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root/cebix/mon/src/mon_6502.cpp
Revision: 1.1
Committed: 1999-10-04T19:31:09Z (24 years, 7 months ago) by cebix
Branch: MAIN
Branch point for: cebix
Log Message: 
Initial revision

File Contents

# Content
1 /*
2 * mon_6502.cpp - 6502 disassembler
3 *
4 * (C) 1997-1999 Christian Bauer
5 */
6
7 #include <stdio.h>
8
9 #include "mon.h"
10 #include "mon_6502.h"
11
12
13 // Addressing modes
14 enum {
15 A_IMPL,
16 A_ACCU, // A
17 A_IMM, // #zz
18 A_REL, // Branches
19 A_ZERO, // zz
20 A_ZEROX, // zz,x
21 A_ZEROY, // zz,y
22 A_ABS, // zzzz
23 A_ABSX, // zzzz,x
24 A_ABSY, // zzzz,y
25 A_IND, // (zzzz)
26 A_INDX, // (zz,x)
27 A_INDY // (zz),y
28 };
29
30 // Mnemonics
31 enum {
32 M_ADC, M_AND, M_ASL, M_BCC, M_BCS, M_BEQ, M_BIT, M_BMI, M_BNE, M_BPL,
33 M_BRK, M_BVC, M_BVS, M_CLC, M_CLD, M_CLI, M_CLV, M_CMP, M_CPX, M_CPY,
34 M_DEC, M_DEX, M_DEY, M_EOR, M_INC, M_INX, M_INY, M_JMP, M_JSR, M_LDA,
35 M_LDX, M_LDY, M_LSR, M_NOP, M_ORA, M_PHA, M_PHP, M_PLA, M_PLP, M_ROL,
36 M_ROR, M_RTI, M_RTS, M_SBC, M_SEC, M_SED, M_SEI, M_STA, M_STX, M_STY,
37 M_TAX, M_TAY, M_TSX, M_TXA, M_TXS, M_TYA,
38
39 M_ILLEGAL, // Undocumented opcodes start here
40
41 M_IANC, M_IANE, M_IARR, M_IASR, M_IDCP, M_IISB, M_IJAM, M_INOP, M_ILAS,
42 M_ILAX, M_ILXA, M_IRLA, M_IRRA, M_ISAX, M_ISBC, M_ISBX, M_ISHA, M_ISHS,
43 M_ISHX, M_ISHY, M_ISLO, M_ISRE,
44
45 M_MAXIMUM // Highest element
46 };
47
48 // Mnemonic for each opcode
49 static const char mnemonic[256] = {
50 M_BRK , M_ORA , M_IJAM, M_ISLO, M_INOP, M_ORA, M_ASL , M_ISLO, // 00
51 M_PHP , M_ORA , M_ASL , M_IANC, M_INOP, M_ORA, M_ASL , M_ISLO,
52 M_BPL , M_ORA , M_IJAM, M_ISLO, M_INOP, M_ORA, M_ASL , M_ISLO, // 10
53 M_CLC , M_ORA , M_INOP, M_ISLO, M_INOP, M_ORA, M_ASL , M_ISLO,
54 M_JSR , M_AND , M_IJAM, M_IRLA, M_BIT , M_AND, M_ROL , M_IRLA, // 20
55 M_PLP , M_AND , M_ROL , M_IANC, M_BIT , M_AND, M_ROL , M_IRLA,
56 M_BMI , M_AND , M_IJAM, M_IRLA, M_INOP, M_AND, M_ROL , M_IRLA, // 30
57 M_SEC , M_AND , M_INOP, M_IRLA, M_INOP, M_AND, M_ROL , M_IRLA,
58 M_RTI , M_EOR , M_IJAM, M_ISRE, M_INOP, M_EOR, M_LSR , M_ISRE, // 40
59 M_PHA , M_EOR , M_LSR , M_IASR, M_JMP , M_EOR, M_LSR , M_ISRE,
60 M_BVC , M_EOR , M_IJAM, M_ISRE, M_INOP, M_EOR, M_LSR , M_ISRE, // 50
61 M_CLI , M_EOR , M_INOP, M_ISRE, M_INOP, M_EOR, M_LSR , M_ISRE,
62 M_RTS , M_ADC , M_IJAM, M_IRRA, M_INOP, M_ADC, M_ROR , M_IRRA, // 60
63 M_PLA , M_ADC , M_ROR , M_IARR, M_JMP , M_ADC, M_ROR , M_IRRA,
64 M_BVS , M_ADC , M_IJAM, M_IRRA, M_INOP, M_ADC, M_ROR , M_IRRA, // 70
65 M_SEI , M_ADC , M_INOP, M_IRRA, M_INOP, M_ADC, M_ROR , M_IRRA,
66 M_INOP, M_STA , M_INOP, M_ISAX, M_STY , M_STA, M_STX , M_ISAX, // 80
67 M_DEY , M_INOP, M_TXA , M_IANE, M_STY , M_STA, M_STX , M_ISAX,
68 M_BCC , M_STA , M_IJAM, M_ISHA, M_STY , M_STA, M_STX , M_ISAX, // 90
