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root/cebix/Frodo4/Src/CIA.h
Revision: 1.5
Committed: 2010-04-25T12:02:13Z (12 years, 7 months ago) by cebix
Content type: text/plain
Branch: MAIN
CVS Tags: HEAD
Changes since 1.4: +6 -2 lines
Log Message:
TA/TB output to PB6/PB7

File Contents

# Content
1 /*
2 * CIA.h - 6526 emulation
3 *
4 * Frodo Copyright (C) Christian Bauer
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #ifndef _CIA_H
22 #define _CIA_H
23
24 #include "Prefs.h"
25
26
27 class MOS6510;
28 class MOS6502_1541;
29 class MOS6569;
30 struct MOS6526State;
31
32
33 class MOS6526 {
34 public:
35 MOS6526(MOS6510 *CPU);
36
37 void Reset(void);
38 void GetState(MOS6526State *cs);
39 void SetState(MOS6526State *cs);
40 #ifdef FRODO_SC
41 void CheckIRQs(void);
42 void EmulateCycle(void);
43 #else
44 void EmulateLine(int cycles);
45 #endif
46 void CountTOD(void);
47 virtual void TriggerInterrupt(int bit)=0;
48
49 protected:
50 MOS6510 *the_cpu; // Pointer to 6510
51
52 uint8 pra, prb, ddra, ddrb;
53
54 uint16 ta, tb, latcha, latchb;
55
56 uint8 tod_10ths, tod_sec, tod_min, tod_hr;
57 uint8 alm_10ths, alm_sec, alm_min, alm_hr;
58
59 uint8 sdr, icr, cra, crb;
60 uint8 int_mask;
61
62 int tod_divider; // TOD frequency divider
63
64 bool tod_halt, // Flag: TOD halted
65 ta_cnt_phi2, // Flag: Timer A is counting Phi 2
66 tb_cnt_phi2, // Flag: Timer B is counting Phi 2
67 tb_cnt_ta; // Flag: Timer B is counting underflows of Timer A
68
69 #ifdef FRODO_SC
70 uint8 timer_on_pb(uint8 prb);
71
72 bool ta_irq_next_cycle, // Flag: Trigger TA IRQ in next cycle
73 tb_irq_next_cycle, // Flag: Trigger TB IRQ in next cycle
74 has_new_cra, // Flag: New value for CRA pending
75 has_new_crb, // Flag: New value for CRB pending
76 ta_toggle, // TA output to PB6 toggle state
77 tb_toggle; // TB output to PB7 toggle state
78 char ta_state, tb_state; // Timer A/B states
79 uint8 new_cra, new_crb; // New values for CRA/CRB
80 #endif
81 };
82
83
84 class MOS6526_1 : public MOS6526 {
85 public:
86 MOS6526_1(MOS6510 *CPU, MOS6569 *VIC);
87
88 void Reset(void);
89 uint8 ReadRegister(uint16 adr);
90 void WriteRegister(uint16 adr, uint8 byte);
91 virtual void TriggerInterrupt(int bit);
92
93 uint8 KeyMatrix[8]; // C64 keyboard matrix, 1 bit/key (0: key down, 1: key up)
94 uint8 RevMatrix[8]; // Reversed keyboard matrix
95
96 uint8 Joystick1; // Joystick 1 AND value
97 uint8 Joystick2; // Joystick 2 AND value
98
99 private:
100 void check_lp(void);
101
102 MOS6569 *the_vic;
103
104 uint8 prev_lp; // Previous state of LP line (bit 4)
105 };
106
107
108 class MOS6526_2 : public MOS6526{
109 public:
110 MOS6526_2(MOS6510 *CPU, MOS6569 *VIC, MOS6502_1541 *CPU1541);
111
112 void Reset(void);
113 uint8 ReadRegister(uint16 adr);
114 void WriteRegister(uint16 adr, uint8 byte);
115 virtual void TriggerInterrupt(int bit);
116
117 uint8 IECLines; // State of IEC lines (bit 7 - DATA, bit 6 - CLK, bit 4 - ATN)
118
119 private:
120 MOS6569 *the_vic;
121 MOS6502_1541 *the_cpu_1541;
122 };
123
124
125 // CIA state
126 struct MOS6526State {
127 uint8 pra;
128 uint8 ddra;
129 uint8 prb;
130 uint8 ddrb;
131 uint8 ta_lo;
132 uint8 ta_hi;
133 uint8 tb_lo;
134 uint8 tb_hi;
135 uint8 tod_10ths;
136 uint8 tod_sec;
137 uint8 tod_min;
138 uint8 tod_hr;
139 uint8 sdr;
140 uint8 int_data; // Pending interrupts
141 uint8 cra;
142 uint8 crb;
143 // Additional registers
144 uint16 latcha; // Timer latches
145 uint16 latchb;
146 uint8 alm_10ths; // Alarm time
147 uint8 alm_sec;
148 uint8 alm_min;
149 uint8 alm_hr;
150 uint8 int_mask; // Enabled interrupts
151 };
152
153
154 /*
155 * Emulate CIA for one cycle/raster line
156 */
157
158 #ifdef FRODO_SC
159 inline void MOS6526::CheckIRQs(void)
160 {
161 // Trigger pending interrupts
162 if (ta_irq_next_cycle) {
163 ta_irq_next_cycle = false;
164 TriggerInterrupt(1);
165 }
166 if (tb_irq_next_cycle) {
167 tb_irq_next_cycle = false;
168 TriggerInterrupt(2);
169 }
170 }
171 #else
172 inline void MOS6526::EmulateLine(int cycles)
173 {
174 unsigned long tmp;
175
176 // Timer A
177 if (ta_cnt_phi2) {
178 ta = tmp = ta - cycles; // Decrement timer
179
180 if (tmp > 0xffff) { // Underflow?
181 ta = latcha; // Reload timer
182
183 if (cra & 8) { // One-shot?
184 cra &= 0xfe;
185 ta_cnt_phi2 = false;
186 }
187 TriggerInterrupt(1);
188 if (tb_cnt_ta) { // Timer B counting underflows of Timer A?
189 tb = tmp = tb - 1; // tmp = --tb doesn't work
190 if (tmp > 0xffff) goto tb_underflow;
191 }
192 }
193 }
194
195 // Timer B
196 if (tb_cnt_phi2) {
197 tb = tmp = tb - cycles; // Decrement timer
198
199 if (tmp > 0xffff) { // Underflow?
200 tb_underflow:
201 tb = latchb;
202
203 if (crb & 8) { // One-shot?
204 crb &= 0xfe;
205 tb_cnt_phi2 = false;
206 tb_cnt_ta = false;
207 }
208 TriggerInterrupt(2);
209 }
210 }
211 }
212 #endif
213
214 #endif