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Refactored disassembly code to combine steps
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@tcarmelveilleux
tcarmelveilleux committed Jul 24, 2014
1 parent 7985830 commit 4c9a2da
Showing 1 changed file with 37 additions and 107 deletions.
144 changes: 37 additions & 107 deletions dcc6502.c
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Original file line number Diff line number Diff line change
Expand Up @@ -43,8 +43,8 @@
#define ABSIY 6 /* Absolute indexed with Y */
#define ZEPIX 7 /* Zero page indexed with X */
#define ZEPIY 8 /* Zero page indexed with Y */
#define INDIN 9 /* Indexed indirect (with x) */
#define ININD 10 /* Indirect indexed (with y) */
#define INDIN 9 /* Indexed indirect (with X) */
#define ININD 10 /* Indirect indexed (with Y) */
#define RELAT 11 /* Relative */
#define ACCUM 12 /* Accumulator */

Expand Down Expand Up @@ -304,7 +304,7 @@ void emit_header(char *filename, int fsize, uint16_t org) {
}

/* This function appends cycle counting to the comment block */
void append_cycle(char *input, uint8_t entry, uint16_t arg, uint16_t cur_PC) {
char *append_cycle(char *input, uint8_t entry) {
char tmpstr[256];
int cycles = opcode_table[entry].cycles;

Expand All @@ -316,6 +316,7 @@ void append_cycle(char *input, uint8_t entry, uint16_t arg, uint16_t cur_PC) {
}

strcat(input, tmpstr);
return (input + strlen(input));
}

void add_nes_str(char *instr, char *instr2) {
Expand Down Expand Up @@ -368,14 +369,13 @@ void append_nes(char *input, uint16_t arg) {
// FIXME: Refactor code to reduce line duplication and make more readable
/* This function disassembles the opcode at the PC and outputs it in *output */
void disassemble(char *output) {
uint8_t tmp_byte1, opcode;
char tmpstr[256], opcode_repr[256], hex_dump[256];
word tmp_word;
int i;
int entry = 0;
int found = 0;
int len = 0;
unsigned int current_addr = org + PC;
uint8_t tmp_byte1, opcode;
word tmp_word = 0;
uint16_t current_addr = org + PC;

opcode = buffer[current_addr - org];

Expand All @@ -390,12 +390,11 @@ void disassemble(char *output) {
sprintf(opcode_repr, ".byte $%02x", opcode);
if (hex_output) {
sprintf(hex_dump, "$%04X> %02X:", current_addr, opcode);
len = sprintf(output, "%-16s%-16s; INVALID OPCODE !!!\n", hex_dump, opcode_repr);
sprintf(output, "%-16s%-16s; INVALID OPCODE !!!\n", hex_dump, opcode_repr);
} else {
sprintf(hex_dump, "$%04X", current_addr);
len = sprintf(output, "%-8s%-16s; INVALID OPCODE !!!\n", hex_dump, opcode_repr);
sprintf(output, "%-8s%-16s; INVALID OPCODE !!!\n", hex_dump, opcode_repr);
}
output += len;
} else {
switch (opcode_table[entry].addressing) {
case IMMED:
Expand All @@ -407,38 +406,24 @@ void disassemble(char *output) {
} else {
sprintf(hex_dump, "$%04X", current_addr);
}
len = sprintf(output, DUMP_FORMAT, hex_dump, opcode_repr);
output += len;
sprintf(output, DUMP_FORMAT, hex_dump, opcode_repr);

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(output, entry, current_addr, current_addr);
}
PC++;
break;

case ABSOL:
/* Get address */
tmp_word = LOAD_WORD(buffer, PC);

if (hex_output)
sprintf(tmpstr, "$%04X> %02X %02X%02X:\t%s $%02X%02X\t;", current_addr, opcode, LOW_PART(tmp_word), HIGH_PART(tmp_word), name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
else
sprintf(tmpstr, "$%04X\t%s $%02X%02X\t;", current_addr, name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, tmp_word, current_addr);
sprintf(opcode_repr, "%s $%02X%02X", name_table[opcode_table[entry].name], HIGH_PART(tmp_word), LOW_PART(tmp_word));
if (hex_output) {
sprintf(hex_dump, "$%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);

