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root/cebix/Frodo4/Src/CIA.h
Revision: 1.3
Committed: 2004-01-12T15:13:20Z (20 years, 2 months ago) by cebix
Content type: text/plain
Branch: MAIN
Changes since 1.2: +1 -1 lines
Log Message:
Happy New Year!

File Contents

# Content
1 /*
2 * CIA.h - 6526 emulation
3 *
4 * Frodo (C) 1994-1997,2002-2004 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 bool ta_irq_next_cycle, // Flag: Trigger TA IRQ in next cycle
71 tb_irq_next_cycle, // Flag: Trigger TB IRQ in next cycle
72 has_new_cra, // Flag: New value for CRA pending
73 has_new_crb; // Flag: New value for CRB pending
74 char ta_state, tb_state; // Timer A/B states
75 uint8 new_cra, new_crb; // New values for CRA/CRB
76 #endif
77 };
78
79
80 class MOS6526_1 : public MOS6526 {
81 public:
82 MOS6526_1(MOS6510 *CPU, MOS6569 *VIC);
83
84 void Reset(void);
85 uint8 ReadRegister(uint16 adr);
86 void WriteRegister(uint16 adr, uint8 byte);
87 virtual void TriggerInterrupt(int bit);
88
89 uint8 KeyMatrix[8]; // C64 keyboard matrix, 1 bit/key (0: key down, 1: key up)
90 uint8 RevMatrix[8]; // Reversed keyboard matrix
91
92 uint8 Joystick1; // Joystick 1 AND value
93 uint8 Joystick2; // Joystick 2 AND value
94
95 private:
96 void check_lp(void);
97
98 MOS6569 *the_vic;
99
100 uint8 prev_lp; // Previous state of LP line (bit 4)
101 };
102
103
104 class MOS6526_2 : public MOS6526{
105 public:
106 MOS6526_2(MOS6510 *CPU, MOS6569 *VIC, MOS6502_1541 *CPU1541);
107
108 void Reset(void);
109 uint8 ReadRegister(uint16 adr);
110 void WriteRegister(uint16 adr, uint8 byte);
111 virtual void TriggerInterrupt(int bit);
112
113 uint8 IECLines; // State of IEC lines (bit 7 - DATA, bit 6 - CLK, bit 4 - ATN)
114
115 private:
116 MOS6569 *the_vic;
117 MOS6502_1541 *the_cpu_1541;
118 };
119
120
121 // CIA state
122 struct MOS6526State {
123 uint8 pra;
124 uint8 ddra;
125 uint8 prb;
126 uint8 ddrb;
127 uint8 ta_lo;
128 uint8 ta_hi;
129 uint8 tb_lo;
130 uint8 tb_hi;
131 uint8 tod_10ths;
132 uint8 tod_sec;
133 uint8 tod_min;
134 uint8 tod_hr;
135 uint8 sdr;
136 uint8 int_data; // Pending interrupts
137 uint8 cra;
138 uint8 crb;
139 // Additional registers
140 uint16 latcha; // Timer latches
141 uint16 latchb;
142 uint8 alm_10ths; // Alarm time
143 uint8 alm_sec;
144 uint8 alm_min;
145 uint8 alm_hr;
146 uint8 int_mask; // Enabled interrupts
147 };
148
149
150 /*
151 * Emulate CIA for one cycle/raster line
152 */
153
154 #ifdef FRODO_SC
155 inline void MOS6526::CheckIRQs(void)
156 {
157 // Trigger pending interrupts
158 if (ta_irq_next_cycle) {
159 ta_irq_next_cycle = false;
160 TriggerInterrupt(1);
161 }
162 if (tb_irq_next_cycle) {
163 tb_irq_next_cycle = false;
164 TriggerInterrupt(2);
165 }
166 }
167 #else
168 inline void MOS6526::EmulateLine(int cycles)
169 {
170 unsigned long tmp;
171
172 // Timer A
173 if (ta_cnt_phi2) {
174 ta = tmp = ta - cycles; // Decrement timer
175
176 if (tmp > 0xffff) { // Underflow?
177 ta = latcha; // Reload timer
178
179 if (cra & 8) { // One-shot?
180 cra &= 0xfe;
181 ta_cnt_phi2 = false;
182 }
183 TriggerInterrupt(1);
184 if (tb_cnt_ta) { // Timer B counting underflows of Timer A?
185 tb = tmp = tb - 1; // tmp = --tb doesn't work
186 if (tmp > 0xffff) goto tb_underflow;
187 }
188 }
189 }
190
191 // Timer B
192 if (tb_cnt_phi2) {
193 tb = tmp = tb - cycles; // Decrement timer
194
195 if (tmp > 0xffff) { // Underflow?
196 tb_underflow:
197 tb = latchb;
198
199 if (crb & 8) { // One-shot?
200 crb &= 0xfe;
201 tb_cnt_phi2 = false;
202 tb_cnt_ta = false;
203 }
204 TriggerInterrupt(2);
205 }
206 }
207 }
208 #endif
209
210 #endif