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bsnes/Core/debugger.c

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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "debugger.h"
#include "memory.h"
#include "z80_cpu.h"
#include "gb.h"
typedef struct {
enum {
LVALUE_MEMORY,
LVALUE_REG16,
LVALUE_REG_H,
LVALUE_REG_L,
} kind;
union {
unsigned short *register_address;
unsigned short memory_address;
};
} lvalue_t;
static unsigned short read_lvalue(GB_gameboy_t *gb, lvalue_t lvalue)
{
/* Not used until we add support for operators like += */
switch (lvalue.kind) {
case LVALUE_MEMORY:
return read_memory(gb, lvalue.memory_address);
case LVALUE_REG16:
return *lvalue.register_address;
case LVALUE_REG_L:
return *lvalue.register_address & 0x00FF;
case LVALUE_REG_H:
return *lvalue.register_address >> 8;
}
}
static void write_lvalue(GB_gameboy_t *gb, lvalue_t lvalue, unsigned short value)
{
switch (lvalue.kind) {
case LVALUE_MEMORY:
write_memory(gb, lvalue.memory_address, value);
return;
case LVALUE_REG16:
*lvalue.register_address = value;
return;
case LVALUE_REG_L:
*lvalue.register_address &= 0xFF00;
*lvalue.register_address |= value & 0xFF;
return;
case LVALUE_REG_H:
*lvalue.register_address &= 0x00FF;
*lvalue.register_address |= value << 8;
return;
}
}
static unsigned short add(unsigned short a, unsigned short b) {return a + b;};
static unsigned short sub(unsigned short a, unsigned short b) {return a - b;};
static unsigned short mul(unsigned short a, unsigned short b) {return a * b;};
static unsigned short _div(unsigned short a, unsigned short b) {
if (b == 0) {
return 0;
}
return a / b;
};
static unsigned short mod(unsigned short a, unsigned short b) {
if (b == 0) {
return 0;
}
return a % b;
};
static unsigned short and(unsigned short a, unsigned short b) {return a & b;};
static unsigned short or(unsigned short a, unsigned short b) {return a | b;};
static unsigned short xor(unsigned short a, unsigned short b) {return a ^ b;};
static unsigned short shleft(unsigned short a, unsigned short b) {return a << b;};
static unsigned short shright(unsigned short a, unsigned short b) {return a >> b;};
static unsigned short assign(GB_gameboy_t *gb, lvalue_t a, unsigned short b)
{
write_lvalue(gb, a, b);
return read_lvalue(gb, a);
}
static struct {
const char *string;
char priority;
unsigned short (*operator)(unsigned short, unsigned short);
unsigned short (*lvalue_operator)(GB_gameboy_t *, lvalue_t, unsigned short);
} operators[] =
{
// Yes. This is not C-like. But it makes much more sense.
// Deal with it.
{"+", 0, add},
{"-", 0, sub},
{"|", 0, or},
{"*", 1, mul},
{"/", 1, _div},
{"%", 1, mod},
{"&", 1, and},
{"^", 1, xor},
{"<<", 2, shleft},
{">>", 2, shright},
{"=", 2, NULL, assign},
};
unsigned short debugger_evaluate(GB_gameboy_t *gb, const char *string, unsigned int length, bool *error);
static lvalue_t debugger_evaluate_lvalue(GB_gameboy_t *gb, const char *string, unsigned int length, bool *error)
{
*error = false;
// Strip whitespace
while (length && (string[0] == ' ' || string[0] == '\n' || string[0] == '\r' || string[0] == '\t')) {
string++;
length--;
}
while (length && (string[length-1] == ' ' || string[length-1] == '\n' || string[length-1] == '\r' || string[length-1] == '\t')) {
length--;
}
if (length == 0)
{
gb_log(gb, "Expected expression.\n");
*error = true;
return (lvalue_t){0,};
}
if (string[0] == '(' && string[length - 1] == ')') {
// Attempt to strip parentheses
signed int depth = 0;
for (int i = 0; i < length; i++) {
if (string[i] == '(') depth++;
if (depth == 0) {
// First and last are not matching
depth = 1;
break;
}
if (string[i] == ')') depth--;
}
if (depth == 0) return debugger_evaluate_lvalue(gb, string + 1, length - 2, error);
}
else if (string[0] == '[' && string[length - 1] == ']') {
// Attempt to strip square parentheses (memory dereference)
