mudgangster

Tiny, scriptable MUD client
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lvm.cc (44393B)


      1 /*
      2 ** $Id: lvm.c,v 2.268.1.1 2017/04/19 17:39:34 roberto Exp $
      3 ** Lua virtual machine
      4 ** See Copyright Notice in lua.h
      5 */
      6 
      7 #define lvm_c
      8 #define LUA_CORE
      9 
     10 #include "lprefix.h"
     11 
     12 #include <float.h>
     13 #include <limits.h>
     14 #include <math.h>
     15 #include <stdio.h>
     16 #include <stdlib.h>
     17 #include <string.h>
     18 
     19 #include "lua.h"
     20 
     21 #include "ldebug.h"
     22 #include "ldo.h"
     23 #include "lfunc.h"
     24 #include "lgc.h"
     25 #include "lobject.h"
     26 #include "lopcodes.h"
     27 #include "lstate.h"
     28 #include "lstring.h"
     29 #include "ltable.h"
     30 #include "ltm.h"
     31 #include "lvm.h"
     32 
     33 
     34 /* limit for table tag-method chains (to avoid loops) */
     35 #define MAXTAGLOOP	2000
     36 
     37 
     38 
     39 /*
     40 ** 'l_intfitsf' checks whether a given integer can be converted to a
     41 ** float without rounding. Used in comparisons. Left undefined if
     42 ** all integers fit in a float precisely.
     43 */
     44 #if !defined(l_intfitsf)
     45 
     46 /* number of bits in the mantissa of a float */
     47 #define NBM		(l_mathlim(MANT_DIG))
     48 
     49 /*
     50 ** Check whether some integers may not fit in a float, that is, whether
     51 ** (maxinteger >> NBM) > 0 (that implies (1 << NBM) <= maxinteger).
     52 ** (The shifts are done in parts to avoid shifting by more than the size
     53 ** of an integer. In a worst case, NBM == 113 for long double and
     54 ** sizeof(integer) == 32.)
     55 */
     56 #if ((((LUA_MAXINTEGER >> (NBM / 4)) >> (NBM / 4)) >> (NBM / 4)) \
     57 	>> (NBM - (3 * (NBM / 4))))  >  0
     58 
     59 #define l_intfitsf(i)  \
     60   (-((lua_Integer)1 << NBM) <= (i) && (i) <= ((lua_Integer)1 << NBM))
     61 
     62 #endif
     63 
     64 #endif
     65 
     66 
     67 
     68 /*
     69 ** Try to convert a value to a float. The float case is already handled
     70 ** by the macro 'tonumber'.
     71 */
     72 int luaV_tonumber_ (const TValue *obj, lua_Number *n) {
     73   TValue v;
     74   if (ttisinteger(obj)) {
     75     *n = cast_num(ivalue(obj));
     76     return 1;
     77   }
     78   else if (cvt2num(obj) &&  /* string convertible to number? */
     79             luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
     80     *n = nvalue(&v);  /* convert result of 'luaO_str2num' to a float */
     81     return 1;
     82   }
     83   else
     84     return 0;  /* conversion failed */
     85 }
     86 
     87 
     88 /*
     89 ** try to convert a value to an integer, rounding according to 'mode':
     90 ** mode == 0: accepts only integral values
     91 ** mode == 1: takes the floor of the number
     92 ** mode == 2: takes the ceil of the number
     93 */
     94 int luaV_tointeger (const TValue *obj, lua_Integer *p, int mode) {
     95   TValue v;
     96  again:
     97   if (ttisfloat(obj)) {
     98     lua_Number n = fltvalue(obj);
     99     lua_Number f = l_floor(n);
    100     if (n != f) {  /* not an integral value? */
    101       if (mode == 0) return 0;  /* fails if mode demands integral value */
    102       else if (mode > 1)  /* needs ceil? */
    103         f += 1;  /* convert floor to ceil (remember: n != f) */
    104     }
    105     return lua_numbertointeger(f, p);
    106   }
    107   else if (ttisinteger(obj)) {
    108     *p = ivalue(obj);
    109     return 1;
    110   }
    111   else if (cvt2num(obj) &&
    112             luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
    113     obj = &v;
    114     goto again;  /* convert result from 'luaO_str2num' to an integer */
    115   }
    116   return 0;  /* conversion failed */
    117 }
    118 
    119 
    120 /*
    121 ** Try to convert a 'for' limit to an integer, preserving the
    122 ** semantics of the loop.
    123 ** (The following explanation assumes a non-negative step; it is valid
    124 ** for negative steps mutatis mutandis.)
    125 ** If the limit can be converted to an integer, rounding down, that is
    126 ** it.
    127 ** Otherwise, check whether the limit can be converted to a number.  If
    128 ** the number is too large, it is OK to set the limit as LUA_MAXINTEGER,
    129 ** which means no limit.  If the number is too negative, the loop
    130 ** should not run, because any initial integer value is larger than the
    131 ** limit. So, it sets the limit to LUA_MININTEGER. 'stopnow' corrects
    132 ** the extreme case when the initial value is LUA_MININTEGER, in which
    133 ** case the LUA_MININTEGER limit would still run the loop once.
    134 */
    135 static int forlimit (const TValue *obj, lua_Integer *p, lua_Integer step,
    136                      int *stopnow) {
    137   *stopnow = 0;  /* usually, let loops run */
    138   if (!luaV_tointeger(obj, p, (step < 0 ? 2 : 1))) {  /* not fit in integer? */
    139     lua_Number n;  /* try to convert to float */
    140     if (!tonumber(obj, &n)) /* cannot convert to float? */
    141       return 0;  /* not a number */
    142     if (luai_numlt(0, n)) {  /* if true, float is larger than max integer */
    143       *p = LUA_MAXINTEGER;
    144       if (step < 0) *stopnow = 1;
    145     }
    146     else {  /* float is smaller than min integer */
    147       *p = LUA_MININTEGER;
    148       if (step >= 0) *stopnow = 1;
    149     }
    150   }
    151   return 1;
    152 }
    153 
    154 
    155 /*
    156 ** Finish the table access 'val = t[key]'.
    157 ** if 'slot' is NULL, 't' is not a table; otherwise, 'slot' points to
    158 ** t[k] entry (which must be nil).
    159 */
    160 void luaV_finishget (lua_State *L, const TValue *t, TValue *key, StkId val,
    161                       const TValue *slot) {
    162   int loop;  /* counter to avoid infinite loops */
    163   const TValue *tm;  /* metamethod */
    164   for (loop = 0; loop < MAXTAGLOOP; loop++) {
    165     if (slot == NULL) {  /* 't' is not a table? */
    166       lua_assert(!ttistable(t));
    167       tm = luaT_gettmbyobj(L, t, TM_INDEX);
    168       if (ttisnil(tm))
    169         luaG_typeerror(L, t, "index");  /* no metamethod */
    170       /* else will try the metamethod */
    171     }
    172     else {  /* 't' is a table */
    173       lua_assert(ttisnil(slot));
    174       tm = fasttm(L, hvalue(t)->metatable, TM_INDEX);  /* table's metamethod */
    175       if (tm == NULL) {  /* no metamethod? */
    176         setnilvalue(val);  /* result is nil */
    177         return;
    178       }
    179       /* else will try the metamethod */
    180     }
    181     if (ttisfunction(tm)) {  /* is metamethod a function? */
    182       luaT_callTM(L, tm, t, key, val, 1);  /* call it */
    183       return;
    184     }
    185     t = tm;  /* else try to access 'tm[key]' */
    186     if (luaV_fastget(L,t,key,slot,luaH_get)) {  /* fast track? */
    187       setobj2s(L, val, slot);  /* done */
    188       return;
    189     }
    190     /* else repeat (tail call 'luaV_finishget') */
    191   }
    192   luaG_runerror(L, "'__index' chain too long; possible loop");
    193 }
    194 
    195 
    196 /*
    197 ** Finish a table assignment 't[key] = val'.