69 M_TYA , M_STA , M_TXS , M_ISHS, M_ISHY, M_STA, M_ISHX, M_ISHA,
70 M_LDY , M_LDA , M_LDX , M_ILAX, M_LDY , M_LDA, M_LDX , M_ILAX, // a0
71 M_TAY , M_LDA , M_TAX , M_ILXA, M_LDY , M_LDA, M_LDX , M_ILAX,
72 M_BCS , M_LDA , M_IJAM, M_ILAX, M_LDY , M_LDA, M_LDX , M_ILAX, // b0
73 M_CLV , M_LDA , M_TSX , M_ILAS, M_LDY , M_LDA, M_LDX , M_ILAX,
74 M_CPY , M_CMP , M_INOP, M_IDCP, M_CPY , M_CMP, M_DEC , M_IDCP, // c0
75 M_INY , M_CMP , M_DEX , M_ISBX, M_CPY , M_CMP, M_DEC , M_IDCP,
76 M_BNE , M_CMP , M_IJAM, M_IDCP, M_INOP, M_CMP, M_DEC , M_IDCP, // d0
77 M_CLD , M_CMP , M_INOP, M_IDCP, M_INOP, M_CMP, M_DEC , M_IDCP,
78 M_CPX , M_SBC , M_INOP, M_IISB, M_CPX , M_SBC, M_INC , M_IISB, // e0
79 M_INX , M_SBC , M_NOP , M_ISBC, M_CPX , M_SBC, M_INC , M_IISB,
80 M_BEQ , M_SBC , M_IJAM, M_IISB, M_INOP, M_SBC, M_INC , M_IISB, // f0
81 M_SED , M_SBC , M_INOP, M_IISB, M_INOP, M_SBC, M_INC , M_IISB
82 };
83
84 // Addressing mode for each opcode
85 static const char adr_mode[256] = {
86 A_IMPL, A_INDX, A_IMPL, A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // 00
87 A_IMPL, A_IMM , A_ACCU, A_IMM , A_ABS , A_ABS , A_ABS , A_ABS,
88 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROX, A_ZEROX, // 10
89 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSX , A_ABSX,
90 A_ABS , A_INDX, A_IMPL, A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // 20
91 A_IMPL, A_IMM , A_ACCU, A_IMM , A_ABS , A_ABS , A_ABS , A_ABS,
92 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROX, A_ZEROX, // 30
93 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSX , A_ABSX,
94 A_IMPL, A_INDX, A_IMPL, A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // 40
95 A_IMPL, A_IMM , A_ACCU, A_IMM , A_ABS , A_ABS , A_ABS , A_ABS,
96 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROX, A_ZEROX, // 50
97 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSX , A_ABSX,
98 A_IMPL, A_INDX, A_IMPL, A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // 60
99 A_IMPL, A_IMM , A_ACCU, A_IMM , A_IND , A_ABS , A_ABS , A_ABS,
100 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROX, A_ZEROX, // 70
101 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSX , A_ABSX,
102 A_IMM , A_INDX, A_IMM , A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // 80
103 A_IMPL, A_IMM , A_IMPL, A_IMM , A_ABS , A_ABS , A_ABS , A_ABS,
104 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROY, A_ZEROY, // 90
105 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSY , A_ABSY,
106 A_IMM , A_INDX, A_IMM , A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // a0
107 A_IMPL, A_IMM , A_IMPL, A_IMM , A_ABS , A_ABS , A_ABS , A_ABS,
108 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROY, A_ZEROY, // b0
109 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSY , A_ABSY,
