Add Lua source, not compiled yet as libc/libm functions remain unimplemented

1 files changed, 800 insertions, 0 deletions

diff --git a/src/lib/lua/ldo.c b/src/lib/lua/ldo.c
new file mode 100644
index 0000000..8804c99
--- /dev/null
+++ b/src/lib/lua/ldo.c
@@ -0,0 +1,800 @@
+/*
+** $Id: ldo.c,v 2.151 2015/12/16 16:40:07 roberto Exp $
+** Stack and Call structure of Lua
+** See Copyright Notice in lua.h
+*/
+
+#define ldo_c
+#define LUA_CORE
+
+#include "lprefix.h"
+
+
+#include <setjmp.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "lua.h"
+
+#include "lapi.h"
+#include "ldebug.h"
+#include "ldo.h"
+#include "lfunc.h"
+#include "lgc.h"
+#include "lmem.h"
+#include "lobject.h"
+#include "lopcodes.h"
+#include "lparser.h"
+#include "lstate.h"
+#include "lstring.h"
+#include "ltable.h"
+#include "ltm.h"
+#include "lundump.h"
+#include "lvm.h"
+#include "lzio.h"
+
+
+
+#define errorstatus(s)	((s) > LUA_YIELD)
+
+
+/*
+** {======================================================
+** Error-recovery functions
+** =======================================================
+*/
+
+/*
+** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
+** default, Lua handles errors with exceptions when compiling as
+** C++ code, with _longjmp/_setjmp when asked to use them, and with
+** longjmp/setjmp otherwise.
+*/
+#if !defined(LUAI_THROW)				/* { */
+
+#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)	/* { */
+
+/* C++ exceptions */
+#define LUAI_THROW(L,c)		throw(c)
+#define LUAI_TRY(L,c,a) \
+	try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
+#define luai_jmpbuf		int  /* dummy variable */
+
+#elif defined(LUA_USE_POSIX)				/* }{ */
+
+/* in POSIX, try _longjmp/_setjmp (more efficient) */
+#define LUAI_THROW(L,c)		_longjmp((c)->b, 1)
+#define LUAI_TRY(L,c,a)		if (_setjmp((c)->b) == 0) { a }
+#define luai_jmpbuf		jmp_buf
+
+#else							/* }{ */
+
+/* ISO C handling with long jumps */
+#define LUAI_THROW(L,c)		longjmp((c)->b, 1)
+#define LUAI_TRY(L,c,a)		if (setjmp((c)->b) == 0) { a }
+#define luai_jmpbuf		jmp_buf
+
+#endif							/* } */
+
+#endif							/* } */
+
+
+
+/* chain list of long jump buffers */
+struct lua_longjmp {
+  struct lua_longjmp *previous;
+  luai_jmpbuf b;
+  volatile int status;  /* error code */
+};
+
+
+static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
+  switch (errcode) {
+    case LUA_ERRMEM: {  /* memory error? */
+      setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
+      break;
+    }
+    case LUA_ERRERR: {
+      setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
+      break;
+    }
+    default: {
+      setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
+      break;
+    }
+  }
+  L->top = oldtop + 1;
+}
+
+
+l_noret luaD_throw (lua_State *L, int errcode) {
+  if (L->errorJmp) {  /* thread has an error handler? */
+    L->errorJmp->status = errcode;  /* set status */
+    LUAI_THROW(L, L->errorJmp);  /* jump to it */
+  }
+  else {  /* thread has no error handler */
+    global_State *g = G(L);
+    L->status = cast_byte(errcode);  /* mark it as dead */
+    if (g->mainthread->errorJmp) {  /* main thread has a handler? */
+      setobjs2s(L, g->mainthread->top++, L->top - 1);  /* copy error obj. */
+      luaD_throw(g->mainthread, errcode);  /* re-throw in main thread */
+    }
+    else {  /* no handler at all; abort */
+      if (g->panic) {  /* panic function? */
+        seterrorobj(L, errcode, L->top);  /* assume EXTRA_STACK */
+        if (L->ci->top < L->top)
+          L->ci->top = L->top;  /* pushing msg. can break this invariant */
+        lua_unlock(L);
+        g->panic(L);  /* call panic function (last chance to jump out) */
