// license:BSD-3-Clause
// copyright-holders:Wilbert Pol
#include "emu.h"
#include "msx_s1985.h"
const uint8_t manufacturer_id = 0xfe;
DEFINE_DEVICE_TYPE(MSX_S1985, msx_s1985_device, "msx_s1985", "MSX-Engine S1985")
msx_s1985_device::msx_s1985_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, MSX_S1985, tag, owner, clock)
, device_nvram_interface(mconfig, *this)
, m_selected(false)
, m_backup_ram_address(0)
, m_color1(0)
, m_color2(0)
, m_pattern(0)
{
}
void msx_s1985_device::device_start()
{
save_item(NAME(m_selected));
save_item(NAME(m_backup_ram_address));
save_item(NAME(m_backup_ram));
save_item(NAME(m_color1));
save_item(NAME(m_color2));
save_item(NAME(m_pattern));
}
void msx_s1985_device::nvram_default()
{
memset(m_backup_ram, 0xff, sizeof(m_backup_ram));
}
void msx_s1985_device::nvram_read(emu_file &file)
{
file.read(m_backup_ram, sizeof(m_backup_ram));
}
void msx_s1985_device::nvram_write(emu_file &file)
{
file.write(m_backup_ram, sizeof(m_backup_ram));
}
READ8_MEMBER(msx_s1985_device::switched_read)
{
if (m_selected)
{
switch (offset)
{
case 0:
/// Manufacturer ID number register
return manufacturer_id ^ 0xff;
case 2:
/// Back-up RAM read
return m_backup_ram[m_backup_ram_address];
case 7:
{
// Pattern and foreground/background color read
uint8_t data = (m_pattern & 0x80) ? m_color2 : m_color1;
if(!machine().side_effects_disabled())
m_pattern = (m_pattern << 1) | (m_pattern >> 7);
return data;
}
default:
printf("msx_s1985: unhandled read from offset %02x\n", offset);
break;
}
}
return 0xff;
}
WRITE8_MEMBER(msx_s1985_device::switched_write)
{
if (offset == 0)
{
/// Manufacturer ID number register
m_selected = (data == manufacturer_id);
}
else if (m_selected)
{
switch (offset)
{
case 1:
/// Back-up RAM address latch
m_backup_ram_address = data & 0x0f;
break;
case 2:
/// Back-up RAM write
m_backup_ram[m_backup_ram_address] = data;
break;
case 6:
// Foreground/background color write
m_color2 = m_color1;
m_color1 = data;
break;
case 7:
// Pattern write
m_pattern = data;
break;
default:
printf("msx_s1985: unhandled write %02x to offset %02x\n", data, offset);
break;
}
}
}