#include <stdio.h>
#include <ruby.h>
#include <node.h>
#include <rubysig.h>
#include <st.h>

#define DEBUG_VERSION "0.9.3"

#ifdef _WIN32
struct FRAME {
    VALUE self;
    int argc;
    ID last_func;
    ID orig_func;
    VALUE last_class;
    struct FRAME *prev;
    struct FRAME *tmp;
    struct RNode *node;
    int iter;
    int flags;
    unsigned long uniq;
};

struct SCOPE {
    struct RBasic super;
    ID *local_tbl;
    VALUE *local_vars;
    int flags;
};

struct RVarmap {
    struct RBasic super;
    ID id;
    VALUE val;
    struct RVarmap *next;
};

RUBY_EXTERN struct SCOPE   *ruby_scope;
RUBY_EXTERN struct FRAME   *ruby_frame;
RUBY_EXTERN struct RVarmap *ruby_dyna_vars;
#else
#include <env.h>
#endif

#define CTX_FL_SUSPEND      (1<<1)
#define CTX_FL_TRACING      (1<<2)
#define CTX_FL_SKIPPED      (1<<3)
#define CTX_FL_IGNORE       (1<<4)
#define CTX_FL_DEAD         (1<<5)
#define CTX_FL_WAS_RUNNING  (1<<6)
#define CTX_FL_ENABLE_BKPT  (1<<7)
#define CTX_FL_STEPPED      (1<<8)
#define CTX_FL_FORCE_MOVE   (1<<9)

#define CTX_FL_TEST(c,f)  ((c)->flags & (f))
#define CTX_FL_SET(c,f)   do { (c)->flags |= (f); } while (0)
#define CTX_FL_UNSET(c,f) do { (c)->flags &= ~(f); } while (0)

#define IS_STARTED  (threads_tbl != Qnil)
#define FRAME_N(n)  (&debug_context->frames[debug_context->stack_size-(n)-1])
#define GET_FRAME   (FRAME_N(check_frame_number(debug_context, frame)))

#ifndef min
#define min(x,y) ((x) < (y) ? (x) : (y))
#endif

#define STACK_SIZE_INCREMENT 128

typedef struct {
    VALUE binding;
    ID id;
    ID orig_id;
    int line;
    const char * file;
    short dead;
    VALUE self;
    union {
        struct {
            struct FRAME *frame;
            struct SCOPE *scope;
            struct RVarmap *dyna_vars;
        } runtime;
        struct {
            VALUE locals;
        } copy;
    } info;
} debug_frame_t;

enum ctx_stop_reason {CTX_STOP_NONE, CTX_STOP_STEP, CTX_STOP_BREAKPOINT, CTX_STOP_CATCHPOINT};

typedef struct {
    VALUE thread_id;
    int thnum;
    int flags;
    enum ctx_stop_reason stop_reason;
    int stop_next;
    int dest_frame;
    int stop_line;
    int stop_frame;
    int stack_size;
    int stack_len;
    debug_frame_t *frames;
    const char * last_file;
    int last_line;
    VALUE breakpoint;
} debug_context_t;

enum bp_type {BP_POS_TYPE, BP_METHOD_TYPE};
enum hit_condition {HIT_COND_NONE, HIT_COND_GE, HIT_COND_EQ, HIT_COND_MOD};

typedef struct {
    int   id;
    enum bp_type type;
    VALUE source;
    union
    {
        int line;
        ID  mid;
    } pos;
    VALUE expr;
    int hit_count;
    int hit_value;
    enum hit_condition hit_condition;
} debug_breakpoint_t;

typedef struct {
    st_table *tbl;
} threads_table_t;

static VALUE threads_tbl        = Qnil;
static VALUE breakpoints        = Qnil;
static VALUE catchpoint         = Qnil;
static VALUE tracing            = Qfalse;
static VALUE locker             = Qnil;
static VALUE post_mortem        = Qfalse;
static VALUE keep_frame_binding = Qfalse;
static VALUE debug              = Qfalse;

static VALUE last_context = Qnil;
static VALUE last_thread  = Qnil;
static debug_context_t *last_debug_context = NULL;

static VALUE mDebugger;
static VALUE cThreadsTable;
static VALUE cContext;
static VALUE cBreakpoint;
static VALUE cDebugThread;

static VALUE rb_mObjectSpace;

static ID idAtLine;
static ID idAtBreakpoint;
static ID idAtCatchpoint;
static ID idAtTracing;
static ID idList;
static ID idEval;

static int start_count = 0;
static int thnum_max = 0;
static int bkp_count = 0;
static int last_debugged_thnum = -1;
static unsigned long last_check = 0;
static unsigned long hook_count = 0;

static VALUE create_binding(VALUE);
static VALUE debug_stop(VALUE);
static void save_current_position(debug_context_t *);
static VALUE context_copy_locals(debug_frame_t *);
static void context_suspend_0(debug_context_t *);
static void context_resume_0(debug_context_t *);

typedef struct locked_thread_t {
    VALUE thread_id;
    struct locked_thread_t *next;
} locked_thread_t;

static locked_thread_t *locked_head = NULL;
static locked_thread_t *locked_tail = NULL;

inline static VALUE
real_class(VALUE klass)
{
    if (klass) {
        if (TYPE(klass) == T_ICLASS) {
            return RBASIC(klass)->klass;
        }
        else if (FL_TEST(klass, FL_SINGLETON)) {
            return rb_iv_get(klass, "__attached__");
        }
    }
    return klass;
}

inline static void *
ruby_method_ptr(VALUE class, ID meth_id)
{
    NODE *body, *method;
    st_lookup(RCLASS(class)->m_tbl, meth_id, (st_data_t *)&body);
    method = (NODE *)body->u2.value;
    return (void *)method->u1.value;
}

inline static VALUE
ref2id(VALUE obj)
{
    return rb_obj_id(obj);
}

static VALUE
id2ref_unprotected(VALUE id)
{
    typedef VALUE (*id2ref_func_t)(VALUE, VALUE);
    static id2ref_func_t f_id2ref = NULL;
    if(f_id2ref == NULL)
    {
        f_id2ref = (id2ref_func_t)ruby_method_ptr(rb_mObjectSpace, rb_intern("_id2ref"));
    }
    return f_id2ref(rb_mObjectSpace, id);
}

static VALUE
id2ref_error()
{
    rb_p(ruby_errinfo);
    return Qnil;
}

static VALUE
id2ref(VALUE id)
{
    return rb_rescue(id2ref_unprotected, id, id2ref_error, 0);
}

inline static VALUE
context_thread_0(debug_context_t *debug_context)
{
    return id2ref(debug_context->thread_id);
}

static int
is_in_locked(VALUE thread_id)
{
    locked_thread_t *node;

    if(!locked_head)
        return 0;

    for(node = locked_head; node != locked_tail; node = node->next)
    {
        if(node->thread_id == thread_id) return 1;
    }
    return 0;
}

static void
add_to_locked(VALUE thread)
{
    locked_thread_t *node;
    VALUE thread_id = ref2id(thread);

    if(is_in_locked(thread_id))
        return;

    node = ALLOC(locked_thread_t);
    node->thread_id = thread_id;
    node->next = NULL;
    if(locked_tail)
        locked_tail->next = node;
    locked_tail = node;
    if(!locked_head)
        locked_head = node;
}

static VALUE
remove_from_locked()
{
    VALUE thread;
    locked_thread_t *node;

    if(locked_head == NULL)
        return Qnil;
    node = locked_head;
    locked_head = locked_head->next;
    if(locked_tail == node)
        locked_tail = NULL;
    thread = id2ref(node->thread_id);
    xfree(node);
    return thread;
}

static int
threads_table_mark_keyvalue(VALUE key, VALUE value, int dummy)
{
    rb_gc_mark(value);
    return ST_CONTINUE;
}

static void
threads_table_mark(void* data)
{
    threads_table_t *threads_table = (threads_table_t*)data;
    st_foreach(threads_table->tbl, threads_table_mark_keyvalue, 0);
}

static void
threads_table_free(void* data)
{
    threads_table_t *threads_table = (threads_table_t*)data;
    st_free_table(threads_table->tbl);
    xfree(threads_table);
}

static VALUE
threads_table_create()
{
    threads_table_t *threads_table;

    threads_table = ALLOC(threads_table_t);
    threads_table->tbl = st_init_numtable();
    return Data_Wrap_Struct(cThreadsTable, threads_table_mark, threads_table_free, threads_table);
}

static int
threads_table_clear_i(VALUE key, VALUE value, VALUE dummy)
{
    return ST_DELETE;
}

static void
threads_table_clear(VALUE table)
{
    threads_table_t *threads_table;

