboardBuffer.isEmpty  // Clear flag when buffer becomes empty
+                key
+            }
             38L -> keyboardInputRequested.toInt().toByte()
             39L -> rawInputFunctionLatched.toInt().toByte()
             in 40..47 -> keyEventBuffers[adi - 40]
@@ -174,6 +178,7 @@ class IOSpace(val vm: VM) : PeriBase("io"), InputProcessor {
                     keyboardInputRequested = (byte.isNonZero())
                     if (keyboardInputRequested) {
                         keyboardBuffer.clear()
+                        keyPushed = false  // Reset flag when buffer is cleared
                         vm.isIdle.set(true)
                     }
                     else
@@ -344,14 +349,11 @@ class IOSpace(val vm: VM) : PeriBase("io"), InputProcessor {
     override fun keyTyped(p0: Char): Boolean {
         if (keyboardInputRequested && p0.toInt() > 0) {
             //println("[IO] key typed = ${p0.toInt()}")
-            keyPushed = true
             keyboardBuffer.appendHead(p0.toByte())
-            Thread.sleep(6L)
-            keyPushed = false
+            keyPushed = true  // Set after append; cleared when buffer is emptied via mmio_read(37)
             return true
         }
         else {
-            keyPushed = false
             return false
         }
     }
@@ -389,11 +391,13 @@ class IOSpace(val vm: VM) : PeriBase("io"), InputProcessor {
         if (keyboardInputRequested) {
             if (p0 in Input.Keys.A..Input.Keys.Z && (Gdx.input.isKeyPressed(Input.Keys.CONTROL_LEFT) || Gdx.input.isKeyPressed(Input.Keys.CONTROL_RIGHT))) {
                 keyboardBuffer.appendHead((p0 - 28).toByte())
+                keyPushed = true
             }
             else {
                 specialKeys[p0]?.let {
                     //println("[IO] key special = ${it.toUInt()}")
                     keyboardBuffer.appendHead(it)
+                    keyPushed = true
                 }
             }
             return true