C++ resethookcount函数代码示例

static void traceexec (lua_State *L) {
  CallInfo *ci = L->ci;
  lu_byte mask = L->hookmask;
  int counthook = ((mask & LUA_MASKCOUNT) && L->hookcount == 0);
  if (counthook)
    resethookcount(L);  /* reset count */
  if (ci->callstatus & CIST_HOOKYIELD) {  /* called hook last time? */
    ci->callstatus &= ~CIST_HOOKYIELD;  /* erase mark */
    return;  /* do not call hook again (VM yielded, so it did not move) */
  }
  if (counthook)
    luaD_hook(L, LUA_HOOKCOUNT, -1);  /* call count hook */
  if (mask & LUA_MASKLINE) {
    Proto *p = ci_func(ci)->p;
    int npc = pcRel(ci->u.l.savedpc, p);
    int newline = getfuncline(p, npc);
    if (npc == 0 ||  /* call linehook when enter a new function, */
        ci->u.l.savedpc <= L->oldpc ||  /* when jump back (loop), or when */
        newline != getfuncline(p, pcRel(L->oldpc, p)))  /* enter a new line */
      luaD_hook(L, LUA_HOOKLINE, newline);  /* call line hook */
  }
  L->oldpc = ci->u.l.savedpc;
  if (L->status == LUA_YIELD) {  /* did hook yield? */
    if (counthook)
      L->hookcount = 1;  /* undo decrement to zero */
    ci->u.l.savedpc--;  /* undo increment (resume will increment it again) */
    ci->callstatus |= CIST_HOOKYIELD;  /* mark that it yielded */
    ci->func = L->top - 1;  /* protect stack below results */
    luaD_throw(L, LUA_YIELD);
  }
}

LUA_API lua_State *lua_newthread (lua_State *L) {
  global_State *g = G(L);
  lua_State *L1;
  lua_lock(L);
  luaC_checkGC(L);
  /* create new thread */
  L1 = &cast(LX *, luaM_newobject(L, LUA_TTHREAD, sizeof(LX)))->l;
  L1->marked = luaC_white(g);
  L1->tt = LUA_TTHREAD;
  /* link it on list 'allgc' */
  L1->next = g->allgc;
  g->allgc = obj2gco(L1);
  /* anchor it on L stack */
  setthvalue(L, L->top, L1);
  api_incr_top(L);
  preinit_thread(L1, g);
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  /* initialize L1 extra space */
  c_memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
         LUA_EXTRASPACE);
  luai_userstatethread(L, L1);
  stack_init(L1, L);  /* init stack */
  lua_unlock(L);
  return L1;
}

static void traceexec (lua_State *L) {
  lu_byte mask = L->hookmask;
  if (mask > LUA_MASKLINE) {  /* instruction-hook set? */
    if (L->hookcount == 0) {
      resethookcount(L);
      luaD_callhook(L, LUA_HOOKCOUNT, -1);
      return;
    }
  }
  if (mask & LUA_MASKLINE) {
    CallInfo *ci = L->ci;
    Proto *p = ci_func(ci)->l.p;
    int newline = getline(p, pcRel(*ci->u.l.pc, p));
    if (!L->hookinit) {
      luaG_inithooks(L);
      return;
    }
    lua_assert(ci->state & CI_HASFRAME);
    if (pcRel(*ci->u.l.pc, p) == 0)  /* tracing may be starting now? */
      ci->u.l.savedpc = *ci->u.l.pc;  /* initialize `savedpc' */
    /* calls linehook when enters a new line or jumps back (loop) */
    if (*ci->u.l.pc <= ci->u.l.savedpc ||
        newline != getline(p, pcRel(ci->u.l.savedpc, p))) {
      luaD_callhook(L, LUA_HOOKLINE, newline);
      ci = L->ci;  /* previous call may reallocate `ci' */
    }
    ci->u.l.savedpc = *ci->u.l.pc;
  }
}

