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-rw-r--r--src/devices/machine/cdp1852.c187
1 files changed, 187 insertions, 0 deletions
diff --git a/src/devices/machine/cdp1852.c b/src/devices/machine/cdp1852.c
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+++ b/src/devices/machine/cdp1852.c
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+// license:BSD-3-Clause
+// copyright-holders:Curt Coder
+/**********************************************************************
+
+ RCA CDP1852 Byte-Wide Input/Output Port emulation
+
+**********************************************************************/
+
+#include "cdp1852.h"
+
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+const device_type CDP1852 = &device_creator<cdp1852_device>;
+
+
+
+//**************************************************************************
+// MACROS / CONSTANTS
+//**************************************************************************
+
+enum
+{
+ MODE_INPUT = 0,
+ MODE_OUTPUT
+};
+
+
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// cdp1852_device - constructor
+//-------------------------------------------------
+
+cdp1852_device::cdp1852_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) :
+ device_t(mconfig, CDP1852, "CDP1852 I/O", tag, owner, clock, "cdp1852", __FILE__),
+ m_read_mode(*this),
+ m_write_sr(*this),
+ m_read_data(*this),
+ m_write_data(*this)
+{
+}
+
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void cdp1852_device::device_start()
+{
+ // resolve callbacks
+ m_read_mode.resolve_safe(0);
+ m_write_sr.resolve_safe();
+ m_read_data.resolve_safe(0);
+ m_write_data.resolve_safe();
+
+ // allocate timers
+ if (clock() > 0)
+ {
+ m_scan_timer = timer_alloc();
+ m_scan_timer->adjust(attotime::zero, 0, attotime::from_hz(clock()));
+ }
+
+ // register for state saving
+ save_item(NAME(m_new_data));
+ save_item(NAME(m_data));
+ save_item(NAME(m_next_data));
+ save_item(NAME(m_sr));
+ save_item(NAME(m_next_sr));
+}
+
+
+//-------------------------------------------------
+// device_reset - device-specific reset
+//-------------------------------------------------
+
+void cdp1852_device::device_reset()
+{
+ // reset data register
+ m_data = 0;
+
+ if (!m_read_mode())
+ {
+ // reset service request flip-flop
+ set_sr_line(1);
+ }
+ else
+ {
+ // output data
+ m_write_data((offs_t)0, m_data);
+
+ // reset service request flip-flop
+ set_sr_line(0);
+ }
+}
+
+
+//-------------------------------------------------
+// device_timer - handler timer events
+//-------------------------------------------------
+
+void cdp1852_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
+{
+ if (!m_read_mode())
+ {
+ // input data into register
+ m_data = m_read_data(0);
+
+ // signal processor
+ set_sr_line(0);
+ }
+ else
+ {
+ if (m_new_data)
+ {
+ m_new_data = 0;
+
+ // latch data into register
+ m_data = m_next_data;
+
+ // output data
+ m_write_data((offs_t)0, m_data);
+
+ // signal peripheral device
+ set_sr_line(1);
+
+ m_next_sr = 0;
+ }
+ else
+ {
+ set_sr_line(m_next_sr);
+ }
+ }
+}
+
+
+//-------------------------------------------------
+// set_sr_line -
+//-------------------------------------------------
+
+void cdp1852_device::set_sr_line(int state)
+{
+ if (m_sr != state)
+ {
+ m_sr = state;
+
+ m_write_sr(m_sr);
+ }
+}
+
+
+//-------------------------------------------------
+// read - data read
+//-------------------------------------------------
+
+READ8_MEMBER( cdp1852_device::read )
+{
+ if (!m_read_mode() && !clock())
+ {
+ // input data into register
+ m_data = m_read_data(0);
+ }
+
+ set_sr_line(1);
+
+ return m_data;
+}
+
+
+//-------------------------------------------------
+// write - data write
+//-------------------------------------------------
+
+WRITE8_MEMBER( cdp1852_device::write )
+{
+ if (m_read_mode())
+ {
+ m_next_data = data;
+ m_new_data = 1;
+ }
+}