-
Notifications
You must be signed in to change notification settings - Fork 0
/
opcodes.cpp
170 lines (152 loc) · 5.58 KB
/
opcodes.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
/*
ok this actually should maybe all be deleted because the jump
table isn't created in memory which is pretty bad for optimizations
this is created at runtime which is sloww w w w w
although i think this is a cute implementation </3
*/
enum CPUFunction {
ADC, AND, ASL, BCC, BCS, BEQ, BIT, BMI, BNE, BPL, BRK,
BVC, BVS, CLC, CLD, CLI, CLV, CMP, CPX, CPY, DEC, DEX,
DEY, EOR, INC, INX, INY, JMP, JSR, LDA, LDX, LDY, LSR,
NOP, ORA, PHA, PHP, PLA, PLP, ROL, ROR, RTI, RTS, SBC,
SEC, SED, SEI, STA, STX, STY, TAX, TAY, TSX, TXA, TXS,
TYA, ISC, SLO, RLA, SRE, RRA, DCP, LAX, AHX, STP, SAX,
TAS, SHY, SHX, LAS
};
enum AddressingMode {
IMPLIED, IMMEDIATE, ZERO_PAGE, ZERO_PAGE_X,
ZERO_PAGE_Y, ABSOLUTE, ABSOLUTE_X, ABSOLUTE_Y,
INDIRECT, INDIRECT_X, INDIRECT_Y, RELATIVE,
ACCUMULATOR
};
uint8_t BYTES_PER_MODE[] = {
1, 2, 2, 2, 2, 3, 3,
3, 2, 2, 2, 2, 1
};
CPUFunction ALL_FUNCTIONS[] = {
BRK, ORA, STP, SLO, NOP, ORA, ASL, SLO, PHP, ORA,
ASL, NOP, NOP, ORA, ASL, SLO, BPL, ORA, STP, SLO,
NOP, ORA, ASL, SLO, CLC, ORA, NOP, SLO, NOP, ORA,
ASL, SLO, JSR, AND, STP, RLA, BIT, AND, ROL, RLA,
PLP, AND, ROL, NOP, BIT, AND, ROL, RLA, BMI, AND,
STP, RLA, NOP, AND, ROL, RLA, SEC, AND, NOP, RLA,
NOP, AND, ROL, RLA, RTI, EOR, STP, SRE, NOP, EOR,
LSR, SRE, PHA, EOR, LSR, NOP, JMP, EOR, LSR, SRE,
BVC, EOR, STP, SRE, NOP, EOR, LSR, SRE, CLI, EOR,
NOP, SRE, NOP, EOR, LSR, SRE, RTS, ADC, STP, RRA,
NOP, ADC, ROR, RRA, PLA, ADC, ROR, NOP, JMP, ADC,
ROR, RRA, BVS, ADC, STP, RRA, NOP, ADC, ROR, RRA,
SEI, ADC, NOP, RRA, NOP, ADC, ROR, RRA, NOP, STA,
NOP, SAX, STY, STA, STX, SAX, DEY, NOP, TXA, NOP,
STY, STA, STX, SAX, BCC, STA, STP, AHX, STY, STA,
STX, SAX, TYA, STA, TXS, TAS, SHY, STA, SHX, AHX,
LDY, LDA, LDX, LAX, LDY, LDA, LDX, LAX, TAY, LDA,
TAX, NOP, LDY, LDA, LDX, LAX, BCS, LDA, STP, LAX,
LDY, LDA, LDX, LAX, CLV, LDA, TSX, LAS, LDY, LDA,
LDX, LAX, CPY, CMP, NOP, DCP, CPY, CMP, DEC, DCP,
INY, CMP, DEX, NOP, CPY, CMP, DEC, DCP, BNE, CMP,
STP, DCP, NOP, CMP, DEC, DCP, CLD, CMP, NOP, DCP,
NOP, CMP, DEC, DCP, CPX, SBC, NOP, ISC, CPX, SBC,
INC, ISC, INX, SBC, NOP, SBC, CPX, SBC, INC, ISC,
BEQ, SBC, STP, ISC, NOP, SBC, INC, ISC, SED, SBC,
NOP, ISC, NOP, SBC, INC, ISC
};
uint8_t ALL_CYCLES[] = {
7, 6, 2, 8, 3, 3, 5, 5, 3, 2, 2, 2, 0, 4, 6, 6, 2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 2, 7, 4, 4, 7, 7,
6, 6, 2, 8, 3, 3, 5, 5, 4, 2, 2, 2, 0, 4, 6, 6, 2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 2, 7, 4, 4, 7, 7,
6, 6, 2, 8, 3, 3, 5, 5, 3, 2, 2, 2, 3, 4, 6, 6, 2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 2, 7, 4, 4, 7, 7,
6, 6, 2, 8, 3, 3, 5, 5, 4, 2, 2, 2, 5, 4, 7, 6, 2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 2, 7, 4, 4, 6, 7,