    198 ** If 'slot' is NULL, 't' is not a table.  Otherwise, 'slot' points
    199 ** to the entry 't[key]', or to 'luaO_nilobject' if there is no such
    200 ** entry.  (The value at 'slot' must be nil, otherwise 'luaV_fastset'
    201 ** would have done the job.)
    202 */
    203 void luaV_finishset (lua_State *L, const TValue *t, TValue *key,
    204                      StkId val, const TValue *slot) {
    205   int loop;  /* counter to avoid infinite loops */
    206   for (loop = 0; loop < MAXTAGLOOP; loop++) {
    207     const TValue *tm;  /* '__newindex' metamethod */
    208     if (slot != NULL) {  /* is 't' a table? */
    209       Table *h = hvalue(t);  /* save 't' table */
    210       lua_assert(ttisnil(slot));  /* old value must be nil */
    211       tm = fasttm(L, h->metatable, TM_NEWINDEX);  /* get metamethod */
    212       if (tm == NULL) {  /* no metamethod? */
    213         if (slot == luaO_nilobject)  /* no previous entry? */
    214           slot = luaH_newkey(L, h, key);  /* create one */
    215         /* no metamethod and (now) there is an entry with given key */
    216         setobj2t(L, cast(TValue *, slot), val);  /* set its new value */
    217         invalidateTMcache(h);
    218         luaC_barrierback(L, h, val);
    219         return;
    220       }
    221       /* else will try the metamethod */
    222     }
    223     else {  /* not a table; check metamethod */
    224       if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
    225         luaG_typeerror(L, t, "index");
    226     }
    227     /* try the metamethod */
    228     if (ttisfunction(tm)) {
    229       luaT_callTM(L, tm, t, key, val, 0);
    230       return;
    231     }
    232     t = tm;  /* else repeat assignment over 'tm' */
    233     if (luaV_fastset(L, t, key, slot, luaH_get, val))
    234       return;  /* done */
    235     /* else loop */
    236   }
    237   luaG_runerror(L, "'__newindex' chain too long; possible loop");
    238 }
    239 
    240 
    241 /*
    242 ** Compare two strings 'ls' x 'rs', returning an integer smaller-equal-
    243 ** -larger than zero if 'ls' is smaller-equal-larger than 'rs'.
    244 ** The code is a little tricky because it allows '\0' in the strings
    245 ** and it uses 'strcoll' (to respect locales) for each segments
    246 ** of the strings.
    247 */
    248 static int l_strcmp (const TString *ls, const TString *rs) {
    249   const char *l = getstr(ls);
    250   size_t ll = tsslen(ls);
    251   const char *r = getstr(rs);
    252   size_t lr = tsslen(rs);
    253   for (;;) {  /* for each segment */
    254     int temp = strcoll(l, r);
    255     if (temp != 0)  /* not equal? */
    256       return temp;  /* done */
    257     else {  /* strings are equal up to a '\0' */
    258       size_t len = strlen(l);  /* index of first '\0' in both strings */
    259       if (len == lr)  /* 'rs' is finished? */
    260         return (len == ll) ? 0 : 1;  /* check 'ls' */
    261       else if (len == ll)  /* 'ls' is finished? */
    262         return -1;  /* 'ls' is smaller than 'rs' ('rs' is not finished) */
    263       /* both strings longer than 'len'; go on comparing after the '\0' */
    264       len++;
    265       l += len; ll -= len; r += len; lr -= len;
    266     }
    267   }
    268 }
    269 
    270 
    271 /*
    272 ** Check whether integer 'i' is less than float 'f'. If 'i' has an
    273 ** exact representation as a float ('l_intfitsf'), compare numbers as
    274 ** floats. Otherwise, if 'f' is outside the range for integers, result
    275 ** is trivial. Otherwise, compare them as integers. (When 'i' has no
    276 ** float representation, either 'f' is "far away" from 'i' or 'f' has
    277 ** no precision left for a fractional part; either way, how 'f' is
    278 ** truncated is irrelevant.) When 'f' is NaN, comparisons must result
    279 ** in false.
    280 */
    281 static int LTintfloat (lua_Integer i, lua_Number f) {
    282 #if defined(l_intfitsf)
    283   if (!l_intfitsf(i)) {
    284     if (f >= -cast_num(LUA_MININTEGER))  /* -minint == maxint + 1 */
    285       return 1;  /* f >= maxint + 1 > i */
    286     else if (f > cast_num(LUA_MININTEGER))  /* minint < f <= maxint ? */
    287       return (i < cast(lua_Integer, f));  /* compare them as integers */
    288     else  /* f <= minint <= i (or 'f' is NaN)  -->  not(i < f) */
    289       return 0;
    290   }
    291 #endif
    292   return luai_numlt(cast_num(i), f);  /* compare them as floats */
    293 }
    294 
    295 
    296 /*
    297 ** Check whether integer 'i' is less than or equal to float 'f'.
    298 ** See comments on previous function.
    299 */
    300 static int LEintfloat (lua_Integer i, lua_Number f) {
    301 #if defined(l_intfitsf)
    302   if (!l_intfitsf(i)) {
    303     if (f >= -cast_num(LUA_MININTEGER))  /* -minint == maxint + 1 */
    304       return 1;  /* f >= maxint + 1 > i */
    305     else if (f >= cast_num(LUA_MININTEGER))  /* minint <= f <= maxint ? */
    306       return (i <= cast(lua_Integer, f));  /* compare them as integers */
    307     else  /* f < minint <= i (or 'f' is NaN)  -->  not(i <= f) */
    308       return 0;
    309   }
    310 #endif
    311   return luai_numle(cast_num(i), f);  /* compare them as floats */
    312 }
    313 
    314 
    315 /*
    316 ** Return 'l < r', for numbers.
    317 */
    318 static int LTnum (const TValue *l, const TValue *r) {
    319   if (ttisinteger(l)) {
    320     lua_Integer li = ivalue(l);
    321     if (ttisinteger(r))
    322       return li < ivalue(r);  /* both are integers */
    323     else  /* 'l' is int and 'r' is float */
    324       return LTintfloat(li, fltvalue(r));  /* l < r ? */
    325   }
    326   else {
    327     lua_Number lf = fltvalue(l);  /* 'l' must be float */
    328     if (ttisfloat(r))
    329       return luai_numlt(lf, fltvalue(r));  /* both are float */
    330     else if (luai_numisnan(lf))  /* 'r' is int and 'l' is float */
    331       return 0;  /* NaN < i is always false */
    332     else  /* without NaN, (l < r)  <-->  not(r <= l) */
    333       return !LEintfloat(ivalue(r), lf);  /* not (r <= l) ? */
    334   }
    335 }
    336 
    337 
    338 /*
    339 ** Return 'l <= r', for numbers.
