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// license:BSD-3-Clause
// copyright-holders:hap
/*
Hughes HLCD 0438 LCD Driver
32 segment outputs, may also be used as a column driver
LCD pin can be driven manually, or oscillating.
*/
#include "emu.h"
#include "video/hlcd0438.h"
DEFINE_DEVICE_TYPE(HLCD0438, hlcd0438_device, "hlcd0438", "Hughes HLCD 0438 LCD Driver")
//-------------------------------------------------
// constructor
//-------------------------------------------------
hlcd0438_device::hlcd0438_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) :
device_t(mconfig, HLCD0438, tag, owner, clock),
m_write_segs(*this), m_write_data(*this)
{ }
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void hlcd0438_device::device_start()
{
// resolve callbacks
m_write_segs.resolve_safe();
m_write_data.resolve_safe();
// timer (when LCD pin is oscillator)
m_lcd_timer = timer_alloc();
attotime period = (clock() != 0) ? attotime::from_hz(2 * clock()) : attotime::never;
m_lcd_timer->adjust(period, 0, period);
// register for savestates
save_item(NAME(m_data_in));
save_item(NAME(m_data_out));
save_item(NAME(m_clk));
save_item(NAME(m_load));
save_item(NAME(m_lcd));
save_item(NAME(m_shift));
save_item(NAME(m_latch));
}
//-------------------------------------------------
// handlers
//-------------------------------------------------
void hlcd0438_device::clock_w(int state)
{
state = state ? 1 : 0;
// shift on falling edge
if (m_clk && !state)
{
// DATA OUT pin follows carry out
m_data_out = BIT(m_shift, 31);
m_shift = m_shift << 1 | m_data_in;
m_write_data(m_data_out);
load_w(m_load);
}
m_clk = state;
}
void hlcd0438_device::load_w(int state)
{
m_load = state ? 1 : 0;
// load to output latches while LOAD pin is high
if (m_load)
m_latch = m_shift;
}
void hlcd0438_device::lcd_w(int state)
{
state = state ? 1 : 0;
// LCD pin drives backplate
if (state != m_lcd)
m_write_segs(m_lcd, m_latch);
m_lcd = state;
}
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