From ad5ae83d7a715beb90584d1c7e788498243fef7b Mon Sep 17 00:00:00 2001
From: AJR <ajrhacker@users.noreply.github.com>
Date: Thu, 22 Dec 2022 21:37:48 -0500
Subject: [PATCH] pic8259: Treat slave IRQs as level-triggered even when LTIM =
 0

---
 src/devices/machine/pic8259.cpp | 17 ++++++++---------
 src/mame/nec/pc88va.cpp         | 17 +----------------
 src/mame/nec/pc88va.h           |  2 --
 3 files changed, 9 insertions(+), 27 deletions(-)

diff --git a/src/devices/machine/pic8259.cpp b/src/devices/machine/pic8259.cpp
index 385f38cfbdb..d9dafec1503 100644
--- a/src/devices/machine/pic8259.cpp
+++ b/src/devices/machine/pic8259.cpp
@@ -63,18 +63,15 @@ void pic8259_device::set_irq_line(int irq, int state)
 {
 	uint8_t mask = (1 << irq);
 
-	if (state)
+	if (state && !(m_irq_lines & mask))
 	{
 		/* setting IRQ line */
 		LOG("set_irq_line(): PIC set IR%d line\n", irq);
 
-		if(m_level_trig_mode || (!m_level_trig_mode && !(m_irq_lines & mask)))
-		{
-			m_irr |= mask;
-		}
+		m_irr |= mask;
 		m_irq_lines |= mask;
 	}
-	else
+	else if (!state && (m_irq_lines & mask))
 	{
 		/* clearing IRQ line */
 		LOG("set_irq_line(): PIC cleared IR%d line\n", irq);
@@ -99,7 +96,7 @@ uint8_t pic8259_device::acknowledge()
 			if (!machine().side_effects_disabled())
 			{
 				LOG("pic8259_acknowledge(): PIC acknowledge IR%d\n", m_current_level);
-				if (!m_level_trig_mode)
+				if (!m_level_trig_mode && (!m_master || !(m_slave & mask)))
 					m_irr &= ~mask;
 
 				if (!m_auto_eoi)
@@ -138,7 +135,7 @@ uint8_t pic8259_device::acknowledge()
 					LOG("pic8259_acknowledge(): PIC acknowledge IR%d\n", m_current_level);
 
 					uint8_t mask = 1 << m_current_level;
-					if (!m_level_trig_mode)
+					if (!m_level_trig_mode && (!m_master || !(m_slave & mask)))
 						m_irr &= ~mask;
 					m_isr |= mask;
 				}
@@ -199,7 +196,7 @@ uint8_t pic8259_device::read(offs_t offset)
 				{
 					data = 0x80 | m_current_level;
 
-					if (!m_level_trig_mode)
+					if (!m_level_trig_mode && (!m_master || !BIT(m_slave, m_current_level)))
 						m_irr &= ~(1 << m_current_level);
 
 					if (!m_auto_eoi)
@@ -246,6 +243,7 @@ void pic8259_device::write(offs_t offset, uint8_t data)
 				m_imr                = 0x00;
 				m_isr                = 0x00;
 				m_irr                = 0x00;
+				m_slave              = 0x00;
 				m_level_trig_mode    = (data & 0x08) ? 1 : 0;
 				m_vector_size        = (data & 0x04) ? 1 : 0;
 				m_cascade            = (data & 0x02) ? 0 : 1;
@@ -263,6 +261,7 @@ void pic8259_device::write(offs_t offset, uint8_t data)
 					/* write OCW3 */
 					LOGOCW("pic8259_device::write(): OCW3; data=0x%02X\n", data);
 
+					// TODO: special mask mode
 					m_ocw3 = data;
 				}
 				else if ((data & 0x18) == 0x00)
diff --git a/src/mame/nec/pc88va.cpp b/src/mame/nec/pc88va.cpp
index 63d71ca849b..d71c9179b1b 100644
--- a/src/mame/nec/pc88va.cpp
+++ b/src/mame/nec/pc88va.cpp
@@ -1114,20 +1114,6 @@ void pc88va_state::machine_reset()
 	m_sound_irq_pending = false;
 }
 
-WRITE_LINE_MEMBER(pc88va_state::slave_irq7)
-{
-	// If we don't follow this dispatch like the other irqs it will mismatch
-	// between sound and FDC, causing an hang or a disk failure during intros
-	// in rtype, olteus, shinraba, 88va2d.
-	// TODO: how pc88va even acknowledge any irq?
-	if (state)
-	{
-		m_maincpu->set_input_line(INPUT_LINE_IRQ7, CLEAR_LINE);
-		m_maincpu->set_input_line(INPUT_LINE_IRQ7, ASSERT_LINE);
-	}
-
-}
-
 void pc88va_state::pc88va(machine_config &config)
 {
 	V50(config, m_maincpu, MASTER_CLOCK); // μPD9002, aka V50 + μPD70008AC (for PC8801 compatibility mode) in place of 8080
@@ -1168,8 +1154,7 @@ void pc88va_state::pc88va(machine_config &config)
 
 	// external PIC
 	PIC8259(config, m_pic2, 0);
-//	m_pic2->out_int_callback().set_inputline(m_maincpu, INPUT_LINE_IRQ7);
-	m_pic2->out_int_callback().set(FUNC(pc88va_state::slave_irq7));
+	m_pic2->out_int_callback().set_inputline(m_maincpu, INPUT_LINE_IRQ7);
 	m_pic2->in_sp_callback().set_constant(0);
 
 	UPD765A(config, m_fdc, 4000000, true, true);
diff --git a/src/mame/nec/pc88va.h b/src/mame/nec/pc88va.h
index 1b868412abb..4dff0279ee1 100644
--- a/src/mame/nec/pc88va.h
+++ b/src/mame/nec/pc88va.h
@@ -156,8 +156,6 @@ private:
 	uint8_t kanji_ram_r(offs_t offset);
 	void kanji_ram_w(offs_t offset, uint8_t data);
 
-	DECLARE_WRITE_LINE_MEMBER(slave_irq7);
-
 	uint8_t hdd_status_r();
 
 	uint16_t sysop_r();