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cebix |
1.1 |
/* |
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* CIA.cpp - 6526 emulation |
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* |
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cebix |
1.2 |
* Frodo (C) 1994-1997,2002-2003 Christian Bauer |
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cebix |
1.1 |
* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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*/ |
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/* |
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* Notes: |
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* ------ |
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* |
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* - The EmulateLine() function is called for every emulated raster |
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* line. It counts down the timers and triggers interrupts if |
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* necessary. |
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* - The TOD clocks are counted by CountTOD() during the VBlank, so |
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* the input frequency is 50Hz |
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* - The fields KeyMatrix and RevMatrix contain one bit for each |
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* key on the C64 keyboard (0: key pressed, 1: key released). |
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* KeyMatrix is used for normal keyboard polling (PRA->PRB), |
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* RevMatrix for reversed polling (PRB->PRA). |
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* |
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* Incompatibilities: |
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* ------------------ |
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* |
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* - The TOD clock should not be stopped on a read access, but |
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* latched |
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* - The SDR interrupt is faked |
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*/ |
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#include "sysdeps.h" |
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#include "CIA.h" |
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#include "CPUC64.h" |
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#include "CPU1541.h" |
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#include "VIC.h" |
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#include "Prefs.h" |
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/* |
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* Constructors |
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*/ |
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MOS6526::MOS6526(MOS6510 *CPU) : the_cpu(CPU) {} |
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MOS6526_1::MOS6526_1(MOS6510 *CPU, MOS6569 *VIC) : MOS6526(CPU), the_vic(VIC) {} |
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MOS6526_2::MOS6526_2(MOS6510 *CPU, MOS6569 *VIC, MOS6502_1541 *CPU1541) : MOS6526(CPU), the_vic(VIC), the_cpu_1541(CPU1541) {} |
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/* |
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* Reset the CIA |
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*/ |
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void MOS6526::Reset(void) |
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{ |
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pra = prb = ddra = ddrb = 0; |
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ta = tb = 0xffff; |
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latcha = latchb = 1; |
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tod_10ths = tod_sec = tod_min = tod_hr = 0; |
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alm_10ths = alm_sec = alm_min = alm_hr = 0; |
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sdr = icr = cra = crb = int_mask = 0; |
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tod_halt = ta_cnt_phi2 = tb_cnt_phi2 = tb_cnt_ta = false; |
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tod_divider = 0; |
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} |
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void MOS6526_1::Reset(void) |
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{ |
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MOS6526::Reset(); |
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// Clear keyboard matrix and joystick states |
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for (int i=0; i<8; i++) |
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KeyMatrix[i] = RevMatrix[i] = 0xff; |
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Joystick1 = Joystick2 = 0xff; |
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prev_lp = 0x10; |
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} |
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void MOS6526_2::Reset(void) |
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{ |
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MOS6526::Reset(); |
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// VA14/15 = 0 |
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the_vic->ChangedVA(0); |
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// IEC |
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IECLines = 0xd0; |
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} |
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/* |
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* Get CIA state |
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*/ |
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void MOS6526::GetState(MOS6526State *cs) |
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{ |
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cs->pra = pra; |
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cs->prb = prb; |
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cs->ddra = ddra; |
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cs->ddrb = ddrb; |
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cs->ta_lo = ta & 0xff; |
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cs->ta_hi = ta >> 8; |
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cs->tb_lo = tb & 0xff; |
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cs->tb_hi = tb >> 8; |
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cs->latcha = latcha; |
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cs->latchb = latchb; |
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cs->cra = cra; |
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cs->crb = crb; |
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cs->tod_10ths = tod_10ths; |
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cs->tod_sec = tod_sec; |
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cs->tod_min = tod_min; |
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cs->tod_hr = tod_hr; |
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cs->alm_10ths = alm_10ths; |
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cs->alm_sec = alm_sec; |
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cs->alm_min = alm_min; |
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cs->alm_hr = alm_hr; |
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cs->sdr = sdr; |
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cs->int_data = icr; |
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cs->int_mask = int_mask; |
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} |
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/* |
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* Restore CIA state |