+      }
+      abort();
+    }
+  }
+}
+
+
+int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
+  unsigned short oldnCcalls = L->nCcalls;
+  struct lua_longjmp lj;
+  lj.status = LUA_OK;
+  lj.previous = L->errorJmp;  /* chain new error handler */
+  L->errorJmp = &lj;
+  LUAI_TRY(L, &lj,
+    (*f)(L, ud);
+  );
+  L->errorJmp = lj.previous;  /* restore old error handler */
+  L->nCcalls = oldnCcalls;
+  return lj.status;
+}
+
+/* }====================================================== */
+
+
+/*
+** {==================================================================
+** Stack reallocation
+** ===================================================================
+*/
+static void correctstack (lua_State *L, TValue *oldstack) {
+  CallInfo *ci;
+  UpVal *up;
+  L->top = (L->top - oldstack) + L->stack;
+  for (up = L->openupval; up != NULL; up = up->u.open.next)
+    up->v = (up->v - oldstack) + L->stack;
+  for (ci = L->ci; ci != NULL; ci = ci->previous) {
+    ci->top = (ci->top - oldstack) + L->stack;
+    ci->func = (ci->func - oldstack) + L->stack;
+    if (isLua(ci))
+      ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
+  }
+}
+
+
+/* some space for error handling */
+#define ERRORSTACKSIZE	(LUAI_MAXSTACK + 200)
+
+
+void luaD_reallocstack (lua_State *L, int newsize) {
+  TValue *oldstack = L->stack;
+  int lim = L->stacksize;
+  lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
+  lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
+  luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
+  for (; lim < newsize; lim++)
+    setnilvalue(L->stack + lim); /* erase new segment */
+  L->stacksize = newsize;
+  L->stack_last = L->stack + newsize - EXTRA_STACK;
+  correctstack(L, oldstack);
+}
+
+
+void luaD_growstack (lua_State *L, int n) {
+  int size = L->stacksize;
+  if (size > LUAI_MAXSTACK)  /* error after extra size? */
+    luaD_throw(L, LUA_ERRERR);
+  else {
+    int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
+    int newsize = 2 * size;
+    if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
+    if (newsize < needed) newsize = needed;
+    if (newsize > LUAI_MAXSTACK) {  /* stack overflow? */
+      luaD_reallocstack(L, ERRORSTACKSIZE);
+      luaG_runerror(L, "stack overflow");
+    }
+    else
+      luaD_reallocstack(L, newsize);
+  }
+}
+
+
+static int stackinuse (lua_State *L) {
+  CallInfo *ci;
+  StkId lim = L->top;
+  for (ci = L->ci; ci != NULL; ci = ci->previous) {
+    lua_assert(ci->top <= L->stack_last);
+    if (lim < ci->top) lim = ci->top;
+  }
+  return cast_int(lim - L->stack) + 1;  /* part of stack in use */
+}
+
+
+void luaD_shrinkstack (lua_State *L) {
+  int inuse = stackinuse(L);
+  int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
+  if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
+  if (L->stacksize > LUAI_MAXSTACK)  /* was handling stack overflow? */
+    luaE_freeCI(L);  /* free all CIs (list grew because of an error) */
+  else
+    luaE_shrinkCI(L);  /* shrink list */
+  if (inuse <= LUAI_MAXSTACK &&  /* not handling stack overflow? */
+      goodsize < L->stacksize)  /* trying to shrink? */
+    luaD_reallocstack(L, goodsize);  /* shrink it */
+  else
+    condmovestack(L,,);  /* don't change stack (change only for debugging) */
+}
+
+
+void luaD_inctop (lua_State *L) {
+  luaD_checkstack(L, 1);
+  L->top++;
+}
+
+/* }================================================================== */
+
+
+/*
+** Call a hook for the given event. Make sure there is a hook to be
+** called. (Both 'L->hook' and 'L->hookmask', which triggers this
+** function, can be changed asynchronously by signals.)
