ldtoa: fix dropping too many digits from output
ldtoa cuts the number of digits it returns based on a computation of number of supported bits (144) divide by log10(2). Not only is the integer approximation of log10(2) ~= 8/27 missing a digit here, it also fails to take really small double and long double values into account. Allow for the full potential precision of long double values. At the same time, change the local string array allocation to request only as much bytes as necessary to support the caller-requested number of digits, to keep the stack size low on small targets. In the long run a better fix would be to switch to gdtoa, as the BSD variants, as well as Mingw64 do. Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
parent
b3d2f35cb1
commit
97dac2bbcb
|
@ -34,9 +34,9 @@ void _IO_ldtostr (long double *, char *, int, int, char);
|
||||||
#define NBITS ((NI-4)*16)
|
#define NBITS ((NI-4)*16)
|
||||||
|
|
||||||
/* Maximum number of decimal digits in ASCII conversion
|
/* Maximum number of decimal digits in ASCII conversion
|
||||||
* = NBITS*log10(2)
|
* Take full possible size of output into account
|
||||||
*/
|
*/
|
||||||
#define NDEC (NBITS*8/27)
|
#define NDEC 1023
|
||||||
|
|
||||||
/* The exponent of 1.0 */
|
/* The exponent of 1.0 */
|
||||||
#define EXONE (0x3fff)
|
#define EXONE (0x3fff)
|
||||||
|
@ -2794,7 +2794,6 @@ _ldtoa_r (struct _reent *ptr, long double d, int mode, int ndigits,
|
||||||
LDPARMS rnd;
|
LDPARMS rnd;
|
||||||
LDPARMS *ldp = &rnd;
|
LDPARMS *ldp = &rnd;
|
||||||
char *outstr;
|
char *outstr;
|
||||||
char outbuf[NDEC + MAX_EXP_DIGITS + 10];
|
|
||||||
union uconv du;
|
union uconv du;
|
||||||
du.d = d;
|
du.d = d;
|
||||||
|
|
||||||
|
@ -2841,6 +2840,8 @@ _ldtoa_r (struct _reent *ptr, long double d, int mode, int ndigits,
|
||||||
if (ndigits > NDEC)
|
if (ndigits > NDEC)
|
||||||
ndigits = NDEC;
|
ndigits = NDEC;
|
||||||
|
|
||||||
|
char outbuf[ndigits + MAX_EXP_DIGITS + 10];
|
||||||
|
|
||||||
etoasc (e, outbuf, ndigits, mode, ldp);
|
etoasc (e, outbuf, ndigits, mode, ldp);
|
||||||
s = outbuf;
|
s = outbuf;
|
||||||
if (eisinf (e) || eisnan (e))
|
if (eisinf (e) || eisnan (e))
|
||||||
|
@ -3111,6 +3112,8 @@ tnzro:
|
||||||
else
|
else
|
||||||
{
|
{
|
||||||
emovi (y, w);
|
emovi (y, w);
|
||||||
|
/* Note that this loop does not access the incoming string array,
|
||||||
|
* which may be shorter than NDEC + 1 bytes! */
|
||||||
for (i = 0; i < NDEC + 1; i++)
|
for (i = 0; i < NDEC + 1; i++)
|
||||||
{
|
{
|
||||||
if ((w[NI - 1] & 0x7) != 0)
|
if ((w[NI - 1] & 0x7) != 0)
|
||||||
|
|
Loading…
Reference in New Issue