signed int depth = 0;
for (int i = 0; i < length; i++) {
if (string[i] == '[') depth++;
if (depth == 0) {
// First and last are not matching
depth = 1;
break;
}
if (string[i] == ']') depth--;
}
if (depth == 0) {
return (lvalue_t){LVALUE_MEMORY, .memory_address = debugger_evaluate(gb, string + 1, length - 2, error)};
}
}
// Registers
if (string[0] == '$') {
if (length == 2) {
switch (string[1]) {
case 'a': return (lvalue_t){LVALUE_REG_H, .register_address = &gb->registers[GB_REGISTER_AF]};
case 'f': return (lvalue_t){LVALUE_REG_L, .register_address = &gb->registers[GB_REGISTER_AF]};
case 'b': return (lvalue_t){LVALUE_REG_H, .register_address = &gb->registers[GB_REGISTER_BC]};
case 'c': return (lvalue_t){LVALUE_REG_L, .register_address = &gb->registers[GB_REGISTER_BC]};
case 'd': return (lvalue_t){LVALUE_REG_H, .register_address = &gb->registers[GB_REGISTER_DE]};
case 'e': return (lvalue_t){LVALUE_REG_L, .register_address = &gb->registers[GB_REGISTER_DE]};
case 'h': return (lvalue_t){LVALUE_REG_H, .register_address = &gb->registers[GB_REGISTER_HL]};
case 'l': return (lvalue_t){LVALUE_REG_L, .register_address = &gb->registers[GB_REGISTER_HL]};
}
}
else if (length == 3) {
switch (string[1]) {
case 'a': if (string[2] == 'f') return (lvalue_t){LVALUE_REG16, .register_address = &gb->registers[GB_REGISTER_AF]};
case 'b': if (string[2] == 'c') return (lvalue_t){LVALUE_REG16, .register_address = &gb->registers[GB_REGISTER_BC]};
case 'd': if (string[2] == 'e') return (lvalue_t){LVALUE_REG16, .register_address = &gb->registers[GB_REGISTER_DE]};
case 'h': if (string[2] == 'l') return (lvalue_t){LVALUE_REG16, .register_address = &gb->registers[GB_REGISTER_HL]};
case 's': if (string[2] == 'p') return (lvalue_t){LVALUE_REG16, .register_address = &gb->registers[GB_REGISTER_SP]};
case 'p': if (string[2] == 'c') return (lvalue_t){LVALUE_REG16, .register_address = &gb->pc};
}
}
gb_log(gb, "Unknown register: %.*s\n", length, string);
*error = true;
return (lvalue_t){0,};
}
gb_log(gb, "Expression is not an lvalue: %.*s\n", length, string);
*error = true;
return (lvalue_t){0,};
}
unsigned short debugger_evaluate(GB_gameboy_t *gb, const char *string, unsigned int length, bool *error)
{
*error = false;
// Strip whitespace
while (length && (string[0] == ' ' || string[0] == '\n' || string[0] == '\r' || string[0] == '\t')) {
string++;
length--;
}
while (length && (string[length-1] == ' ' || string[length-1] == '\n' || string[length-1] == '\r' || string[length-1] == '\t')) {
length--;
}
if (length == 0)
{
gb_log(gb, "Expected expression.\n");
*error = true;
return -1;
}
if (string[0] == '(' && string[length - 1] == ')') {
// Attempt to strip parentheses
signed int depth = 0;
for (int i = 0; i < length; i++) {
if (string[i] == '(') depth++;
if (depth == 0) {
// First and last are not matching
depth = 1;
break;
}
if (string[i] == ')') depth--;
}
if (depth == 0) return debugger_evaluate(gb, string + 1, length - 2, error);
}
else if (string[0] == '[' && string[length - 1] == ']') {
// Attempt to strip square parentheses (memory dereference)
signed int depth = 0;
for (int i = 0; i < length; i++) {
if (string[i] == '[') depth++;
if (depth == 0) {
// First and last are not matching
depth = 1;
break;
}
if (string[i] == ']') depth--;
}
if (depth == 0) return read_memory(gb, debugger_evaluate(gb, string + 1, length - 2, error));
}
// Search for lowest priority operator
signed int depth = 0;
unsigned int operator_index = -1;
unsigned int operator_pos = 0;
for (int i = 0; i < length; i++) {
if (string[i] == '(') depth++;
else if (string[i] == ')') depth--;
else if (string[i] == '[') depth++;
else if (string[i] == ']') depth--;
else if (depth == 0) {
for (int j = 0; j < sizeof(operators) / sizeof(operators[0]); j++) {
if (strlen(operators[j].string) > length - i) continue; // Operator too big.