/*
** this function can be called asynchronous (e.g. during a signal)
*/
LUA_API int lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
  if (func == NULL || mask == 0) {  /* turn off hooks? */
    mask = 0;
    func = NULL;
  }
  L->hook = func;
  L->basehookcount = count;
  resethookcount(L);
  L->hookmask = cast_byte(mask);
  return 1;
}

/*
** This function can be called asynchronously (e.g. during a signal).
** Fields 'oldpc', 'basehookcount', and 'hookcount' (set by
** 'resethookcount') are for debug only, and it is no problem if they
** get arbitrary values (causes at most one wrong hook call). 'hookmask'
** is an atomic value. We assume that pointers are atomic too (e.g., gcc
** ensures that for all platforms where it runs). Moreover, 'hook' is
** always checked before being called (see 'luaD_hook').
*/
LUA_API void lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
  if (func == NULL || mask == 0) {  /* turn off hooks? */
    mask = 0;
    func = NULL;
  }
  if (isLua(L->ci))
    L->oldpc = L->ci->u.l.savedpc;
  L->hook = func;
  L->basehookcount = count;
  resethookcount(L);
  L->hookmask = cast_byte(mask);
}

lua_State *luaE_newthread (lua_State *L) {
  lua_State *L1 = tostate(luaM_malloc(L, state_size(lua_State)));
  luaC_link(L, obj2gco(L1), LUA_TTHREAD);
  preinit_state(L1, G(L));
  stack_init(L1, L);  /* init stack */
  setobj2n(L, gt(L1), gt(L));  /* share table of globals */
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  lua_assert(iswhite(obj2gco(L1)));
  return L1;
}

static void preinit_state (lua_State *L) {
  L->stack = NULL;
  L->stacksize = 0;
  L->errorJmp = NULL;
  L->hook = NULL;
  L->hookmask = L->hookinit = 0;
  L->basehookcount = 0;
  L->allowhook = 1;
  resethookcount(L);
  L->openupval = NULL;
  L->size_ci = 0;
  L->nCcalls = 0;
  L->base_ci = L->ci = NULL;
  L->errfunc = 0;
  setnilvalue(gt(L));
}

lua_State *luaE_newthread (lua_State *L) {
  lua_State *L1 = tostate(luaM_malloc(L, state_size(lua_State)));
  luaC_link(L, obj2gco(L1), LUA_TTHREAD);
  setthvalue(L, L->top, L1); /* put thread on stack */
  incr_top(L);
  preinit_state(L1, G(L));
  stack_init(L1, L);  /* init stack */
  setobj2n(L, gt(L1), gt(L));  /* share table of globals */
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  lua_assert(!isdead(G(L), obj2gco(L1)));
  L->top--; /* remove thread from stack */
  return L1;
}

LUA_API lua_State *lua_newthread (lua_State *L) {
  lua_State *L1;
  lua_lock(L);
  luaC_checkGC(L);
  L1 = &luaC_newobj(L, LUA_TTHREAD, sizeof(LX), NULL, offsetof(LX, l))->th;
  setthvalue(L, L->top, L1);
  api_incr_top(L);
  preinit_state(L1, G(L));
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  luai_userstatethread(L, L1);
  stack_init(L1, L);  /* init stack */
  lua_unlock(L);
  return L1;
}

/*
** preinitialize a state with consistent values without allocating
** any memory (to avoid errors)
*/
static void preinit_state (lua_State *L, global_State *g) {
  G(L) = g;
  L->stack = NULL;
  L->ci = NULL;
  L->stacksize = 0;
  L->errorJmp = NULL;
  L->nCcalls = 0;
  L->hook = NULL;
  L->hookmask = 0;
  L->basehookcount = 0;
  L->allowhook = 1;
  resethookcount(L);
  L->openupval = NULL;
  L->nny = 1;
  L->status = LUA_OK;
  L->errfunc = 0;
}

