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// license:BSD-3-Clause
// copyright-holders:Mark McDougall
/***************************************************************************
stfight.c
Functions to emulate general aspects of the machine (RAM, ROM, interrupts,
I/O ports)
***************************************************************************/
#include "emu.h"
#include "includes/stfight.h"
#include "cpu/m6805/m68705.h"
#include "cpu/z80/z80.h"
#include "sound/msm5205.h"
/*
Encryption PAL 16R4 on CPU board
+---U---+
CP --| |-- VCC
ROM D1 --| |-- ROM D0 M1 = 0 M1 = 1
ROM D3 --| |-- (NC)
ROM D4 --| |-- D6 D6 = D1 ^^ D3 D6 = / ( D1 ^^ D0 )
ROM D6 --| |-- D4 D4 = / ( D6 ^^ A7 ) D4 = D3 ^^ A0
A0 --| |-- D3 D3 = / ( D0 ^^ A1 ) D3 = D4 ^^ A4
A1 --| |-- D0 D0 = D1 ^^ D4 D0 = / ( D6 ^^ A0 )
A4 --| |-- (NC)
A7 --| |-- /M1
GND --| |-- /OE
+-------+
*/
void stfight_state::init_stfight()
{
uint8_t *rom = memregion("maincpu")->base();
for (uint32_t A = 0; A < 0x8000; ++A)
{
uint8_t src = rom[A];
// decode opcode
m_decrypted_opcodes[A] =
( src & 0xA6 ) |
( ( ( ( src << 2 ) ^ src ) << 3 ) & 0x40 ) |
( ~( ( src ^ ( A >> 1 ) ) >> 2 ) & 0x10 ) |
( ~( ( ( src << 1 ) ^ A ) << 2 ) & 0x08 ) |
( ( ( src ^ ( src >> 3 ) ) >> 1 ) & 0x01 );
// decode operand
rom[A] =
( src & 0xA6 ) |
( ~( ( src ^ ( src << 1 ) ) << 5 ) & 0x40 ) |
( ( ( src ^ ( A << 3 ) ) << 1 ) & 0x10 ) |
( ( ( src ^ A ) >> 1 ) & 0x08 ) |
( ~( ( src >> 6 ) ^ A ) & 0x01 );
}
// Set clock prescaler FM:1/2 PSG:1/1
m_ym[0]->write(0, 0x2f);
m_ym[1]->write(0, 0x2f);
}
void stfight_state::machine_start()
{
m_main_bank->configure_entries(0, 4, memregion("maincpu")->base() + 0x10000, 0x4000);
m_main_bank->set_entry(0);
m_int1_timer = timer_alloc(FUNC(stfight_state::rst08_tick), this);
save_item(NAME(m_coin_state));
save_item(NAME(m_fm_data));
save_item(NAME(m_cpu_to_mcu_empty));
save_item(NAME(m_cpu_to_mcu_data));
save_item(NAME(m_port_a_out));
save_item(NAME(m_port_c_out));
save_item(NAME(m_vck2));
save_item(NAME(m_adpcm_reset));
save_item(NAME(m_adpcm_data_offs));
}
void stfight_state::machine_reset()
{
m_fm_data = 0;
m_cpu_to_mcu_empty = true;
m_adpcm_reset = true;
// Coin signals are active low
m_coin_state = 3;
}
// It's entirely possible that this bank is never switched out
// - in fact I don't even know how/where it's switched in!
void stfight_state::stfight_bank_w(uint8_t data)
{
m_main_bank->set_entry(bitswap(data, 7, 2));
}
/*
* CPU 1 timed interrupt - 60Hz???
*/
TIMER_CALLBACK_MEMBER(stfight_state::rst08_tick)
{
m_maincpu->set_input_line_and_vector(0, HOLD_LINE, 0xd7); // Z80
}
INTERRUPT_GEN_MEMBER(stfight_state::stfight_vb_interrupt)
{
// Do a RST10
device.execute().set_input_line_and_vector(0, HOLD_LINE, 0xcf); // Z80
m_int1_timer->adjust(attotime::from_hz(120));
}
/*
* Hardware handlers
*/
void stfight_state::stfight_io_w(uint8_t data)
{
// TODO: What is bit 4?
machine().bookkeeping().coin_counter_w(0, data & 1);
machine().bookkeeping().coin_counter_w(1, data & 2);
}
uint8_t stfight_state::stfight_coin_r()
{
return m_coin_state;
}
void stfight_state::stfight_coin_w(uint8_t data)
{
// Acknowledge coin signals (active low)
if (!BIT(data, 0))
m_coin_state |= 1;
if (!BIT(data, 1))
m_coin_state |= 2;
}
/*
* Machine hardware for MSM5205 ADPCM sound control
*/
WRITE_LINE_MEMBER(stfight_state::stfight_adpcm_int)
{
if (!state)
return;
// Falling edge triggered interrupt at half the rate of /VCK?
m_mcu->set_input_line(M68705_IRQ_LINE, m_vck2 ? ASSERT_LINE : CLEAR_LINE);
m_vck2 = !m_vck2;
if (!m_adpcm_reset)
{
uint8_t adpcm_data = m_samples[(m_adpcm_data_offs >> 1) & 0x7fff];
if (!BIT(m_adpcm_data_offs, 0))
adpcm_data >>= 4;
++m_adpcm_data_offs;
m_msm->data_w(adpcm_data & 0x0f);
}
}
/*
* Machine hardware for YM2303 FM sound control
*/
void stfight_state::stfight_fm_w(uint8_t data)
{
// The sound cpu ignores any FM data without bit 7 set
m_fm_data = 0x80 | data;
}
uint8_t stfight_state::stfight_fm_r()
{
uint8_t const data = m_fm_data;
// Acknowledge the command
if (!machine().side_effects_disabled())
m_fm_data &= ~0x80;
return data;
}
/*
* MCU communications
*/
void stfight_state::stfight_mcu_w(uint8_t data)
{
m_cpu_to_mcu_data = data & 0x0f;
m_cpu_to_mcu_empty = false;
}
void stfight_state::stfight_68705_port_a_w(uint8_t data)
{
m_port_a_out = data;
}
uint8_t stfight_state::stfight_68705_port_b_r()
{
return
(m_coin_mech->read() << 6) |
(m_cpu_to_mcu_empty ? 0x10 : 0x00) |
(m_cpu_to_mcu_data & 0x0f);
}
void stfight_state::stfight_68705_port_b_w(uint8_t data)
{
// Acknowledge Z80 command
if (!BIT(data, 5))
m_cpu_to_mcu_empty = true;
}
void stfight_state::stfight_68705_port_c_w(uint8_t data)
{
// Signal a valid coin on the falling edge
if (BIT(m_port_c_out, 0) && !BIT(data, 0))
m_coin_state &= ~1;
if (BIT(m_port_c_out, 1) && !BIT(data, 1))
m_coin_state &= ~2;
// Latch ADPCM data address when dropping the reset line
m_adpcm_reset = BIT(data, 2);
if (!m_adpcm_reset && BIT(m_port_c_out, 2))
m_adpcm_data_offs = m_port_a_out << 9;
m_msm->reset_w(m_adpcm_reset ? ASSERT_LINE : CLEAR_LINE);
// Generate NMI on host CPU (used on handshake error or stuck coin)
m_maincpu->set_input_line(INPUT_LINE_NMI, BIT(data, 3) ? CLEAR_LINE : ASSERT_LINE);
m_port_c_out = data;
}
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