    340 */
    341 static int LEnum (const TValue *l, const TValue *r) {
    342   if (ttisinteger(l)) {
    343     lua_Integer li = ivalue(l);
    344     if (ttisinteger(r))
    345       return li <= ivalue(r);  /* both are integers */
    346     else  /* 'l' is int and 'r' is float */
    347       return LEintfloat(li, fltvalue(r));  /* l <= r ? */
    348   }
    349   else {
    350     lua_Number lf = fltvalue(l);  /* 'l' must be float */
    351     if (ttisfloat(r))
    352       return luai_numle(lf, fltvalue(r));  /* both are float */
    353     else if (luai_numisnan(lf))  /* 'r' is int and 'l' is float */
    354       return 0;  /*  NaN <= i is always false */
    355     else  /* without NaN, (l <= r)  <-->  not(r < l) */
    356       return !LTintfloat(ivalue(r), lf);  /* not (r < l) ? */
    357   }
    358 }
    359 
    360 
    361 /*
    362 ** Main operation less than; return 'l < r'.
    363 */
    364 int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
    365   int res;
    366   if (ttisnumber(l) && ttisnumber(r))  /* both operands are numbers? */
    367     return LTnum(l, r);
    368   else if (ttisstring(l) && ttisstring(r))  /* both are strings? */
    369     return l_strcmp(tsvalue(l), tsvalue(r)) < 0;
    370   else if ((res = luaT_callorderTM(L, l, r, TM_LT)) < 0)  /* no metamethod? */
    371     luaG_ordererror(L, l, r);  /* error */
    372   return res;
    373 }
    374 
    375 
    376 /*
    377 ** Main operation less than or equal to; return 'l <= r'. If it needs
    378 ** a metamethod and there is no '__le', try '__lt', based on
    379 ** l <= r iff !(r < l) (assuming a total order). If the metamethod
    380 ** yields during this substitution, the continuation has to know
    381 ** about it (to negate the result of r<l); bit CIST_LEQ in the call
    382 ** status keeps that information.
    383 */
    384 int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r) {
    385   int res;
    386   if (ttisnumber(l) && ttisnumber(r))  /* both operands are numbers? */
    387     return LEnum(l, r);
    388   else if (ttisstring(l) && ttisstring(r))  /* both are strings? */
    389     return l_strcmp(tsvalue(l), tsvalue(r)) <= 0;
    390   else if ((res = luaT_callorderTM(L, l, r, TM_LE)) >= 0)  /* try 'le' */
    391     return res;
    392   else {  /* try 'lt': */
    393     L->ci->callstatus |= CIST_LEQ;  /* mark it is doing 'lt' for 'le' */
    394     res = luaT_callorderTM(L, r, l, TM_LT);
    395     L->ci->callstatus ^= CIST_LEQ;  /* clear mark */
    396     if (res < 0)
    397       luaG_ordererror(L, l, r);
    398     return !res;  /* result is negated */
    399   }
    400 }
    401 
    402 
    403 /*
    404 ** Main operation for equality of Lua values; return 't1 == t2'.
    405 ** L == NULL means raw equality (no metamethods)
    406 */
    407 int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
    408   const TValue *tm;
    409   if (ttype(t1) != ttype(t2)) {  /* not the same variant? */
    410     if (ttnov(t1) != ttnov(t2) || ttnov(t1) != LUA_TNUMBER)
    411       return 0;  /* only numbers can be equal with different variants */
    412     else {  /* two numbers with different variants */
    413       lua_Integer i1, i2;  /* compare them as integers */
    414       return (tointeger(t1, &i1) && tointeger(t2, &i2) && i1 == i2);
    415     }
    416   }
    417   /* values have same type and same variant */
    418   switch (ttype(t1)) {
    419     case LUA_TNIL: return 1;
    420     case LUA_TNUMINT: return (ivalue(t1) == ivalue(t2));
    421     case LUA_TNUMFLT: return luai_numeq(fltvalue(t1), fltvalue(t2));
    422     case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */
    423     case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
    424     case LUA_TLCF: return fvalue(t1) == fvalue(t2);
    425     case LUA_TSHRSTR: return eqshrstr(tsvalue(t1), tsvalue(t2));
    426     case LUA_TLNGSTR: return luaS_eqlngstr(tsvalue(t1), tsvalue(t2));
    427     case LUA_TUSERDATA: {
    428       if (uvalue(t1) == uvalue(t2)) return 1;
    429       else if (L == NULL) return 0;
    430       tm = fasttm(L, uvalue(t1)->metatable, TM_EQ);
    431       if (tm == NULL)
    432         tm = fasttm(L, uvalue(t2)->metatable, TM_EQ);
    433       break;  /* will try TM */
    434     }
    435     case LUA_TTABLE: {
    436       if (hvalue(t1) == hvalue(t2)) return 1;
    437       else if (L == NULL) return 0;
    438       tm = fasttm(L, hvalue(t1)->metatable, TM_EQ);
    439       if (tm == NULL)
    440         tm = fasttm(L, hvalue(t2)->metatable, TM_EQ);
    441       break;  /* will try TM */
    442     }
    443     default:
    444       return gcvalue(t1) == gcvalue(t2);
    445   }
    446   if (tm == NULL)  /* no TM? */
    447     return 0;  /* objects are different */
    448   luaT_callTM(L, tm, t1, t2, L->top, 1);  /* call TM */
    449   return !l_isfalse(L->top);
    450 }
    451 
    452 
    453 /* macro used by 'luaV_concat' to ensure that element at 'o' is a string */
    454 #define tostring(L,o)  \
    455 	(ttisstring(o) || (cvt2str(o) && (luaO_tostring(L, o), 1)))
    456 
    457 #define isemptystr(o)	(ttisshrstring(o) && tsvalue(o)->shrlen == 0)
    458 
    459 /* copy strings in stack from top - n up to top - 1 to buffer */
    460 static void copy2buff (StkId top, int n, char *buff) {
    461   size_t tl = 0;  /* size already copied */
    462   do {
    463     size_t l = vslen(top - n);  /* length of string being copied */
    464     memcpy(buff + tl, svalue(top - n), l * sizeof(char));
    465     tl += l;
    466   } while (--n > 0);
    467 }
    468 
    469 
    470 /*
    471 ** Main operation for concatenation: concat 'total' values in the stack,
    472 ** from 'L->top - total' up to 'L->top - 1'.
