dirty_trick2.c

#define INSTRUCTIONS \
    _(0x7D, ADC, ABSOLUTE_X)
    // ...

// Execution

#define _(byte, operation, mode) \
    case byte: \
        mode \
        b = READ8(address); \
        operation \
        break;

#define ABSOLUTE_X \
    { \
        address = READ16(pc + 1) + x; \
        pc += 3; \
    }

#define ADC \
    { \
        int sum = (int)a + (int)b + (int)c; \
        SET_CV(a, b, sum); \
        a = (uint8_t)sum; \
        SET_ZN(a); \
    }

void execute() {
    // ...

    switch (instruction) {
        INSTRUCTIONS
    }
}

#undef ABSOLUTE_X
#undef ADC
#undef _

// Disassembly

#define _(byte, operation, mode) \
    case byte: \
        printf(#operation); \
        mode \
        printf("\n"); \
        break;

#define ABSOLUTE_X \
    printf(" ($%04x,x)", code[1] | (code[2] << 8)); \
    code += 3;

void disassemble(uint8_t *code) {
    switch (code[0]) {
        INSTRUCTIONS
    }
}

#undef ABSOLUTE_X
#undef ADC
#undef _