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https://github.com/Gnucash/gnucash.git
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Bug 796949 - Fix division and rounding of zero.
Fix division of 128-bit integers so that the remainder inherits the dividend's sign. Fix rounding for truncated zero.
This commit is contained in:
David Palma
parent
94c5fe9f1d
commit
aab89065da
@ -142,7 +142,7 @@ GncInt128::operator int64_t() const
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GncInt128::operator uint64_t() const
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{
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auto flags = get_flags(m_hi);
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if (flags & neg)
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if ((flags & neg) && !isZero()) // exclude negative zero
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throw std::underflow_error ("Can't represent negative value as uint64_t");
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if ((flags & (overflow | NaN)) || (m_hi || m_lo > UINT64_MAX))
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throw std::overflow_error ("Value to large to represent as uint64_t");
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@ -160,6 +160,7 @@ GncInt128::cmp (const GncInt128& b) const noexcept
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return 1;
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auto hi = get_num(m_hi);
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auto bhi = get_num(b.m_hi);
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if (isZero() && b.isZero()) return 0;
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if (flags & neg)
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{
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if (!b.isNeg()) return -1;
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@ -478,6 +479,8 @@ GncInt128::operator*= (const GncInt128& b) noexcept
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{
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/* Test for 0 first */
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auto flags = get_flags(m_hi);
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/* Handle the sign; ^ flips if b is negative */
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flags ^= (get_flags(b.m_hi) & neg);
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if (isZero() || b.isZero())
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{
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m_lo = 0;
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@ -514,8 +517,7 @@ GncInt128::operator*= (const GncInt128& b) noexcept
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m_hi = set_flags(m_hi, flags);
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return *this;
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}
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/* Handle the sign; ^ flips if b is negative */
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flags ^= (get_flags(b.m_hi) & neg);
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/* The trivial case */
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if (abits + bbits <= legbits)
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{
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@ -602,6 +604,7 @@ div_multi_leg (uint64_t* u, size_t m, uint64_t* v, size_t n,
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uint64_t d {(UINT64_C(1) << sublegbits)/(v[n - 1] + UINT64_C(1))};
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uint64_t carry {UINT64_C(0)};
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bool negative {q.isNeg()};
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bool rnegative {r.isNeg()};
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for (size_t i = 0; i < m; ++i)
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{
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u[i] = u[i] * d + carry;
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@ -689,6 +692,7 @@ div_multi_leg (uint64_t* u, size_t m, uint64_t* v, size_t n,
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r = GncInt128 ((u[3] << sublegbits) + u[2], (u[1] << sublegbits) + u[0]);
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r /= d;
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if (negative) q = -q;
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if (rnegative) r = -r;
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}
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void
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@ -698,6 +702,7 @@ div_single_leg (uint64_t* u, size_t m, uint64_t v,
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uint64_t qv[sublegs] {};
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uint64_t carry {};
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bool negative {q.isNeg()};
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bool rnegative {r.isNeg()};
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for (int i = m - 1; i >= 0; --i)
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{
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qv[i] = u[i] / v;
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@ -713,13 +718,18 @@ div_single_leg (uint64_t* u, size_t m, uint64_t v,
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q = GncInt128 ((qv[3] << sublegbits) + qv[2], (qv[1] << sublegbits) + qv[0]);
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r = GncInt128 ((u[3] << sublegbits) + u[2], (u[1] << sublegbits) + u[0]);
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if (negative) q = -q;
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if (rnegative) r = -r;
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}
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}// namespace
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void
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void
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GncInt128::div (const GncInt128& b, GncInt128& q, GncInt128& r) const noexcept
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{
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// clear remainder and quotient
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r = GncInt128(0);
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q = GncInt128(0);
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auto qflags = get_flags(q.m_hi);
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auto rflags = get_flags(r.m_hi);
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if (isOverflow() || b.isOverflow())
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@ -745,6 +755,7 @@ GncInt128::div (const GncInt128& b, GncInt128& q, GncInt128& r) const noexcept
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assert (&r != &b);
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q.zero(), r.zero();
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qflags = rflags = 0;
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if (b.isZero())
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{
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qflags |= NaN;
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@ -755,11 +766,17 @@ GncInt128::div (const GncInt128& b, GncInt128& q, GncInt128& r) const noexcept
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}
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if (isNeg())
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{
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qflags |= neg;
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rflags |= neg; // the remainder inherits the dividend's sign
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}
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if (b.isNeg())
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qflags ^= neg;
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q.m_hi = set_flags(q.m_hi, qflags);
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r.m_hi = set_flags(r.m_hi, rflags);
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if (abs() < b.abs())
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{
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r = *this;
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@ -767,7 +784,7 @@ GncInt128::div (const GncInt128& b, GncInt128& q, GncInt128& r) const noexcept
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}
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auto hi = get_num(m_hi);
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auto bhi = get_num(b.m_hi);
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q.m_hi = set_flags(hi, qflags);
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if (hi == 0 && bhi == 0) //let the hardware do it
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{
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assert (b.m_lo != 0); // b.m_hi is 0 but b isn't or we didn't get here.
