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Fix x / y precision when prec limit is huge #412

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Merged
tompng merged 1 commit into from
Aug 22, 2025
Merged

Fix x / y precision when prec limit is huge #412

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5 changes: 2 additions & 3 deletions ext/bigdecimal/bigdecimal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1905,18 +1905,17 @@ BigDecimal_div2(VALUE self, VALUE b, VALUE n)
/* div in BigDecimal sense */
ix = check_int_precision(n);

if (ix == 0) ix = VpGetPrecLimit();

av = GetBDValueMust(self);
bv = GetBDValueWithPrecMust(b, GetCoercePrec(av.real, ix));

if (ix == 0) {
ssize_t a_prec, b_prec;
ssize_t a_prec, b_prec, limit = VpGetPrecLimit();
VpCountPrecisionAndScale(av.real, &a_prec, NULL);
VpCountPrecisionAndScale(bv.real, &b_prec, NULL);
ix = ((a_prec > b_prec) ? a_prec : b_prec) + BIGDECIMAL_DOUBLE_FIGURES;
if (2 * BIGDECIMAL_DOUBLE_FIGURES > ix)
ix = 2 * BIGDECIMAL_DOUBLE_FIGURES;
if (limit && limit < ix) ix = limit;
}

// Needs to calculate 1 extra digit for rounding.
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9 changes: 9 additions & 0 deletions test/bigdecimal/test_bigdecimal.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -2032,6 +2032,15 @@ def test_arithmetic_operation_with_limit
end
end

def test_div_with_huge_limit
BigDecimal.save_limit do
x, y = BigDecimal(2), BigDecimal(3)
div = x / y
BigDecimal.limit(1000)
assert_equal(div, x / y)
end
end

def test_div_mod_rem_operation_with_limit
x = -(9 ** 100)
y = 7 ** 100
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