    473 */
    474 void luaV_concat (lua_State *L, int total) {
    475   lua_assert(total >= 2);
    476   do {
    477     StkId top = L->top;
    478     int n = 2;  /* number of elements handled in this pass (at least 2) */
    479     if (!(ttisstring(top-2) || cvt2str(top-2)) || !tostring(L, top-1))
    480       luaT_trybinTM(L, top-2, top-1, top-2, TM_CONCAT);
    481     else if (isemptystr(top - 1))  /* second operand is empty? */
    482       cast_void(tostring(L, top - 2));  /* result is first operand */
    483     else if (isemptystr(top - 2)) {  /* first operand is an empty string? */
    484       setobjs2s(L, top - 2, top - 1);  /* result is second op. */
    485     }
    486     else {
    487       /* at least two non-empty string values; get as many as possible */
    488       size_t tl = vslen(top - 1);
    489       TString *ts;
    490       /* collect total length and number of strings */
    491       for (n = 1; n < total && tostring(L, top - n - 1); n++) {
    492         size_t l = vslen(top - n - 1);
    493         if (l >= (MAX_SIZE/sizeof(char)) - tl)
    494           luaG_runerror(L, "string length overflow");
    495         tl += l;
    496       }
    497       if (tl <= LUAI_MAXSHORTLEN) {  /* is result a short string? */
    498         char buff[LUAI_MAXSHORTLEN];
    499         copy2buff(top, n, buff);  /* copy strings to buffer */
    500         ts = luaS_newlstr(L, buff, tl);
    501       }
    502       else {  /* long string; copy strings directly to final result */
    503         ts = luaS_createlngstrobj(L, tl);
    504         copy2buff(top, n, getstr(ts));
    505       }
    506       setsvalue2s(L, top - n, ts);  /* create result */
    507     }
    508     total -= n-1;  /* got 'n' strings to create 1 new */
    509     L->top -= n-1;  /* popped 'n' strings and pushed one */
    510   } while (total > 1);  /* repeat until only 1 result left */
    511 }
    512 
    513 
    514 /*
    515 ** Main operation 'ra' = #rb'.
    516 */
    517 void luaV_objlen (lua_State *L, StkId ra, const TValue *rb) {
    518   const TValue *tm;
    519   switch (ttype(rb)) {
    520     case LUA_TTABLE: {
    521       Table *h = hvalue(rb);
    522       tm = fasttm(L, h->metatable, TM_LEN);
    523       if (tm) break;  /* metamethod? break switch to call it */
    524       setivalue(ra, luaH_getn(h));  /* else primitive len */
    525       return;
    526     }
    527     case LUA_TSHRSTR: {
    528       setivalue(ra, tsvalue(rb)->shrlen);
    529       return;
    530     }
    531     case LUA_TLNGSTR: {
    532       setivalue(ra, tsvalue(rb)->u.lnglen);
    533       return;
    534     }
    535     default: {  /* try metamethod */
    536       tm = luaT_gettmbyobj(L, rb, TM_LEN);
    537       if (ttisnil(tm))  /* no metamethod? */
    538         luaG_typeerror(L, rb, "get length of");
    539       break;
    540     }
    541   }
    542   luaT_callTM(L, tm, rb, rb, ra, 1);
    543 }
    544 
    545 
    546 /*
    547 ** Integer division; return 'm // n', that is, floor(m/n).
    548 ** C division truncates its result (rounds towards zero).
    549 ** 'floor(q) == trunc(q)' when 'q >= 0' or when 'q' is integer,
    550 ** otherwise 'floor(q) == trunc(q) - 1'.
    551 */
    552 lua_Integer luaV_div (lua_State *L, lua_Integer m, lua_Integer n) {
    553   if (l_castS2U(n) + 1u <= 1u) {  /* special cases: -1 or 0 */
    554     if (n == 0)
    555       luaG_runerror(L, "attempt to divide by zero");
    556     return intop(-, 0, m);   /* n==-1; avoid overflow with 0x80000...//-1 */
    557   }
    558   else {
    559     lua_Integer q = m / n;  /* perform C division */
    560     if ((m ^ n) < 0 && m % n != 0)  /* 'm/n' would be negative non-integer? */
    561       q -= 1;  /* correct result for different rounding */
    562     return q;
    563   }
    564 }
    565 
    566 
    567 /*
    568 ** Integer modulus; return 'm % n'. (Assume that C '%' with
    569 ** negative operands follows C99 behavior. See previous comment
    570 ** about luaV_div.)
    571 */
    572 lua_Integer luaV_mod (lua_State *L, lua_Integer m, lua_Integer n) {
    573   if (l_castS2U(n) + 1u <= 1u) {  /* special cases: -1 or 0 */
    574     if (n == 0)
    575       luaG_runerror(L, "attempt to perform 'n%%0'");
    576     return 0;   /* m % -1 == 0; avoid overflow with 0x80000...%-1 */
    577   }
    578   else {
    579     lua_Integer r = m % n;
    580     if (r != 0 && (m ^ n) < 0)  /* 'm/n' would be non-integer negative? */
    581       r += n;  /* correct result for different rounding */
    582     return r;
    583   }
    584 }
    585 
    586 
    587 /* number of bits in an integer */
    588 #define NBITS	cast_int(sizeof(lua_Integer) * CHAR_BIT)
    589 
    590 /*
    591 ** Shift left operation. (Shift right just negates 'y'.)
    592 */
    593 lua_Integer luaV_shiftl (lua_Integer x, lua_Integer y) {
    594   if (y < 0) {  /* shift right? */
    595     if (y <= -NBITS) return 0;
    596     else return intop(>>, x, -y);
    597   }
    598   else {  /* shift left */
    599     if (y >= NBITS) return 0;
    600     else return intop(<<, x, y);
    601   }
    602 }
    603 
    604 
    605 /*
    606 ** check whether cached closure in prototype 'p' may be reused, that is,
    607 ** whether there is a cached closure with the same upvalues needed by
    608 ** new closure to be created.
    609 */
    610 static LClosure *getcached (Proto *p, UpVal **encup, StkId base) {
    611   LClosure *c = p->cache;
    612   if (c != NULL) {  /* is there a cached closure? */
    613     int nup = p->sizeupvalues;
    614     Upvaldesc *uv = p->upvalues;
    615     int i;
    616     for (i = 0; i < nup; i++) {  /* check whether it has right upvalues */
    617       TValue *v = uv[i].instack ? base + uv[i].idx : encup[uv[i].idx]->v;
    618       if (c->upvals[i]->v != v)
    619         return NULL;  /* wrong upvalue; cannot reuse closure */
    620     }
    621   }
    622   return c;  /* return cached closure (or NULL if no cached closure) */
    623 }
    624 
    625 
    626 /*
    627 ** create a new Lua closure, push it in the stack, and initialize
    628 ** its upvalues. Note that the closure is not cached if prototype is
    629 ** already black (which means that 'cache' was already cleared by the
    630 ** GC).