/* Add NES port info if necessary */
if (nes_mode) {
append_nes(tmpstr, tmp_word);
}
strncpy(output, tmpstr, 254);
PC += 2;
break;

case ZEROP:
PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
Expand All @@ -448,30 +433,17 @@ void disassemble(char *output) {
} else {
sprintf(tmpstr, "$%04X\t%s $%02X\t\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC-1, org+PC-1);
}

strncpy(output, tmpstr, 254);
break;

case IMPLI:
if (hex_output) {
sprintf(tmpstr, "$%04X> %02X:\t%s\t\t;", org+PC, opcode, name_table[opcode_table[entry].name]);
} else {
sprintf(tmpstr, "$%04X\t%s\t\t;", org+PC, name_table[opcode_table[entry].name]);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC, org+PC);
}

strncpy(output, tmpstr, 254);
break;

case INDIA:
PC++;
PC++;
Expand All @@ -483,14 +455,8 @@ void disassemble(char *output) {
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));
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, tmp_word, org+PC-2);
}

strncpy(output, tmpstr, 254);
break;

case ABSIX:
PC++;
PC++;
Expand All @@ -502,19 +468,8 @@ void disassemble(char *output) {
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));
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, tmp_word, org+PC-2);
}

/* Add NES port info if necessary */
if (nes_mode) {
append_nes(tmpstr, tmp_word);
}

strncpy(output, tmpstr, 254);
break;

case ABSIY:
PC++;
PC++;
Expand All @@ -526,19 +481,8 @@ void disassemble(char *output) {
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));
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, tmp_word, org+PC-2);
}

/* Add NES port info if necessary */
if (nes_mode) {
append_nes(tmpstr, tmp_word);
}

strncpy(output, tmpstr, 254);
break;

case ZEPIX:
PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
Expand All @@ -549,14 +493,8 @@ void disassemble(char *output) {
sprintf(tmpstr, "$%04X\t%s $%02X,X\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC-1, org+PC-1);
}

strncpy(output, tmpstr, 254);
break;

case ZEPIY:
PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
Expand All @@ -567,14 +505,8 @@ void disassemble(char *output) {
sprintf(tmpstr, "$%04X\t%s $%02X,Y\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC-1, org+PC-1);
}

strncpy(output, tmpstr, 254);
break;

case INDIN:
PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
Expand All @@ -585,14 +517,8 @@ void disassemble(char *output) {
sprintf(tmpstr, "$%04X\t%s ($%02X,X)\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC-1, org+PC-1);
}

strncpy(output, tmpstr, 254);
break;

case ININD:
PC++;
tmp_byte1 = buffer[PC]; /* Get low byte of address */
Expand All @@ -603,48 +529,52 @@ void disassemble(char *output) {
sprintf(tmpstr, "$%04X\t%s ($%02X),Y\t;", org+PC-1, name_table[opcode_table[entry].name], tmp_byte1);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC-1, org+PC-1);
}

strncpy(output, tmpstr, 254);
break;

case RELAT:
PC++;
tmp_byte1 = buffer[PC]; /* Get relative modifier */

// FIXME: Resolve undefined behavior of cast for signed relative addressing
if (hex_output) {
sprintf(tmpstr, "$%04X> %02X %02X:\t%s $%04X\t\t;", org+PC-1, opcode, tmp_byte1, name_table[opcode_table[entry].name], (org+PC)+(signed char)(tmp_byte1)+1);
} else {
sprintf(tmpstr, "$%04X\t%s $%04X\t;", org+PC-1, name_table[opcode_table[entry].name], (org+PC)+(signed char)(tmp_byte1)+1);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC, org+PC);
}

strncpy(output, tmpstr, 254);
break;

case ACCUM:
if (hex_output) {
sprintf(tmpstr, "$%04X> %02X:\t%s A\t\t;", org+PC, opcode, name_table[opcode_table[entry].name]);
} else {
sprintf(tmpstr, "$%04X\t%s A\t\t;", org+PC, name_table[opcode_table[entry].name]);
}

/* Add cycle count if necessary */
if (cycle_counting) {
append_cycle(tmpstr, entry, org+PC, org+PC);
}

strncpy(output, tmpstr, 254);
break;
default:
break;
}

output += strlen(output);

/* Add cycle count if necessary */
if (cycle_counting) {
output = append_cycle(output, entry);
}

/* Add NES port info if necessary */
switch (opcode_table[entry].addressing) {
case ABSOL:
case ABSIX:
case ABSIY:
if (nes_mode) {
append_nes(output, tmp_word);
}
break;
default:
/* Other addressing modes: not enough info to add NES register annotation */
break;
}
}
Expand Down

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