127 lines
3.5 KiB
C
127 lines
3.5 KiB
C
/**********************************************************************
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Super Explode! cartridge emulation
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Copyright MESS Team.
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Visit http://mamedev.org for licensing and usage restrictions.
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**********************************************************************/
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#include "c64_super_explode.h"
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//**************************************************************************
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// MACROS/CONSTANTS
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//**************************************************************************
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// t = R*C = 3.3K * 0.47uF * 40% Vtr = 792.2905424610516 usec
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// (3.3K pull-up on the EXROM line inside the C64, PLA Vih min = 2.0V = 40% of 5.0V)
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#define TIMER_PERIOD 792
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//**************************************************************************
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// DEVICE DEFINITIONS
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//**************************************************************************
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const device_type C64_SUPER_EXPLODE = &device_creator<c64_super_explode_cartridge_device>;
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//**************************************************************************
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// LIVE DEVICE
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//**************************************************************************
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//-------------------------------------------------
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// c64_super_explode_cartridge_device - constructor
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//-------------------------------------------------
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c64_super_explode_cartridge_device::c64_super_explode_cartridge_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) :
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device_t(mconfig, C64_SUPER_EXPLODE, "C64 Super Explode! cartridge", tag, owner, clock),
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device_c64_expansion_card_interface(mconfig, *this)
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{
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}
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//-------------------------------------------------
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// device_start - device-specific startup
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//-------------------------------------------------
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void c64_super_explode_cartridge_device::device_start()
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{
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// allocate timer
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m_exrom_timer = timer_alloc();
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// state saving
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save_item(NAME(m_bank));
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}
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//-------------------------------------------------
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// device_reset - device-specific reset
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//-------------------------------------------------
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void c64_super_explode_cartridge_device::device_reset()
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{
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m_bank = 0;
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m_exrom = 0;
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m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
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}
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//-------------------------------------------------
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// device_timer - handler timer events
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//-------------------------------------------------
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void c64_super_explode_cartridge_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
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{
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m_exrom = 1;
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}
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//-------------------------------------------------
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// c64_cd_r - cartridge data read
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//-------------------------------------------------
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UINT8 c64_super_explode_cartridge_device::c64_cd_r(address_space &space, offs_t offset, UINT8 data, int sphi2, int ba, int roml, int romh, int io1, int io2)
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{
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if (!roml)
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{
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m_exrom = 0;
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m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
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data = m_roml[(m_bank << 13) | (offset & 0x1fff)];
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}
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else if (!io1)
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{
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m_exrom = 0;
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m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
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}
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else if (!io2)
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{
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data = m_roml[(m_bank << 13) | (offset & 0x1fff)];
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}
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return data;
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}
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//-------------------------------------------------
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// c64_cd_w - cartridge data write
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//-------------------------------------------------
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void c64_super_explode_cartridge_device::c64_cd_w(address_space &space, offs_t offset, UINT8 data, int sphi2, int ba, int roml, int romh, int io1, int io2)
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{
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if (!io1)
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{
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m_exrom = 0;
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m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
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}
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else if (!io2)
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{
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m_bank = BIT(data, 7);
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}
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}
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