+*/
+void luaD_hook (lua_State *L, int event, int line) {
+  lua_Hook hook = L->hook;
+  if (hook && L->allowhook) {  /* make sure there is a hook */
+    CallInfo *ci = L->ci;
+    ptrdiff_t top = savestack(L, L->top);
+    ptrdiff_t ci_top = savestack(L, ci->top);
+    lua_Debug ar;
+    ar.event = event;
+    ar.currentline = line;
+    ar.i_ci = ci;
+    luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
+    ci->top = L->top + LUA_MINSTACK;
+    lua_assert(ci->top <= L->stack_last);
+    L->allowhook = 0;  /* cannot call hooks inside a hook */
+    ci->callstatus |= CIST_HOOKED;
+    lua_unlock(L);
+    (*hook)(L, &ar);
+    lua_lock(L);
+    lua_assert(!L->allowhook);
+    L->allowhook = 1;
+    ci->top = restorestack(L, ci_top);
+    L->top = restorestack(L, top);
+    ci->callstatus &= ~CIST_HOOKED;
+  }
+}
+
+
+static void callhook (lua_State *L, CallInfo *ci) {
+  int hook = LUA_HOOKCALL;
+  ci->u.l.savedpc++;  /* hooks assume 'pc' is already incremented */
+  if (isLua(ci->previous) &&
+      GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
+    ci->callstatus |= CIST_TAIL;
+    hook = LUA_HOOKTAILCALL;
+  }
+  luaD_hook(L, hook, -1);
+  ci->u.l.savedpc--;  /* correct 'pc' */
+}
+
+
+static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
+  int i;
+  int nfixargs = p->numparams;
+  StkId base, fixed;
+  /* move fixed parameters to final position */
+  fixed = L->top - actual;  /* first fixed argument */
+  base = L->top;  /* final position of first argument */
+  for (i = 0; i < nfixargs && i < actual; i++) {
+    setobjs2s(L, L->top++, fixed + i);
+    setnilvalue(fixed + i);  /* erase original copy (for GC) */
+  }
+  for (; i < nfixargs; i++)
+    setnilvalue(L->top++);  /* complete missing arguments */
+  return base;
+}
+
+
+/*
+** Check whether __call metafield of 'func' is a function. If so, put
+** it in stack below original 'func' so that 'luaD_precall' can call
+** it. Raise an error if __call metafield is not a function.
+*/
+static void tryfuncTM (lua_State *L, StkId func) {
+  const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
+  StkId p;
+  if (!ttisfunction(tm))
+    luaG_typeerror(L, func, "call");
+  /* Open a hole inside the stack at 'func' */
+  for (p = L->top; p > func; p--)
+    setobjs2s(L, p, p-1);
+  L->top++;  /* slot ensured by caller */
+  setobj2s(L, func, tm);  /* tag method is the new function to be called */
+}
+
+
+
+#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
+
+
+/* macro to check stack size, preserving 'p' */
+#define checkstackp(L,n,p)  \
+  luaD_checkstackaux(L, n, \
+    ptrdiff_t t__ = savestack(L, p);  /* save 'p' */ \
+    luaC_checkGC(L),  /* stack grow uses memory */ \
+    p = restorestack(L, t__))  /* 'pos' part: restore 'p' */
+
+
+/*
+** Prepares a function call: checks the stack, creates a new CallInfo
+** entry, fills in the relevant information, calls hook if needed.
+** If function is a C function, does the call, too. (Otherwise, leave
+** the execution ('luaV_execute') to the caller, to allow stackless
+** calls.) Returns true iff function has been executed (C function).
