From 4eaee5d7d058ff7e6e0b628d2cc51a0b150b3e83 Mon Sep 17 00:00:00 2001
From: Nathan Woods <npwoods@mess.org>
Date: Sun, 23 Dec 2012 05:28:04 +0000
Subject: [PATCH] [MSM6242] Fixing RTC regressions regarding interrupt
 callbacks

---
 src/emu/machine/msm6242.c | 42 ++++++++++++++++++++++++++++++++++++---
 src/emu/machine/msm6242.h |  1 +
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/src/emu/machine/msm6242.c b/src/emu/machine/msm6242.c
index 8210658736a..3993f506370 100644
--- a/src/emu/machine/msm6242.c
+++ b/src/emu/machine/msm6242.c
@@ -41,8 +41,9 @@ enum
 
 #define TIMER_RTC_CALLBACK		1
 
-#define LOG_UNMAPPED			1
-#define LOG_IRQ					1
+#define LOG_UNMAPPED			0
+#define LOG_IRQ					0
+#define LOG_IRQ_ENABLE			0
 
 
 
@@ -316,7 +317,17 @@ void msm6242_device::update_timer()
 	// if set, convert ticks to an attotime
 	if (callback_ticks > 0)
 	{
-		callback_time = attotime::from_ticks(callback_ticks, clock()) - machine().time();
+		// get the current time
+		UINT64 curtime = current_time();
+
+		// we need the absolute callback time, in ticks
+		UINT64 absolute_callback_ticks = curtime + callback_ticks;
+
+		// convert that to an attotime
+		attotime absolute_callback_time = attotime::from_ticks(absolute_callback_ticks, clock());		
+
+		// and finally get the delta as an attotime
+		callback_time = absolute_callback_time - machine().time();
 	}
 
 	m_timer->adjust(callback_time);
@@ -342,6 +353,7 @@ void msm6242_device::rtc_clock_updated(int year, int month, int day, int day_of_
 void msm6242_device::rtc_timer_callback()
 {
 	update_rtc_registers();
+	update_timer();
 }
 
 
@@ -359,6 +371,24 @@ UINT8 msm6242_device::get_clock_nibble(int rtc_register, bool high)
 
 
 
+//-------------------------------------------------
+//  get_clock_nibble
+//-------------------------------------------------
+
+const char *msm6242_device::irq_type_string(UINT8 irq_type)
+{
+	switch(irq_type)
+	{
+		case IRQ_64THSECOND:	return "1/64th second";
+		case IRQ_SECOND:		return "second";
+		case IRQ_MINUTE:		return "minute";
+		case IRQ_HOUR:			return "hour";
+		default:				return "???";
+	}
+}
+
+
+
 //**************************************************************************
 //  READ/WRITE HANDLERS
 //**************************************************************************
@@ -487,12 +517,18 @@ WRITE8_MEMBER( msm6242_device::write )
 			{
 				m_irq_flag = 1;
 				m_irq_type = (data & 0xc) >> 2;
+
+				if (LOG_IRQ_ENABLE)
+					logerror("%s: MSM6242 enabling irq '%s'\n", machine().describe_context(), irq_type_string(m_irq_type));
 			}
 			else
 			{
 				m_irq_flag = 0;
 				if ( !m_res_out_int_func.isnull() )
 					m_res_out_int_func( CLEAR_LINE );
+
+				if (LOG_IRQ_ENABLE)
+					logerror("%s: MSM6242 disabling irq\n", machine().describe_context());
 			}
 			break;
 
diff --git a/src/emu/machine/msm6242.h b/src/emu/machine/msm6242.h
index db52a7653de..d3564cb5f83 100644
--- a/src/emu/machine/msm6242.h
+++ b/src/emu/machine/msm6242.h
@@ -81,6 +81,7 @@ private:
 	void update_rtc_registers();
 	void update_timer();
 	UINT8 get_clock_nibble(int rtc_register, bool high);
+	static const char *irq_type_string(UINT8 irq_type);
 };