6502/dcc6502
1
0
Fork 0
mirror of https://github.com/tcarmelveilleux/dcc6502.git synced 2024-06-13 07:29:35 +00:00
Code Issues Projects Releases Wiki Activity

Greatly simplified disassembly code

Browse Source
This commit is contained in:
Tennessee Carmel-Veilleux 2014-07-24 17:22:40 -04:00
parent 4c9a2daeb4
commit 0ffacd9e5d
1 changed files with 163 additions and 160 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

155
dcc6502.c
View File

@ -369,8 +369,9 @@ void append_nes(char *input, uint16_t arg) {
// FIXME: Refactor code to reduce line duplication and make more readable // FIXME: Refactor code to reduce line duplication and make more readable
/* This function disassembles the opcode at the PC and outputs it in *output */ /* This function disassembles the opcode at the PC and outputs it in *output */
void disassemble(char *output) { void disassemble(char *output) {
char tmpstr[256], opcode_repr[256], hex_dump[256]; char opcode_repr[256], hex_dump[256];
int i; int i;
int len = 0;
int entry = 0; int entry = 0;
int found = 0; int found = 0;
uint8_t tmp_byte1, opcode; uint8_t tmp_byte1, opcode;
@ -378,14 +379,20 @@ void disassemble(char *output) {
uint16_t current_addr = org + PC; uint16_t current_addr = org + PC;
opcode = buffer[current_addr - org]; opcode = buffer[current_addr - org];
opcode_repr[0] = '\0';
hex_dump[0] = '\0';
// Linear search for opcode
for (i = 0; i < NUMBER_OPCODES; i++) { for (i = 0; i < NUMBER_OPCODES; i++) {
if (opcode == opcode_table[i].number) { if (opcode == opcode_table[i].number) {
found = 1; /* Found the opcode */ /* Found the opcode, record its table index */
entry = i; /* Note the entry number in the table */ found = 1;
entry = i;
} }
} }
// TODO: Normalize %02x versus %02X
// For opcode not found, terminate early
if (!found) { if (!found) {
sprintf(opcode_repr, ".byte $%02x", opcode); sprintf(opcode_repr, ".byte $%02x", opcode);
if (hex_output) { if (hex_output) {
@ -395,169 +402,166 @@ void disassemble(char *output) {
sprintf(hex_dump, "$%04X", current_addr); sprintf(hex_dump, "$%04X", current_addr);
sprintf(output, "%-8s%-16s; INVALID OPCODE !!!\n", hex_dump, opcode_repr); sprintf(output, "%-8s%-16s; INVALID OPCODE !!!\n", hex_dump, opcode_repr);
} }
} else { return;
}
// Opcode found in table: disassemble properly according to addressing mode
// Set hex dump to default single address format. Will be overwritten
// by more complex output in case of hex dump mode enabled
sprintf(hex_dump, "$%04X", current_addr);
switch (opcode_table[entry].addressing) { switch (opcode_table[entry].addressing) {
case IMMED: case IMMED:
tmp_byte1 = buffer[PC + 1]; /* Get immediate value */ /* Get immediate value operand */
tmp_byte1 = buffer[PC + 1];
PC++;
sprintf(opcode_repr, "%s #$%02x", name_table[opcode_table[entry].name], tmp_byte1); sprintf(opcode_repr, "%s #$%02x", name_table[opcode_table[entry].name], tmp_byte1);
if (hex_output) { if (hex_output) {
sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1); sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1);
} else {
sprintf(hex_dump, "$%04X", current_addr);
} }
sprintf(output, DUMP_FORMAT, hex_dump, opcode_repr);
PC++;
break; break;
case ABSOL: case ABSOL:
/* Get address */ /* Get absolute address operand */
tmp_word = LOAD_WORD(buffer, PC); tmp_word = LOAD_WORD(buffer, PC);
PC += 2;
sprintf(opcode_repr, "%s $%02X%02X", name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word)); sprintf(opcode_repr, "%s $%02X%02X", name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
if (hex_output) { if (hex_output) {
sprintf(hex_dump, "$%04X> %02X %02X%02X:", current_addr, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word)); sprintf(hex_dump, "$%04X> %02X %02X%02X:", current_addr, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word));