+*/
+int luaD_precall (lua_State *L, StkId func, int nresults) {
+  lua_CFunction f;
+  CallInfo *ci;
+  switch (ttype(func)) {
+    case LUA_TCCL:  /* C closure */
+      f = clCvalue(func)->f;
+      goto Cfunc;
+    case LUA_TLCF:  /* light C function */
+      f = fvalue(func);
+     Cfunc: {
+      int n;  /* number of returns */
+      checkstackp(L, LUA_MINSTACK, func);  /* ensure minimum stack size */
+      ci = next_ci(L);  /* now 'enter' new function */
+      ci->nresults = nresults;
+      ci->func = func;
+      ci->top = L->top + LUA_MINSTACK;
+      lua_assert(ci->top <= L->stack_last);
+      ci->callstatus = 0;
+      if (L->hookmask & LUA_MASKCALL)
+        luaD_hook(L, LUA_HOOKCALL, -1);
+      lua_unlock(L);
+      n = (*f)(L);  /* do the actual call */
+      lua_lock(L);
+      api_checknelems(L, n);
+      luaD_poscall(L, ci, L->top - n, n);
+      return 1;
+    }
+    case LUA_TLCL: {  /* Lua function: prepare its call */
+      StkId base;
+      Proto *p = clLvalue(func)->p;
+      int n = cast_int(L->top - func) - 1;  /* number of real arguments */
+      int fsize = p->maxstacksize;  /* frame size */
+      checkstackp(L, fsize, func);
+      if (p->is_vararg != 1) {  /* do not use vararg? */
+        for (; n < p->numparams; n++)
+          setnilvalue(L->top++);  /* complete missing arguments */
+        base = func + 1;
+      }
+      else
+        base = adjust_varargs(L, p, n);
+      ci = next_ci(L);  /* now 'enter' new function */
+      ci->nresults = nresults;
+      ci->func = func;
+      ci->u.l.base = base;
+      L->top = ci->top = base + fsize;
+      lua_assert(ci->top <= L->stack_last);
+      ci->u.l.savedpc = p->code;  /* starting point */
+      ci->callstatus = CIST_LUA;
+      if (L->hookmask & LUA_MASKCALL)
+        callhook(L, ci);
+      return 0;
+    }
+    default: {  /* not a function */
+      checkstackp(L, 1, func);  /* ensure space for metamethod */
+      tryfuncTM(L, func);  /* try to get '__call' metamethod */
+      return luaD_precall(L, func, nresults);  /* now it must be a function */
+    }
+  }
+}
+
+
+/*
+** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'.
+** Handle most typical cases (zero results for commands, one result for
+** expressions, multiple results for tail calls/single parameters)
+** separated.
+*/
+static int moveresults (lua_State *L, const TValue *firstResult, StkId res,
+                                      int nres, int wanted) {
+  switch (wanted) {  /* handle typical cases separately */
+    case 0: break;  /* nothing to move */
+    case 1: {  /* one result needed */
+      if (nres == 0)   /* no results? */
+        firstResult = luaO_nilobject;  /* adjust with nil */
+      setobjs2s(L, res, firstResult);  /* move it to proper place */
+      break;
+    }
+    case LUA_MULTRET: {
+      int i;
+      for (i = 0; i < nres; i++)  /* move all results to correct place */
+        setobjs2s(L, res + i, firstResult + i);
+      L->top = res + nres;
+      return 0;  /* wanted == LUA_MULTRET */
+    }
+    default: {
+      int i;
+      if (wanted <= nres) {  /* enough results? */
+        for (i = 0; i < wanted; i++)  /* move wanted results to correct place */
+          setobjs2s(L, res + i, firstResult + i);
+      }
+      else {  /* not enough results; use all of them plus nils */
+        for (i = 0; i < nres; i++)  /* move all results to correct place */
+          setobjs2s(L, res + i, firstResult + i);
+        for (; i < wanted; i++)  /* complete wanted number of results */
+          setnilvalue(res + i);
+      }
+      break;
+    }
+  }
+  L->top = res + wanted;  /* top points after the last result */
+  return 1;
+}
+
+
+/*
+** Finishes a function call: calls hook if necessary, removes CallInfo,
+** moves current number of results to proper place; returns 0 iff call
+** wanted multiple (variable number of) results.
