M devices/clock.c → devices/clock.c

@@ -81,6 +81,39 @@ return remaining_ticks;
 #endif
 }
 
+#define CLOCK_POLL_SLEEP_MS 100
+
+int clock_poll(xyw_byte *data)
+{
+    xyw_word on_timer_handler = XYW_PEEKW(&data[CLOCK_ON_TIMER_ELAPSED]);
+    if (!on_timer_handler)
+        return 0; // no handler registered
+
+    // Check if timer has elapsed (non-blocking)
+    clock_get_timer_value();
+    if (clock_timer_elapsed_pending)
+    {
+        clock_timer_elapsed_pending = 0;
+        xyw_vm_set_running(1);
+        xyw_vm_push_frame(XYW_DEVICE_AREA_START);
+        *pc = on_timer_handler;
+        return 1;
+    }
+
+    if (!clock_timer_active)
+        return 0; // no timer running
+
+    // Timer is active but hasn't elapsed yet — sleep briefly to avoid busy loop.
+    // When terminal_poll is also active, it provides its own 100ms sleep via
+    // getch_timeout, so this sleep only matters for timer-only programs.
+#ifdef _WIN32
+    Sleep(CLOCK_POLL_SLEEP_MS);
+#else
+    usleep((useconds_t)(CLOCK_POLL_SLEEP_MS * 1000));
+#endif
+    return -1; // active handler, no event yet
+}
+
 void clock_setup(xyw_byte *data)
 {
     (void)data;

M devices/clock.h → devices/clock.h

@@ -3,3 +3,4 @@ 
 void clock_setup(xyw_byte *data);
 xyw_byte clock_input(xyw_byte *data, xyw_byte addr, xyw_byte *error);
 void clock_output(xyw_byte *data, xyw_byte addr, xyw_byte *error);
+int clock_poll(xyw_byte *data);

M xywrun.c → xywrun.c

@@ -391,7 +391,7 @@ {&xyw_memory[0xff00], system_setup, system_input, system_output, 0, 0, 0, 0},
     // Terminal device
     {&xyw_memory[0xff10], terminal_init, terminal_input, terminal_output, terminal_teardown, terminal_poll, terminal_save, terminal_restore},
     // Clock device
-    {&xyw_memory[0xff20], clock_setup, clock_input, clock_output, 0, 0, 0, 0},
+    {&xyw_memory[0xff20], clock_setup, clock_input, clock_output, 0, clock_poll, 0, 0},
     // File device
     {&xyw_memory[0xff30], file_setup, file_input, file_output, 0, 0, 0, 0},
     // Beeper device
@@ -611,8 +611,7 @@ }
 
 //// Event dispatch (WAITING state)
 
-// Addresses of all event handler slots — add new handlers here.
-// Both has_event_handlers() and feed_next_event() stay in sync via this table.
+// Addresses of event handler slots — used by HLT to decide whether to enter WAITING.
 static const xyw_word event_handler_addrs[] = {
     TERMINAL_ON_ARGUMENT,
     TERMINAL_ON_KEYPRESS,
@@ -628,32 +627,6 @@ return 1;
     return 0;
 }
 
-// Feed legacy event (timer only — terminal is handled by terminal_poll).
-// Returns 1 if an event was dispatched, 0 if no more events.
-static int feed_next_event(void)
-{
-    xyw_word on_keypress_handler = XYW_PEEKW(&xyw_memory[TERMINAL_ON_KEYPRESS]);
-    xyw_word on_timer_handler = XYW_PEEKW(&xyw_memory[CLOCK_ON_TIMER_ELAPSED]);
-
-    if (on_timer_handler)
-    {
-        // If keypress handler is also active, do non-blocking check
-        // (terminal_poll provides the sleep via getch_timeout)
-        int elapsed = on_keypress_handler
-            ? (readw(CLOCK_TIMER) == 0 && readb(CLOCK_ON_TIMER_ELAPSED))
-            : readb(CLOCK_ON_TIMER_ELAPSED); // blocking: timer-only program
-        if (elapsed)
-        {
-            xyw_memory[SYSTEM_STATE] |= SYSTEM_STATE_RUNNING;
-            ss_push_frame(DEVICE_AREA_START);
-            *pc = on_timer_handler;
-            return 1;
-        }
-    }
-
-    return 0;
-}
-
 //// Main evaluation function - runs from current pc until BRK
 int xyw_eval(xyw_word start_pc)
 {
@@ -693,9 +666,6 @@ if (r > 0) { dispatched = 1; break; }
                         if (r < 0) active = 1;
                     }
                     if (dispatched) break;
-                    // Legacy: timer handling (will be moved to clock_poll in step 4)
-                    if (feed_next_event()) { dispatched = 1; break; }
-                    // If no device is actively waiting, exit
                     if (!active) break;
                 }
                 if (dispatched)