// Priority higher than what we already have.
if (operator_index != -1 && operators[operator_index].priority > operators[j].priority) continue;
if (memcmp(string + i, operators[j].string, strlen(operators[j].string)) == 0) {
// Found an operator!
operator_pos = i;
operator_index = j;
}
}
}
}
if (operator_index != -1) {
unsigned int right_start = (unsigned int)(operator_pos + strlen(operators[operator_index].string));
unsigned short right = debugger_evaluate(gb, string + right_start, length - right_start, error);
if (*error) return -1;
if (operators[operator_index].lvalue_operator) {
lvalue_t left = debugger_evaluate_lvalue(gb, string, operator_pos, error);
if (*error) return -1;
return operators[operator_index].lvalue_operator(gb, left, right);
}
unsigned short left = debugger_evaluate(gb, string, operator_pos, error);
if (*error) return -1;
return operators[operator_index].operator(left, right);
}
// Not an expression - must be a register or a literal
// Registers
if (string[0] == '$') {
if (length == 2) {
switch (string[1]) {
case 'a': return gb->registers[GB_REGISTER_AF] >> 8;
case 'f': return gb->registers[GB_REGISTER_AF] & 0xFF;
case 'b': return gb->registers[GB_REGISTER_BC] >> 8;
case 'c': return gb->registers[GB_REGISTER_BC] & 0xFF;
case 'd': return gb->registers[GB_REGISTER_DE] >> 8;
case 'e': return gb->registers[GB_REGISTER_DE] & 0xFF;
case 'h': return gb->registers[GB_REGISTER_HL] >> 8;
case 'l': return gb->registers[GB_REGISTER_HL] & 0xFF;
}
}
else if (length == 3) {
switch (string[1]) {
case 'a': if (string[2] == 'f') return gb->registers[GB_REGISTER_AF];
case 'b': if (string[2] == 'c') return gb->registers[GB_REGISTER_BC];
case 'd': if (string[2] == 'e') return gb->registers[GB_REGISTER_DE];
case 'h': if (string[2] == 'l') return gb->registers[GB_REGISTER_HL];
case 's': if (string[2] == 'p') return gb->registers[GB_REGISTER_SP];
case 'p': if (string[2] == 'c') return gb->pc;
}
}
gb_log(gb, "Unknown register: %.*s\n", length, string);
*error = true;
return -1;
}
char *end;
unsigned short literal = (unsigned short) (strtol(string, &end, 16));
if (end != string + length) {
gb_log(gb, "Failed to parse: %.*s\n", length, string);
*error = true;
return -1;
}
return literal;
}
typedef bool debugger_command_imp_t(GB_gameboy_t *gb, char *arguments);
typedef struct {
const char *command;
unsigned char min_length;
debugger_command_imp_t *implementation;
const char *help_string; // Null if should not appear in help
} debugger_command_t;
static const char *lstrip(const char *str)
{
while (*str == ' ' || *str == '\t') {
str++;
}
return str;
}
static bool cont(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments))) {
gb_log(gb, "Usage: continue\n");
return true;
}
gb->debug_stopped = false;
return false;
}
static bool next(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments))) {
gb_log(gb, "Usage: next\n");
return true;
}
gb->debug_stopped = false;
gb->debug_next_command = true;
gb->debug_call_depth = 0;
return false;
}
static bool step(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments))) {
gb_log(gb, "Usage: step\n");
return true;
}
return false;
}
static bool finish(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments))) {
gb_log(gb, "Usage: finish\n");
return true;
}
gb->debug_stopped = false;
gb->debug_fin_command = true;
gb->debug_call_depth = 0;
return false;
}
static bool registers(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments))) {
gb_log(gb, "Usage: registers\n");
return true;
}
