static void
command_regs(struct mi_process proc)
{
    struct mi_registers regs = get_process_registers(proc);
    printf("rax = %#018lx rcx = %#018lx\n"
           "rbp = %#018lx rbx = %#018lx\n"
           "rdx = %#018lx rsi = %#018lx\n"
           "rdi = %#018lx rip = %#018lx\n"
           "rsp = %#018lx\n", 
           regs.rax, regs.rcx, regs.rbp, regs.rbx, 
           regs.rdx, regs.rsi, regs.rdi, regs.rip, 
           regs.rsp);
}

static void
command_step(struct mi_process proc)
{
    int comp_unit;
    
    struct mi_registers regs = get_process_registers(proc);
    struct mi_sourcepoint *sp = pc_to_sourcepoint(proc, regs.rip - proc.base_address, &comp_unit);
    struct mi_sourcepoint *next_sp;
    
    do {
        // TODO: step until source line changes !for active file!
        ptrace(PTRACE_SINGLESTEP, proc.pid, 0, 0);
        waitpid(proc.pid, 0, 0);
        regs = get_process_registers(proc);
        long instruction = ptrace(PTRACE_PEEKDATA, proc.pid, regs.rip, NULL);
        next_sp = pc_to_sourcepoint(proc, regs.rip - proc.base_address, &comp_unit);
        if (!next_sp) break;
    } while (next_sp->line == sp->line);
    
    print_sourcepoint(proc, comp_unit, next_sp);
}

static void
command_start(struct mi_process proc)
{
    u64 main_address = proc.base_address + proc.main_address;
    long saved_instruction = place_breakpoint_at(proc, main_address);
    run_until_breakpoint_and_restore(proc, main_address, saved_instruction);
    
    // TODO: restart if already running/paused
    // TODO: process state: not running / running / paused
}

static void
command_next(struct mi_process proc)
{
    int comp_unit;
    
    struct mi_registers regs = get_process_registers(proc);
    struct mi_sourcepoint *sp = pc_to_sourcepoint(proc, regs.rip - proc.base_address, &comp_unit);
    struct mi_sourcepoint *next_sp;
    
    do {
        // TODO: step until source line changes !for active file!
        
        ptrace(PTRACE_SINGLESTEP, proc.pid, 0, 0);
        waitpid(proc.pid, 0, 0);
        regs = get_process_registers(proc);
        
        long instruction = ptrace(PTRACE_PEEKDATA, proc.pid, regs.rip, NULL);
        
        if (is_call_instruction(instruction)) {
            long base_address = regs.rbp;
            
            // NOTE do single step, get return address from stack, place breakpoint there, continue
            ptrace(PTRACE_SINGLESTEP, proc.pid, 0, 0);
            waitpid(proc.pid, 0, 0);
            regs = get_process_registers(proc);
            
            long return_address = ptrace(PTRACE_PEEKDATA, proc.pid, regs.rsp, NULL);
            
            // NOTE: disambiguate recursive calls
            for (;;) {
                long saved_instruction = place_breakpoint_at(proc, return_address);
                run_until_breakpoint_and_restore(proc, return_address, saved_instruction);
                regs = get_process_registers(proc);
                long actual_base_address = regs.rbp;
                
                if (base_address == actual_base_address) {
                    break;
                } else {
                    // NOTE: step to the next instruction after the return address, so that we can add a  breakpoint there
                    ptrace(PTRACE_SINGLESTEP, proc.pid, 0, 0);
                    waitpid(proc.pid, 0, 0);
                }
            }
        }
        // TODO: repXXX
        
        //printf("%#lx\n", regs.rip - proc.base_address);
        next_sp = pc_to_sourcepoint(proc, regs.rip - proc.base_address, &comp_unit);
        
        if (!next_sp) break;
    } while (next_sp->line == sp->line);
    
    print_sourcepoint(proc, comp_unit, next_sp);
}

static void
command_list(struct mi_process proc)
{
    int comp_unit;
    struct mi_registers regs = get_process_registers(proc);
    struct mi_sourcepoint *sp = pc_to_sourcepoint(proc, regs.rip - proc.base_address, &comp_unit);
    print_sourcepoint(proc, comp_unit, sp);
}

static void
command_cont(struct mi_process proc)
{
    ptrace(PTRACE_CONT, proc.pid, 0, 0);
}

static void
command_kill(struct mi_process proc)
{
    kill(proc.pid, SIGKILL);
}

static void
command_backtrace(struct mi_process proc)
{
    struct mi_registers regs = get_process_registers(proc);
    struct mi_function *func = get_function_around_pc(proc, regs.rip - proc.base_address);
    
    u64 fb = regs.rbp;
    u64 return_address = ptrace(PTRACE_PEEKDATA, proc.pid, fb + 8, NULL);
    
    printf("%s: %#lx\n", func->name, regs.rip);
    
    for (int i = 0; i < 3; ++i) {
        func = get_function_around_pc(proc, return_address - proc.base_address);
        if (func) {
            printf("%s: %#lx\n", func->name, regs.rip);
        }
        fb = ptrace(PTRACE_PEEKDATA, proc.pid, fb, NULL);
        return_address = ptrace(PTRACE_PEEKDATA, proc.pid, fb + 8, NULL);
    }
}

static void
command_print(struct mi_process proc, char *name, int name_length)
{
    struct mi_registers regs = get_process_registers(proc);
    u64 pc = regs.rip - proc.base_address;
    u64 cfa = get_cfa_at_pc(proc, pc);
    struct mi_variable *variable = get_variable(proc, name, name_length, pc);
    
    if (variable) {
        u64 address = cfa + variable->location;
        long value = ptrace(PTRACE_PEEKDATA, proc.pid, address, NULL);
        int val4 = value & 0x00000000FFFFFFFF;
        printf("%.*s = %d\n", name_length, name, val4);
    } else {
        printf("variable %.*s not found\n", name_length, name);
    }
}