    Data_Get_Struct(table, threads_table_t, threads_table);
    st_foreach(threads_table->tbl, threads_table_clear_i, 0);
}

static VALUE
is_thread_alive(VALUE thread)
{
    typedef VALUE (*thread_alive_func_t)(VALUE);
    static thread_alive_func_t f_thread_alive = NULL;
    if(!f_thread_alive)
    {
        f_thread_alive = (thread_alive_func_t)ruby_method_ptr(rb_cThread, rb_intern("alive?"));
    }
    return f_thread_alive(thread);
}

static int
threads_table_check_i(VALUE key, VALUE value, VALUE dummy)
{
    VALUE thread;

    thread = id2ref(key);
    if(!rb_obj_is_kind_of(thread, rb_cThread))
    {
        return ST_DELETE;
    }
    if(rb_protect(is_thread_alive, thread, 0) != Qtrue)
    {
        return ST_DELETE;
    }
    return ST_CONTINUE;
}

static void
check_thread_contexts()
{
    threads_table_t *threads_table;

    Data_Get_Struct(threads_tbl, threads_table_t, threads_table);
    st_foreach(threads_table->tbl, threads_table_check_i, 0);
}

/*
 *   call-seq:
 *      Debugger.started? -> bool
 *
 *   Returns +true+ the debugger is started.
 */
static VALUE
debug_is_started(VALUE self)
{
    return IS_STARTED ? Qtrue : Qfalse;
}

static void
debug_check_started()
{
    if(!IS_STARTED)
    {
        rb_raise(rb_eRuntimeError, "Debugger.start is not called yet.");
    }
}

static void
debug_context_mark(void *data)
{
    debug_frame_t *frame;
    int i;

    debug_context_t *debug_context = (debug_context_t *)data;
    for(i = 0; i < debug_context->stack_size; i++)
    {
        frame = &(debug_context->frames[i]);
        rb_gc_mark(frame->binding);
        rb_gc_mark(frame->self);
        if(frame->dead)
        {
            rb_gc_mark(frame->info.copy.locals);
        }
    }
    rb_gc_mark(debug_context->breakpoint);
}

static void
debug_context_free(void *data)
{
    debug_context_t *debug_context = (debug_context_t *)data;
    xfree(debug_context->frames);
}

static VALUE
debug_context_create(VALUE thread)
{
    debug_context_t *debug_context;

    debug_context = ALLOC(debug_context_t);
    debug_context-> thnum = ++thnum_max;

    debug_context->last_file = NULL;
    debug_context->last_line = 0;
    debug_context->flags = 0;

    debug_context->stop_next = -1;
    debug_context->dest_frame = -1;
    debug_context->stop_line = -1;
    debug_context->stop_frame = -1;
    debug_context->stop_reason = CTX_STOP_NONE;
    debug_context->stack_len = STACK_SIZE_INCREMENT;
    debug_context->frames = ALLOC_N(debug_frame_t, STACK_SIZE_INCREMENT);
    debug_context->stack_size = 0;
    debug_context->thread_id = ref2id(thread);
    debug_context->breakpoint = Qnil;
    if(rb_obj_class(thread) == cDebugThread)
      CTX_FL_SET(debug_context, CTX_FL_IGNORE);
    return Data_Wrap_Struct(cContext, debug_context_mark, debug_context_free, debug_context);
}

static VALUE
debug_context_dup(debug_context_t *debug_context)
{
    debug_context_t *new_debug_context;
    debug_frame_t *new_frame, *old_frame;
    int i;

    new_debug_context = ALLOC(debug_context_t);
    memcpy(new_debug_context, debug_context, sizeof(debug_context_t));
    new_debug_context->stop_next = -1;
    new_debug_context->dest_frame = -1;
    new_debug_context->stop_line = -1;
    new_debug_context->stop_frame = -1;
    new_debug_context->breakpoint = Qnil;
    CTX_FL_SET(new_debug_context, CTX_FL_DEAD);
    new_debug_context->frames = ALLOC_N(debug_frame_t, debug_context->stack_size);
    new_debug_context->stack_len = debug_context->stack_size;
    memcpy(new_debug_context->frames, debug_context->frames, sizeof(debug_frame_t) * debug_context->stack_size);
    for(i = 0; i < debug_context->stack_size; i++)
    {
        new_frame = &(new_debug_context->frames[i]);
        old_frame = &(debug_context->frames[i]);
        new_frame->dead = 1;
        new_frame->info.copy.locals = context_copy_locals(old_frame);
    }
    return Data_Wrap_Struct(cContext, debug_context_mark, debug_context_free, new_debug_context);
}

static void
thread_context_lookup(VALUE thread, VALUE *context, debug_context_t **debug_context)
{
    threads_table_t *threads_table;
    VALUE thread_id;
    debug_context_t *l_debug_context;

    debug_check_started();

    if(last_thread == thread && last_context != Qnil)
    {
        *context = last_context;
        if(debug_context)
            *debug_context = last_debug_context;
        return;
    }
    thread_id = ref2id(thread);
    Data_Get_Struct(threads_tbl, threads_table_t, threads_table);
    if(!st_lookup(threads_table->tbl, thread_id, context))
    {
        *context = debug_context_create(thread);
        st_insert(threads_table->tbl, thread_id, *context);
    }

    Data_Get_Struct(*context, debug_context_t, l_debug_context);
    if(debug_context)
        *debug_context = l_debug_context;

    last_thread = thread;
    last_context = *context;
    last_debug_context = l_debug_context;
}

static VALUE
call_at_line_unprotected(VALUE args)
{
    VALUE context;
    context = *RARRAY(args)->ptr;
    return rb_funcall2(context, idAtLine, RARRAY(args)->len - 1, RARRAY(args)->ptr + 1);
}

static VALUE
call_at_line(VALUE context, debug_context_t *debug_context, VALUE file, VALUE line)
{
    VALUE args;

    last_debugged_thnum = debug_context->thnum;
    save_current_position(debug_context);

    args = rb_ary_new3(3, context, file, line);
    return rb_protect(call_at_line_unprotected, args, 0);
}

static void
save_call_frame(rb_event_t event, VALUE self, char *file, int line, ID mid, debug_context_t *debug_context)
{
    VALUE binding;
    debug_frame_t *debug_frame;
    int frame_n;

    binding = self && RTEST(keep_frame_binding)? create_binding(self) : Qnil;

    frame_n = debug_context->stack_size++;
    if(frame_n >= debug_context->stack_len)
    {
        debug_context->stack_len += STACK_SIZE_INCREMENT;
        debug_context->frames = REALLOC_N(debug_context->frames, debug_frame_t, debug_context->stack_len);
    }
    debug_frame = &debug_context->frames[frame_n];
    debug_frame->file = file;
    debug_frame->line = line;
    debug_frame->binding = binding;
    debug_frame->id = mid;
    debug_frame->orig_id = mid;
    debug_frame->dead = 0;
    debug_frame->self = self;
    debug_frame->info.runtime.frame = ruby_frame;
    debug_frame->info.runtime.scope = ruby_scope;
    debug_frame->info.runtime.dyna_vars = event == RUBY_EVENT_LINE ? ruby_dyna_vars : NULL;
}

#if defined DOSISH
#define isdirsep(x) ((x) == '/' || (x) == '\\')
#else
#define isdirsep(x) ((x) == '/')
#endif

static int
filename_cmp(VALUE source, char *file)
{
    char *source_ptr, *file_ptr;
    int s_len, f_len, min_len;
    int s,f;
    int dirsep_flag = 0;

    s_len = RSTRING(source)->len;
    f_len = strlen(file);
    min_len = min(s_len, f_len);

    source_ptr = RSTRING(source)->ptr;
    file_ptr   = file;

    for( s = s_len - 1, f = f_len - 1; s >= s_len - min_len && f >= f_len - min_len; s--, f-- )
    {
        if((source_ptr[s] == '.' || file_ptr[f] == '.') && dirsep_flag)
            return 1;
        if(isdirsep(source_ptr[s]) && isdirsep(file_ptr[f]))
            dirsep_flag = 1;
        else if(source_ptr[s] != file_ptr[f])
            return 0;
    }
    return 1;
}

inline static int
classname_cmp(VALUE name, VALUE klass)
{
    return (klass != Qnil && rb_str_cmp(name, rb_mod_name(klass)) == 0);
}

static int
check_breakpoint_hit_condition(VALUE breakpoint)
{
    debug_breakpoint_t *debug_breakpoint;
    
    if(breakpoint == Qnil)
        return 0;
    Data_Get_Struct(breakpoint, debug_breakpoint_t, debug_breakpoint);

    debug_breakpoint->hit_count++;
    switch(debug_breakpoint->hit_condition)
    {
        case HIT_COND_NONE:
            return 1;
        case HIT_COND_GE:
        {
            if(debug_breakpoint->hit_count >= debug_breakpoint->hit_value)
                return 1;
            break;
        }
        case HIT_COND_EQ:
        {
            if(debug_breakpoint->hit_count == debug_breakpoint->hit_value)
                return 1;
            break;
        }
        case HIT_COND_MOD:
        {
            if(debug_breakpoint->hit_count % debug_breakpoint->hit_value == 0)
                return 1;
            break;
        }
    }
    return 0;
}

static int
check_breakpoint_by_pos(VALUE breakpoint, char *file, int line)
{
    debug_breakpoint_t *debug_breakpoint;