gb_log(gb, "AF = %04x\n", gb->registers[GB_REGISTER_AF]);
gb_log(gb, "BC = %04x\n", gb->registers[GB_REGISTER_BC]);
gb_log(gb, "DE = %04x\n", gb->registers[GB_REGISTER_DE]);
gb_log(gb, "HL = %04x\n", gb->registers[GB_REGISTER_HL]);
gb_log(gb, "SP = %04x\n", gb->registers[GB_REGISTER_SP]);
gb_log(gb, "PC = %04x\n", gb->pc);
gb_log(gb, "TIMA = %d/%lu\n", gb->io_registers[GB_IO_TIMA], gb->tima_cycles);
gb_log(gb, "Display Controller: LY = %d/%lu\n", gb->io_registers[GB_IO_LY], gb->display_cycles % 456);
return true;
}
/* Find the index of the closest breakpoint equal or greater to addr */
static unsigned short find_breakpoint(GB_gameboy_t *gb, unsigned short addr)
{
if (!gb->breakpoints) {
return 0;
}
int min = 0;
int max = gb->n_breakpoints;
while (min < max) {
unsigned short pivot = (min + max) / 2;
if (gb->breakpoints[pivot] == addr) return pivot;
if (gb->breakpoints[pivot] > addr) {
max = pivot - 1;
}
else {
min = pivot + 1;
}
}
return (unsigned short) min;
}
static bool breakpoint(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments)) == 0) {
gb_log(gb, "Usage: breakpoint <expression>\n");
return true;
}
bool error;
unsigned short result = debugger_evaluate(gb, arguments, (unsigned int)strlen(arguments), &error);
if (error) return true;
unsigned short index = find_breakpoint(gb, result);
if (index < gb->n_breakpoints && gb->breakpoints[index] == result) {
gb_log(gb, "Breakpoint already set at %04x\n", result);
return true;
}
gb->breakpoints = realloc(gb->breakpoints, gb->n_breakpoints * sizeof(gb->breakpoints[0]));
memmove(&gb->breakpoints[index + 1], &gb->breakpoints[index], (gb->n_breakpoints - index) * sizeof(gb->breakpoints[0]));
gb->breakpoints[index] = result;
gb->n_breakpoints++;
gb_log(gb, "Breakpoint set at %04x\n", result);
return true;
}
static bool delete(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments)) == 0) {
gb_log(gb, "Delete all breakpoints? ");
char *answer = gb->input_callback(gb);
if (answer[0] == 'Y' || answer[0] == 'y') {
free(gb->breakpoints);
gb->breakpoints = NULL;
gb->n_breakpoints = 0;
}
return true;
}
bool error;
unsigned short result = debugger_evaluate(gb, arguments, (unsigned int)strlen(arguments), &error);
if (error) return true;
unsigned short index = find_breakpoint(gb, result);
if (index >= gb->n_breakpoints || gb->breakpoints[index] != result) {
gb_log(gb, "No breakpoint set at %04x\n", result);
return true;
}
gb->breakpoints = realloc(gb->breakpoints, gb->n_breakpoints * sizeof(gb->breakpoints[0]));
memmove(&gb->breakpoints[index], &gb->breakpoints[index + 1], (gb->n_breakpoints - index) * sizeof(gb->breakpoints[0]));
gb->n_breakpoints--;
gb_log(gb, "Breakpoint removed from %04x\n", result);
return true;
}
static bool list(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments))) {
gb_log(gb, "Usage: list\n");
return true;
}
if (gb->n_breakpoints == 0) {
gb_log(gb, "No breakpoints set.\n");
return true;
}
gb_log(gb, "%d breakpoint(s) set:\n", gb->n_breakpoints);
for (unsigned short i = 0; i < gb->n_breakpoints; i++) {
gb_log(gb, " %d. %04x\n", i + 1, gb->breakpoints[i]);
}
return true;
}
static bool should_break(GB_gameboy_t *gb, unsigned short addr)
{
unsigned short index = find_breakpoint(gb, addr);
if (index < gb->n_breakpoints && gb->breakpoints[index] == addr) {
return true;
}
return false;
}
static bool print(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments)) == 0) {
gb_log(gb, "Usage: print <expression>\n");
return true;
}
bool error;
