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// license:BSD-3-Clause
// copyright-holders:Ryan Holtz
/*****************************************************************************
7400 Quad 2-Input NAND Gate
*****************************************************************************/
#include "emu.h"
#include "7400.h"
DEFINE_DEVICE_TYPE(TTL7400, ttl7400_device, "7400", "7400 Quad 2-Input NAND Gate")
ttl7400_device::ttl7400_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, TTL7400, tag, owner, clock)
, m_y_func(*this)
, m_a(0)
, m_b(0)
, m_y(0)
{
}
void ttl7400_device::device_start()
{
m_y_func.resolve_all_safe();
save_item(NAME(m_a));
save_item(NAME(m_b));
save_item(NAME(m_y));
}
void ttl7400_device::device_reset()
{
m_a = 0;
m_b = 0;
m_y = 0;
}
void ttl7400_device::update()
{
uint8_t last_y = m_y;
m_y = (m_a & m_b) & 0xf;
if (m_y != last_y)
{
for (std::size_t bit = 0; bit < 4; bit++)
{
if (BIT(m_y, bit) == BIT(last_y, bit))
continue;
m_y_func[bit](BIT(m_y, bit));
}
}
}
void ttl7400_device::a_w(uint8_t line, uint8_t state)
{
uint8_t old_a = m_a;
m_a &= ~(1 << line);
m_a |= (state << line);
if (old_a != m_a)
update();
}
void ttl7400_device::b_w(uint8_t line, uint8_t state)
{
uint8_t old_b = m_b;
m_b &= ~(1 << line);
m_b |= (state << line);
if (old_b != m_b)
update();
}
uint8_t ttl7400_device::y_r(uint8_t line)
{
return (m_y >> line) & 1;
}
WRITE_LINE_MEMBER( ttl7400_device::a1_w ) { a_w(0, state); }
WRITE_LINE_MEMBER( ttl7400_device::a2_w ) { a_w(1, state); }
WRITE_LINE_MEMBER( ttl7400_device::a3_w ) { a_w(2, state); }
WRITE_LINE_MEMBER( ttl7400_device::a4_w ) { a_w(3, state); }
WRITE_LINE_MEMBER( ttl7400_device::b1_w ) { b_w(0, state); }
WRITE_LINE_MEMBER( ttl7400_device::b2_w ) { b_w(1, state); }
WRITE_LINE_MEMBER( ttl7400_device::b3_w ) { b_w(2, state); }
WRITE_LINE_MEMBER( ttl7400_device::b4_w ) { b_w(3, state); }
READ_LINE_MEMBER( ttl7400_device::y1_r ) { return y_r(0); }
READ_LINE_MEMBER( ttl7400_device::y2_r ) { return y_r(1); }
READ_LINE_MEMBER( ttl7400_device::y3_r ) { return y_r(2); }
READ_LINE_MEMBER( ttl7400_device::y4_r ) { return y_r(3); }
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