    if(breakpoint == Qnil)
        return 0;
    Data_Get_Struct(breakpoint, debug_breakpoint_t, debug_breakpoint);
    if(debug_breakpoint->type != BP_POS_TYPE)
        return 0;
    if(debug_breakpoint->pos.line != line)
        return 0;
    if(filename_cmp(debug_breakpoint->source, file))
        return 1;
    return 0;
}

static int
check_breakpoint_by_method(VALUE breakpoint, VALUE klass, ID mid)
{
    debug_breakpoint_t *debug_breakpoint;

    if(breakpoint == Qnil)
        return 0;
    Data_Get_Struct(breakpoint, debug_breakpoint_t, debug_breakpoint);
    if(debug_breakpoint->type != BP_METHOD_TYPE)
        return 0;
    if(debug_breakpoint->pos.mid != mid)
        return 0;
    if(classname_cmp(debug_breakpoint->source, klass))
        return 1;
    return 0;
}

static VALUE
check_breakpoints_by_pos(debug_context_t *debug_context, char *file, int line)
{
    VALUE breakpoint;
    int i;

    if(!CTX_FL_TEST(debug_context, CTX_FL_ENABLE_BKPT))
        return Qnil;
    
    if(check_breakpoint_by_pos(debug_context->breakpoint, file, line))
        return debug_context->breakpoint;

    if(RARRAY(breakpoints)->len == 0)
        return Qnil;
    for(i = 0; i < RARRAY(breakpoints)->len; i++)
    {
        breakpoint = rb_ary_entry(breakpoints, i);
        if(check_breakpoint_by_pos(breakpoint, file, line))
            return breakpoint;
    }
    return Qnil;
}

static VALUE
check_breakpoints_by_method(debug_context_t *debug_context, VALUE klass, ID mid)
{
    VALUE breakpoint;
    int i;

    if(!CTX_FL_TEST(debug_context, CTX_FL_ENABLE_BKPT))
        return Qnil;
        
    if(check_breakpoint_by_method(debug_context->breakpoint, klass, mid))
        return debug_context->breakpoint;

    if(RARRAY(breakpoints)->len == 0)
        return Qnil;
    for(i = 0; i < RARRAY(breakpoints)->len; i++)
    {
        breakpoint = rb_ary_entry(breakpoints, i);
        if(check_breakpoint_by_method(breakpoint, klass, mid))
            return breakpoint;
    }
    return Qnil;
}

/*
 * This is a NASTY HACK. For some reasons rb_f_binding is decalred
 * static in eval.c
 */
static VALUE
create_binding(VALUE self)
{
    typedef VALUE (*bind_func_t)(VALUE);
    static bind_func_t f_binding = NULL;

    if(f_binding == NULL)
    {
        f_binding = (bind_func_t)ruby_method_ptr(rb_mKernel, rb_intern("binding"));
    }
    return f_binding(self);
}

static VALUE
eval_expression(VALUE args)
{
    return rb_funcall2(rb_mKernel, idEval, 2, RARRAY(args)->ptr);
}

inline static int
check_breakpoint_expression(VALUE breakpoint, VALUE binding)
{
    debug_breakpoint_t *debug_breakpoint;
    VALUE args, expr_result;

    Data_Get_Struct(breakpoint, debug_breakpoint_t, debug_breakpoint);
    if(NIL_P(debug_breakpoint->expr))
        return 1;

    args = rb_ary_new3(2, debug_breakpoint->expr, binding);
    expr_result = rb_protect(eval_expression, args, 0);
    return RTEST(expr_result);
}

inline static debug_frame_t *
get_top_frame(debug_context_t *debug_context)
{
    if(debug_context->stack_size == 0)
        return NULL;
    else
        return &(debug_context->frames[debug_context->stack_size-1]);
}

inline static void
save_top_binding(debug_context_t *debug_context, VALUE binding)
{
    debug_frame_t *debug_frame;
    debug_frame = get_top_frame(debug_context);
    if(debug_frame)
        debug_frame->binding = binding;
}

inline static void
set_frame_source(rb_event_t event, debug_context_t *debug_context, VALUE self, char *file, int line, ID mid)
{
    debug_frame_t *top_frame;
    top_frame = get_top_frame(debug_context);
    if(top_frame)
    {
        top_frame->self = self;
        top_frame->file = file;
        top_frame->line = line;
        top_frame->id   = mid;
        top_frame->info.runtime.dyna_vars = event == RUBY_EVENT_C_CALL ? NULL : ruby_dyna_vars;
    }
}

inline static void
reset_frame_mid(debug_context_t *debug_context)
{
    debug_frame_t *top_frame;
    top_frame = get_top_frame(debug_context);
    if(top_frame)
    {
        top_frame->id = 0;
    }
}

static void
save_current_position(debug_context_t *debug_context)
{
    debug_frame_t *debug_frame;

    debug_frame = get_top_frame(debug_context);
    if(!debug_frame) return;
    debug_context->last_file = debug_frame->file;
    debug_context->last_line = debug_frame->line;
    CTX_FL_UNSET(debug_context, CTX_FL_ENABLE_BKPT);
    CTX_FL_UNSET(debug_context, CTX_FL_STEPPED);
    CTX_FL_UNSET(debug_context, CTX_FL_FORCE_MOVE);
}

inline static char *
get_event_name(rb_event_t event)
{
  switch (event) {
    case RUBY_EVENT_LINE:
      return "line";
    case RUBY_EVENT_CLASS:
      return "class";
    case RUBY_EVENT_END:
      return "end";
    case RUBY_EVENT_CALL:
      return "call";
    case RUBY_EVENT_RETURN:
      return "return";
    case RUBY_EVENT_C_CALL:
      return "c-call";
    case RUBY_EVENT_C_RETURN:
      return "c-return";
    case RUBY_EVENT_RAISE:
      return "raise";
    default:
      return "unknown";
  }
}

inline static int
c_call_new_frame_p(VALUE klass, ID mid)
{
    klass = real_class(klass);
    if(rb_block_given_p()) return 1;
    if(klass == rb_cProc || klass == rb_mKernel || klass == rb_cModule) return 1;
    return 0;
}

static void
debug_event_hook(rb_event_t event, NODE *node, VALUE self, ID mid, VALUE klass)
{
    VALUE thread, context;
    VALUE breakpoint = Qnil, binding = Qnil;
    debug_context_t *debug_context;
    char *file = NULL;
    int line = 0, moved = 0;

    hook_count++;

    if (mid == ID_ALLOCATOR) return;
    
    thread = rb_thread_current();
    thread_context_lookup(thread, &context, &debug_context);

    /* return if thread is marked as 'ignored'.
       debugger's threads are marked this way
    */
    if(CTX_FL_TEST(debug_context, CTX_FL_IGNORE)) return;

    while(1)
    {
        /* halt execution of the current thread if the debugger
           is activated in another
        */
        while(locker != Qnil && locker != thread)
        {
            add_to_locked(thread);
            rb_thread_stop();
        }

        /* stop the current thread if it's marked as suspended */
        if(CTX_FL_TEST(debug_context, CTX_FL_SUSPEND) && locker != thread)
        {
            CTX_FL_SET(debug_context, CTX_FL_WAS_RUNNING);
            rb_thread_stop();
        }
        else break;
    }

    /* return if the current thread is the locker */
    if(locker != Qnil) return;

    /* only the current thread can proceed */
    locker = thread;

    /* ignore a skipped section of code */
    if(CTX_FL_TEST(debug_context, CTX_FL_SKIPPED)) goto cleanup;

    if(node)
    {
      file = node->nd_file;
      line = nd_line(node);
      
      if(debug == Qtrue)
          fprintf(stderr, "%s:%d [%s] %s\n", file, line, get_event_name(event), rb_id2name(mid));

      if(debug_context->last_line != line || debug_context->last_file == NULL ||
          strcmp(debug_context->last_file, file) != 0)
      {
          CTX_FL_SET(debug_context, CTX_FL_ENABLE_BKPT);
          moved = 1;
      }
    }
    else if(event != RUBY_EVENT_RETURN && event != RUBY_EVENT_C_RETURN)
    {
        if(debug == Qtrue)
            fprintf(stderr, "nodeless [%s] %s\n", get_event_name(event), rb_id2name(mid));
        goto cleanup;
    }
    else
    {
        if(debug == Qtrue)
            fprintf(stderr, "nodeless [%s] %s\n", get_event_name(event), rb_id2name(mid));
    }
    
    if(event != RUBY_EVENT_LINE)
        CTX_FL_SET(debug_context, CTX_FL_STEPPED);

    switch(event)
    {
    case RUBY_EVENT_LINE:
    {
        
        if(debug_context->stack_size == 0)
            save_call_frame(event, self, file, line, mid, debug_context);
        else
            set_frame_source(event, debug_context, self, file, line, mid);
        
        if(RTEST(tracing) || CTX_FL_TEST(debug_context, CTX_FL_TRACING))
            rb_funcall(context, idAtTracing, 2, rb_str_new2(file), INT2FIX(line));

        if(debug_context->dest_frame == -1 ||
            debug_context->stack_size == debug_context->dest_frame)
        {
            if(moved || !CTX_FL_TEST(debug_context, CTX_FL_FORCE_MOVE))
                debug_context->stop_next--;
            if(debug_context->stop_next < 0)
                debug_context->stop_next = -1;
            if(moved || (CTX_FL_TEST(debug_context, CTX_FL_STEPPED) && 
                        !CTX_FL_TEST(debug_context, CTX_FL_FORCE_MOVE)))
            {
                debug_context->stop_line--;
                CTX_FL_UNSET(debug_context, CTX_FL_STEPPED);
            }
        }
        else if(debug_context->stack_size < debug_context->dest_frame)
        {
            debug_context->stop_next = 0;
        }

        if(debug_context->stop_next == 0 || debug_context->stop_line == 0 ||
            (breakpoint = check_breakpoints_by_pos(debug_context, file, line)) != Qnil)
        {
            binding = self? create_binding(self) : Qnil;
            save_top_binding(debug_context, binding);

            debug_context->stop_reason = CTX_STOP_STEP;