} else {
sprintf(hex_dump, "$%04X", current_addr);
} }
sprintf(output, DUMP_FORMAT, hex_dump, opcode_repr);
PC += 2;
break; break;
case ZEROP: case ZEROP:
/* Get zero page address */
tmp_byte1 = buffer[PC + 1];
PC++; PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
sprintf(opcode_repr, "%s $%02X", name_table[opcode_table[entry].name], tmp_byte1);
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X:\t%s $%02X\t\t;", org+PC-1, opcode, tmp_byte1, name_table[opcode_table[entry].name], tmp_byte1); sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1);
} else {
sprintf(tmpstr, "$%04X\t%s $%02X\t\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
} }
strncpy(output, tmpstr, 254);
break; break;
case IMPLI: case IMPLI:
sprintf(opcode_repr, "%s", name_table[opcode_table[entry].name]);
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X:\t%s\t\t;", org+PC, opcode, name_table[opcode_table[entry].name]); sprintf(hex_dump, "$%04X> %02X:", current_addr, opcode);
} else {
sprintf(tmpstr, "$%04X\t%s\t\t;", org+PC, name_table[opcode_table[entry].name]);
} }
strncpy(output, tmpstr, 254);
break; break;
case INDIA: case INDIA:
PC++; /* Get indirection address */
PC++; tmp_word = LOAD_WORD(buffer, PC);
tmp_word = LOAD_WORD(buffer, PC-2); PC += 2;
sprintf(opcode_repr, "%s ($%02X%02X)", name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X%02X:\t%s ($%02X%02X)\t;", org+PC-2, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word), name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word)); sprintf(hex_dump, "$%04X> %02X %02X%02X:", current_addr, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word));
} else {
sprintf(tmpstr, "$%04X\t%s ($%02X%02X)\t;", org+PC-2, name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
} }
strncpy(output, tmpstr, 254);
break; break;
case ABSIX: case ABSIX:
PC++; /* Get base address */
PC++; tmp_word = LOAD_WORD(buffer, PC);
tmp_word = LOAD_WORD(buffer, PC-2); PC += 2;
sprintf(opcode_repr, "%s $%02X%02X,X", name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X%02X:\t%s $%02X%02X,X\t;", org+PC-2, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word), name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word)); sprintf(hex_dump, "$%04X> %02X %02X%02X:", current_addr, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word));
} else {
sprintf(tmpstr, "$%04X\t%s $%02X%02X,X\t;", org+PC-2, name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
} }
strncpy(output, tmpstr, 254);
break; break;
case ABSIY: case ABSIY:
PC++; /* Get baser address */
PC++; tmp_word = LOAD_WORD(buffer, PC);
tmp_word = LOAD_WORD(buffer, PC-2); PC += 2;
sprintf(opcode_repr, "%s $%02X%02X,Y", name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X%02X:\t%s $%02X%02X,Y\t;", org+PC-2, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word), name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word)); sprintf(hex_dump, "$%04X> %02X %02X%02X:", current_addr, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word));
} else {
sprintf(tmpstr, "$%04X\t%s $%02X%02X,Y\t;", org+PC-2, name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
} }
strncpy(output, tmpstr, 254);
break; break;
case ZEPIX: case ZEPIX:
/* Get zero-page base address */
tmp_byte1 = buffer[PC + 1];
PC++; PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
sprintf(opcode_repr, "%s $%02X,X", name_table[opcode_table[entry].name], tmp_byte1);
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X:\t%s $%02X,X\t\t;", org+PC-1, opcode, tmp_byte1, name_table[opcode_table[entry].name], tmp_byte1); sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1);
} else {
sprintf(tmpstr, "$%04X\t%s $%02X,X\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
} }
strncpy(output, tmpstr, 254);
break; break;
case ZEPIY: case ZEPIY:
