bacent软件，脚本软件，代码

/* ** $Id: lvm.c $ ** Lua virtual machine ** See Copyright Notice in lua.h */ #define lvm_c #define LUA_CORE #include "lprefix.h" #include <float.h> #include <limits.h> #include <math.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include "lua.h" #include "ldebug.h" #include "ldo.h" #include "lfunc.h" #include "lgc.h" #include "lobject.h" #include "lopcodes.h" #include "lstate.h" #include "lstring.h" #include "ltable.h" #include "ltm.h" #include "lvm.h" /* ** By default, use jump tables in the main interpreter loop on gcc ** and compatible compilers. */ #if !defined(LUA_USE_JUMPTABLE) #if defined(__GNUC__) #define LUA_USE_JUMPTABLE 1 #else #define LUA_USE_JUMPTABLE 0 #endif #endif /* limit for table tag-method chains (to avoid infinite loops) */ #define MAXTAGLOOP 2000 /* ** 'l_intfitsf' checks whether a given integer is in the range that ** can be converted to a float without rounding. Used in comparisons. */ /* number of bits in the mantissa of a float */ #define NBM (l_floatatt(MANT_DIG)) /* ** Check whether some integers may not fit in a float, testing whether ** (maxinteger >> NBM) > 0. (That implies (1 << NBM) <= maxinteger.) ** (The shifts are done in parts, to avoid shifting by more than the size ** of an integer. In a worst case, NBM == 113 for long double and ** sizeof(long) == 32.) */ #if ((((LUA_MAXINTEGER >> (NBM / 4)) >> (NBM / 4)) >> (NBM / 4)) \ >> (NBM - (3 * (NBM / 4)))) > 0 /* limit for integers that fit in a float */ #define MAXINTFITSF ((lua_Unsigned)1 << NBM) /* check whether 'i' is in the interval [-MAXINTFITSF, MAXINTFITSF] */ #define l_intfitsf(i) ((MAXINTFITSF + l_castS2U(i)) <= (2 * MAXINTFITSF)) #else /* all integers fit in a float precisely */ #define l_intfitsf(i) 1 #endif /* ** Try to convert a value from string to a number value. ** If the value is not a string or is a string not representing ** a valid numeral (or if coercions from strings to numbers ** are disabled via macro 'cvt2num'), do not modify 'result' ** and return 0. */ static int l_strton (const TValue *obj, TValue *result) { lua_assert(obj != result); if (!cvt2num(obj)) /* is object not a string? */ return 0; else return (luaO_str2num(svalue(obj), result) == vslen(obj) + 1); } /* ** Try to convert a value to a float. The float case is already handled ** by the macro 'tonumber'. */ int luaV_tonumber_ (const TValue *obj, lua_Number *n) { TValue v; if (ttisinteger(obj)) { *n = cast_num(ivalue(obj)); return 1; } else if (l_strton(obj, &v)) { /* string coercible to number? */ *n = nvalue(&v); /* convert result of 'luaO_str2num' to a float */ return 1; } else return 0; /* conversion failed */ } /* ** try to convert a float to an integer, rounding according to 'mode'. */ int luaV_flttointeger (lua_Number n, lua_Integer *p, F2Imod mode) { lua_Number f = l_floor(n); if (n != f) { /* not an integral value? */ if (mode == F2Ieq) return 0; /* fails if mode demands integral value */ else if (mode == F2Iceil) /* needs ceil? */ f += 1; /* convert floor to ceil (remember: n != f) */ } return lua_numbertointeger(f, p); } /* ** try to convert a value to an integer, rounding according to 'mode', ** without string coercion. ** ("Fast track" handled by macro 'tointegerns'.) */ int luaV_tointegerns (const TValue *obj, lua_Integer *p, F2Imod mode) { if (ttisfloat(obj)) return luaV_flttointeger(fltvalue(obj), p, mode); else if (ttisinteger(obj)) { *p = ivalue(obj); return 1; } else return 0; } /* ** try to convert a value to an integer. */ int luaV_tointeger (const TValue *obj, lua_Integer *p, F2Imod mode) { TValue v; if (l_strton(obj, &v)) /* does 'obj' point to a numerical string? */ obj = &v; /* change it to point to its corresponding number */ return