            /* check breakpoint expression */
            if(breakpoint != Qnil)
            {
                if(!check_breakpoint_expression(breakpoint, binding))
                    break;
                if(!check_breakpoint_hit_condition(breakpoint))
                    break;
                if(breakpoint != debug_context->breakpoint)
                {
                  debug_context->stop_reason = CTX_STOP_BREAKPOINT;
                  rb_funcall(context, idAtBreakpoint, 1, breakpoint);
                }
                else
                    debug_context->breakpoint = Qnil;
            }

            /* reset all pointers */
            debug_context->dest_frame = -1;
            debug_context->stop_line = -1;
            debug_context->stop_next = -1;

            call_at_line(context, debug_context, rb_str_new2(file), INT2FIX(line));
        }
        break;
    }
    case RUBY_EVENT_CALL:
    {
        save_call_frame(event, self, file, line, mid, debug_context);
        breakpoint = check_breakpoints_by_method(debug_context, klass, mid);
        if(breakpoint != Qnil)
        {
            debug_frame_t *debug_frame;
            debug_frame = get_top_frame(debug_context);
            if(debug_frame)
                binding = debug_frame->binding;
            if(NIL_P(binding) && self)
                binding = create_binding(self);
            save_top_binding(debug_context, binding);

            if(!check_breakpoint_expression(breakpoint, binding))
                break;
            if(!check_breakpoint_hit_condition(breakpoint))
                break;
            if(breakpoint != debug_context->breakpoint)
            {
                debug_context->stop_reason = CTX_STOP_BREAKPOINT;
                rb_funcall(context, idAtBreakpoint, 1, breakpoint);
            }
            else
                debug_context->breakpoint = Qnil;
            call_at_line(context, debug_context, rb_str_new2(file), INT2FIX(line));
        }
        break;
    }
    case RUBY_EVENT_C_CALL:
    {
        if(c_call_new_frame_p(klass, mid))
            save_call_frame(event, self, file, line, mid, debug_context);
        else
            set_frame_source(event, debug_context, self, file, line, mid);
        break;
    }
    case RUBY_EVENT_C_RETURN:
    {
        /* note if a block is given we fall through! */
        if(!node || !c_call_new_frame_p(klass, mid))
            break;
    }
    case RUBY_EVENT_RETURN:
    case RUBY_EVENT_END:
    {
        if(debug_context->stack_size == debug_context->stop_frame)
        {
            debug_context->stop_next = 1;
            debug_context->stop_frame = 0;
        }
        while(debug_context->stack_size > 0)
        {
            debug_context->stack_size--;
            if(debug_context->frames[debug_context->stack_size].orig_id == mid)
                break;
        }
        CTX_FL_SET(debug_context, CTX_FL_ENABLE_BKPT);
        break;
    }
    case RUBY_EVENT_CLASS:
    {
        reset_frame_mid(debug_context);
        save_call_frame(event, self, file, line, mid, debug_context);
        break;
    }
    case RUBY_EVENT_RAISE:
    {
        VALUE ancestors;
        VALUE expn_class, aclass;
        int i;

        set_frame_source(event, debug_context, self, file, line, mid);

        if(post_mortem == Qtrue && self)
        {
            binding = create_binding(self);
            rb_ivar_set(ruby_errinfo, rb_intern("@__debug_file"), rb_str_new2(file));
            rb_ivar_set(ruby_errinfo, rb_intern("@__debug_line"), INT2FIX(line));
            rb_ivar_set(ruby_errinfo, rb_intern("@__debug_binding"), binding);
            rb_ivar_set(ruby_errinfo, rb_intern("@__debug_context"), debug_context_dup(debug_context));
        }

        expn_class = rb_obj_class(ruby_errinfo);
        if( !NIL_P(rb_class_inherited_p(expn_class, rb_eSystemExit)) )
        {
            debug_stop(mDebugger);
            break;
        }

        if(catchpoint == Qnil)
            break;

        ancestors = rb_mod_ancestors(expn_class);
        for(i = 0; i < RARRAY(ancestors)->len; i++)
        {
            aclass = rb_ary_entry(ancestors, i);
            if(rb_str_cmp(rb_mod_name(aclass), catchpoint) == 0)
            {
                debug_context->stop_reason = CTX_STOP_CATCHPOINT;
                rb_funcall(context, idAtCatchpoint, 1, ruby_errinfo);
                if(self && binding == Qnil)
                    binding = create_binding(self);
                save_top_binding(debug_context, binding);
                call_at_line(context, debug_context, rb_str_new2(file), INT2FIX(line));
                break;
            }
        }

        break;
    }
    }

    cleanup:
    
    debug_context->stop_reason = CTX_STOP_NONE;

    /* check that all contexts point to alive threads */
    if(hook_count - last_check > 3000)
    {
        check_thread_contexts();
        last_check = hook_count;
    }

    /* release a lock */
    locker = Qnil;
    /* let the next thread to run */
    thread = remove_from_locked();
    if(thread != Qnil)
        rb_thread_run(thread);
}

static VALUE
debug_stop_i(VALUE self)
{
    if(IS_STARTED)
        debug_stop(self);
    return Qnil;
}

/*
 *   call-seq:
 *      Debugger.start -> bool
 *      Debugger.start { ... } -> obj
 *
 *   This method activates the debugger.
 *   If it's called without a block it returns +true+, unless debugger was already started.
 *   If a block is given, it starts debugger and yields to block. When the block is finished
 *   executing it stops the debugger with Debugger.stop method.
 *
 *   <i>Note that if you want to stop debugger, you must call Debugger.stop as many time as you
 *   called Debugger.start method.</i>
 */
static VALUE
debug_start(VALUE self)
{
    VALUE result;
    start_count++;

    if(IS_STARTED)
        result = Qfalse;
    else
    {
        breakpoints = rb_ary_new();
        locker      = Qnil;
        threads_tbl = threads_table_create();

        rb_add_event_hook(debug_event_hook, RUBY_EVENT_ALL);
        result = Qtrue;
    }

    if(rb_block_given_p())
        return rb_ensure(rb_yield, self, debug_stop_i, self);
    return result;
}

/*
 *   call-seq:
 *      Debugger.stop -> bool
 *
 *   This method disacivates the debugger. It returns +true+ if the debugger is disacivated,
 *   otherwise it returns +false+.
 *
 *   <i>Note that if you want to stop debugger, you must call Debugger.stop as many time as you
 *   called Debugger.start method.</i>
 */
static VALUE
debug_stop(VALUE self)
{
    debug_check_started();

    start_count--;
    if(start_count)
        return Qfalse;

    rb_remove_event_hook(debug_event_hook);

    locker      = Qnil;
    breakpoints = Qnil;
    threads_tbl = Qnil;

    return Qtrue;
}

static void
breakpoint_mark(void *data)
{
    debug_breakpoint_t *breakpoint;
    breakpoint = (debug_breakpoint_t *)data;
    rb_gc_mark(breakpoint->source);
    rb_gc_mark(breakpoint->expr);
}

static VALUE
create_breakpoint_from_args(int argc, VALUE *argv, int id)
{
    VALUE source, pos, expr;
    debug_breakpoint_t *breakpoint;
    int type;

    if(rb_scan_args(argc, argv, "21", &source, &pos, &expr) == 2)
    {
        expr = Qnil;
    }
    type = FIXNUM_P(pos) ? BP_POS_TYPE : BP_METHOD_TYPE;
    if(type == BP_POS_TYPE)
        source = StringValue(source);
    else
        pos = StringValue(pos);
    breakpoint = ALLOC(debug_breakpoint_t);
    breakpoint->id = id;
    breakpoint->source = source;
    breakpoint->type = type;
    if(type == BP_POS_TYPE)
        breakpoint->pos.line = FIX2INT(pos);
    else
        breakpoint->pos.mid = rb_intern(RSTRING(pos)->ptr);
    breakpoint->expr = NIL_P(expr) ? expr: StringValue(expr);
    breakpoint->hit_count = 0;
    breakpoint->hit_value = 0;
    breakpoint->hit_condition = HIT_COND_NONE;
    return Data_Wrap_Struct(cBreakpoint, breakpoint_mark, xfree, breakpoint);
}