+*/
+int luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult, int nres) {
+  StkId res;
+  int wanted = ci->nresults;
+  if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
+    if (L->hookmask & LUA_MASKRET) {
+      ptrdiff_t fr = savestack(L, firstResult);  /* hook may change stack */
+      luaD_hook(L, LUA_HOOKRET, -1);
+      firstResult = restorestack(L, fr);
+    }
+    L->oldpc = ci->previous->u.l.savedpc;  /* 'oldpc' for caller function */
+  }
+  res = ci->func;  /* res == final position of 1st result */
+  L->ci = ci->previous;  /* back to caller */
+  /* move results to proper place */
+  return moveresults(L, firstResult, res, nres, wanted);
+}
+
+
+/*
+** Check appropriate error for stack overflow ("regular" overflow or
+** overflow while handling stack overflow). If 'nCalls' is larger than
+** LUAI_MAXCCALLS (which means it is handling a "regular" overflow) but
+** smaller than 9/8 of LUAI_MAXCCALLS, does not report an error (to
+** allow overflow handling to work)
+*/
+static void stackerror (lua_State *L) {
+  if (L->nCcalls == LUAI_MAXCCALLS)
+    luaG_runerror(L, "C stack overflow");
+  else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
+    luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
+}
+
+
+/*
+** Call a function (C or Lua). The function to be called is at *func.
+** The arguments are on the stack, right after the function.
+** When returns, all the results are on the stack, starting at the original
+** function position.
+*/
+void luaD_call (lua_State *L, StkId func, int nResults) {
+  if (++L->nCcalls >= LUAI_MAXCCALLS)
+    stackerror(L);
+  if (!luaD_precall(L, func, nResults))  /* is a Lua function? */
+    luaV_execute(L);  /* call it */
+  L->nCcalls--;
+}
+
+
+/*
+** Similar to 'luaD_call', but does not allow yields during the call
+*/
+void luaD_callnoyield (lua_State *L, StkId func, int nResults) {
+  L->nny++;
+  luaD_call(L, func, nResults);
+  L->nny--;
+}
+
+
+/*
+** Completes the execution of an interrupted C function, calling its
+** continuation function.
+*/
+static void finishCcall (lua_State *L, int status) {
+  CallInfo *ci = L->ci;
+  int n;
+  /* must have a continuation and must be able to call it */
+  lua_assert(ci->u.c.k != NULL && L->nny == 0);
+  /* error status can only happen in a protected call */
+  lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD);
+  if (ci->callstatus & CIST_YPCALL) {  /* was inside a pcall? */
+    ci->callstatus &= ~CIST_YPCALL;  /* finish 'lua_pcall' */
+    L->errfunc = ci->u.c.old_errfunc;
+  }
+  /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already
+     handled */
+  adjustresults(L, ci->nresults);
+  /* call continuation function */
+  lua_unlock(L);
+  n = (*ci->u.c.k)(L, status, ci->u.c.ctx);
+  lua_lock(L);
+  api_checknelems(L, n);
+  /* finish 'luaD_precall' */
+  luaD_poscall(L, ci, L->top - n, n);
+}
+
+
+/*
+** Executes "full continuation" (everything in the stack) of a
+** previously interrupted coroutine until the stack is empty (or another
+** interruption long-jumps out of the loop). If the coroutine is
+** recovering from an error, 'ud' points to the error status, which must
+** be passed to the first continuation function (otherwise the default
+** status is LUA_YIELD).
+*/
+static void unroll (lua_State *L, void *ud) {
+  if (ud != NULL)  /* error status? */
+    finishCcall(L, *(int *)ud);  /* finish 'lua_pcallk' callee */
+  while (L->ci != &L->base_ci) {  /* something in the stack */
+    if (!isLua(L->ci))  /* C function? */
+      finishCcall(L, LUA_YIELD);  /* complete its execution */
+    else {  /* Lua function */
+      luaV_finishOp(L);  /* finish interrupted instruction */
+      luaV_execute(L);  /* execute down to higher C 'boundary' */
+    }
+  }
+}
+
+
+/*
+** Try to find a suspended protected call (a "recover point") for the
+** given thread.
+*/
+static CallInfo *findpcall (lua_State *L) {
+  CallInfo *ci;
+  for (ci = L->ci; ci != NULL; ci = ci->previous) {  /* search for a pcall */
+    if (ci->callstatus & CIST_YPCALL)
+      return ci;
+  }
+  return NULL;  /* no pending pcall */
+}
+
+
+/*
+** Recovers from an error in a coroutine. Finds a recover point (if
+** there is one) and completes the execution of the interrupted
+** 'luaD_pcall'. If there is no recover point, returns zero.
