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gigatron: some more work

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- Add comments for the jumps
- Mask out the 15-bit ROM space as necessary
- Hook up gamepad
This commit is contained in:
Sterophonick 2020-06-19 23:04:17 -07:00
parent db01fc5e55
commit 207695334f
3 changed files with 24 additions and 13 deletions
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27
src/devices/cpu/gigatron/gigatron.cpp
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@ -13,7 +13,7 @@
#include "gigatrondasm.h"
DEFINE_DEVICE_TYPE(GTRON, gigatron_cpu_device, "gigatron_cpu", "Gigatron CPU")
DEFINE_DEVICE_TYPE(GTRON, gigatron_cpu_device, "gigatron_cpu", "Gigatron")
/* FLAGS */
@ -24,7 +24,6 @@ DEFINE_DEVICE_TYPE(GTRON, gigatron_cpu_device, "gigatron_cpu", "Gigatron CPU")
#define C 0x10
#endif
#define gigatron_readop(A) m_program->read_word(A)
#define gigatron_readmem16(A) m_data->read_dword(A)
#define gigatron_readmem8(A) m_data->read_byte(A)
@ -52,7 +51,8 @@ void gigatron_cpu_device::execute_run()
debugger_instruction_hook(m_pc);
opcode = gigatron_readop(m_pc);
m_pc = m_npc++;
m_pc = m_npc;
m_npc = (m_pc + 1) & 0x7FFF;
uint8_t op = (opcode >> 13) & 0x0007;
uint8_t mode = (opcode >> 10) & 0x0007;
@ -98,7 +98,7 @@ void gigatron_cpu_device::init()
m_x = 0;
m_y = 0;
m_pc = 0;
m_npc = (m_pc + 1);
m_npc = (m_pc + 1) & 0x7FFF;
m_ppc = 0;
m_inReg = 0xFF;
@ -109,6 +109,7 @@ void gigatron_cpu_device::init()
state_add(GTRON_AC, "AC", m_ac);
state_add(GTRON_X, "X", m_x);
state_add(GTRON_Y, "Y", m_y);
state_add(GTRON_IREG, "IREG", m_inReg);
set_icountptr(m_icount);
@ -121,6 +122,7 @@ void gigatron_cpu_device::init()
save_item(NAME(m_pc));
m_outx_cb.resolve_safe();
m_ir_cb.resolve_safe();
}
void gigatron_cpu_device::branchOp(uint8_t op, uint8_t mode, uint8_t bus, uint8_t d)
@ -131,29 +133,29 @@ void gigatron_cpu_device::branchOp(uint8_t op, uint8_t mode, uint8_t bus, uint8_
uint16_t base = m_pc & 0xff00;
switch (mode)
{
case 0:
case 0: //jmp
c = true;
base = m_y << 8;
break;
case 1:
case 1: //bgt
c = (ac2 > ZERO);
break;
case 2:
case 2: //blt
c = (ac2 < ZERO);
break;
case 3:
case 3: //bne
c = (ac2 != ZERO);
break;
case 4:
case 4: //beq
c = (ac2 == ZERO);
break;
case 5:
case 5: //bge
c = (ac2 >= ZERO);
break;
case 6:
case 6: //ble
c = (ac2 <= ZERO);
break;
case 7:
case 7: //bra
c = true;
break;
}
@ -320,6 +322,7 @@ gigatron_cpu_device::gigatron_cpu_device(const machine_config &mconfig, const ch
, m_program_config("program", ENDIANNESS_BIG, 16, 14, -1)
, m_data_config("data", ENDIANNESS_BIG, 8, 15, 0)
, m_outx_cb(*this)
, m_ir_cb(*this)
{
}

4
src/devices/cpu/gigatron/gigatron.h
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@ -16,7 +16,7 @@
enum
{
GTRON_PC, GTRON_NPC,
GTRON_AC, GTRON_X, GTRON_Y
GTRON_AC, GTRON_X, GTRON_Y, GTRON_IREG
};
@ -26,6 +26,7 @@ public:
// construction/destruction
gigatron_cpu_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
auto outx_cb() { return m_outx_cb.bind(); }
auto ir_cb() { return m_ir_cb.bind(); }
protected:
// device-level overrides
@ -79,6 +80,7 @@ private:
void gigatron_illegal();
devcb_write8 m_outx_cb;
devcb_read8 m_ir_cb;
};

6
src/mame/drivers/gigatron.cpp
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@ -82,6 +82,11 @@ void gigatron_state::blinkenlights(uint8_t data)
lights_changed ^= light;
}
void gigatron_state::inputs()
{
return m_io_inputs->read() ^ 0xFF;
}
static INPUT_PORTS_START(gigatron)
PORT_START("GAMEPAD")
PORT_BIT( 0x0004, IP_ACTIVE_LOW, IPT_JOYSTICK_DOWN ) PORT_PLAYER(1)
@ -100,6 +105,7 @@ void gigatron_state::gigatron(machine_config &config)
m_maincpu->set_addrmap(AS_PROGRAM, &gigatron_state::prog_map);
m_maincpu->set_addrmap(AS_DATA, &gigatron_state::data_map);
m_maincpu->outx_cb().set(FUNC(gigatron_state::blinkenlights));
m_maincpu->ir_cb().set(FUNC(gigatron_state::inputs));
/* video hardware */
screen_device &screen(SCREEN(config, "screen", SCREEN_TYPE_RASTER));