/*
 *   call-seq:
 *      Debugger.add_breakpoint(source, pos, condition = nil) -> breakpoint
 *
 *   Adds a new breakpoint.
 *   <i>source</i> is a name of a file or a class.
 *   <i>pos</i> is a line number or a method name if <i>source</i> is a class name.
 *   <i>condition</i> is a string which is evaluated to +true+ when this breakpoint
 *   is activated.
 */
static VALUE
debug_add_breakpoint(int argc, VALUE *argv, VALUE self)
{
    VALUE result;

    debug_check_started();

    result = create_breakpoint_from_args(argc, argv, ++bkp_count);
    rb_ary_push(breakpoints, result);
    return result;
}

/*
 *   call-seq:
 *      Debugger.remove_breakpoint(id) -> breakpoint
 *
 *   Removes breakpoint by its id.
 *   <i>id</i> is an identificator of a breakpoint.
 */
static VALUE
debug_remove_breakpoint(VALUE self, VALUE id_value)
{
    int i;
    int id;
    VALUE breakpoint;
    debug_breakpoint_t *debug_breakpoint;

    id = FIX2INT(id_value);

    for( i = 0; i < RARRAY(breakpoints)->len; i += 1 )
    {
        breakpoint = rb_ary_entry(breakpoints, i);
        Data_Get_Struct(breakpoint, debug_breakpoint_t, debug_breakpoint);
        if(debug_breakpoint->id == id)
        {
            rb_ary_delete_at(breakpoints, i);
            return breakpoint;
        }
    }
    return Qnil;
}

/*
 *   call-seq:
 *      Debugger.breakpoints -> array
 *
 *   Returns an array of breakpoints.
 */
static VALUE
debug_breakpoints(VALUE self)
{
    debug_check_started();

    return breakpoints;
}

/*
 *   call-seq:
 *      Debugger.checkpoint -> string
 *
 *   Returns a current checkpoint, which is a name of exception that will
 *   trigger a debugger when raised.
 */
static VALUE
debug_catchpoint(VALUE self)
{
    debug_check_started();

    return catchpoint;
}

/*
 *   call-seq:
 *      Debugger.checkpoint = string -> string
 *
 *   Sets checkpoint.
 */
static VALUE
debug_set_catchpoint(VALUE self, VALUE value)
{
    debug_check_started();

    if (!NIL_P(value) && TYPE(value) != T_STRING) {
        rb_raise(rb_eTypeError, "value of checkpoint must be String");
    }
    if(NIL_P(value))
    catchpoint = Qnil;
    else
    catchpoint = rb_str_dup(value);
    return value;
}

static int
find_last_context_func(VALUE key, VALUE value, VALUE *result)
{
    debug_context_t *debug_context;
    Data_Get_Struct(value, debug_context_t, debug_context);
    if(debug_context->thnum == last_debugged_thnum)
    {
        *result = value;
        return ST_STOP;
    }
    return ST_CONTINUE;
}

/*
 *   call-seq:
 *      Debugger.last_interrupted -> context
 *
 *   Returns last debugged context.
 */
static VALUE
debug_last_interrupted(VALUE self)
{
    VALUE result = Qnil;
    threads_table_t *threads_table;

    debug_check_started();

    Data_Get_Struct(threads_tbl, threads_table_t, threads_table);

    st_foreach(threads_table->tbl, find_last_context_func, (st_data_t)&result);
    return result;
}

/*
 *   call-seq:
 *      Debugger.current_context -> context
 *
 *   Returns current context.
 *   <i>Note:</i> Debugger.current_context.thread == Thread.current
 */
static VALUE
debug_current_context(VALUE self)
{
    VALUE thread, context;

    debug_check_started();

    thread = rb_thread_current();
    thread_context_lookup(thread, &context, NULL);

    return context;
}

/*
 *   call-seq:
 *      Debugger.thread_context(thread) -> context
 *
 *   Returns context of the thread passed as an argument.
 */
static VALUE
debug_thread_context(VALUE self, VALUE thread)
{
    VALUE context;

    debug_check_started();
    thread_context_lookup(thread, &context, NULL);
    return context;
}

/*
 *   call-seq:
 *      Debugger.contexts -> array
 *
 *   Returns an array of all contexts.
 */
static VALUE
debug_contexts(VALUE self)
{
    volatile VALUE list;
    volatile VALUE new_list;
    VALUE thread, context;
    threads_table_t *threads_table;
    debug_context_t *debug_context;
    int i;

    debug_check_started();

    new_list = rb_ary_new();
    list = rb_funcall(rb_cThread, idList, 0);
    for(i = 0; i < RARRAY(list)->len; i++)
    {
        thread = rb_ary_entry(list, i);
        thread_context_lookup(thread, &context, NULL);
        rb_ary_push(new_list, context);
    }
    threads_table_clear(threads_tbl);
    Data_Get_Struct(threads_tbl, threads_table_t, threads_table);
    for(i = 0; i < RARRAY(new_list)->len; i++)
    {
        context = rb_ary_entry(new_list, i);
        Data_Get_Struct(context, debug_context_t, debug_context);
        st_insert(threads_table->tbl, debug_context->thread_id, context);
    }

    return new_list;
}

/*
 *   call-seq:
 *      Debugger.suspend -> Debugger
 *
 *   Suspends all contexts.
 */
static VALUE
debug_suspend(VALUE self)
{
    VALUE current, context;
    VALUE saved_crit;
    VALUE context_list;
    debug_context_t *debug_context;
    int i;

    debug_check_started();

    saved_crit = rb_thread_critical;
    rb_thread_critical = Qtrue;
    context_list = debug_contexts(self);
    thread_context_lookup(rb_thread_current(), &current, NULL);

    for(i = 0; i < RARRAY(context_list)->len; i++)
    {
        context = rb_ary_entry(context_list, i);
        if(current == context)
            continue;
        Data_Get_Struct(context, debug_context_t, debug_context);
        context_suspend_0(debug_context);
    }
    rb_thread_critical = saved_crit;

    if(rb_thread_critical == Qfalse)
        rb_thread_schedule();

    return self;
}

/*
 *   call-seq:
 *      Debugger.resume -> Debugger
 *
 *   Resumes all contexts.
 */
static VALUE
debug_resume(VALUE self)
{
    VALUE current, context;
    VALUE saved_crit;
    VALUE context_list;
    debug_context_t *debug_context;
    int i;

    debug_check_started();

    saved_crit = rb_thread_critical;
    rb_thread_critical = Qtrue;
    context_list = debug_contexts(self);

    thread_context_lookup(rb_thread_current(), &current, NULL);
    for(i = 0; i < RARRAY(context_list)->len; i++)
    {
        context = rb_ary_entry(context_list, i);
        if(current == context)
            continue;
        Data_Get_Struct(context, debug_context_t, debug_context);
        context_resume_0(debug_context);
    }
    rb_thread_critical = saved_crit;

    rb_thread_schedule();

    return self;
}

/*
 *   call-seq:
 *      Debugger.tracing -> bool
 *
 *   Returns +true+ if the global tracing is activated.
 */
static VALUE
debug_tracing(VALUE self)
{
    return tracing;
}

/*
 *   call-seq:
 *      Debugger.tracing = bool
 *
 *   Sets the global tracing flag.
 */
static VALUE
debug_set_tracing(VALUE self, VALUE value)
{
    tracing = RTEST(value) ? Qtrue : Qfalse;
    return value;
}

/*
 *   call-seq:
 *      Debugger.post_mortem? -> bool
 *
 *   Returns +true+ if post-moterm debugging is enabled.
 */
static VALUE
debug_post_mortem(VALUE self)
{
    return post_mortem;
}

/*
 *   call-seq:
 *      Debugger.post_mortem = bool
 *
 *   Sets post-moterm flag.
 *   FOR INTERNAL USE ONLY.
 */
static VALUE
debug_set_post_mortem(VALUE self, VALUE value)
{
    debug_check_started();

    post_mortem = RTEST(value) ? Qtrue : Qfalse;
    return value;
}

/*
 *   call-seq:
 *      Debugger.keep_frame_binding? -> bool
 *
 *   Returns +true+ if the debugger will collect frame bindings.
 */
static VALUE
debug_keep_frame_binding(VALUE self)
{
    return keep_frame_binding;
}

/*
 *   call-seq:
 *      Debugger.keep_frame_binding = bool
 *
 *   Setting to +true+ will make the debugger create frame bindings.
 */
static VALUE
debug_set_keep_frame_binding(VALUE self, VALUE value)
{
    keep_frame_binding = RTEST(value) ? Qtrue : Qfalse;
    return value;
}

/* :nodoc: */
static VALUE
debug_debug(VALUE self)
{
    return debug;
}

/* :nodoc: */
static VALUE
debug_set_debug(VALUE self, VALUE value)
{
    debug = RTEST(value) ? Qtrue : Qfalse;
    return value;
}

/* :nodoc: */
static VALUE
debug_thread_inherited(VALUE klass)
{
  rb_raise(rb_eRuntimeError, "Can't inherite Debugger::DebugThread class");
}