+*/
+static int recover (lua_State *L, int status) {
+  StkId oldtop;
+  CallInfo *ci = findpcall(L);
+  if (ci == NULL) return 0;  /* no recovery point */
+  /* "finish" luaD_pcall */
+  oldtop = restorestack(L, ci->extra);
+  luaF_close(L, oldtop);
+  seterrorobj(L, status, oldtop);
+  L->ci = ci;
+  L->allowhook = getoah(ci->callstatus);  /* restore original 'allowhook' */
+  L->nny = 0;  /* should be zero to be yieldable */
+  luaD_shrinkstack(L);
+  L->errfunc = ci->u.c.old_errfunc;
+  return 1;  /* continue running the coroutine */
+}
+
+
+/*
+** signal an error in the call to 'resume', not in the execution of the
+** coroutine itself. (Such errors should not be handled by any coroutine
+** error handler and should not kill the coroutine.)
+*/
+static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
+  L->top = firstArg;  /* remove args from the stack */
+  setsvalue2s(L, L->top, luaS_new(L, msg));  /* push error message */
+  api_incr_top(L);
+  luaD_throw(L, -1);  /* jump back to 'lua_resume' */
+}
+
+
+/*
+** Do the work for 'lua_resume' in protected mode. Most of the work
+** depends on the status of the coroutine: initial state, suspended
+** inside a hook, or regularly suspended (optionally with a continuation
+** function), plus erroneous cases: non-suspended coroutine or dead
+** coroutine.
+*/
+static void resume (lua_State *L, void *ud) {
+  int nCcalls = L->nCcalls;
+  int n = *(cast(int*, ud));  /* number of arguments */
+  StkId firstArg = L->top - n;  /* first argument */
+  CallInfo *ci = L->ci;
+  if (nCcalls >= LUAI_MAXCCALLS)
+    resume_error(L, "C stack overflow", firstArg);
+  if (L->status == LUA_OK) {  /* may be starting a coroutine */
+    if (ci != &L->base_ci)  /* not in base level? */
+      resume_error(L, "cannot resume non-suspended coroutine", firstArg);
+    /* coroutine is in base level; start running it */
+    if (!luaD_precall(L, firstArg - 1, LUA_MULTRET))  /* Lua function? */
+      luaV_execute(L);  /* call it */
+  }
+  else if (L->status != LUA_YIELD)
+    resume_error(L, "cannot resume dead coroutine", firstArg);
+  else {  /* resuming from previous yield */
+    L->status = LUA_OK;  /* mark that it is running (again) */
+    ci->func = restorestack(L, ci->extra);
+    if (isLua(ci))  /* yielded inside a hook? */
+      luaV_execute(L);  /* just continue running Lua code */
+    else {  /* 'common' yield */
+      if (ci->u.c.k != NULL) {  /* does it have a continuation function? */
+        lua_unlock(L);
+        n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */
+        lua_lock(L);
+        api_checknelems(L, n);
+        firstArg = L->top - n;  /* yield results come from continuation */
+      }
+      luaD_poscall(L, ci, firstArg, n);  /* finish 'luaD_precall' */
+    }
+    unroll(L, NULL);  /* run continuation */
+  }
+  lua_assert(nCcalls == L->nCcalls);
+}
+
+
+LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
+  int status;
+  unsigned short oldnny = L->nny;  /* save "number of non-yieldable" calls */
+  lua_lock(L);
+  luai_userstateresume(L, nargs);
+  L->nCcalls = (from) ? from->nCcalls + 1 : 1;
+  L->nny = 0;  /* allow yields */
+  api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
+  status = luaD_rawrunprotected(L, resume, &nargs);
+  if (status == -1)  /* error calling 'lua_resume'? */
+    status = LUA_ERRRUN;
+  else {  /* continue running after recoverable errors */
+    while (errorstatus(status) && recover(L, status)) {
+      /* unroll continuation */
+      status = luaD_rawrunprotected(L, unroll, &status);
+    }
+    if (errorstatus(status)) {  /* unrecoverable error? */
+      L->status = cast_byte(status);  /* mark thread as 'dead' */
+      seterrorobj(L, status, L->top);  /* push error message */
+      L->ci->top = L->top;