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*/ |
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void MOS6526::SetState(MOS6526State *cs) |
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{ |
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pra = cs->pra; |
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prb = cs->prb; |
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ddra = cs->ddra; |
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ddrb = cs->ddrb; |
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ta = (cs->ta_hi << 8) | cs->ta_lo; |
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tb = (cs->tb_hi << 8) | cs->tb_lo; |
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latcha = cs->latcha; |
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latchb = cs->latchb; |
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cra = cs->cra; |
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crb = cs->crb; |
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tod_10ths = cs->tod_10ths; |
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tod_sec = cs->tod_sec; |
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tod_min = cs->tod_min; |
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tod_hr = cs->tod_hr; |
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alm_10ths = cs->alm_10ths; |
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alm_sec = cs->alm_sec; |
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alm_min = cs->alm_min; |
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alm_hr = cs->alm_hr; |
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sdr = cs->sdr; |
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icr = cs->int_data; |
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int_mask = cs->int_mask; |
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tod_halt = false; |
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ta_cnt_phi2 = ((cra & 0x21) == 0x01); |
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tb_cnt_phi2 = ((crb & 0x61) == 0x01); |
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tb_cnt_ta = ((crb & 0x61) == 0x41); |
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} |
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/* |
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* Read from register (CIA 1) |
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*/ |
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uint8 MOS6526_1::ReadRegister(uint16 adr) |
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{ |
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switch (adr) { |
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case 0x00: { |
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uint8 ret = pra | ~ddra, tst = (prb | ~ddrb) & Joystick1; |
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if (!(tst & 0x01)) ret &= RevMatrix[0]; // AND all active columns |
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if (!(tst & 0x02)) ret &= RevMatrix[1]; |
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if (!(tst & 0x04)) ret &= RevMatrix[2]; |
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if (!(tst & 0x08)) ret &= RevMatrix[3]; |
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if (!(tst & 0x10)) ret &= RevMatrix[4]; |
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if (!(tst & 0x20)) ret &= RevMatrix[5]; |
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if (!(tst & 0x40)) ret &= RevMatrix[6]; |
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if (!(tst & 0x80)) ret &= RevMatrix[7]; |
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return ret & Joystick2; |
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} |
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case 0x01: { |
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uint8 ret = ~ddrb, tst = (pra | ~ddra) & Joystick2; |
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if (!(tst & 0x01)) ret &= KeyMatrix[0]; // AND all active rows |
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if (!(tst & 0x02)) ret &= KeyMatrix[1]; |
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if (!(tst & 0x04)) ret &= KeyMatrix[2]; |
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if (!(tst & 0x08)) ret &= KeyMatrix[3]; |
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if (!(tst & 0x10)) ret &= KeyMatrix[4]; |
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if (!(tst & 0x20)) ret &= KeyMatrix[5]; |
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if (!(tst & 0x40)) ret &= KeyMatrix[6]; |
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if (!(tst & 0x80)) ret &= KeyMatrix[7]; |
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return (ret | (prb & ddrb)) & Joystick1; |
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} |
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case 0x02: return ddra; |
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case 0x03: return ddrb; |
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case 0x04: return ta; |
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case 0x05: return ta >> 8; |
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case 0x06: return tb; |
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case 0x07: return tb >> 8; |
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case 0x08: tod_halt = false; return tod_10ths; |
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case 0x09: return tod_sec; |
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case 0x0a: return tod_min; |
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case 0x0b: tod_halt = true; return tod_hr; |
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case 0x0c: return sdr; |
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case 0x0d: { |
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uint8 ret = icr; // Read and clear ICR |
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icr = 0; |
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the_cpu->ClearCIAIRQ(); // Clear IRQ |
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return ret; |
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} |
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case 0x0e: return cra; |
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case 0x0f: return crb; |
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} |
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return 0; // Can't happen |
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} |
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/* |
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* Read from register (CIA 2) |
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*/ |
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uint8 MOS6526_2::ReadRegister(uint16 adr) |
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{ |
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switch (adr) { |
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case 0x00: |
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return (pra | ~ddra) & 0x3f |
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| IECLines & the_cpu_1541->IECLines; |
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case 0x01: return prb | ~ddrb; |
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case 0x02: return ddra; |
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case 0x03: return ddrb; |
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case 0x04: return ta; |
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case 0x05: return ta >> 8; |
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case 0x06: return tb; |
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case 0x07: return tb >> 8; |
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case 0x08: tod_halt = false; return tod_10ths; |