/*
 *   call-seq:
 *      Debugger.debug_load(file, stop = false) -> nil
 *
 *   Same as Kernel#load but resets current context's frames.
 *   +stop+ parameter force the debugger to stop at the first line of code in the +file+
 *   FOR INTERNAL USE ONLY.
 */
static VALUE
debug_debug_load(int argc, VALUE *argv, VALUE self)
{
    VALUE file, stop, context;
    debug_context_t *debug_context;

    if(rb_scan_args(argc, argv, "11", &file, &stop) == 1)
      stop = Qfalse;

    debug_start(self);
    context = debug_current_context(self);
    Data_Get_Struct(context, debug_context_t, debug_context);
    debug_context->stack_size = 0;
    if(RTEST(stop))
      debug_context->stop_next = 1;
    rb_load(file, 0);

    debug_stop(self);
    return Qnil;
}

static VALUE
set_current_skipped_status(VALUE status)
{
    VALUE context;
    debug_context_t *debug_context;

    context = debug_current_context(Qnil);
    Data_Get_Struct(context, debug_context_t, debug_context);
    if(status)
        CTX_FL_SET(debug_context, CTX_FL_SKIPPED);
    else
        CTX_FL_UNSET(debug_context, CTX_FL_SKIPPED);
    return Qnil;
}

/*
 *   call-seq:
 *      Debugger.skip { block } -> obj or nil
 *
 *   The code inside of the block is escaped from the debugger.
 */
static VALUE
debug_skip(VALUE self)
{
    if (!rb_block_given_p()) {
        rb_raise(rb_eArgError, "called without a block");
    }
    if(!IS_STARTED)
        return rb_yield(Qnil);
    set_current_skipped_status(Qtrue);
    return rb_ensure(rb_yield, Qnil, set_current_skipped_status, Qfalse);
}

static VALUE
debug_at_exit_c(VALUE proc)
{
    return rb_funcall(proc, rb_intern("call"), 0);
}

static void
debug_at_exit_i(VALUE proc)
{
    if(!IS_STARTED)
    {
        debug_at_exit_c(proc);
    }
    else
    {
        set_current_skipped_status(Qtrue);
        rb_ensure(debug_at_exit_c, proc, set_current_skipped_status, Qfalse);
    }
}

/*
 *   call-seq:
 *      Debugger.debug_at_exit { block } -> proc
 *
 *   Register <tt>at_exit</tt> hook which is escaped from the debugger.
 *   FOR INTERNAL USE ONLY.
 */
static VALUE
debug_at_exit(VALUE self)
{
    VALUE proc;
    if (!rb_block_given_p())
        rb_raise(rb_eArgError, "called without a block");
    proc = rb_block_proc();
    rb_set_end_proc(debug_at_exit_i, proc);
    return proc;
}

/*
 *   call-seq:
 *      context.step(steps, force = false)
 *
 *   Stops the current context after a number of +steps+ are made.
 *   +force+ parameter (if true) ensures that the cursor moves from the current line.
 */
static VALUE
context_stop_next(int argc, VALUE *argv, VALUE self)
{
    VALUE steps, force;
    debug_context_t *debug_context;

    debug_check_started();

    rb_scan_args(argc, argv, "11", &steps, &force);
    if(FIX2INT(steps) < 0)
        rb_raise(rb_eRuntimeError, "Steps argument can't be negative.");

    Data_Get_Struct(self, debug_context_t, debug_context);
    debug_context->stop_next = FIX2INT(steps);
    if(RTEST(force))
        CTX_FL_SET(debug_context, CTX_FL_FORCE_MOVE);
    else
        CTX_FL_UNSET(debug_context, CTX_FL_FORCE_MOVE);

    return steps;
}

/*
 *   call-seq:
 *      context.step_over(steps, frame = nil, force = false)
 *
 *   Steps over a +steps+ number of times.
 *   Make step over operation on +frame+, by default the current frame.
 *   +force+ parameter (if true) ensures that the cursor moves from the current line.
 */
static VALUE
context_step_over(int argc, VALUE *argv, VALUE self)
{
    VALUE lines, frame, force;
    debug_context_t *debug_context;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);
    if(debug_context->stack_size == 0)
        rb_raise(rb_eRuntimeError, "No frames collected.");

    rb_scan_args(argc, argv, "12", &lines, &frame, &force);
    debug_context->stop_line = FIX2INT(lines);
    CTX_FL_UNSET(debug_context, CTX_FL_STEPPED);
    if(frame == Qnil)
    {
        debug_context->dest_frame = debug_context->stack_size;
    }
    else
    {
        if(FIX2INT(frame) < 0 && FIX2INT(frame) >= debug_context->stack_size)
            rb_raise(rb_eRuntimeError, "Destination frame is out of range.");
        debug_context->dest_frame = debug_context->stack_size - FIX2INT(frame);
    }
    if(RTEST(force))
        CTX_FL_SET(debug_context, CTX_FL_FORCE_MOVE);
    else
        CTX_FL_UNSET(debug_context, CTX_FL_FORCE_MOVE);

    return Qnil;
}

/*
 *   call-seq:
 *      context.stop_frame(frame)
 *
 *   Stops when a frame with number +frame+ is activated. Implements +up+ and +down+ commands.
 */
static VALUE
context_stop_frame(VALUE self, VALUE frame)
{
    debug_context_t *debug_context;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);
    if(FIX2INT(frame) < 0 && FIX2INT(frame) >= debug_context->stack_size)
        rb_raise(rb_eRuntimeError, "Stop frame is out of range.");
    debug_context->stop_frame = debug_context->stack_size - FIX2INT(frame);

    return frame;
}

inline static int
check_frame_number(debug_context_t *debug_context, VALUE frame)
{
    int frame_n;

    frame_n = FIX2INT(frame);
    if(frame_n < 0 || frame_n >= debug_context->stack_size)
    rb_raise(rb_eArgError, "Invalid frame number %d, stack (0...%d)",
        frame_n, debug_context->stack_size);
    return frame_n;
}

/*
 *   call-seq:
 *      context.frame_binding(frame) -> binding
 *
 *   Returns frame's binding.
 */
static VALUE
context_frame_binding(VALUE self, VALUE frame)
{
    debug_context_t *debug_context;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);
    return GET_FRAME->binding;
}

/*
 *   call-seq:
 *      context.frame_method(frame) -> sym
 *
 *   Returns the sym of the called method.
 */
static VALUE
context_frame_id(VALUE self, VALUE frame)
{

    debug_context_t *debug_context;
    ID id;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);

    id = GET_FRAME->id;
    return id ? ID2SYM(id): Qnil;
}

/*
 *   call-seq:
 *      context.frame_line(frame) -> int
 *
 *   Returns the line number in the file.
 */
static VALUE
context_frame_line(VALUE self, VALUE frame)
{
    debug_context_t *debug_context;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);

    return INT2FIX(GET_FRAME->line);
}

/*
 *   call-seq:
 *      context.frame_file(frame) -> string
 *
 *   Returns the name of the file.
 */
static VALUE
context_frame_file(VALUE self, VALUE frame)
{
    debug_context_t *debug_context;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);

    return rb_str_new2(GET_FRAME->file);
}

static VALUE
context_copy_locals(debug_frame_t *debug_frame)
{
    ID *tbl;
    int n, i;
    struct SCOPE *scope;
    struct RVarmap *vars;
    VALUE hash = rb_hash_new();

    scope = debug_frame->info.runtime.scope;
    tbl = scope->local_tbl;

    if (tbl && scope->local_vars) 
    {
        n = *tbl++;
        for (i=2; i<n; i++) 
        {   /* skip first 2 ($_ and $~) */
            if (!rb_is_local_id(tbl[i])) continue; /* skip flip states */
            rb_hash_aset(hash, rb_str_new2(rb_id2name(tbl[i])), scope->local_vars[i]);
        }
    }

    vars = debug_frame->info.runtime.dyna_vars;
    while (vars) 
    {
        if (vars->id && rb_is_local_id(vars->id)) 
        { /* skip $_, $~ and flip states */
            rb_hash_aset(hash, rb_str_new2(rb_id2name(vars->id)), vars->val);
        }
        vars = vars->next;
    }
    return hash;
}

/*
 *   call-seq:
 *      context.frame_locals(frame) -> hash
 *
 *   Returns frame's local variables.
 */
static VALUE
context_frame_locals(VALUE self, VALUE frame)
{
    debug_context_t *debug_context;
    debug_frame_t *debug_frame;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);

    debug_frame = GET_FRAME;
    if(debug_frame->dead)
        return debug_frame->info.copy.locals;
    else
        return context_copy_locals(debug_frame);
}

