frodo-wii/Src/CIA.h
2009-01-13 18:46:42 +00:00

211 lines
4.5 KiB
C++

/*
* CIA.h - 6526 emulation
*
* Frodo (C) 1994-1997,2002-2005 Christian Bauer
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _CIA_H
#define _CIA_H
#include "Prefs.h"
class MOS6510;
class MOS6502_1541;
class MOS6569;
struct MOS6526State;
class MOS6526 {
public:
MOS6526(MOS6510 *CPU);
void Reset(void);
void GetState(MOS6526State *cs);
void SetState(MOS6526State *cs);
#ifdef FRODO_SC
void CheckIRQs(void);
void EmulateCycle(void);
#else
void EmulateLine(int cycles);
#endif
void CountTOD(void);
virtual void TriggerInterrupt(int bit)=0;
protected:
MOS6510 *the_cpu; // Pointer to 6510
uint8 pra, prb, ddra, ddrb;
uint16 ta, tb, latcha, latchb;
uint8 tod_10ths, tod_sec, tod_min, tod_hr;
uint8 alm_10ths, alm_sec, alm_min, alm_hr;
uint8 sdr, icr, cra, crb;
uint8 int_mask;
int tod_divider; // TOD frequency divider
bool tod_halt, // Flag: TOD halted
ta_cnt_phi2, // Flag: Timer A is counting Phi 2
tb_cnt_phi2, // Flag: Timer B is counting Phi 2
tb_cnt_ta; // Flag: Timer B is counting underflows of Timer A
#ifdef FRODO_SC
bool ta_irq_next_cycle, // Flag: Trigger TA IRQ in next cycle
tb_irq_next_cycle, // Flag: Trigger TB IRQ in next cycle
has_new_cra, // Flag: New value for CRA pending
has_new_crb; // Flag: New value for CRB pending
char ta_state, tb_state; // Timer A/B states
uint8 new_cra, new_crb; // New values for CRA/CRB
#endif
};
class MOS6526_1 : public MOS6526 {
public:
MOS6526_1(MOS6510 *CPU, MOS6569 *VIC);
void Reset(void);
uint8 ReadRegister(uint16 adr);
void WriteRegister(uint16 adr, uint8 byte);
virtual void TriggerInterrupt(int bit);
uint8 KeyMatrix[8]; // C64 keyboard matrix, 1 bit/key (0: key down, 1: key up)
uint8 RevMatrix[8]; // Reversed keyboard matrix
uint8 Joystick1; // Joystick 1 AND value
uint8 Joystick2; // Joystick 2 AND value
private:
void check_lp(void);
MOS6569 *the_vic;
uint8 prev_lp; // Previous state of LP line (bit 4)
};
class MOS6526_2 : public MOS6526{
public:
MOS6526_2(MOS6510 *CPU, MOS6569 *VIC, MOS6502_1541 *CPU1541);
void Reset(void);
uint8 ReadRegister(uint16 adr);
void WriteRegister(uint16 adr, uint8 byte);
virtual void TriggerInterrupt(int bit);
uint8 IECLines; // State of IEC lines (bit 7 - DATA, bit 6 - CLK, bit 4 - ATN)
private:
MOS6569 *the_vic;
MOS6502_1541 *the_cpu_1541;
};
// CIA state
struct MOS6526State {
uint8 pra;
uint8 ddra;
uint8 prb;
uint8 ddrb;
uint8 ta_lo;
uint8 ta_hi;
uint8 tb_lo;
uint8 tb_hi;
uint8 tod_10ths;
uint8 tod_sec;
uint8 tod_min;
uint8 tod_hr;
uint8 sdr;
uint8 int_data; // Pending interrupts
uint8 cra;
uint8 crb;
// Additional registers
uint16 latcha; // Timer latches
uint16 latchb;
uint8 alm_10ths; // Alarm time
uint8 alm_sec;
uint8 alm_min;
uint8 alm_hr;
uint8 int_mask; // Enabled interrupts
};
/*
* Emulate CIA for one cycle/raster line
*/
#ifdef FRODO_SC
inline void MOS6526::CheckIRQs(void)
{
// Trigger pending interrupts
if (ta_irq_next_cycle) {
ta_irq_next_cycle = false;
TriggerInterrupt(1);
}
if (tb_irq_next_cycle) {
tb_irq_next_cycle = false;
TriggerInterrupt(2);
}
}
#else
inline void MOS6526::EmulateLine(int cycles)
{
unsigned long tmp;
// Timer A
if (ta_cnt_phi2) {
ta = tmp = ta - cycles; // Decrement timer
if (tmp > 0xffff) { // Underflow?
ta = latcha; // Reload timer
if (cra & 8) { // One-shot?
cra &= 0xfe;
ta_cnt_phi2 = false;
}
TriggerInterrupt(1);
if (tb_cnt_ta) { // Timer B counting underflows of Timer A?
tb = tmp = tb - 1; // tmp = --tb doesn't work
if (tmp > 0xffff) goto tb_underflow;
}
}
}
// Timer B
if (tb_cnt_phi2) {
tb = tmp = tb - cycles; // Decrement timer
if (tmp > 0xffff) { // Underflow?
tb_underflow:
tb = latchb;
if (crb & 8) { // One-shot?
crb &= 0xfe;
tb_cnt_phi2 = false;
tb_cnt_ta = false;
}
TriggerInterrupt(2);
}
}
}
#endif
#endif