mirrors/lua
1
0
Fork 0
mirror of https://github.com/lua/lua synced 2024-11-22 12:51:30 +03:00
Code Issues Packages Projects Releases Wiki Activity

new implementation for 'lua_strx2number' to correct small

Browse Source 
problems with numbers like 0x10000...000p-100
This commit is contained in:
Roberto Ierusalimschy 2013-05-27 14:42:38 -03:00
parent d630daca1a
commit ee865b9fe7
1 changed files with 36 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
lobject.c
View File

@ -1,5 +1,5 @@
/*
** $Id: lobject.c,v 2.63 2013/05/14 15:59:04 roberto Exp roberto $
** $Id: lobject.c,v 2.64 2013/05/26 14:43:35 roberto Exp roberto $
** Some generic functions over Lua objects
** See Copyright Notice in lua.h
*/
@ -145,52 +145,64 @@ static int isneg (const char **s) {
#include <math.h>
static lua_Number readhexa (const char **s, lua_Number r, int *count) {
for (; lisxdigit(cast_uchar(**s)); (*s)++) { /* read integer part */
r = (r * cast_num(16.0)) + cast_num(luaO_hexavalue(cast_uchar(**s)));
(*count)++;
}
return r;
}
/* maximum number of significant digits to read (to avoid overflows
even with single floats) */
#define MAXSIGDIG 30
/*
** convert an hexadecimal numeric string to a number, following
** C99 specification for 'strtod'
*/
static lua_Number lua_strx2number (const char *s, char **endptr) {
lua_Number r = 0.0;
int e = 0, i = 0;
lua_Number r = 0.0; /* result (accumulator) */
int sigdig = 0; /* number of significant digits */
int nosigdig = 0; /* number of non-significant digits */
int e = 0; /* exponent correction */
int neg = 0; /* 1 if number is negative */
int dot = 0; /* true after seen a dot */
*endptr = cast(char *, s); /* nothing is valid yet */
while (lisspace(cast_uchar(*s))) s++; /* skip initial spaces */
neg = isneg(&s); /* check signal */
if (!(*s == '0' && (*(s + 1) == 'x' || *(s + 1) == 'X'))) /* check '0x' */
return 0.0; /* invalid format (no '0x') */
s += 2; /* skip '0x' */
r = readhexa(&s, r, &i); /* read integer part */
if (*s == '.') {
s++; /* skip dot */
r = readhexa(&s, r, &e); /* read fractional part */
for (s += 2; ; s++) { /* skip '0x' and read numeral */
if (*s == '.') {
if (dot) break; /* second dot? stop loop */
else dot = 1;
}
else if (lisxdigit(cast_uchar(*s))) {
if (sigdig == 0 && *s == '0') { /* non-significant zero? */
nosigdig++;
if (dot) e--; /* zero after dot? correct exponent */
}
else {
if (++sigdig <= MAXSIGDIG) { /* can read it without overflow? */
r = (r * cast_num(16.0)) + luaO_hexavalue(cast_uchar(*s));
if (dot) e--; /* decimal digit */
}
else /* too many digits; ignore */
if (!dot) e++; /* still count it for exponent */
}
}
else break; /* neither a dot nor a digit */
}
if (i == 0 && e == 0)
return 0.0; /* invalid format (no digit) */
e *= -4; /* each fractional digit divides value by 2^-4 */
if (nosigdig + sigdig == 0) /* no digits? */
return 0.0; /* invalid format */
*endptr = cast(char *, s); /* valid up to here */
e *= 4; /* each digit multiplies/divides value by 2^4 */
if (*s == 'p' || *s == 'P') { /* exponent part? */
int exp1 = 0;
int neg1;
int exp1 = 0; /* exponent value */
int neg1; /* exponent signal */
s++; /* skip 'p' */
neg1 = isneg(&s); /* signal */
if (!lisdigit(cast_uchar(*s)))
goto ret; /* must have at least one digit */
return 0.0; /* invalid; must have at least one digit */
while (lisdigit(cast_uchar(*s))) /* read exponent */
exp1 = exp1 * 10 + *(s++) - '0';
if (neg1) exp1 = -exp1;
e += exp1;
*endptr = cast(char *, s); /* valid up to here */
}
*endptr = cast(char *, s); /* valid up to here */
ret:
if (neg) r = -r;
return l_mathop(ldexp)(r, e);
}