/*
 *   call-seq:
 *      context.frame_self(frame) -> obj
 *
 *   Returns self object of the frame.
 */
static VALUE
context_frame_self(VALUE self, VALUE frame)
{
    debug_context_t *debug_context;
    debug_frame_t *debug_frame;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);

    debug_frame = GET_FRAME;
    return debug_frame->self;
}

/*
 *   call-seq:
 *      context.frame_class(frame) -> obj
 *
 *   Returns the real class of the frame. 
 *   It could be different than context.frame_self(frame).class
 */
static VALUE
context_frame_class(VALUE self, VALUE frame)
{
    debug_context_t *debug_context;
    debug_frame_t *debug_frame;
    VALUE klass;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);

    debug_frame = GET_FRAME;
    
    if(CTX_FL_TEST(debug_context, CTX_FL_DEAD))
        return Qnil;
    
    klass = debug_frame->info.runtime.frame->last_class;
    klass = real_class(klass);
    if(TYPE(klass) == T_CLASS || TYPE(klass) == T_MODULE)
        return klass;
    return Qnil;
}


/*
 *   call-seq:
 *      context.stack_size-> int
 *
 *   Returns the size of the context stack.
 */
static VALUE
context_stack_size(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);

    return INT2FIX(debug_context->stack_size);
}

/*
 *   call-seq:
 *      context.thread -> trhread
 *
 *   Returns a thread this context is associated with.
 */
static VALUE
context_thread(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();
    Data_Get_Struct(self, debug_context_t, debug_context);
    return context_thread_0(debug_context);
}

/*
 *   call-seq:
 *      context.thnum -> int
 *
 *   Returns the context's number.
 */
static VALUE
context_thnum(VALUE self)
{
    debug_context_t *debug_context;

    Data_Get_Struct(self, debug_context_t, debug_context);
    return INT2FIX(debug_context->thnum);
}

static void
context_suspend_0(debug_context_t *debug_context)
{
    VALUE status;

    status = rb_funcall(context_thread_0(debug_context), rb_intern("status"), 0);
    if(rb_str_cmp(status, rb_str_new2("run")) == 0)
      CTX_FL_SET(debug_context, CTX_FL_WAS_RUNNING);
    else if(rb_str_cmp(status, rb_str_new2("sleep")) == 0)
      CTX_FL_UNSET(debug_context, CTX_FL_WAS_RUNNING);
    else
      return;
    CTX_FL_SET(debug_context, CTX_FL_SUSPEND);
}

static void
context_resume_0(debug_context_t *debug_context)
{
    if(!CTX_FL_TEST(debug_context, CTX_FL_SUSPEND))
      return;
    CTX_FL_UNSET(debug_context, CTX_FL_SUSPEND);
    if(CTX_FL_TEST(debug_context, CTX_FL_WAS_RUNNING))
      rb_thread_wakeup(context_thread_0(debug_context));
}

/*
 *   call-seq:
 *      context.suspend -> nil
 *
 *   Suspends the thread when it is running.
 */
static VALUE
context_suspend(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    if(CTX_FL_TEST(debug_context, CTX_FL_SUSPEND))
        rb_raise(rb_eRuntimeError, "Already suspended.");
    context_suspend_0(debug_context);
    return Qnil;
}

/*
 *   call-seq:
 *      context.suspended? -> bool
 *
 *   Returns +true+ if the thread is suspended by debugger.
 */
static VALUE
context_is_suspended(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    return CTX_FL_TEST(debug_context, CTX_FL_SUSPEND) ? Qtrue : Qfalse;
}

/*
 *   call-seq:
 *      context.resume -> nil
 *
 *   Resumes the thread from the suspended mode.
 */
static VALUE
context_resume(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    if(!CTX_FL_TEST(debug_context, CTX_FL_SUSPEND))
        rb_raise(rb_eRuntimeError, "Thread is not suspended.");
    context_resume_0(debug_context);
    return Qnil;
}

/*
 *   call-seq:
 *      context.tracing -> bool
 *
 *   Returns the tracing flag for the current context.
 */
static VALUE
context_tracing(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    return CTX_FL_TEST(debug_context, CTX_FL_TRACING) ? Qtrue : Qfalse;
}

/*
 *   call-seq:
 *      context.tracking = bool
 *
 *   Controls the tracing for this context.
 */
static VALUE
context_set_tracing(VALUE self, VALUE value)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    if(RTEST(value))
        CTX_FL_SET(debug_context, CTX_FL_TRACING);
    else
        CTX_FL_UNSET(debug_context, CTX_FL_TRACING);
    return value;
}

/*
 *   call-seq:
 *      context.ignored? -> bool
 *
 *   Returns the ignore flag for the current context.
 */
static VALUE
context_ignored(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    return CTX_FL_TEST(debug_context, CTX_FL_IGNORE) ? Qtrue : Qfalse;
}

/*
 *   call-seq:
 *      context.dead? -> bool
 *
 *   Returns +true+ if context doesn't represent a live context and is created
 *   during post-mortem exception handling.
 */
static VALUE
context_dead(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    return CTX_FL_TEST(debug_context, CTX_FL_DEAD) ? Qtrue : Qfalse;
}

/*
 *   call-seq:
 *      context.breakpoint -> breakpoint
 *
 *   Returns a context-specific temporary Breakpoint object.
 */
static VALUE
context_breakpoint(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    return debug_context->breakpoint;
}

/*
 *   call-seq:
 *      context.set_breakpoint(source, pos, condition = nil) -> breakpoint
 *
 *   Sets a context-specific temporary breakpoint, which can be used to implement
 *   'Run to Cursor' debugger function. When this breakpoint is reached, it will be
 *   cleared out.
 *
 *   <i>source</i> is a name of a file or a class.
 *   <i>pos</i> is a line number or a method name if <i>source</i> is a class name.
 *   <i>condition</i> is a string which is evaluated to +true+ when this breakpoint
 *   is activated.
 */
static VALUE
context_set_breakpoint(int argc, VALUE *argv, VALUE self)
{
    VALUE result;
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    result = create_breakpoint_from_args(argc, argv, 0);
    debug_context->breakpoint = result;
    return result;
}

/*
 *   call-seq:
 *      context.stop_reason -> sym
 *   
 *   Returns the reason for the stop. It maybe of the following values:
 *   :initial, :step, :breakpoint, :catchpoint, :post-mortem
 */
static VALUE
context_stop_reason(VALUE self)
{
    debug_context_t *debug_context;
    char * sym_name;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    
    switch(debug_context->stop_reason)
    {
        case CTX_STOP_STEP:
            sym_name = "step";
            break;
        case CTX_STOP_BREAKPOINT:
            sym_name = "breakpoint";
            break;
        case CTX_STOP_CATCHPOINT:
            sym_name = "catchpoint";
            break;
        case CTX_STOP_NONE:
        default:
            sym_name = "none";
    }
    if(CTX_FL_TEST(debug_context, CTX_FL_DEAD))
        sym_name = "post-mortem";
    
    return ID2SYM(rb_intern(sym_name));
}


/*
 *   call-seq:
 *      breakpoint.source -> string
 *
 *   Returns a source of the breakpoint.
 */
static VALUE
breakpoint_source(VALUE self)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    return breakpoint->source;
}

/*
 *   call-seq:
 *      breakpoint.source = string
 *
 *   Sets the source of the breakpoint.
 */
static VALUE
breakpoint_set_source(VALUE self, VALUE value)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    breakpoint->source = StringValue(value);
    return value;
}

/*
 *   call-seq:
 *      breakpoint.pos -> string or int
 *
 *   Returns a position of this breakpoint.
 */
static VALUE
breakpoint_pos(VALUE self)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    if(breakpoint->type == BP_METHOD_TYPE)
        return rb_str_new2(rb_id2name(breakpoint->pos.mid));
    else
        return INT2FIX(breakpoint->pos.line);
}

/*
 *   call-seq:
 *      breakpoint.pos = string or int
 *
 *   Sets the position of this breakpoint.
 */
static VALUE
breakpoint_set_pos(VALUE self, VALUE value)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    if(breakpoint->type == BP_METHOD_TYPE)
    {
        breakpoint->pos.mid = rb_to_id(StringValue(value));
    }
    else
        breakpoint->pos.line = FIX2INT(value);
    return value;
}

/*
 *   call-seq:
 *      breakpoint.expr -> string
 *
 *   Returns a codition expression when this breakpoint should be activated.
 */
static VALUE
breakpoint_expr(VALUE self)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    return breakpoint->expr;
}

/*
 *   call-seq:
 *      breakpoint.expr = string
 *
 *   Sets the codition expression when this breakpoint should be activated.
 */
static VALUE
breakpoint_set_expr(VALUE self, VALUE value)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    breakpoint->expr = StringValue(value);
    return value;
}

/*
 *   call-seq:
 *      breakpoint.id -> int
 *
 *   Returns id of the breakpoint.
 */
static VALUE
breakpoint_id(VALUE self)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    return INT2FIX(breakpoint->id);
}

/*
 *   call-seq:
 *      breakpoint.hit_count -> int
 *
 *   Returns the hit count of the breakpoint.
 */
static VALUE
breakpoint_hit_count(VALUE self)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    return INT2FIX(breakpoint->hit_count);
}

/*
 *   call-seq:
 *      breakpoint.hit_value -> int
 *
 *   Returns the hit value of the breakpoint.
 */
static VALUE
breakpoint_hit_value(VALUE self)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    return INT2FIX(breakpoint->hit_value);
}

