diff --git a/lvm.c b/lvm.c index a1b750dc..76ce2636 100644 --- a/lvm.c +++ b/lvm.c @@ -1,5 +1,5 @@ /* -** $Id: lvm.c,v 2.342 2018/02/19 20:06:56 roberto Exp roberto $ +** $Id: lvm.c,v 2.343 2018/02/21 12:54:26 roberto Exp roberto $ ** Lua virtual machine ** See Copyright Notice in lua.h */ @@ -31,17 +31,14 @@ #include "lvm.h" -/* limit for table tag-method chains (to avoid loops) */ +/* limit for table tag-method chains (to avoid infinite loops) */ #define MAXTAGLOOP 2000 /* ** 'l_intfitsf' checks whether a given integer can be converted to a -** float without rounding. Used in comparisons. Left undefined if -** all integers fit in a float precisely. +** float without rounding. Used in comparisons. */ -#if !defined(l_intfitsf) - /* number of bits in the mantissa of a float */ #define NBM (l_mathlim(MANT_DIG)) @@ -58,7 +55,9 @@ #define l_intfitsf(i) \ (-((lua_Integer)1 << NBM) <= (i) && (i) <= ((lua_Integer)1 << NBM)) -#endif +#else /* all integers fit in a float precisely */ + +#define l_intfitsf(i) 1 #endif @@ -157,7 +156,7 @@ static int forlimit (const TValue *obj, lua_Integer *p, lua_Integer step, *p = LUA_MAXINTEGER; if (step < 0) *stopnow = 1; } - else { /* float is smaller than min integer */ + else { /* float is less than min integer */ *p = LUA_MININTEGER; if (step >= 0) *stopnow = 1; } @@ -255,8 +254,8 @@ void luaV_finishset (lua_State *L, const TValue *t, TValue *key, /* -** Compare two strings 'ls' x 'rs', returning an integer smaller-equal- -** -larger than zero if 'ls' is smaller-equal-larger than 'rs'. +** Compare two strings 'ls' x 'rs', returning an integer less-equal- +** -greater than zero if 'ls' is less-equal-greater than 'rs'. ** The code is a little tricky because it allows '\0' in the strings ** and it uses 'strcoll' (to respect locales) for each segments ** of the strings. @@ -275,7 +274,7 @@ static int l_strcmp (const TString *ls, const TString *rs) { if (len == lr) /* 'rs' is finished? */ return (len == ll) ? 0 : 1; /* check 'ls' */ else if (len == ll) /* 'ls' is finished? */ - return -1; /* 'ls' is smaller than 'rs' ('rs' is not finished) */ + return -1; /* 'ls' is less than 'rs' ('rs' is not finished) */ /* both strings longer than 'len'; go on comparing after the '\0' */ len++; l += len; ll -= len; r += len; lr -= len; @@ -287,25 +286,24 @@ static int l_strcmp (const TString *ls, const TString *rs) { /* ** Check whether integer 'i' is less than float 'f'. If 'i' has an ** exact representation as a float ('l_intfitsf'), compare numbers as -** floats. Otherwise, if 'f' is outside the range for integers, result -** is trivial. Otherwise, compare them as integers. (When 'i' has no -** float representation, either 'f' is "far away" from 'i' or 'f' has -** no precision left for a fractional part; either way, how 'f' is -** truncated is irrelevant.) When 'f' is NaN, comparisons must result -** in false. +** floats. Otherwise, use the equivalence 'i < f <=> i < ceil(f)'. +** If 'ceil(f)' is out of integer range, either 'f' is greater than +** all integers or less than all integers. +** (The test with 'l_intfitsf' is only for performance; the else +** case is correct for all values, but it is slow due to the conversion +** from float to int.) +** When 'f' is NaN, comparisons must result in false. */ static int LTintfloat (lua_Integer i, lua_Number f) { -#if defined(l_intfitsf) - if (!l_intfitsf(i)) { - if (f >= -cast_num(LUA_MININTEGER)) /* -minint == maxint + 1 */ - return 1; /* f >= maxint + 1 > i */ - else if (f > cast_num(LUA_MININTEGER)) /* minint < f <= maxint ? */ - return (i < cast(lua_Integer, f)); /* compare them as integers */ - else /* f <= minint <= i (or 'f' is NaN) --> not(i < f) */ - return 0; + if (l_intfitsf(i)) + return luai_numlt(cast_num(i), f); /* compare them as floats */ + else { /* i < f <=> i < ceil(f) */ + lua_Integer fi; + if (luaV_flttointeger(f, &fi, 2)) /* fi = ceil(f) */ + return i < fi; /* compare them as integers */ + else /* 'f' is either greater or less than all integers */ + return f > 0; /* greater? */ } -#endif - return luai_numlt(cast_num(i), f); /* compare them as floats */ } @@ -314,17 +312,49 @@ static int LTintfloat (lua_Integer i, lua_Number f) { ** See comments on previous function. */ static int LEintfloat (lua_Integer i, lua_Number f) { -#if defined(l_intfitsf) - if (!l_intfitsf(i)) { - if (f >= -cast_num(LUA_MININTEGER)) /* -minint == maxint + 1 */ - return 1; /* f >= maxint + 1 > i */ - else if (f >= cast_num(LUA_MININTEGER)) /* minint <= f <= maxint ? */ - return (i <= cast(lua_Integer, f)); /* compare them as integers */ - else /* f < minint <= i (or 'f' is NaN) --> not(i <= f) */ - return 0; + if (l_intfitsf(i)) + return luai_numle(cast_num(i), f); /* compare them as floats */ + else { /* i <= f <=> i <= floor(f) */ + lua_Integer fi; + if (luaV_flttointeger(f, &fi, 1)) /* fi = floor(f) */ + return i <= fi; /* compare them as integers */ + else /* 'f' is either greater or less than all integers */ + return f > 0; /* greater? */ + } +} + + +/* +** Check whether float 'f' is less than integer 'i'. +** See comments on previous function. +*/ +static int LTfloatint (lua_Number f, lua_Integer i) { + if (l_intfitsf(i)) + return luai_numlt(f, cast_num(i)); /* compare them as floats */ + else { /* f < i <=> floor(f) < i */ + lua_Integer fi; + if (luaV_flttointeger(f, &fi, 1)) /* fi = floor(f) */ + return fi < i; /* compare them as integers */ + else /* 'f' is either greater or less than all integers */ + return f < 0; /* less? */ + } +} + + +/* +** Check whether float 'f' is less than or equal to integer 'i'. +** See comments on previous function. +*/ +static int LEfloatint (lua_Number f, lua_Integer i) { + if (l_intfitsf(i)) + return luai_numle(f, cast_num(i)); /* compare them as floats */ + else { /* f <= i <=> ceil(f) <= i */ + lua_Integer fi; + if (luaV_flttointeger(f, &fi, 2)) /* fi = ceil(f) */ + return fi <= i; /* compare them as integers */ + else /* 'f' is either greater or less than all integers */ + return f < 0; /* less? */ } -#endif - return luai_numle(cast_num(i), f); /* compare them as floats */ } @@ -344,10 +374,8 @@ static int LTnum (const TValue *l, const TValue *r) { lua_Number lf = fltvalue(l); /* 'l' must be float */ if (ttisfloat(r)) return luai_numlt(lf, fltvalue(r)); /* both are float */ - else if (luai_numisnan(lf)) /* 'r' is int and 'l' is float */ - return 0; /* NaN < i is always false */ - else /* without NaN, (l < r) <--> not(r <= l) */ - return !LEintfloat(ivalue(r), lf); /* not (r <= l) ? */ + else /* 'l' is float and 'r' is int */ + return LTfloatint(lf, ivalue(r)); } } @@ -368,10 +396,8 @@ static int LEnum (const TValue *l, const TValue *r) { lua_Number lf = fltvalue(l); /* 'l' must be float */ if (ttisfloat(r)) return luai_numle(lf, fltvalue(r)); /* both are float */ - else if (luai_numisnan(lf)) /* 'r' is int and 'l' is float */ - return 0; /* NaN <= i is always false */ - else /* without NaN, (l <= r) <--> not(r < l) */ - return !LTintfloat(ivalue(r), lf); /* not (r < l) ? */ + else /* 'l' is float and 'r' is int */ + return LEfloatint(lf, ivalue(r)); } }