2, 6, 2, 6, 3, 3, 3, 3, 2, 2, 2, 2, 4, 4, 4, 4, 2, 6, 0, 5, 4, 4, 4, 4, 2, 5, 2, 4, 4, 5, 6, 7,
2, 6, 2, 6, 3, 3, 3, 3, 2, 2, 2, 2, 4, 4, 4, 4, 2, 5, 0, 5, 4, 4, 4, 4, 2, 4, 2, 4, 4, 4, 4, 7,
2, 6, 2, 8, 3, 3, 5, 5, 2, 2, 2, 2, 4, 4, 6, 6, 2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 2, 7, 4, 4, 7, 7,
2, 6, 2, 8, 3, 3, 5, 5, 2, 2, 2, 2, 4, 4, 6, 6, 2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 2, 7, 4, 4, 7, 7
};
AddressingMode ALL_ADDRESSES[] = {
IMMEDIATE, INDIRECT_X, IMMEDIATE, INDIRECT_X, ZERO_PAGE,
ZERO_PAGE, ZERO_PAGE, ZERO_PAGE, IMPLIED, IMMEDIATE,
ACCUMULATOR, IMMEDIATE, ABSOLUTE, ABSOLUTE, ABSOLUTE,
ABSOLUTE, RELATIVE, INDIRECT_Y, INDIRECT_Y, INDIRECT_Y,
ZERO_PAGE_X, ZERO_PAGE_X, ZERO_PAGE_X, ZERO_PAGE_X,
IMPLIED, ABSOLUTE_Y, IMPLIED, ABSOLUTE_Y, ABSOLUTE_X,
ABSOLUTE_X, ABSOLUTE_X, ABSOLUTE_X
};
// TODO: consider using std::array
CPUFunction no_page_boundary[] = {ASL, DEC, INC, LSR, ROL, ROR, STA};
class Opcode {
public:
uint8_t opcode;
uint8_t cycles;
uint8_t instruction_length;
AddressingMode addressing_mode;
bool page_boundary_cycle_allowed;
CPUFunction instruction;
};
class OpcodeGenerator {
public:
Opcode* generate_all_opcodes();
void set_addressing_mode(Opcode& op);
void set_length_cycles(Opcode& op);
void set_instruction(Opcode& op);
};
void OpcodeGenerator::set_addressing_mode(Opcode& op) {
uint8_t opcode = op.opcode;
uint8_t address_mask = opcode & 0x1f;
uint8_t upper_mask = opcode & 0xe0;
AddressingMode opcode_admode;
opcode_admode = ALL_ADDRESSES[address_mask];
// exceptions
if (opcode == 0x20) {
opcode_admode = ABSOLUTE;
} else if (opcode == 0x6c) {
opcode_admode = INDIRECT;
} else if (
upper_mask >= 0x80 &&
upper_mask <= 0xa0 &&
address_mask >= 0x16 &&
address_mask <= 0x17
) {
opcode_admode = ZERO_PAGE_Y;
} else if (
upper_mask >= 0x80 &&
upper_mask <= 0xa0 &&
address_mask >= 0x1e &&
address_mask <= 0x1f
) {
opcode_admode = ABSOLUTE_Y;
}
op.addressing_mode = opcode_admode;
}
void OpcodeGenerator::set_length_cycles(Opcode& op) {
AddressingMode addressing_mode = op.addressing_mode;
op.instruction_length = BYTES_PER_MODE[addressing_mode];
op.cycles = ALL_CYCLES[op.opcode];
}
void OpcodeGenerator::set_instruction(Opcode& op) {
op.instruction = ALL_FUNCTIONS[op.opcode];
if (
op.addressing_mode == ABSOLUTE_X ||
op.addressing_mode == ABSOLUTE_Y ||
op.addressing_mode == INDIRECT_Y
) {
bool set_page_boundary = true;
for (int i = 0; i < 7; i++) {
if (op.instruction == no_page_boundary[i]) {
set_page_boundary = false;
break;
}
}
}
}
Opcode* OpcodeGenerator::generate_all_opcodes() {
static Opcode all_opcodes[256];
for (int i = 0; i <= 0xff; ++i) {
Opcode current = all_opcodes[i];
current.opcode = i;
all_opcodes[i] = current;
set_addressing_mode(current);
set_length_cycles(current);
set_instruction(current);
all_opcodes[i] = current;
}
return all_opcodes;
}