diff options
Diffstat (limited to 'src/backend/utils/adt/numeric.c')
| -rw-r--r-- | src/backend/utils/adt/numeric.c | 36 |
1 files changed, 15 insertions, 21 deletions
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c index effc4b886c1..47475bf695b 100644 --- a/src/backend/utils/adt/numeric.c +++ b/src/backend/utils/adt/numeric.c @@ -8605,31 +8605,25 @@ div_var(const NumericVar *var1, const NumericVar *var2, NumericVar *result, /* As above, need do nothing more when quotient digit is 0 */ if (qhat > 0) { + NumericDigit *dividend_j = ÷nd[j]; + /* * Multiply the divisor by qhat, and subtract that from the - * working dividend. "carry" tracks the multiplication, - * "borrow" the subtraction (could we fold these together?) + * working dividend. The multiplication and subtraction are + * folded together here, noting that qhat <= NBASE (since it + * might be one too large), and so the intermediate result + * "tmp_result" is in the range [-NBASE^2, NBASE - 1], and + * "borrow" is in the range [0, NBASE]. */ - carry = 0; borrow = 0; for (i = var2ndigits; i >= 0; i--) { - carry += divisor[i] * qhat; - borrow -= carry % NBASE; - carry = carry / NBASE; - borrow += dividend[j + i]; - if (borrow < 0) - { - dividend[j + i] = borrow + NBASE; - borrow = -1; - } - else - { - dividend[j + i] = borrow; - borrow = 0; - } + int tmp_result; + + tmp_result = dividend_j[i] - borrow - divisor[i] * qhat; + borrow = (NBASE - 1 - tmp_result) / NBASE; + dividend_j[i] = tmp_result + borrow * NBASE; } - Assert(carry == 0); /* * If we got a borrow out of the top dividend digit, then @@ -8645,15 +8639,15 @@ div_var(const NumericVar *var1, const NumericVar *var2, NumericVar *result, carry = 0; for (i = var2ndigits; i >= 0; i--) { - carry += dividend[j + i] + divisor[i]; + carry += dividend_j[i] + divisor[i]; if (carry >= NBASE) { - dividend[j + i] = carry - NBASE; + dividend_j[i] = carry - NBASE; carry = 1; } else { - dividend[j + i] = carry; + dividend_j[i] = carry; carry = 0; } } |