110 A_IMM , A_INDX, A_IMM , A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // c0
111 A_IMPL, A_IMM , A_IMPL, A_IMM , A_ABS , A_ABS , A_ABS , A_ABS,
112 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROX, A_ZEROX, // d0
113 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSX , A_ABSX,
114 A_IMM , A_INDX, A_IMM , A_INDX, A_ZERO , A_ZERO , A_ZERO , A_ZERO, // e0
115 A_IMPL, A_IMM , A_IMPL, A_IMM , A_ABS , A_ABS , A_ABS , A_ABS,
116 A_REL , A_INDY, A_IMPL, A_INDY, A_ZEROX, A_ZEROX, A_ZEROX, A_ZEROX, // f0
117 A_IMPL, A_ABSY, A_IMPL, A_ABSY, A_ABSX , A_ABSX , A_ABSX , A_ABSX
118 };
119
120 // Chars for each mnemonic
121 static const char mnem_1[] = "aaabbbbbbbbbbcccccccdddeiiijjllllnopppprrrrssssssstttttt?aaaadijnlllrrsssssssss";
122 static const char mnem_2[] = "dnscceimnprvvllllmppeeeonnnmsdddsorhhlloottbeeetttaasxxy?nnrscsaoaaxlrabbhhhhlr";
123 static const char mnem_3[] = "cdlcsqtielkcscdivpxycxyrcxypraxyrpaapaplrisccdiaxyxyxasa?cerrpbmpsxaaaxcxasxyoe";
124
125 // Instruction length for each addressing mode
126 static const char adr_length[] = {1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 2, 2};
127
128
129 /*
130 * Disassemble one instruction, return number of bytes
131 */
132
133 int disass_6502(FILE *f, uint32 adr, uint8 op, uint8 lo, uint8 hi)
134 {
135 char mode = adr_mode[op], mnem = mnemonic[op];
136
137 // Display instruction bytes in hex
138 switch (adr_length[mode]) {
139 case 1:
140 fprintf(f, "%02x\t\t", op);
141 break;
142
143 case 2:
144 fprintf(f, "%02x %02x\t\t", op, lo);
145 break;
146
147 case 3:
148 fprintf(f, "%02x %02x %02x\t", op, lo, hi);
149 break;
150 }
151
152 // Tag undocumented opcodes with an asterisk
153 if (mnem > M_ILLEGAL)
154 fputc('*', f);
155 else
156 fputc(' ', f);
157
158 // Print mnemonic
159 fprintf(f, "%c%c%c ", mnem_1[mnem], mnem_2[mnem], mnem_3[mnem]);
160
161 // Print argument
162 switch (mode) {
163 case A_IMPL:
164 break;
165
166 case A_ACCU:
167 fprintf(f, "a");
168 break;
169
170 case A_IMM:
171 fprintf(f, "#$%02x", lo);
172 break;
173
174 case A_REL:
175 fprintf(f, "$%04lx", (adr + 2) + (int8)lo);
176 break;
177
178 case A_ZERO:
179 fprintf(f, "$%02x", lo);
180 break;
181
182 case A_ZEROX:
183 fprintf(f, "$%02x,x", lo);
184 break;
185
186 case A_ZEROY:
187 fprintf(f, "$%02x,y", lo);
188 break;
189
190 case A_ABS:
191 fprintf(f, "$%04x", (hi << 8) | lo);
192 break;
193
194 case A_ABSX:
195 fprintf(f, "$%04x,x", (hi << 8) | lo);
196 break;
197
198 case A_ABSY:
199 fprintf(f, "$%04x,y", (hi << 8) | lo);
200 break;
201
202 case A_IND:
203 fprintf(f, "($%04x)", (hi << 8) | lo);
204 break;
205
206 case A_INDX:
207 fprintf(f, "($%02x,x)", lo);
208 break;
209
210 case A_INDY:
211 fprintf(f, "($%02x),y", lo);
212 break;
213 }
214
215 fputc('\n', f);
216 return adr_length[mode];
217 }