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MDEV-17256 Decimal field multiplication bug.

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We should clear trailing zeroes in frac part. Otherwise
that tail is growing quickly and forces unnecessary truncating of
arguments.
This commit is contained in:
Alexey Botchkov
2018-10-30 18:15:41 +04:00
parent 65cfc5873e
commit 57898316b6
3 changed files with 105 additions and 16 deletions
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35
strings/decimal.c
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@ -2077,26 +2077,21 @@ int decimal_mul(const decimal_t *from1, const decimal_t *from2, decimal_t *to)
}
}
/* Now we have to check for -0.000 case */
if (to->sign)
/* Remove trailing zero words in frac part */
frac0= ROUND_UP(to->frac);
if (frac0 > 0 && to->buf[intg0 + frac0 - 1] == 0)
{
dec1 *buf= to->buf;
dec1 *end= to->buf + intg0 + frac0;
DBUG_ASSERT(buf != end);
for (;;)
do
{
if (*buf)
break;
if (++buf == end)
{
/* We got decimal zero */
decimal_make_zero(to);
break;
}
}
frac0--;
} while (frac0 > 0 && to->buf[intg0 + frac0 - 1] == 0);
to->frac= DIG_PER_DEC1 * frac0;
}
/* Remove heading zero words in intg part */
buf1= to->buf;
d_to_move= intg0 + ROUND_UP(to->frac);
d_to_move= intg0 + frac0;
while (!*buf1 && (to->intg > DIG_PER_DEC1))
{
buf1++;
@ -2109,6 +2104,14 @@ int decimal_mul(const decimal_t *from1, const decimal_t *from2, decimal_t *to)
for (; d_to_move--; cur_d++, buf1++)
*cur_d= *buf1;
}
/* Now we have to check for -0.000 case */
if (to->sign && to->frac == 0 && to->buf[0] == 0)
{
DBUG_ASSERT(to->intg <= DIG_PER_DEC1);
/* We got decimal zero */
decimal_make_zero(to);
}
return error;
}