    631 */
    632 static void pushclosure (lua_State *L, Proto *p, UpVal **encup, StkId base,
    633                          StkId ra) {
    634   int nup = p->sizeupvalues;
    635   Upvaldesc *uv = p->upvalues;
    636   int i;
    637   LClosure *ncl = luaF_newLclosure(L, nup);
    638   ncl->p = p;
    639   setclLvalue(L, ra, ncl);  /* anchor new closure in stack */
    640   for (i = 0; i < nup; i++) {  /* fill in its upvalues */
    641     if (uv[i].instack)  /* upvalue refers to local variable? */
    642       ncl->upvals[i] = luaF_findupval(L, base + uv[i].idx);
    643     else  /* get upvalue from enclosing function */
    644       ncl->upvals[i] = encup[uv[i].idx];
    645     ncl->upvals[i]->refcount++;
    646     /* new closure is white, so we do not need a barrier here */
    647   }
    648   if (!isblack(p))  /* cache will not break GC invariant? */
    649     p->cache = ncl;  /* save it on cache for reuse */
    650 }
    651 
    652 
    653 /*
    654 ** finish execution of an opcode interrupted by an yield
    655 */
    656 void luaV_finishOp (lua_State *L) {
    657   CallInfo *ci = L->ci;
    658   StkId base = ci->u.l.base;
    659   Instruction inst = *(ci->u.l.savedpc - 1);  /* interrupted instruction */
    660   OpCode op = GET_OPCODE(inst);
    661   switch (op) {  /* finish its execution */
    662     case OP_ADD: case OP_SUB: case OP_MUL: case OP_DIV: case OP_IDIV:
    663     case OP_BAND: case OP_BOR: case OP_BXOR: case OP_SHL: case OP_SHR:
    664     case OP_MOD: case OP_POW:
    665     case OP_UNM: case OP_BNOT: case OP_LEN:
    666     case OP_GETTABUP: case OP_GETTABLE: case OP_SELF: {
    667       setobjs2s(L, base + GETARG_A(inst), --L->top);
    668       break;
    669     }
    670     case OP_LE: case OP_LT: case OP_EQ: {
    671       int res = !l_isfalse(L->top - 1);
    672       L->top--;
    673       if (ci->callstatus & CIST_LEQ) {  /* "<=" using "<" instead? */
    674         lua_assert(op == OP_LE);
    675         ci->callstatus ^= CIST_LEQ;  /* clear mark */
    676         res = !res;  /* negate result */
    677       }
    678       lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_JMP);
    679       if (res != GETARG_A(inst))  /* condition failed? */
    680         ci->u.l.savedpc++;  /* skip jump instruction */
    681       break;
    682     }
    683     case OP_CONCAT: {
    684       StkId top = L->top - 1;  /* top when 'luaT_trybinTM' was called */
    685       int b = GETARG_B(inst);      /* first element to concatenate */
    686       int total = cast_int(top - 1 - (base + b));  /* yet to concatenate */
    687       setobj2s(L, top - 2, top);  /* put TM result in proper position */
    688       if (total > 1) {  /* are there elements to concat? */
    689         L->top = top - 1;  /* top is one after last element (at top-2) */
    690         luaV_concat(L, total);  /* concat them (may yield again) */
    691       }
    692       /* move final result to final position */
    693       setobj2s(L, ci->u.l.base + GETARG_A(inst), L->top - 1);
    694       L->top = ci->top;  /* restore top */
    695       break;
    696     }
    697     case OP_TFORCALL: {
    698       lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_TFORLOOP);
    699       L->top = ci->top;  /* correct top */
    700       break;
    701     }
    702     case OP_CALL: {
    703       if (GETARG_C(inst) - 1 >= 0)  /* nresults >= 0? */
    704         L->top = ci->top;  /* adjust results */
    705       break;
    706     }
    707     case OP_TAILCALL: case OP_SETTABUP: case OP_SETTABLE:
    708       break;
    709     default: lua_assert(0);
    710   }
    711 }
    712 
    713 
    714 
    715 
    716 /*
    717 ** {==================================================================
    718 ** Function 'luaV_execute': main interpreter loop
    719 ** ===================================================================
    720 */
    721 
    722 
    723 /*
    724 ** some macros for common tasks in 'luaV_execute'
    725 */
    726 
    727 
    728 #define RA(i)	(base+GETARG_A(i))
    729 #define RB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
    730 #define RC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
    731 #define RKB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
    732 	ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
    733 #define RKC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
    734 	ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
    735 
    736 
    737 /* execute a jump instruction */
    738 #define dojump(ci,i,e) \
    739   { int a = GETARG_A(i); \
    740     if (a != 0) luaF_close(L, ci->u.l.base + a - 1); \
    741     ci->u.l.savedpc += GETARG_sBx(i) + e; }
    742 
    743 /* for test instructions, execute the jump instruction that follows it */
    744 #define donextjump(ci)	{ i = *ci->u.l.savedpc; dojump(ci, i, 1); }
    745 
    746 
    747 #define Protect(x)	{ {x;}; base = ci->u.l.base; }
    748 
    749 #define checkGC(L,c)  \
    750 	{ luaC_condGC(L, L->top = (c),  /* limit of live values */ \
    751                          Protect(L->top = ci->top));  /* restore top */ \
    752            luai_threadyield(L); }
    753 
    754 
    755 /* fetch an instruction and prepare its execution */
    756 #define vmfetch()	{ \
    757   i = *(ci->u.l.savedpc++); \
    758   if (L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) \
    759     Protect(luaG_traceexec(L)); \
    760   ra = RA(i); /* WARNING: any stack reallocation invalidates 'ra' */ \
    761   lua_assert(base == ci->u.l.base); \
    762   lua_assert(base <= L->top && L->top < L->stack + L->stacksize); \
    763 }
    764 
    765 #define vmdispatch(o)	switch(o)
    766 #define vmcase(l)	case l:
    767 #define vmbreak		break
    768 
    769 
    770 /*
    771 ** copy of 'luaV_gettable', but protecting the call to potential
    772 ** metamethod (which can reallocate the stack)
    773 */
    774 #define gettableProtected(L,t,k,v)  { const TValue *slot; \
    775   if (luaV_fastget(L,t,k,slot,luaH_get)) { setobj2s(L, v, slot); } \
    776   else Protect(luaV_finishget(L,t,k,v,slot)); }
    777 
    778 
    779 /* same for 'luaV_settable' */
    780 #define settableProtected(L,t,k,v) { const TValue *slot; \
    781   if (!luaV_fastset(L,t,k,slot,luaH_get,v)) \
    782     Protect(luaV_finishset(L,t,k,v,slot)); }
    783 
    784 
    785 
    786 void luaV_execute (lua_State *L) {
    787   CallInfo *ci = L->ci;
    788   LClosure *cl;
    789   TValue *k;
    790   StkId base;
    791   ci->callstatus |= CIST_FRESH;  /* fresh invocation of 'luaV_execute" */
    792  newframe:  /* reentry point when frame changes (call/return) */
    793   lua_assert(ci == L->ci);
    794   cl = clLvalue(ci->func);  /* local reference to function's closure */
    795   k = cl->p->k;  /* local reference to function's constant table */
    796   base = ci->u.l.base;  /* local copy of function's base */
    797   /* main loop of interpreter */
    798   for (;;) {
    799     Instruction i;
    800     StkId ra;
    801     vmfetch();
    802     vmdispatch (GET_OPCODE(i)) {
    803       vmcase(OP_MOVE) {
