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libdecnumber: Introduce decNumberIntegralToInt64

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Introduce a new conversion function to the libdecnumber library.
This function converts a decNumber to a signed 64-bit integer.
In order to support 64-bit integers (which may have up to 19
decimal digits), the existing "powers of 10" array is expanded
from 10 to 19 entries.

Signed-off-by: Tom Musta <tommusta@gmail.com>
[agraf: fix 32bit host compile]
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Tom Musta 2014-04-21 15:54:54 -05:00 • committed by Alexander Graf
parent 8e706db21e
commit 79af357225
4 changed files with 51 additions and 4 deletions
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46
libdecnumber/decNumber.c
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@ -465,6 +465,50 @@ decNumber *decNumberFromUInt64(decNumber *dn, uint64_t uin)
return dn;
} /* decNumberFromUInt64 */
/* ------------------------------------------------------------------ */
/* to-int64 -- conversion to int64 */
/* */
/* dn is the decNumber to convert. dn is assumed to have been */
/* rounded to a floating point integer value. */
/* set is the context for reporting errors */
/* returns the converted decNumber, or 0 if Invalid is set */
/* */
/* Invalid is set if the decNumber is a NaN, Infinite or is out of */
/* range for a signed 64 bit integer. */
/* ------------------------------------------------------------------ */
int64_t decNumberIntegralToInt64(const decNumber *dn, decContext *set)
{
if (decNumberIsSpecial(dn) || (dn->exponent < 0) ||
(dn->digits + dn->exponent > 19)) {
goto Invalid;
} else {
int64_t d; /* work */
const Unit *up; /* .. */
uint64_t hi = 0;
up = dn->lsu; /* -> lsu */
for (d = 1; d <= dn->digits; up++, d += DECDPUN) {
uint64_t prev = hi;
hi += *up * powers[d-1];
if ((hi < prev) || (hi > INT64_MAX)) {
goto Invalid;
}
}
uint64_t prev = hi;
hi *= (uint64_t)powers[dn->exponent];
if ((hi < prev) || (hi > INT64_MAX)) {
goto Invalid;
}
return (decNumberIsNegative(dn)) ? -((int64_t)hi) : (int64_t)hi;
}
Invalid:
decContextSetStatus(set, DEC_Invalid_operation);
return 0;
} /* decNumberIntegralToInt64 */
/* ------------------------------------------------------------------ */
/* to-scientific-string -- conversion to numeric string */
@ -4259,7 +4303,7 @@ static decNumber * decDivideOp(decNumber *res,
uByte bits; /* working sign */
Unit *target; /* work */
const Unit *source; /* .. */
uInt const *pow; /* .. */
uLong const *pow; /* .. */
Int shift, cut; /* .. */
#if DECSUBSET
Int dropped; /* work */