unsigned short result = debugger_evaluate(gb, arguments, (unsigned int)strlen(arguments), &error);
if (!error) {
gb_log(gb, "=%04x\n", result);
}
return true;
}
static bool examine(GB_gameboy_t *gb, char *arguments)
{
if (strlen(lstrip(arguments)) == 0) {
gb_log(gb, "Usage: examine <expression>\n");
return true;
}
bool error;
unsigned short addr = debugger_evaluate(gb, arguments, (unsigned int)strlen(arguments), &error);
if (!error) {
gb_log(gb, "%4x: ", addr);
for (int i = 0; i < 16; i++) {
gb_log(gb, "%02x ", read_memory(gb, addr + i));
}
gb_log(gb, "\n");
}
return true;
}
static bool help(GB_gameboy_t *gb, char *arguments);
static const debugger_command_t commands[] = {
{"continue", 1, cont, "Continue running until next stop"},
{"next", 1, next, "Run the next instruction, skipping over function calls"},
{"step", 1, step, "Run the next instruction, stepping into function calls"},
{"finish", 1, finish, "Run until the current function returns"},
{"registers", 1, registers, "Print values of processor registers and other important registers"},
{"breakpoint", 1, breakpoint, "Move the breakpoint to a new position"},
{"list", 1, list, "List all set breakpoints"},
{"delete", 2, delete, "Delete a breakpoint by its address, or all breakpoints"},
{"print", 1, print, "Evaluate and print an expression"},
{"eval", 2, print, NULL},
{"examine", 2, examine, "Examine values at address"},
{"x", 1, examine, NULL},
{"help", 1, help, "List available commands"},
};
static bool help(GB_gameboy_t *gb, char *arguments)
{
/* Todo: command specific help */
const debugger_command_t *command = commands;
for (size_t i = sizeof(commands) / sizeof(*command); i--; command++) {
if (command->help_string) {
gb_attributed_log(gb, GB_LOG_BOLD, "%s", command->command);
gb_log(gb, ": %s\n", command->help_string);
}
}
return true;
}
static const debugger_command_t *find_command(const char *string)
{
const debugger_command_t *command = commands;
size_t length = strlen(string);
for (size_t i = sizeof(commands) / sizeof(*command); i--; command++) {
if (command->min_length > length) continue;
if (memcmp(command->command, string, length) == 0) { /* Is a substring? */
return command;
}
}
return NULL;
}
/* The debugger interface is quite primitive. One letter commands with a single parameter maximum.
Only one breakpoint is allowed at a time. More features will be added later. */
void debugger_run(GB_gameboy_t *gb)
{
char *input = NULL;
if (gb->debug_next_command && gb->debug_call_depth <= 0) {
gb->debug_stopped = true;
}
if (gb->debug_fin_command && gb->debug_call_depth == -1) {
gb->debug_stopped = true;
}
if (gb->debug_stopped) {
cpu_disassemble(gb, gb->pc, 5);
}
next_command:
if (input) {
free(input);
}
if (!gb->debug_stopped && should_break(gb, gb->pc)) {
gb->debug_stopped = true;
gb_log(gb, "Breakpoint: PC = %04x\n", gb->pc);
cpu_disassemble(gb, gb->pc, 5);
}
if (gb->debug_stopped) {
gb->debug_next_command = false;
gb->debug_fin_command = false;
input = gb->input_callback(gb);
if (!input[0]) {
goto next_command;
}
char *command_string = input;
char *arguments = strchr(input, ' ');
if (arguments) {
/* Actually "split" the string. */
arguments[0] = 0;
arguments++;
}
else {
arguments = "";
}
const debugger_command_t *command = find_command(command_string);
if (command) {
if (command->implementation(gb, arguments)) {
goto next_command;
}
}
else {
gb_log(gb, "%s: no such command.\n", command_string);
goto next_command;
}
/* Split to arguments and command */
free(input);
}
}
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