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case 0x09: return tod_sec; |
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case 0x0a: return tod_min; |
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case 0x0b: tod_halt = true; return tod_hr; |
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case 0x0c: return sdr; |
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case 0x0d: { |
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uint8 ret = icr; // Read and clear ICR |
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icr = 0; |
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the_cpu->ClearNMI(); // Clear NMI |
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return ret; |
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} |
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case 0x0e: return cra; |
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case 0x0f: return crb; |
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} |
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return 0; // Can't happen |
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} |
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/* |
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* Write to register (CIA 1) |
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*/ |
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// Write to port B, check for lightpen interrupt |
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inline void MOS6526_1::check_lp(void) |
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{ |
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if ((prb | ~ddrb) & 0x10 != prev_lp) |
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the_vic->TriggerLightpen(); |
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prev_lp = (prb | ~ddrb) & 0x10; |
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} |
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void MOS6526_1::WriteRegister(uint16 adr, uint8 byte) |
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{ |
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switch (adr) { |
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case 0x0: pra = byte; break; |
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case 0x1: |
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prb = byte; |
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check_lp(); |
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break; |
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case 0x2: ddra = byte; break; |
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case 0x3: |
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ddrb = byte; |
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check_lp(); |
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break; |
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case 0x4: latcha = (latcha & 0xff00) | byte; break; |
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case 0x5: |
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latcha = (latcha & 0xff) | (byte << 8); |
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if (!(cra & 1)) // Reload timer if stopped |
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ta = latcha; |
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break; |
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case 0x6: latchb = (latchb & 0xff00) | byte; break; |
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case 0x7: |
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latchb = (latchb & 0xff) | (byte << 8); |
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if (!(crb & 1)) // Reload timer if stopped |
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tb = latchb; |
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break; |
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case 0x8: |
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if (crb & 0x80) |
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alm_10ths = byte & 0x0f; |
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else |
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tod_10ths = byte & 0x0f; |
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break; |
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case 0x9: |
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if (crb & 0x80) |
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alm_sec = byte & 0x7f; |
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else |
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tod_sec = byte & 0x7f; |
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break; |
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case 0xa: |
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if (crb & 0x80) |
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alm_min = byte & 0x7f; |
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else |
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tod_min = byte & 0x7f; |
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break; |
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case 0xb: |
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if (crb & 0x80) |
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alm_hr = byte & 0x9f; |
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else |
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tod_hr = byte & 0x9f; |
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break; |
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case 0xc: |
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sdr = byte; |
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TriggerInterrupt(8); // Fake SDR interrupt for programs that need it |
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break; |
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case 0xd: |
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if (ThePrefs.CIAIRQHack) // Hack for addressing modes that read from the address |
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icr = 0; |
| 343 |
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if (byte & 0x80) { |
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int_mask |= byte & 0x7f; |
| 345 |
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if (icr & int_mask & 0x1f) { // Trigger IRQ if pending |
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icr |= 0x80; |
| 347 |
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the_cpu->TriggerCIAIRQ(); |
| 348 |
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} |
| 349 |
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} else |
| 350 |
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int_mask &= ~byte; |
| 351 |
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break; |
| 352 |
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| 353 |
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case 0xe: |
| 354 |
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cra = byte & 0xef; |
| 355 |
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if (byte & 0x10) // Force load |
| 356 |
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ta = latcha; |
| 357 |
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ta_cnt_phi2 = ((byte & 0x21) == 0x01); |
| 358 |
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break; |
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case 0xf: |
| 361 |
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crb = byte & 0xef; |
| 362 |
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if (byte & 0x10) // Force load |
| 363 |
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tb = latchb; |
| 364 |
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tb_cnt_phi2 = ((byte & 0x61) == 0x01); |
| 365 |
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tb_cnt_ta = ((byte & 0x61) == 0x41); |
| 366 |
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break; |
| 367 |
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} |
