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ldtoa: Fix insufficient valid output digits for "%f" format. 

- If the number has large integer part and small fraction part is
  specified in output format, e.g. printf("%.3f", sqrt(2)*1e60);,
  valid output digits were insufficient. This patch fixes the issue.
This commit is contained in:
Takashi Yano 2021-11-26 06:47:27 +09:00
parent 4f47e64b11
commit f885632f4f
1 changed files with 25 additions and 16 deletions
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41
newlib/libc/stdlib/ldtoa.c
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@ -83,7 +83,7 @@ static void eclear (register short unsigned int *x);
static void einfin (register short unsigned int *x, register LDPARMS * ldp); static void einfin (register short unsigned int *x, register LDPARMS * ldp);
static void efloor (short unsigned int *x, short unsigned int *y, static void efloor (short unsigned int *x, short unsigned int *y,
LDPARMS * ldp); LDPARMS * ldp);
static void etoasc (short unsigned int *x, char *string, int ndigs, static void etoasc (short unsigned int *x, char *string, int ndec, int ndigs,
int outformat, LDPARMS * ldp); int outformat, LDPARMS * ldp);
union uconv union uconv
@ -217,7 +217,7 @@ static const char *const ermsg[7] = {
* e24toasc( &f, str, n ) single to ASCII string, n digits after decimal * e24toasc( &f, str, n ) single to ASCII string, n digits after decimal
* e53toasc( &d, str, n ) double to ASCII string, n digits after decimal * e53toasc( &d, str, n ) double to ASCII string, n digits after decimal
* e64toasc( &d, str, n ) long double to ASCII string * e64toasc( &d, str, n ) long double to ASCII string
* etoasc(e,str,n,fmt,ldp)e to ASCII string, n digits after decimal * etoasc(e,str,ndec,n,fmt,ldp)e to ASCII string, n digits after decimal
* etoe24( e, &f ) convert e type to IEEE single precision * etoe24( e, &f ) convert e type to IEEE single precision
* etoe53( e, &d ) convert e type to IEEE double precision * etoe53( e, &d ) convert e type to IEEE double precision
* etoe64( e, &d ) convert e type to IEEE long double precision * etoe64( e, &d ) convert e type to IEEE long double precision
@ -2839,23 +2839,33 @@ _ldtoa_r (struct _reent *ptr, long double d, int mode, int ndigits,
/* This sanity limit must agree with the corresponding one in etoasc, to /* This sanity limit must agree with the corresponding one in etoasc, to
keep straight the returned value of outexpon. Note that we use a dynamic keep straight the returned value of outexpon. Note that we use a dynamic
limit now, either NDEC or NDEC_SML, depending on ndigits. See the usage limit now, either ndec (<= NDEC) or NDEC_SML, depending on ndigits. */
of "my_NDEC" in etoasc. */ __int32_t ndec;
if (ndigits > NDEC) if (mode == 3) /* %f */
ndigits = NDEC; {
__int32_t expon = (e[NE - 1] & 0x7fff) - (EXONE - 1); /* exponent part */
/* log2(10) approximately 485/146 */
ndec = expon * 146 / 485 + ndigits;
}
else /* %g/%e */
ndec = ndigits;
if (ndec < 0)
ndec = 0;
if (ndec > NDEC)
ndec = NDEC;
/* Allocate buffer if more than NDEC_SML digits are requested. */ /* Allocate buffer if more than NDEC_SML digits are requested. */
if (ndigits > NDEC_SML) if (ndec > NDEC_SML)
{ {
outbuf = (char *) _malloc_r (ptr, NDEC + MAX_EXP_DIGITS + 10); outbuf = (char *) _malloc_r (ptr, ndec + MAX_EXP_DIGITS + 10);
if (!outbuf) if (!outbuf)
{ {
ndigits = NDEC_SML; ndec = NDEC_SML;
outbuf = outbuf_sml; outbuf = outbuf_sml;
} }
} }
etoasc (e, outbuf, ndigits, mode, ldp); etoasc (e, outbuf, (int) ndec, ndigits, mode, ldp);
s = outbuf; s = outbuf;
if (eisinf (e) || eisnan (e)) if (eisinf (e) || eisnan (e))
{ {
@ -2992,8 +3002,8 @@ _ldcheck (long double *d)
} /* _ldcheck */ } /* _ldcheck */
static void static void
etoasc (short unsigned int *x, char *string, int ndigits, int outformat, etoasc (short unsigned int *x, char *string, int ndec, int ndigits,
LDPARMS * ldp) int outformat, LDPARMS * ldp)
{ {
long digit; long digit;
unsigned short y[NI], t[NI], u[NI], w[NI]; unsigned short y[NI], t[NI], u[NI], w[NI];
@ -3003,7 +3013,6 @@ etoasc (short unsigned int *x, char *string, int ndigits, int outformat,
char *s, *ss; char *s, *ss;
unsigned short m; unsigned short m;
unsigned short *equot = ldp->equot; unsigned short *equot = ldp->equot;
int my_NDEC = (ndigits > NDEC_SML) ? NDEC : NDEC_SML;
ndigs = ndigits; ndigs = ndigits;
rndsav = ldp->rndprc; rndsav = ldp->rndprc;
@ -3129,7 +3138,7 @@ tnzro:
else else
{ {
emovi (y, w); emovi (y, w);
for (i = 0; i < my_NDEC + 1; i++) for (i = 0; i < ndec + 1; i++)
{ {
if ((w[NI - 1] & 0x7) != 0) if ((w[NI - 1] & 0x7) != 0)
break; break;
@ -3205,8 +3214,8 @@ isone:
else if( ndigs < 0 ) else if( ndigs < 0 )
ndigs = 0; ndigs = 0;
*/ */
if (ndigs > my_NDEC) if (ndigs > ndec)
ndigs = my_NDEC; ndigs = ndec;
if (digit == 10) if (digit == 10)
{ {
*s++ = '1'; *s++ = '1';