    804         setobjs2s(L, ra, RB(i));
    805         vmbreak;
    806       }
    807       vmcase(OP_LOADK) {
    808         TValue *rb = k + GETARG_Bx(i);
    809         setobj2s(L, ra, rb);
    810         vmbreak;
    811       }
    812       vmcase(OP_LOADKX) {
    813         TValue *rb;
    814         lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
    815         rb = k + GETARG_Ax(*ci->u.l.savedpc++);
    816         setobj2s(L, ra, rb);
    817         vmbreak;
    818       }
    819       vmcase(OP_LOADBOOL) {
    820         setbvalue(ra, GETARG_B(i));
    821         if (GETARG_C(i)) ci->u.l.savedpc++;  /* skip next instruction (if C) */
    822         vmbreak;
    823       }
    824       vmcase(OP_LOADNIL) {
    825         int b = GETARG_B(i);
    826         do {
    827           setnilvalue(ra++);
    828         } while (b--);
    829         vmbreak;
    830       }
    831       vmcase(OP_GETUPVAL) {
    832         int b = GETARG_B(i);
    833         setobj2s(L, ra, cl->upvals[b]->v);
    834         vmbreak;
    835       }
    836       vmcase(OP_GETTABUP) {
    837         TValue *upval = cl->upvals[GETARG_B(i)]->v;
    838         TValue *rc = RKC(i);
    839         gettableProtected(L, upval, rc, ra);
    840         vmbreak;
    841       }
    842       vmcase(OP_GETTABLE) {
    843         StkId rb = RB(i);
    844         TValue *rc = RKC(i);
    845         gettableProtected(L, rb, rc, ra);
    846         vmbreak;
    847       }
    848       vmcase(OP_SETTABUP) {
    849         TValue *upval = cl->upvals[GETARG_A(i)]->v;
    850         TValue *rb = RKB(i);
    851         TValue *rc = RKC(i);
    852         settableProtected(L, upval, rb, rc);
    853         vmbreak;
    854       }
    855       vmcase(OP_SETUPVAL) {
    856         UpVal *uv = cl->upvals[GETARG_B(i)];
    857         setobj(L, uv->v, ra);
    858         luaC_upvalbarrier(L, uv);
    859         vmbreak;
    860       }
    861       vmcase(OP_SETTABLE) {
    862         TValue *rb = RKB(i);
    863         TValue *rc = RKC(i);
    864         settableProtected(L, ra, rb, rc);
    865         vmbreak;
    866       }
    867       vmcase(OP_NEWTABLE) {
    868         int b = GETARG_B(i);
    869         int c = GETARG_C(i);
    870         Table *t = luaH_new(L);
    871         sethvalue(L, ra, t);
    872         if (b != 0 || c != 0)
    873           luaH_resize(L, t, luaO_fb2int(b), luaO_fb2int(c));
    874         checkGC(L, ra + 1);
    875         vmbreak;
    876       }
    877       vmcase(OP_SELF) {
    878         const TValue *aux;
    879         StkId rb = RB(i);
    880         TValue *rc = RKC(i);
    881         TString *key = tsvalue(rc);  /* key must be a string */
    882         setobjs2s(L, ra + 1, rb);
    883         if (luaV_fastget(L, rb, key, aux, luaH_getstr)) {
    884           setobj2s(L, ra, aux);
    885         }
    886         else Protect(luaV_finishget(L, rb, rc, ra, aux));
    887         vmbreak;
    888       }
    889       vmcase(OP_ADD) {
    890         TValue *rb = RKB(i);
    891         TValue *rc = RKC(i);
    892         lua_Number nb; lua_Number nc;
    893         if (ttisinteger(rb) && ttisinteger(rc)) {
    894           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
    895           setivalue(ra, intop(+, ib, ic));
    896         }
    897         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
    898           setfltvalue(ra, luai_numadd(L, nb, nc));
    899         }
    900         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_ADD)); }
    901         vmbreak;
    902       }
    903       vmcase(OP_SUB) {
    904         TValue *rb = RKB(i);
    905         TValue *rc = RKC(i);
    906         lua_Number nb; lua_Number nc;
    907         if (ttisinteger(rb) && ttisinteger(rc)) {
    908           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
    909           setivalue(ra, intop(-, ib, ic));
    910         }
    911         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
    912           setfltvalue(ra, luai_numsub(L, nb, nc));
    913         }
    914         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SUB)); }
    915         vmbreak;
    916       }
    917       vmcase(OP_MUL) {
    918         TValue *rb = RKB(i);
    919         TValue *rc = RKC(i);
    920         lua_Number nb; lua_Number nc;
    921         if (ttisinteger(rb) && ttisinteger(rc)) {
    922           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
    923           setivalue(ra, intop(*, ib, ic));
    924         }
    925         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
    926           setfltvalue(ra, luai_nummul(L, nb, nc));
    927         }
    928         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_MUL)); }
    929         vmbreak;
    930       }
    931       vmcase(OP_DIV) {  /* float division (always with floats) */
    932         TValue *rb = RKB(i);
    933         TValue *rc = RKC(i);
    934         lua_Number nb; lua_Number nc;
    935         if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
    936           setfltvalue(ra, luai_numdiv(L, nb, nc));
    937         }
    938         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_DIV)); }
    939         vmbreak;
    940       }
    941       vmcase(OP_BAND) {
    942         TValue *rb = RKB(i);
    943         TValue *rc = RKC(i);
    944         lua_Integer ib; lua_Integer ic;
    945         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
    946           setivalue(ra, intop(&, ib, ic));
    947         }
    948         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BAND)); }
    949         vmbreak;
    950       }
    951       vmcase(OP_BOR) {
    952         TValue *rb = RKB(i);
    953         TValue *rc = RKC(i);
    954         lua_Integer ib; lua_Integer ic;
    955         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
    956           setivalue(ra, intop(|, ib, ic));
    957         }
    958         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BOR)); }
    959         vmbreak;
    960       }
    961       vmcase(OP_BXOR) {
    962         TValue *rb = RKB(i);
    963         TValue *rc = RKC(i);
    964         lua_Integer ib; lua_Integer ic;
    965         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
    966           setivalue(ra, intop(^, ib, ic));
    967         }
    968         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BXOR)); }
    969         vmbreak;
    970       }
    971       vmcase(OP_SHL) {
    972         TValue *rb = RKB(i);
    973         TValue *rc = RKC(i);
    974         lua_Integer ib; lua_Integer ic;
    975         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
    976           setivalue(ra, luaV_shiftl(ib, ic));
    977         }
    978         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHL)); }
    979         vmbreak;
    980       }
    981       vmcase(OP_SHR) {
    982         TValue *rb = RKB(i);
    983         TValue *rc = RKC(i);
    984         lua_Integer ib; lua_Integer ic;
    985         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
    986           setivalue(ra, luaV_shiftl(ib, -ic));