| 368 |
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} |
| 369 |
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| 370 |
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| 371 |
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/* |
| 372 |
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* Write to register (CIA 2) |
| 373 |
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*/ |
| 374 |
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| 375 |
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void MOS6526_2::WriteRegister(uint16 adr, uint8 byte) |
| 376 |
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{ |
| 377 |
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switch (adr) { |
| 378 |
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case 0x0:{ |
| 379 |
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pra = byte; |
| 380 |
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byte = ~pra & ddra; |
| 381 |
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the_vic->ChangedVA(byte & 3); |
| 382 |
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uint8 old_lines = IECLines; |
| 383 |
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IECLines = (byte << 2) & 0x80 // DATA |
| 384 |
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| (byte << 2) & 0x40 // CLK |
| 385 |
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| (byte << 1) & 0x10; // ATN |
| 386 |
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if ((IECLines ^ old_lines) & 0x10) { // ATN changed |
| 387 |
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the_cpu_1541->NewATNState(); |
| 388 |
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if (old_lines & 0x10) // ATN 1->0 |
| 389 |
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the_cpu_1541->IECInterrupt(); |
| 390 |
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} |
| 391 |
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break; |
| 392 |
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} |
| 393 |
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case 0x1: prb = byte; break; |
| 394 |
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| 395 |
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case 0x2: |
| 396 |
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ddra = byte; |
| 397 |
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the_vic->ChangedVA(~(pra | ~ddra) & 3); |
| 398 |
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break; |
| 399 |
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case 0x3: ddrb = byte; break; |
| 400 |
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| 401 |
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case 0x4: latcha = (latcha & 0xff00) | byte; break; |
| 402 |
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case 0x5: |
| 403 |
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latcha = (latcha & 0xff) | (byte << 8); |
| 404 |
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if (!(cra & 1)) // Reload timer if stopped |
| 405 |
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ta = latcha; |
| 406 |
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break; |
| 407 |
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| 408 |
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case 0x6: latchb = (latchb & 0xff00) | byte; break; |
| 409 |
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case 0x7: |
| 410 |
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latchb = (latchb & 0xff) | (byte << 8); |
| 411 |
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if (!(crb & 1)) // Reload timer if stopped |
| 412 |
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tb = latchb; |
| 413 |
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break; |
| 414 |
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| 415 |
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case 0x8: |
| 416 |
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if (crb & 0x80) |
| 417 |
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alm_10ths = byte & 0x0f; |
| 418 |
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else |
| 419 |
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tod_10ths = byte & 0x0f; |
| 420 |
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break; |
| 421 |
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case 0x9: |
| 422 |
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if (crb & 0x80) |
| 423 |
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alm_sec = byte & 0x7f; |
| 424 |
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else |
| 425 |
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tod_sec = byte & 0x7f; |
| 426 |
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break; |
| 427 |
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case 0xa: |
| 428 |
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if (crb & 0x80) |
| 429 |
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alm_min = byte & 0x7f; |
| 430 |
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else |
| 431 |
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tod_min = byte & 0x7f; |
| 432 |
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break; |
| 433 |
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case 0xb: |
| 434 |
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if (crb & 0x80) |
| 435 |
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alm_hr = byte & 0x9f; |
| 436 |
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else |
| 437 |
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tod_hr = byte & 0x9f; |
| 438 |
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break; |
| 439 |
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| 440 |
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case 0xc: |
| 441 |
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sdr = byte; |
| 442 |
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TriggerInterrupt(8); // Fake SDR interrupt for programs that need it |
| 443 |
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break; |
| 444 |
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| 445 |
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case 0xd: |
| 446 |
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if (ThePrefs.CIAIRQHack) |
| 447 |
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icr = 0; |
| 448 |
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if (byte & 0x80) { |
| 449 |
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int_mask |= byte & 0x7f; |
| 450 |
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if (icr & int_mask & 0x1f) { // Trigger NMI if pending |
| 451 |
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icr |= 0x80; |
| 452 |
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the_cpu->TriggerNMI(); |
| 453 |
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} |
| 454 |
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} else |
| 455 |
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int_mask &= ~byte; |
| 456 |
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break; |
| 457 |
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| 458 |
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case 0xe: |
| 459 |
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cra = byte & 0xef; |
| 460 |
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if (byte & 0x10) // Force load |
| 461 |
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ta = latcha; |
| 462 |
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ta_cnt_phi2 = ((byte & 0x21) == 0x01); |
| 463 |
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break; |
| 464 |
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| 465 |
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case 0xf: |
| 466 |
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crb = byte & 0xef; |