static void traceexec (lua_State *L, const Instruction *pc) {
  lu_byte mask = L->hookmask;
  const Instruction *oldpc = L->savedpc;
  L->savedpc = pc;
  if ((mask & LUA_MASKCOUNT) && L->hookcount == 0) {
    resethookcount(L);
    luaD_callhook(L, LUA_HOOKCOUNT, -1);
  }
  if (mask & LUA_MASKLINE) {
    Proto *p = ci_func(L->ci)->l.p;
    int npc = pcRel(pc, p);
    int newline = getline(p, npc);
    /* call linehook when enter a new function, when jump back (loop),
       or when enter a new line */
    if (npc == 0 || pc <= oldpc || newline != getline(p, pcRel(oldpc, p)))
      luaD_callhook(L, LUA_HOOKLINE, newline);
  }
}

static void preinit_state (lua_State *L, global_State *g) {
  G(L) = g;
  L->stack = NULL;
  L->stacksize = 0;
  L->hook = NULL;
  L->hookmask = 0;
  L->basehookcount = 0;
  L->allowhook = 1;
  resethookcount(L);
  L->openupval = NULL;
  L->size_ci = 0;
  L->nCcalls = L->baseCcalls = 0;
  L->status = 0;
  L->base_ci = L->ci = NULL;
  L->savedpc = NULL;
  L->errfunc = 0;
  setnilvalue(gt(L));
}

/*
** preinitialize a thread with consistent values without allocating
** any memory (to avoid errors)
*/
static void preinit_thread (lua_State *L, global_State *g) {
  G(L) = g;
  L->stack = NULL;
  L->ci = NULL;
  L->nci = 0;
  L->stacksize = 0;
  L->twups = L;  /* thread has no upvalues */
  L->errorJmp = NULL;
  L->nCcalls = 0;
  L->hook = NULL;
  L->hookmask = 0;
  L->basehookcount = 0;
  L->allowhook = 1;
  resethookcount(L);
  L->openupval = NULL;
  L->nny = 1;
  L->status = LUA_OK;
  L->errfunc = 0;
  L->base_ci.stacklevel = 0; /* RAVI base stack level */
}

// [@lvm] 检查并调用hook函数
static void traceexec (lua_State *L, const Instruction *pc) {
  lu_byte mask = L->hookmask;
  const Instruction *oldpc = L->savedpc;
  L->savedpc = pc;
  if (mask > LUA_MASKLINE) {  /* instruction-hook set? */
    if (L->hookcount == 0) {
      resethookcount(L);
      luaD_callhook(L, LUA_HOOKCOUNT, -1);
    }
  }
  if (mask & LUA_MASKLINE) {
    Proto *p = ci_func(L->ci)->l.p;
    int npc = pcRel(pc, p);			//now pc
    int newline = getline(p, npc);
    /* call linehook when enter a new function, when jump back (loop),
       or when enter a new line */
	// 看仔细了：`when jump back`，对应pc <= oldpc。这也算newline，所以导致
	// LDT会在同一行停呀停！
    if (npc == 0 || pc <= oldpc || newline != getline(p, pcRel(oldpc, p)))
      luaD_callhook(L, LUA_HOOKLINE, newline);
  }
}

static void traceexec (lua_State *L) {
  CallInfo *ci = L->ci;
  lu_byte mask = L->hookmask;
  if ((mask & LUA_MASKCOUNT) && L->hookcount == 0) {
    resethookcount(L);
    luaD_hook(L, LUA_HOOKCOUNT, -1);
  }
  if (mask & LUA_MASKLINE) {
    Proto *p = ci_func(ci)->p;
    int npc = pcRel(ci->u.l.savedpc, p);
    int newline = getfuncline(p, npc);
    if (npc == 0 ||  /* call linehook when enter a new function, */
        ci->u.l.savedpc <= L->oldpc ||  /* when jump back (loop), or when */
        newline != getfuncline(p, pcRel(L->oldpc, p)))  /* enter a new line */
      luaD_hook(L, LUA_HOOKLINE, newline);
  }
  L->oldpc = ci->u.l.savedpc;
  if (L->status == LUA_YIELD) {  /* did hook yield? */
    ci->u.l.savedpc--;  /* undo increment (resume will increment it again) */
    luaD_throw(L, LUA_YIELD);
  }
}