/*
 *   call-seq:
 *      breakpoint.hit_value = int
 *
 *   Sets the hit value of the breakpoint.
 */
static VALUE
breakpoint_set_hit_value(VALUE self, VALUE value)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    breakpoint->hit_value = FIX2INT(value);
    return value;
}

/*
 *   call-seq:
 *      breakpoint.hit_condition -> symbol
 *
 *   Returns the hit condition of the breakpoint:
 *
 *   +nil+ if it is an unconditional breakpoint, or
 *   :greater_or_equal, :equal, :modulo
 */
static VALUE
breakpoint_hit_condition(VALUE self)
{
    debug_breakpoint_t *breakpoint;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    switch(breakpoint->hit_condition)
    {
        case HIT_COND_GE:
            return ID2SYM(rb_intern("greater_or_equal"));
        case HIT_COND_EQ:
            return ID2SYM(rb_intern("equal"));
        case HIT_COND_MOD:
            return ID2SYM(rb_intern("modulo"));
        case HIT_COND_NONE:
        default:
            return Qnil;
    }
}

/*
 *   call-seq:
 *      breakpoint.hit_condition = symbol
 *
 *   Sets the hit condition of the breakpoint which must be one of the following values:
 *
 *   +nil+ if it is an unconditional breakpoint, or
 *   :greater_or_equal(:ge), :equal(:eq), :modulo(:mod)
 */
static VALUE
breakpoint_set_hit_condition(VALUE self, VALUE value)
{
    debug_breakpoint_t *breakpoint;
    ID id_value;

    Data_Get_Struct(self, debug_breakpoint_t, breakpoint);
    id_value = rb_to_id(value);
    
    if(rb_intern("greater_or_equal") == id_value || rb_intern("ge") == id_value)
        breakpoint->hit_condition = HIT_COND_GE;
    else if(rb_intern("equal") == id_value || rb_intern("eq") == id_value)
        breakpoint->hit_condition = HIT_COND_EQ;
    else if(rb_intern("modulo") == id_value || rb_intern("mod") == id_value)
        breakpoint->hit_condition = HIT_COND_MOD;
    else
        rb_raise(rb_eArgError, "Invalid condition parameter");
    return value;
}

/*
 *   Document-class: Context
 *
 *   == Summary
 *
 *   Debugger keeps a single instance of this class for each Ruby thread.
 */
static void
Init_context()
{
    cContext = rb_define_class_under(mDebugger, "Context", rb_cObject);
    rb_define_method(cContext, "stop_next=", context_stop_next, -1);
    rb_define_method(cContext, "step", context_stop_next, -1);
    rb_define_method(cContext, "step_over", context_step_over, -1);
    rb_define_method(cContext, "stop_frame=", context_stop_frame, 1);
    rb_define_method(cContext, "thread", context_thread, 0);
    rb_define_method(cContext, "thnum", context_thnum, 0);
    rb_define_method(cContext, "stop_reason", context_stop_reason, 0);
    rb_define_method(cContext, "suspend", context_suspend, 0);
    rb_define_method(cContext, "suspended?", context_is_suspended, 0);
    rb_define_method(cContext, "resume", context_resume, 0);
    rb_define_method(cContext, "tracing", context_tracing, 0);
    rb_define_method(cContext, "tracing=", context_set_tracing, 1);
    rb_define_method(cContext, "ignored?", context_ignored, 0);
    rb_define_method(cContext, "frame_binding", context_frame_binding, 1);
    rb_define_method(cContext, "frame_id", context_frame_id, 1);
    rb_define_method(cContext, "frame_method", context_frame_id, 1);
    rb_define_method(cContext, "frame_line", context_frame_line, 1);
    rb_define_method(cContext, "frame_file", context_frame_file, 1);
    rb_define_method(cContext, "frame_locals", context_frame_locals, 1);
    rb_define_method(cContext, "frame_self", context_frame_self, 1);
    rb_define_method(cContext, "frame_class", context_frame_class, 1);
    rb_define_method(cContext, "stack_size", context_stack_size, 0);
    rb_define_method(cContext, "dead?", context_dead, 0);
    rb_define_method(cContext, "breakpoint", context_breakpoint, 0);
    rb_define_method(cContext, "set_breakpoint", context_set_breakpoint, -1);
}

/*
 *   Document-class: Breakpoint
 *
 *   == Summary
 *
 *   This class represents a breakpoint. It defines position of the breakpoint and
 *   condition when this breakpoint should be triggered.
 */
static void
Init_breakpoint()
{
    cBreakpoint = rb_define_class_under(mDebugger, "Breakpoint", rb_cObject);
    rb_define_method(cBreakpoint, "id", breakpoint_id, 0);
    rb_define_method(cBreakpoint, "source", breakpoint_source, 0);
    rb_define_method(cBreakpoint, "source=", breakpoint_set_source, 1);
    rb_define_method(cBreakpoint, "pos", breakpoint_pos, 0);
    rb_define_method(cBreakpoint, "pos=", breakpoint_set_pos, 1);
    rb_define_method(cBreakpoint, "expr", breakpoint_expr, 0);
    rb_define_method(cBreakpoint, "expr=", breakpoint_set_expr, 1);
    rb_define_method(cBreakpoint, "hit_count", breakpoint_hit_count, 0);
    rb_define_method(cBreakpoint, "hit_value", breakpoint_hit_value, 0);
    rb_define_method(cBreakpoint, "hit_value=", breakpoint_set_hit_value, 1);
    rb_define_method(cBreakpoint, "hit_condition", breakpoint_hit_condition, 0);
    rb_define_method(cBreakpoint, "hit_condition=", breakpoint_set_hit_condition, 1);
}


/*
 *   Document-class: Debugger
 *
 *   == Summary
 *
 *   This is a singleton class allows controlling the debugger. Use it to start/stop debugger,
 *   set/remove breakpoints, etc.
 */
#if defined(_WIN32)
__declspec(dllexport)
#endif
void
Init_ruby_debug()
{
    mDebugger = rb_define_module("Debugger");
    rb_define_const(mDebugger, "VERSION", rb_str_new2(DEBUG_VERSION));
    rb_define_module_function(mDebugger, "start", debug_start, 0);
    rb_define_module_function(mDebugger, "stop", debug_stop, 0);
    rb_define_module_function(mDebugger, "started?", debug_is_started, 0);
    rb_define_module_function(mDebugger, "breakpoints", debug_breakpoints, 0);
    rb_define_module_function(mDebugger, "add_breakpoint", debug_add_breakpoint, -1);
    rb_define_module_function(mDebugger, "remove_breakpoint", debug_remove_breakpoint, 1);
    rb_define_module_function(mDebugger, "catchpoint", debug_catchpoint, 0);
    rb_define_module_function(mDebugger, "catchpoint=", debug_set_catchpoint, 1);
    rb_define_module_function(mDebugger, "last_context", debug_last_interrupted, 0);
    rb_define_module_function(mDebugger, "contexts", debug_contexts, 0);
    rb_define_module_function(mDebugger, "current_context", debug_current_context, 0);
    rb_define_module_function(mDebugger, "thread_context", debug_thread_context, 1);
    rb_define_module_function(mDebugger, "suspend", debug_suspend, 0);
    rb_define_module_function(mDebugger, "resume", debug_resume, 0);
    rb_define_module_function(mDebugger, "tracing", debug_tracing, 0);
    rb_define_module_function(mDebugger, "tracing=", debug_set_tracing, 1);
    rb_define_module_function(mDebugger, "debug_load", debug_debug_load, -1);
    rb_define_module_function(mDebugger, "skip", debug_skip, 0);
    rb_define_module_function(mDebugger, "debug_at_exit", debug_at_exit, 0);
    rb_define_module_function(mDebugger, "post_mortem?", debug_post_mortem, 0);
    rb_define_module_function(mDebugger, "post_mortem=", debug_set_post_mortem, 1);
    rb_define_module_function(mDebugger, "keep_frame_binding?", debug_keep_frame_binding, 0);
    rb_define_module_function(mDebugger, "keep_frame_binding=", debug_set_keep_frame_binding, 1);
    rb_define_module_function(mDebugger, "debug", debug_debug, 0);
    rb_define_module_function(mDebugger, "debug=", debug_set_debug, 1);

    cThreadsTable = rb_define_class_under(mDebugger, "ThreadsTable", rb_cObject);

    cDebugThread  = rb_define_class_under(mDebugger, "DebugThread", rb_cThread);
    rb_define_singleton_method(cDebugThread, "inherited", debug_thread_inherited, 1);

    Init_context();
    Init_breakpoint();

    idAtLine       = rb_intern("at_line");
    idAtBreakpoint = rb_intern("at_breakpoint");
    idAtCatchpoint = rb_intern("at_catchpoint");
    idAtTracing    = rb_intern("at_tracing");
    idEval         = rb_intern("eval");
    idList         = rb_intern("list");

    rb_mObjectSpace = rb_const_get(rb_mKernel, rb_intern("ObjectSpace"));

    rb_global_variable(&threads_tbl);
    rb_global_variable(&breakpoints);
    rb_global_variable(&catchpoint);
    rb_global_variable(&locker);
    rb_global_variable(&last_context);
    rb_global_variable(&last_thread);
}