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root/cebix/mon/src/mon_6502.cpp
Revision: 1.1
Committed: 1999-10-04T19:31:09Z (25 years, 1 month ago) by cebix
Branch: MAIN
Branch point for: cebix
Log Message: 
Initial revision

File Contents

# User Rev Content
1 cebix 1.1 /*
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     }