/*
* This procedure converts a double-precision number in IEEE format
* into a string of hexadecimal digits and an exponent of 2. Its
* behavior is bug-for-bug compatible with dtoa() in mode 2, with the
* following exceptions:
*
* - An ndigits < 0 causes it to use as many digits as necessary to
* represent the number exactly.
* - The additional xdigs argument should point to either the string
* "0123456789ABCDEF" or the string "0123456789abcdef", depending on
* which case is desired.
* - This routine does not repeat dtoa's mistake of setting decpt
* to 9999 in the case of an infinity or NaN. INT_MAX is used
* for this purpose instead.
*
* Note that the C99 standard does not specify what the leading digit
* should be for non-zero numbers. For instance, 0x1.3p3 is the same
* as 0x2.6p2 is the same as 0x4.cp3. This implementation chooses the
* first digit so that subsequent digits are aligned on nibble
* boundaries (before rounding).
*
* Inputs: d, xdigs, ndigits
* Outputs: decpt, sign, rve
*/
char *
__hdtoa(double d, const char *xdigs, int ndigits, int *decpt, int *sign,
char **rve)
{
static const int sigfigs = (DBL_MANT_DIG + 3) / 4;
struct vax_d_floating *p = (struct vax_d_floating *)&d;
char *s, *s0;
int bufsize;
*sign = p->dflt_sign;
switch (fpclassify(d)) {
case FP_NORMAL:
*decpt = p->dflt_exp - DBL_ADJ;
break;
case FP_ZERO:
*decpt = 1;
return (nrv_alloc("0", rve, 1));
default:
abort();
}
/* FP_NORMAL or FP_SUBNORMAL */
if (ndigits == 0) /* dtoa() compatibility */
ndigits = 1;
/*
* For simplicity, we generate all the digits even if the
* caller has requested fewer.
*/
bufsize = (sigfigs > ndigits) ? sigfigs : ndigits;
s0 = rv_alloc(bufsize);
if (s0 == NULL)
return (NULL);
/*
* We work from right to left, first adding any requested zero
* padding, then the least significant portion of the
* mantissa, followed by the most significant. The buffer is
* filled with the byte values 0x0 through 0xf, which are
* converted to xdigs[0x0] through xdigs[0xf] after the
* rounding phase.
*/
for (s = s0 + bufsize - 1; s > s0 + sigfigs - 1; s--)
*s = 0;
for (; s > s0 + sigfigs - (DFLT_FRACLBITS / 4) - 1 && s > s0; s--) {
*s = p->dflt_fracl & 0xf;
p->dflt_fracl >>= 4;
}
for (; s > s0; s--) {
*s = p->dflt_fracm & 0xf;
p->dflt_fracm >>= 4;
}
for (; s > s0; s--) {
*s = p->dflt_frach & 0xf;
p->dflt_frach >>= 4;
}
/*
* At this point, we have snarfed all the bits in the
* mantissa, with the possible exception of the highest-order
* (partial) nibble, which is dealt with by the next
* statement. We also tack on the implicit normalization bit.
*/
*s = p->dflt_frach | (1U << ((DBL_MANT_DIG - 1) % 4));
/* If ndigits < 0, we are expected to auto-size the precision. */
if (ndigits < 0) {
for (ndigits = sigfigs; s0[ndigits - 1] == 0; ndigits--)
;
}
if (sigfigs > ndigits && s0[ndigits] != 0)
dorounding(s0, ndigits, p->dflt_sign, decpt);
s = s0 + ndigits;
if (rve != NULL)
*rve = s;
*s-- = '\0';
for (; s >= s0; s--)
*s = xdigs[(unsigned int)*s];
return (s0);
}
/*
* This is the long double version of __hdtoa().
*/
char *
__hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign,
char **rve)
{
static const int sigfigs = (LDBL_MANT_DIG + 3) / 4;
union IEEEl2bits u;
char *s, *s0;
int bufsize, f;
u.e = e;
*sign = u.bits.sign;
switch (f = fpclassify(e)) {
case FP_NORMAL:
case FP_SUPERNORMAL:
*decpt = u.bits.exp - LDBL_ADJ;
break;
case FP_ZERO:
*decpt = 1;
return (nrv_alloc("0", rve, 1));
case FP_SUBNORMAL:
u.e *= 0x1p514L;
*decpt = u.bits.exp - (514 + LDBL_ADJ);
break;
case FP_INFINITE:
*decpt = INT_MAX;
return (nrv_alloc(INFSTR, rve, sizeof(INFSTR) - 1));
case FP_NAN:
*decpt = INT_MAX;
return (nrv_alloc(NANSTR, rve, sizeof(NANSTR) - 1));
default:
LIBC_ABORT("fpclassify returned %d", f);
}
/* FP_NORMAL or FP_SUBNORMAL */
if (ndigits == 0) /* dtoa() compatibility */
ndigits = 1;
/*
* For simplicity, we generate all the digits even if the
* caller has requested fewer.
*/
bufsize = (sigfigs > ndigits) ? sigfigs : ndigits;
s0 = rv_alloc(bufsize);
/*
* We work from right to left, first adding any requested zero
* padding, then the least significant portion of the
* mantissa, followed by the most significant. The buffer is
* filled with the byte values 0x0 through 0xf, which are
* converted to xdigs[0x0] through xdigs[0xf] after the
* rounding phase.
*/
for (s = s0 + bufsize - 1; s > s0 + sigfigs - 1; s--)
*s = 0;
for (; s > s0 + sigfigs - (LDBL_MANL_SIZE / 4) - 1 && s > s0; s--) {
*s = u.bits.manl & 0xf;
u.bits.manl >>= 4;
}
for (; s > s0; s--) {
*s = u.bits.manh & 0xf;
u.bits.manh >>= 4;
}
/*
* At this point, we have snarfed all the bits in the
* mantissa, with the possible exception of the highest-order
* (partial) nibble, which is dealt with by the next
* statement. We also tack on the implicit normalization bit.
*/
*s = u.bits.manh | (1U << ((LDBL_MANT_DIG - 1) % 4));
/* If ndigits < 0, we are expected to auto-size the precision. */
if (ndigits < 0) {
for (ndigits = sigfigs; s0[ndigits - 1] == 0; ndigits--)
;
}
if (sigfigs > ndigits && s0[ndigits] != 0)
dorounding(s0, ndigits, u.bits.sign, decpt);
s = s0 + ndigits;
if (rve != NULL)
*rve = s;
*s-- = '\0';
for (; s >= s0; s--)
*s = xdigs[(unsigned int)*s];
return (s0);
}
