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/* |
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* CIA.h - 6526 emulation |
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* |
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* Frodo Copyright (C) Christian Bauer |
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* |
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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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#ifndef _CIA_H |
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#define _CIA_H |
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|
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#include "Prefs.h" |
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|
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|
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class MOS6510; |
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class MOS6502_1541; |
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class MOS6569; |
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struct MOS6526State; |
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|
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|
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class MOS6526 { |
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public: |
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MOS6526(MOS6510 *CPU); |
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|
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void Reset(void); |
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void GetState(MOS6526State *cs); |
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void SetState(MOS6526State *cs); |
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#ifdef FRODO_SC |
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void CheckIRQs(void); |
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void EmulateCycle(void); |
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#else |
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void EmulateLine(int cycles); |
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#endif |
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void CountTOD(void); |
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virtual void TriggerInterrupt(int bit)=0; |
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|
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protected: |
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MOS6510 *the_cpu; // Pointer to 6510 |
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|
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uint8 pra, prb, ddra, ddrb; |
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|
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uint16 ta, tb, latcha, latchb; |
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|
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uint8 tod_10ths, tod_sec, tod_min, tod_hr; |
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uint8 alm_10ths, alm_sec, alm_min, alm_hr; |
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|
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uint8 sdr, icr, cra, crb; |
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uint8 int_mask; |
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|
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int tod_divider; // TOD frequency divider |
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|
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bool tod_halt, // Flag: TOD halted |
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ta_cnt_phi2, // Flag: Timer A is counting Phi 2 |
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tb_cnt_phi2, // Flag: Timer B is counting Phi 2 |
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tb_cnt_ta; // Flag: Timer B is counting underflows of Timer A |
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|
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#ifdef FRODO_SC |
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uint8 timer_on_pb(uint8 prb); |
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|
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bool ta_irq_next_cycle, // Flag: Trigger TA IRQ in next cycle |
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tb_irq_next_cycle, // Flag: Trigger TB IRQ in next cycle |
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has_new_cra, // Flag: New value for CRA pending |
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has_new_crb, // Flag: New value for CRB pending |
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ta_toggle, // TA output to PB6 toggle state |
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tb_toggle; // TB output to PB7 toggle state |
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char ta_state, tb_state; // Timer A/B states |
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uint8 new_cra, new_crb; // New values for CRA/CRB |
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#endif |
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}; |
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|
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|
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class MOS6526_1 : public MOS6526 { |
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public: |
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MOS6526_1(MOS6510 *CPU, MOS6569 *VIC); |
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|
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void Reset(void); |
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uint8 ReadRegister(uint16 adr); |
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void WriteRegister(uint16 adr, uint8 byte); |
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virtual void TriggerInterrupt(int bit); |
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|
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uint8 KeyMatrix[8]; // C64 keyboard matrix, 1 bit/key (0: key down, 1: key up) |
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uint8 RevMatrix[8]; // Reversed keyboard matrix |
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|
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uint8 Joystick1; // Joystick 1 AND value |
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uint8 Joystick2; // Joystick 2 AND value |
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|
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private: |
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void check_lp(void); |
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|
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MOS6569 *the_vic; |
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|
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uint8 prev_lp; // Previous state of LP line (bit 4) |
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}; |
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|
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|
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class MOS6526_2 : public MOS6526{ |
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public: |
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MOS6526_2(MOS6510 *CPU, MOS6569 *VIC, MOS6502_1541 *CPU1541); |
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|
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void Reset(void); |
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uint8 ReadRegister(uint16 adr); |
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void WriteRegister(uint16 adr, uint8 byte); |
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virtual void TriggerInterrupt(int bit); |
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|
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uint8 IECLines; // State of IEC lines (bit 7 - DATA, bit 6 - CLK, bit 4 - ATN) |
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|
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private: |
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MOS6569 *the_vic; |
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MOS6502_1541 *the_cpu_1541; |
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}; |
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|
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|
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// CIA state |
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struct MOS6526State { |
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uint8 pra; |
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uint8 ddra; |
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uint8 prb; |
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uint8 ddrb; |
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uint8 ta_lo; |
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uint8 ta_hi; |
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uint8 tb_lo; |
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uint8 tb_hi; |
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uint8 tod_10ths; |
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uint8 tod_sec; |
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uint8 tod_min; |
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uint8 tod_hr; |
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uint8 sdr; |
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uint8 int_data; // Pending interrupts |
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uint8 cra; |
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uint8 crb; |
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// Additional registers |
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uint16 latcha; // Timer latches |
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uint16 latchb; |
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uint8 alm_10ths; // Alarm time |
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uint8 alm_sec; |
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uint8 alm_min; |
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uint8 alm_hr; |
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uint8 int_mask; // Enabled interrupts |
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}; |
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|
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|
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/* |
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* Emulate CIA for one cycle/raster line |
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*/ |
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|
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#ifdef FRODO_SC |
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inline void MOS6526::CheckIRQs(void) |
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{ |
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// Trigger pending interrupts |
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if (ta_irq_next_cycle) { |
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ta_irq_next_cycle = false; |
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TriggerInterrupt(1); |
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} |
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if (tb_irq_next_cycle) { |
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tb_irq_next_cycle = false; |
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TriggerInterrupt(2); |
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} |
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} |
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#else |
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inline void MOS6526::EmulateLine(int cycles) |
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{ |
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unsigned long tmp; |
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|
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// Timer A |
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if (ta_cnt_phi2) { |
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ta = tmp = ta - cycles; // Decrement timer |
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|
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if (tmp > 0xffff) { // Underflow? |
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ta = latcha; // Reload timer |
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|
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if (cra & 8) { // One-shot? |
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cra &= 0xfe; |
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ta_cnt_phi2 = false; |
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} |
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TriggerInterrupt(1); |
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if (tb_cnt_ta) { // Timer B counting underflows of Timer A? |
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tb = tmp = tb - 1; // tmp = --tb doesn't work |
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if (tmp > 0xffff) goto tb_underflow; |
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} |
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} |
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} |
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|
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// Timer B |
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if (tb_cnt_phi2) { |
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tb = tmp = tb - cycles; // Decrement timer |
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|
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if (tmp > 0xffff) { // Underflow? |
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tb_underflow: |
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tb = latchb; |
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|
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if (crb & 8) { // One-shot? |
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crb &= 0xfe; |
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tb_cnt_phi2 = false; |
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tb_cnt_ta = false; |
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} |
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TriggerInterrupt(2); |
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} |
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} |
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} |
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#endif |
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|
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#endif |