/* Get zero-page base address */
tmp_byte1 = buffer[PC + 1];
PC++; PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
sprintf(opcode_repr, "%s $%02X,Y", name_table[opcode_table[entry].name], tmp_byte1);
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X:\t%s $%02X,Y\t\t;", org+PC-1, opcode, tmp_byte1, name_table[opcode_table[entry].name], tmp_byte1); sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1);
} else {
sprintf(tmpstr, "$%04X\t%s $%02X,Y\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
} }
strncpy(output, tmpstr, 254);
break; break;
case INDIN: case INDIN:
/* Get zero-page base address */
tmp_byte1 = buffer[PC + 1];
PC++; PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
sprintf(opcode_repr, "%s ($%02X,X)", name_table[opcode_table[entry].name], tmp_byte1);
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X:\t%s ($%02X,X)\t\t;", org+PC-1, opcode, tmp_byte1, name_table[opcode_table[entry].name], tmp_byte1); sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1);
} else {
sprintf(tmpstr, "$%04X\t%s ($%02X,X)\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
} }
strncpy(output, tmpstr, 254);
break; break;
case ININD: case ININD:
/* Get zero-page base address */
tmp_byte1 = buffer[PC + 1];
PC++; PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
sprintf(opcode_repr, "%s ($%02X),Y", name_table[opcode_table[entry].name], tmp_byte1);
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X:\t%s ($%02X),Y\t\t;", org+PC-1, opcode, tmp_byte1, name_table[opcode_table[entry].name], tmp_byte1); sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1);
} else {
sprintf(tmpstr, "$%04X\t%s ($%02X),Y\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
} }
strncpy(output, tmpstr, 254);
break; break;
case RELAT: case RELAT:
/* Get relative modifier */
tmp_byte1 = buffer[PC + 1];
PC++; PC++;
tmp_byte1 = buffer[PC]; /* Get relative modifier */
// FIXME: Resolve undefined behavior of cast for signed relative addressing // Compute displacement from first byte after full instruction.
if (hex_output) { tmp_word = current_addr + 2;
sprintf(tmpstr, "$%04X> %02X %02X:\t%s $%04X\t\t;", org+PC-1, opcode, tmp_byte1, name_table[opcode_table[entry].name], (org+PC)+(signed char)(tmp_byte1)+1); if (tmp_byte1 > 0x7Fu) {
tmp_word -= ((~tmp_byte1 & 0x7Fu) + 1);
} else { } else {
sprintf(tmpstr, "$%04X\t%s $%04X\t;", org+PC-1, name_table[opcode_table[entry].name], (org+PC)+(signed char)(tmp_byte1)+1); tmp_word += tmp_byte1 & 0x7Fu;
}
sprintf(opcode_repr, "%s $%04X", name_table[opcode_table[entry].name], tmp_word);
if (hex_output) {
sprintf(hex_dump, "$%04X> %02X %02X:", current_addr, opcode, tmp_byte1);
} }
strncpy(output, tmpstr, 254);
break; break;
case ACCUM: case ACCUM:
sprintf(opcode_repr, "%s A", name_table[opcode_table[entry].name]);
if (hex_output) { if (hex_output) {
sprintf(tmpstr, "$%04X> %02X:\t%s A\t\t;", org+PC, opcode, name_table[opcode_table[entry].name]); sprintf(hex_dump, "$%04X> %02X:", current_addr, opcode);
} else {
sprintf(tmpstr, "$%04X\t%s A\t\t;", org+PC, name_table[opcode_table[entry].name]);
} }
strncpy(output, tmpstr, 254);
break; break;
default: default:
// Will not happen since each entry in opcode_table has address mode set
break; break;
} }
output += strlen(output); len = sprintf(output, DUMP_FORMAT, hex_dump, opcode_repr);
output += len;
/* Add cycle count if necessary */ /* Add cycle count if necessary */
if (cycle_counting) { if (cycle_counting) {
@ -578,7 +582,6 @@ void disassemble(char *output) {
break; break;
} }
} }
}
void version(void) { void version(void) {
fprintf(stderr, "DCC6502 %s (C)1998-2014 Tennessee Carmel-Veilleux <veilleux@tentech.ca>\n", VERSION_INFO); fprintf(stderr, "DCC6502 %s (C)1998-2014 Tennessee Carmel-Veilleux <veilleux@tentech.ca>\n", VERSION_INFO);