+    }
+    else lua_assert(status == L->status);  /* normal end or yield */
+  }
+  L->nny = oldnny;  /* restore 'nny' */
+  L->nCcalls--;
+  lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
+  lua_unlock(L);
+  return status;
+}
+
+
+LUA_API int lua_isyieldable (lua_State *L) {
+  return (L->nny == 0);
+}
+
+
+LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx,
+                        lua_KFunction k) {
+  CallInfo *ci = L->ci;
+  luai_userstateyield(L, nresults);
+  lua_lock(L);
+  api_checknelems(L, nresults);
+  if (L->nny > 0) {
+    if (L != G(L)->mainthread)
+      luaG_runerror(L, "attempt to yield across a C-call boundary");
+    else
+      luaG_runerror(L, "attempt to yield from outside a coroutine");
+  }
+  L->status = LUA_YIELD;
+  ci->extra = savestack(L, ci->func);  /* save current 'func' */
+  if (isLua(ci)) {  /* inside a hook? */
+    api_check(L, k == NULL, "hooks cannot continue after yielding");
+  }
+  else {
+    if ((ci->u.c.k = k) != NULL)  /* is there a continuation? */
+      ci->u.c.ctx = ctx;  /* save context */
+    ci->func = L->top - nresults - 1;  /* protect stack below results */
+    luaD_throw(L, LUA_YIELD);
+  }
+  lua_assert(ci->callstatus & CIST_HOOKED);  /* must be inside a hook */
+  lua_unlock(L);
+  return 0;  /* return to 'luaD_hook' */
+}
+
+
+int luaD_pcall (lua_State *L, Pfunc func, void *u,
+                ptrdiff_t old_top, ptrdiff_t ef) {
+  int status;
+  CallInfo *old_ci = L->ci;
+  lu_byte old_allowhooks = L->allowhook;
+  unsigned short old_nny = L->nny;
+  ptrdiff_t old_errfunc = L->errfunc;
+  L->errfunc = ef;
+  status = luaD_rawrunprotected(L, func, u);
+  if (status != LUA_OK) {  /* an error occurred? */
+    StkId oldtop = restorestack(L, old_top);
+    luaF_close(L, oldtop);  /* close possible pending closures */
+    seterrorobj(L, status, oldtop);
+    L->ci = old_ci;
+    L->allowhook = old_allowhooks;
+    L->nny = old_nny;
+    luaD_shrinkstack(L);
+  }
+  L->errfunc = old_errfunc;
+  return status;
+}
+
+
+
+/*
+** Execute a protected parser.
+*/
+struct SParser {  /* data to 'f_parser' */
+  ZIO *z;
+  Mbuffer buff;  /* dynamic structure used by the scanner */
+  Dyndata dyd;  /* dynamic structures used by the parser */
+  const char *mode;
+  const char *name;
+};
+
+
+static void checkmode (lua_State *L, const char *mode, const char *x) {
+  if (mode && strchr(mode, x[0]) == NULL) {
+    luaO_pushfstring(L,
+       "attempt to load a %s chunk (mode is '%s')", x, mode);
+    luaD_throw(L, LUA_ERRSYNTAX);
+  }
+}
+
+
+static void f_parser (lua_State *L, void *ud) {
+  LClosure *cl;
+  struct SParser *p = cast(struct SParser *, ud);
+  int c = zgetc(p->z);  /* read first character */
+  if (c == LUA_SIGNATURE[0]) {
+    checkmode(L, p->mode, "binary");
+    cl = luaU_undump(L, p->z, p->name);
+  }
+  else {
+    checkmode(L, p->mode, "text");
+    cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
+  }
+  lua_assert(cl->nupvalues == cl->p->sizeupvalues);
+  luaF_initupvals(L, cl);
+}
+
+
+int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
+                                        const char *mode) {
+  struct SParser p;
+  int status;
+  L->nny++;  /* cannot yield during parsing */
+  p.z = z; p.name = name; p.mode = mode;
+  p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
+  p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
+  p.dyd.label.arr = NULL; p.dyd.label.size = 0;
+  luaZ_initbuffer(L, &p.buff);
+  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
+  luaZ_freebuffer(L, &p.buff);
+  luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
+  luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
+  luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
+  L->nny--;
+  return status;
+}
+
+