    987         }
    988         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHR)); }
    989         vmbreak;
    990       }
    991       vmcase(OP_MOD) {
    992         TValue *rb = RKB(i);
    993         TValue *rc = RKC(i);
    994         lua_Number nb; lua_Number nc;
    995         if (ttisinteger(rb) && ttisinteger(rc)) {
    996           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
    997           setivalue(ra, luaV_mod(L, ib, ic));
    998         }
    999         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
   1000           lua_Number m;
   1001           luai_nummod(L, nb, nc, m);
   1002           setfltvalue(ra, m);
   1003         }
   1004         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_MOD)); }
   1005         vmbreak;
   1006       }
   1007       vmcase(OP_IDIV) {  /* floor division */
   1008         TValue *rb = RKB(i);
   1009         TValue *rc = RKC(i);
   1010         lua_Number nb; lua_Number nc;
   1011         if (ttisinteger(rb) && ttisinteger(rc)) {
   1012           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
   1013           setivalue(ra, luaV_div(L, ib, ic));
   1014         }
   1015         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
   1016           setfltvalue(ra, luai_numidiv(L, nb, nc));
   1017         }
   1018         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_IDIV)); }
   1019         vmbreak;
   1020       }
   1021       vmcase(OP_POW) {
   1022         TValue *rb = RKB(i);
   1023         TValue *rc = RKC(i);
   1024         lua_Number nb; lua_Number nc;
   1025         if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
   1026           setfltvalue(ra, luai_numpow(L, nb, nc));
   1027         }
   1028         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_POW)); }
   1029         vmbreak;
   1030       }
   1031       vmcase(OP_UNM) {
   1032         TValue *rb = RB(i);
   1033         lua_Number nb;
   1034         if (ttisinteger(rb)) {
   1035           lua_Integer ib = ivalue(rb);
   1036           setivalue(ra, intop(-, 0, ib));
   1037         }
   1038         else if (tonumber(rb, &nb)) {
   1039           setfltvalue(ra, luai_numunm(L, nb));
   1040         }
   1041         else {
   1042           Protect(luaT_trybinTM(L, rb, rb, ra, TM_UNM));
   1043         }
   1044         vmbreak;
   1045       }
   1046       vmcase(OP_BNOT) {
   1047         TValue *rb = RB(i);
   1048         lua_Integer ib;
   1049         if (tointeger(rb, &ib)) {
   1050           setivalue(ra, intop(^, ~l_castS2U(0), ib));
   1051         }
   1052         else {
   1053           Protect(luaT_trybinTM(L, rb, rb, ra, TM_BNOT));
   1054         }
   1055         vmbreak;
   1056       }
   1057       vmcase(OP_NOT) {
   1058         TValue *rb = RB(i);
   1059         int res = l_isfalse(rb);  /* next assignment may change this value */
   1060         setbvalue(ra, res);
   1061         vmbreak;
   1062       }
   1063       vmcase(OP_LEN) {
   1064         Protect(luaV_objlen(L, ra, RB(i)));
   1065         vmbreak;
   1066       }
   1067       vmcase(OP_CONCAT) {
   1068         int b = GETARG_B(i);
   1069         int c = GETARG_C(i);
   1070         StkId rb;
   1071         L->top = base + c + 1;  /* mark the end of concat operands */
   1072         Protect(luaV_concat(L, c - b + 1));
   1073         ra = RA(i);  /* 'luaV_concat' may invoke TMs and move the stack */
   1074         rb = base + b;
   1075         setobjs2s(L, ra, rb);
   1076         checkGC(L, (ra >= rb ? ra + 1 : rb));
   1077         L->top = ci->top;  /* restore top */
   1078         vmbreak;
   1079       }
   1080       vmcase(OP_JMP) {
   1081         dojump(ci, i, 0);
   1082         vmbreak;
   1083       }
   1084       vmcase(OP_EQ) {
   1085         TValue *rb = RKB(i);
   1086         TValue *rc = RKC(i);
   1087         Protect(
   1088           if (luaV_equalobj(L, rb, rc) != GETARG_A(i))
   1089             ci->u.l.savedpc++;
   1090           else
   1091             donextjump(ci);
   1092         )
   1093         vmbreak;
   1094       }
   1095       vmcase(OP_LT) {
   1096         Protect(
   1097           if (luaV_lessthan(L, RKB(i), RKC(i)) != GETARG_A(i))
   1098             ci->u.l.savedpc++;
   1099           else
   1100             donextjump(ci);
   1101         )
   1102         vmbreak;
   1103       }
   1104       vmcase(OP_LE) {
   1105         Protect(
   1106           if (luaV_lessequal(L, RKB(i), RKC(i)) != GETARG_A(i))
   1107             ci->u.l.savedpc++;
   1108           else
   1109             donextjump(ci);
   1110         )
   1111         vmbreak;
   1112       }
   1113       vmcase(OP_TEST) {
   1114         if (GETARG_C(i) ? l_isfalse(ra) : !l_isfalse(ra))
   1115             ci->u.l.savedpc++;
   1116           else
   1117           donextjump(ci);
   1118         vmbreak;
   1119       }
   1120       vmcase(OP_TESTSET) {
   1121         TValue *rb = RB(i);
   1122         if (GETARG_C(i) ? l_isfalse(rb) : !l_isfalse(rb))
   1123           ci->u.l.savedpc++;
   1124         else {
   1125           setobjs2s(L, ra, rb);
   1126           donextjump(ci);
   1127         }
   1128         vmbreak;
   1129       }
   1130       vmcase(OP_CALL) {
   1131         int b = GETARG_B(i);
   1132         int nresults = GETARG_C(i) - 1;
   1133         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
   1134         if (luaD_precall(L, ra, nresults)) {  /* C function? */
   1135           if (nresults >= 0)
   1136             L->top = ci->top;  /* adjust results */
   1137           Protect((void)0);  /* update 'base' */
   1138         }
   1139         else {  /* Lua function */
   1140           ci = L->ci;
   1141           goto newframe;  /* restart luaV_execute over new Lua function */
   1142         }
   1143         vmbreak;
   1144       }
   1145       vmcase(OP_TAILCALL) {
   1146         int b = GETARG_B(i);
   1147         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
   1148         lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
   1149         if (luaD_precall(L, ra, LUA_MULTRET)) {  /* C function? */
   1150           Protect((void)0);  /* update 'base' */
   1151         }
   1152         else {
   1153           /* tail call: put called frame (n) in place of caller one (o) */
   1154           CallInfo *nci = L->ci;  /* called frame */
   1155           CallInfo *oci = nci->previous;  /* caller frame */
   1156           StkId nfunc = nci->func;  /* called function */
   1157           StkId ofunc = oci->func;  /* caller function */
   1158           /* last stack slot filled by 'precall' */
   1159           StkId lim = nci->u.l.base + getproto(nfunc)->numparams;
   1160           int aux;
   1161           /* close all upvalues from previous call */
   1162           if (cl->p->sizep > 0) luaF_close(L, oci->u.l.base);
   1163           /* move new frame into old one */
   1164           for (aux = 0; nfunc + aux < lim; aux++)
   1165             setobjs2s(L, ofunc + aux, nfunc + aux);
   1166           oci->u.l.base = ofunc + (nci->u.l.base - nfunc);  /* correct base */
   1167           oci->top = L->top = ofunc + (L->top - nfunc);  /* correct top */