| 467 |
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if (byte & 0x10) // Force load |
| 468 |
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tb = latchb; |
| 469 |
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tb_cnt_phi2 = ((byte & 0x61) == 0x01); |
| 470 |
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tb_cnt_ta = ((byte & 0x61) == 0x41); |
| 471 |
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break; |
| 472 |
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} |
| 473 |
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} |
| 474 |
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| 475 |
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| 476 |
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/* |
| 477 |
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* Count CIA TOD clock (called during VBlank) |
| 478 |
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*/ |
| 479 |
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| 480 |
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void MOS6526::CountTOD(void) |
| 481 |
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{ |
| 482 |
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uint8 lo, hi; |
| 483 |
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| 484 |
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// Decrement frequency divider |
| 485 |
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if (tod_divider) |
| 486 |
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tod_divider--; |
| 487 |
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else { |
| 488 |
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| 489 |
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// Reload divider according to 50/60 Hz flag |
| 490 |
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if (cra & 0x80) |
| 491 |
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tod_divider = 4; |
| 492 |
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else |
| 493 |
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tod_divider = 5; |
| 494 |
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| 495 |
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// 1/10 seconds |
| 496 |
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tod_10ths++; |
| 497 |
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if (tod_10ths > 9) { |
| 498 |
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tod_10ths = 0; |
| 499 |
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| 500 |
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// Seconds |
| 501 |
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lo = (tod_sec & 0x0f) + 1; |
| 502 |
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hi = tod_sec >> 4; |
| 503 |
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if (lo > 9) { |
| 504 |
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lo = 0; |
| 505 |
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hi++; |
| 506 |
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} |
| 507 |
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if (hi > 5) { |
| 508 |
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tod_sec = 0; |
| 509 |
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| 510 |
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// Minutes |
| 511 |
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lo = (tod_min & 0x0f) + 1; |
| 512 |
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hi = tod_min >> 4; |
| 513 |
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if (lo > 9) { |
| 514 |
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lo = 0; |
| 515 |
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hi++; |
| 516 |
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} |
| 517 |
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if (hi > 5) { |
| 518 |
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tod_min = 0; |
| 519 |
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| 520 |
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// Hours |
| 521 |
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lo = (tod_hr & 0x0f) + 1; |
| 522 |
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hi = (tod_hr >> 4) & 1; |
| 523 |
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tod_hr &= 0x80; // Keep AM/PM flag |
| 524 |
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if (lo > 9) { |
| 525 |
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lo = 0; |
| 526 |
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hi++; |
| 527 |
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} |
| 528 |
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tod_hr |= (hi << 4) | lo; |
| 529 |
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if ((tod_hr & 0x1f) > 0x11) |
| 530 |
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tod_hr = tod_hr & 0x80 ^ 0x80; |
| 531 |
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} else |
| 532 |
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tod_min = (hi << 4) | lo; |
| 533 |
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} else |
| 534 |
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tod_sec = (hi << 4) | lo; |
| 535 |
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} |
| 536 |
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| 537 |
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// Alarm time reached? Trigger interrupt if enabled |
| 538 |
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if (tod_10ths == alm_10ths && tod_sec == alm_sec && |
| 539 |
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tod_min == alm_min && tod_hr == alm_hr) |
| 540 |
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TriggerInterrupt(4); |
| 541 |
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} |
| 542 |
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} |
| 543 |
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| 544 |
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| 545 |
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/* |
| 546 |
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* Trigger IRQ (CIA 1) |
| 547 |
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*/ |
| 548 |
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| 549 |
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void MOS6526_1::TriggerInterrupt(int bit) |
| 550 |
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{ |
| 551 |
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icr |= bit; |
| 552 |
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if (int_mask & bit) { |
| 553 |
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icr |= 0x80; |
| 554 |
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the_cpu->TriggerCIAIRQ(); |
| 555 |
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} |
| 556 |
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} |
| 557 |
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| 558 |
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| 559 |
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/* |
| 560 |
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* Trigger NMI (CIA 2) |
| 561 |
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*/ |
| 562 |
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| 563 |
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void MOS6526_2::TriggerInterrupt(int bit) |
| 564 |
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{ |
| 565 |
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icr |= bit; |
| 566 |
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if (int_mask & bit) { |
| 567 |
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icr |= 0x80; |
| 568 |
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the_cpu->TriggerNMI(); |
| 569 |
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} |
| 570 |
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} |