luaV_tointegerns(obj, p, mode); } /* ** Try to convert a 'for' limit to an integer, preserving the semantics ** of the loop. Return true if the loop must not run; otherwise, '*p' ** gets the integer limit. ** (The following explanation assumes a positive step; it is valid for ** negative steps mutatis mutandis.) ** If the limit is an integer or can be converted to an integer, ** rounding down, that is the limit. ** Otherwise, check whether the limit can be converted to a float. If ** the float is too large, clip it to LUA_MAXINTEGER. If the float ** is too negative, the loop should not run, because any initial ** integer value is greater than such limit; so, the function returns ** true to signal that. (For this latter case, no integer limit would be ** correct; even a limit of LUA_MININTEGER would run the loop once for ** an initial value equal to LUA_MININTEGER.) */ static int forlimit (lua_State *L, lua_Integer init, const TValue *lim, lua_Integer *p, lua_Integer step) { if (!luaV_tointeger(lim, p, (step < 0 ? F2Iceil : F2Ifloor))) { /* not coercible to in integer */ lua_Number flim; /* try to convert to float */ if (!tonumber(lim, &flim)) /* cannot convert to float? */ luaG_forerror(L, lim, "limit"); /* else 'flim' is a float out of integer bounds */ if (luai_numlt(0, flim)) { /* if it is positive, it is too large */ if (step < 0) return 1; /* initial value must be less than it */ *p = LUA_MAXINTEGER; /* truncate */ } else { /* it is less than min integer */ if (step > 0) return 1; /* initial value must be greater than it */ *p = LUA_MININTEGER; /* truncate */ } } return (step > 0 ? init > *p : init < *p); /* not to run? */ } /* ** Prepare a numerical for loop (opcode OP_FORPREP). ** Return true to skip the loop. Otherwise, ** after preparation, stack will be as follows: ** ra : internal index (safe copy of the control variable) ** ra + 1 : loop counter (integer loops) or limit (float loops) ** ra + 2 : step ** ra + 3 : control variable */ static int forprep (lua_State *L, StkId ra) { TValue *pinit = s2v(ra); TValue *plimit = s2v(ra + 1); TValue *pstep = s2v(ra + 2); if (ttisinteger(pinit) && ttisinteger(pstep)) { /* integer loop? */ lua_Integer init = ivalue(pinit); lua_Integer step = ivalue(pstep); lua_Integer limit; if (step == 0) luaG_runerror(L, "'for' step is zero"); setivalue(s2v(ra + 3), init); /* control variable */ if (forlimit(L, init, plimit, &limit, step)) return 1; /* skip the loop */ else { /* prepare loop counter */ lua_Unsigned count; if (step > 0) { /* ascending loop? */ count = l_castS2U(limit) - l_castS2U(init); if (step != 1) /* avoid division in the too common case */ count /= l_castS2U(step); } else { /* step < 0; descending loop */ count = l_castS2U(init) - l_castS2U(limit); /* 'step+1' avoids negating 'mininteger' */ count /= l_castS2U(-(step + 1)) + 1u; } /* store the counter in place of the limit (which won't be needed anymore) */ setivalue(plimit, l_castU2S(count)); } } else { /* try making all values floats */ lua_Number init; lua_Number limit; lua_Number step; if (l_unlikely(!tonumber(plimit, &limit))) luaG_forerror(L, plimit, "limit"); if (l_unlikely(!tonumber(pstep, &step))) luaG_forerror(L, pstep, "step"); if (l_unlikely(!tonumber(pinit, &init))) luaG_forerror(L, pinit, "initial value"); if (step == 0) luaG_runerror(L, "'for' step is zero"); if (luai_numlt(0, step) ? luai_numlt(limit, init) : luai_numlt(init, limit)) return 1; /* skip the loop */ else { /* make sure internal values are all floats */ setfltvalue(plimit, limit); setfltvalue(pstep, step); setfltvalue(s2v(ra), init); /* internal index */ setfltvalue(s2v(ra + 3), init); /* control variable */ } } return 0; } /* ** Execute a step of a float numerical for loop, ret