   1168           oci->u.l.savedpc = nci->u.l.savedpc;
   1169           oci->callstatus |= CIST_TAIL;  /* function was tail called */
   1170           ci = L->ci = oci;  /* remove new frame */
   1171           lua_assert(L->top == oci->u.l.base + getproto(ofunc)->maxstacksize);
   1172           goto newframe;  /* restart luaV_execute over new Lua function */
   1173         }
   1174         vmbreak;
   1175       }
   1176       vmcase(OP_RETURN) {
   1177         int b = GETARG_B(i);
   1178         if (cl->p->sizep > 0) luaF_close(L, base);
   1179         b = luaD_poscall(L, ci, ra, (b != 0 ? b - 1 : cast_int(L->top - ra)));
   1180         if (ci->callstatus & CIST_FRESH)  /* local 'ci' still from callee */
   1181           return;  /* external invocation: return */
   1182         else {  /* invocation via reentry: continue execution */
   1183           ci = L->ci;
   1184           if (b) L->top = ci->top;
   1185           lua_assert(isLua(ci));
   1186           lua_assert(GET_OPCODE(*((ci)->u.l.savedpc - 1)) == OP_CALL);
   1187           goto newframe;  /* restart luaV_execute over new Lua function */
   1188         }
   1189       }
   1190       vmcase(OP_FORLOOP) {
   1191         if (ttisinteger(ra)) {  /* integer loop? */
   1192           lua_Integer step = ivalue(ra + 2);
   1193           lua_Integer idx = intop(+, ivalue(ra), step); /* increment index */
   1194           lua_Integer limit = ivalue(ra + 1);
   1195           if ((0 < step) ? (idx <= limit) : (limit <= idx)) {
   1196             ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
   1197             chgivalue(ra, idx);  /* update internal index... */
   1198             setivalue(ra + 3, idx);  /* ...and external index */
   1199           }
   1200         }
   1201         else {  /* floating loop */
   1202           lua_Number step = fltvalue(ra + 2);
   1203           lua_Number idx = luai_numadd(L, fltvalue(ra), step); /* inc. index */
   1204           lua_Number limit = fltvalue(ra + 1);
   1205           if (luai_numlt(0, step) ? luai_numle(idx, limit)
   1206                                   : luai_numle(limit, idx)) {
   1207             ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
   1208             chgfltvalue(ra, idx);  /* update internal index... */
   1209             setfltvalue(ra + 3, idx);  /* ...and external index */
   1210           }
   1211         }
   1212         vmbreak;
   1213       }
   1214       vmcase(OP_FORPREP) {
   1215         TValue *init = ra;
   1216         TValue *plimit = ra + 1;
   1217         TValue *pstep = ra + 2;
   1218         lua_Integer ilimit;
   1219         int stopnow;
   1220         if (ttisinteger(init) && ttisinteger(pstep) &&
   1221             forlimit(plimit, &ilimit, ivalue(pstep), &stopnow)) {
   1222           /* all values are integer */
   1223           lua_Integer initv = (stopnow ? 0 : ivalue(init));
   1224           setivalue(plimit, ilimit);
   1225           setivalue(init, intop(-, initv, ivalue(pstep)));
   1226         }
   1227         else {  /* try making all values floats */
   1228           lua_Number ninit; lua_Number nlimit; lua_Number nstep;
   1229           if (!tonumber(plimit, &nlimit))
   1230             luaG_runerror(L, "'for' limit must be a number");
   1231           setfltvalue(plimit, nlimit);
   1232           if (!tonumber(pstep, &nstep))
   1233             luaG_runerror(L, "'for' step must be a number");
   1234           setfltvalue(pstep, nstep);
   1235           if (!tonumber(init, &ninit))
   1236             luaG_runerror(L, "'for' initial value must be a number");
   1237           setfltvalue(init, luai_numsub(L, ninit, nstep));
   1238         }
   1239         ci->u.l.savedpc += GETARG_sBx(i);
   1240         vmbreak;
   1241       }
   1242       vmcase(OP_TFORCALL) {
   1243         StkId cb = ra + 3;  /* call base */
   1244         setobjs2s(L, cb+2, ra+2);
   1245         setobjs2s(L, cb+1, ra+1);
   1246         setobjs2s(L, cb, ra);
   1247         L->top = cb + 3;  /* func. + 2 args (state and index) */
   1248         Protect(luaD_call(L, cb, GETARG_C(i)));
   1249         L->top = ci->top;
   1250         i = *(ci->u.l.savedpc++);  /* go to next instruction */
   1251         ra = RA(i);
   1252         lua_assert(GET_OPCODE(i) == OP_TFORLOOP);
   1253         goto l_tforloop;
   1254       }
   1255       vmcase(OP_TFORLOOP) {
   1256         l_tforloop:
   1257         if (!ttisnil(ra + 1)) {  /* continue loop? */
   1258           setobjs2s(L, ra, ra + 1);  /* save control variable */
   1259            ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
   1260         }
   1261         vmbreak;
   1262       }
   1263       vmcase(OP_SETLIST) {
   1264         int n = GETARG_B(i);
   1265         int c = GETARG_C(i);
   1266         unsigned int last;
   1267         Table *h;
   1268         if (n == 0) n = cast_int(L->top - ra) - 1;
   1269         if (c == 0) {
   1270           lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
   1271           c = GETARG_Ax(*ci->u.l.savedpc++);
   1272         }
   1273         h = hvalue(ra);
   1274         last = ((c-1)*LFIELDS_PER_FLUSH) + n;
   1275         if (last > h->sizearray)  /* needs more space? */
   1276           luaH_resizearray(L, h, last);  /* preallocate it at once */
   1277         for (; n > 0; n--) {
   1278           TValue *val = ra+n;
   1279           luaH_setint(L, h, last--, val);
   1280           luaC_barrierback(L, h, val);
   1281         }
   1282         L->top = ci->top;  /* correct top (in case of previous open call) */
   1283         vmbreak;
   1284       }
   1285       vmcase(OP_CLOSURE) {
   1286         Proto *p = cl->p->p[GETARG_Bx(i)];
   1287         LClosure *ncl = getcached(p, cl->upvals, base);  /* cached closure */
   1288         if (ncl == NULL)  /* no match? */
   1289           pushclosure(L, p, cl->upvals, base, ra);  /* create a new one */
   1290         else
   1291           setclLvalue(L, ra, ncl);  /* push cashed closure */
   1292         checkGC(L, ra + 1);
   1293         vmbreak;
   1294       }
   1295       vmcase(OP_VARARG) {
   1296         int b = GETARG_B(i) - 1;  /* required results */
   1297         int j;
   1298         int n = cast_int(base - ci->func) - cl->p->numparams - 1;
   1299         if (n < 0)  /* less arguments than parameters? */
   1300           n = 0;  /* no vararg arguments */
   1301         if (b < 0) {  /* B == 0? */
   1302           b = n;  /* get all var. arguments */
   1303           Protect(luaD_checkstack(L, n));
   1304           ra = RA(i);  /* previous call may change the stack */
   1305           L->top = ra + n;
   1306         }
   1307         for (j = 0; j < b && j < n; j++)
   1308           setobjs2s(L, ra + j, base - n + j);
   1309         for (; j < b; j++)  /* complete required results with nil */
   1310           setnilvalue(ra + j);
   1311         vmbreak;
   1312       }
   1313       vmcase(OP_EXTRAARG) {
   1314         lua_assert(0);
   1315         vmbreak;
   1316       }
   1317     }
   1318   }
   1319 }
   1320 
   1321 /* }================================================================== */
   1322