From f3f943c60742d10e71a217986db315d027a2d8fe Mon Sep 17 00:00:00 2001
From: Peter Schorn <peter.schorn@acm.org>
Date: Sat, 8 Oct 2022 00:25:15 -0700
Subject: [PATCH] AltairZ80: M68K: Fix hang with 'expect'

---
 AltairZ80/altairz80_sio.c |  4 ++--
 AltairZ80/m68ksim.c       | 13 +++++++------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/AltairZ80/altairz80_sio.c b/AltairZ80/altairz80_sio.c
index 71ea0d6f..61a1112b 100644
--- a/AltairZ80/altairz80_sio.c
+++ b/AltairZ80/altairz80_sio.c
@@ -210,9 +210,9 @@ static int32 markTimeSP             = 0;        /* stack pointer for timer stack
 
                                                 /* default time in milliseconds to sleep for SIMHSleepCmd       */
 #if defined (__MWERKS__) && defined (macintosh)
-static uint32 SIMHSleep             = 0;        /* no sleep on Macintosh OS9                                    */
+       uint32 SIMHSleep             = 0;        /* no sleep on Macintosh OS9                                    */
 #else
-static uint32 SIMHSleep             = 1;        /* default value is one millisecond                             */
+       uint32 SIMHSleep             = 1;        /* default value is one millisecond                             */
 #endif
 static uint32 sleepAllowedCounter   = 0;        /* only sleep on no character available when == 0               */
 static uint32 sleepAllowedStart     = SLEEP_ALLOWED_START_DEFAULT;  /* default start for above counter          */
diff --git a/AltairZ80/m68ksim.c b/AltairZ80/m68ksim.c
index 10d40442..24a57013 100644
--- a/AltairZ80/m68ksim.c
+++ b/AltairZ80/m68ksim.c
@@ -121,6 +121,7 @@
 #define IRQ_MC6850      5
 
 extern uint32 PCX;
+extern uint32 SIMHSleep;
 
 /* Prototypes */
 static void MC6850_reset(void);
@@ -268,7 +269,6 @@ static void MC6850_reset(void) {
 }
 
 #define INITIAL_IDLE    100
-#define IDLE_SLEEP      20
 static uint32 idleCount = INITIAL_IDLE;
 
 static void m68k_input_device_update(void) {
@@ -281,8 +281,8 @@ static void m68k_input_device_update(void) {
     } else if (--idleCount == 0) {
         const t_stat ch = sim_poll_kbd();
         idleCount = INITIAL_IDLE;
-        if (IDLE_SLEEP)
-            sim_os_ms_sleep(IDLE_SLEEP);
+        if (SIMHSleep)
+            sim_os_ms_sleep(SIMHSleep);
         if (ch) {
             characterAvailable = TRUE;
             keyboardCharacter = ch;
@@ -294,15 +294,16 @@ static void m68k_input_device_update(void) {
 static uint32 MC6850_data_read(void) {
     t_stat ch;
     int_controller_clear(IRQ_MC6850);
-    m68k_MC6850_status &= ~0x81;          // clear data ready and interrupt flag
+    m68k_MC6850_status &= ~0x81;        // clear data ready and interrupt flag
     if (characterAvailable) {
         ch = keyboardCharacter;
         characterAvailable = FALSE;
     } else
         ch = sim_poll_kbd();
     while ((ch <= 0) && (!stop_cpu)) {
-        if (IDLE_SLEEP)
-            sim_os_ms_sleep(IDLE_SLEEP);
+        sim_interval -= KBD_POLL_WAIT;  // ensure progress
+        if (SIMHSleep)
+            sim_os_ms_sleep(SIMHSleep);
         ch = sim_poll_kbd();
     }
     if (ch == SCPE_STOP)