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@ -914,6 +931,11 @@ GncInt128::asCharBufR(char* buf) const noexcept
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sprintf (buf, "%s", "NaN");
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return buf;
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}
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if (isZero())
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{
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sprintf (buf, "%d", 0);
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return buf;
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}
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uint64_t d[dec_array_size] {};
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decimal_from_binary(d, get_num(m_hi), m_lo);
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char* next = buf;
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@ -25,6 +25,12 @@
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#include "gnc-numeric.h"
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#include "gnc-int128.hpp"
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template <typename T> inline bool
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quotient_is_positive(T dividend, T divisor)
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{
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return (dividend > 0 && divisor > 0) || (dividend < 0 && divisor < 0);
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}
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enum class RoundType
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{
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floor = GNC_HOW_RND_FLOOR,
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@ -72,8 +78,23 @@ round(T num, T den, T rem, RT2T<RoundType::floor>)
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// << ", and rem " << rem << ".\n";
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if (rem == 0)
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return num;
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if (num < 0)
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return num + 1;
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// floor num==0 that is the quotient of two numbers with opposite signs
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if (num < 0 || (num == 0 && !quotient_is_positive(rem, den)))
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return num - 1;
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return num;
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}
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template <> inline GncInt128
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round<GncInt128>(GncInt128 num, GncInt128 den, GncInt128 rem,
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RT2T<RoundType::floor>)
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{
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// std::cout << "Rounding to floor with num " << num << " den " << den
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// << ", and rem " << rem << ".\n";
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if (rem == 0)
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return num;
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if (num.isNeg())
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return num - 1;
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return num;
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}
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@ -82,7 +103,18 @@ round(T num, T den, T rem, RT2T<RoundType::ceiling>)
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{
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if (rem == 0)
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return num;
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if (num > 0)
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if (num > 0 || (num == 0 && quotient_is_positive(rem, den)))
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return num + 1;
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return num;
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}
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template <> inline GncInt128
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round<GncInt128>(GncInt128 num, GncInt128 den, GncInt128 rem,
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RT2T<RoundType::ceiling>)
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{
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if (rem == 0)
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return num;
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if (!num.isNeg())
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return num + 1;
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return num;
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}
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@ -98,16 +130,31 @@ round(T num, T den, T rem, RT2T<RoundType::promote>)
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{
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if (rem == 0)
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return num;
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if (num == 0)
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return (!quotient_is_positive(rem, den) ? -1 : 1);
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return num + (num < 0 ? -1 : 1);
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}
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template <> inline GncInt128
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round<GncInt128>(GncInt128 num, GncInt128 den, GncInt128 rem,
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RT2T<RoundType::promote>)
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{
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if (rem == 0)
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return num;
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return num + (num.isNeg() ? -1 : 1);
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}
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template <typename T> inline T
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round(T num, T den, T rem, RT2T<RoundType::half_down>)
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{
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if (rem == 0)
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return num;
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if (std::abs(rem * 2) > std::abs(den))
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{
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if (num == 0)
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return (!quotient_is_positive(rem, den) ? -1 : 1);
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return num + (num < 0 ? -1 : 1);
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}
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return num;
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}
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@ -118,7 +165,7 @@ round<GncInt128>(GncInt128 num, GncInt128 den, GncInt128 rem,
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if (rem == 0)
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return num;
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if (rem.abs() * 2 > den.abs())
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return num + (num < 0 ? -1 : 1);
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return num + (num.isNeg() ? -1 : 1);
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return num;
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}
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@ -128,7 +175,11 @@ round(T num, T den, T rem, RT2T<RoundType::half_up>)
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if (rem == 0)
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return num;
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if (std::abs(rem) * 2 >= std::abs(den))
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{
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if (num == 0)
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return (!quotient_is_positive(rem, den) ? -1 : 1);
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return num + (num < 0 ? -1 : 1);
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}
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return num;
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}
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@ -139,7 +190,7 @@ round<GncInt128>(GncInt128 num, GncInt128 den, GncInt128 rem,
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if (rem == 0)
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return num;
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if (rem.abs() * 2 >= den.abs())
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return num + (num < 0 ? -1 : 1);
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return num + (num.isNeg() ? -1 : 1);
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return num;
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}
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@ -150,11 +201,15 @@ round(T num, T den, T rem, RT2T<RoundType::bankers>)
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return num;
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if (std::abs(rem * 2) > std::abs(den) ||
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(std::abs(rem * 2) == std::abs(den) && num % 2))
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return num += (num < 0 ? -1 : 1);
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{
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if (num == 0)
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return (!quotient_is_positive(rem, den) ? -1 : 1);
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return num + (num < 0 ? -1 : 1);
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}
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return num;
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}
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template<> inline GncInt128
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template <> inline GncInt128
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round<GncInt128>(GncInt128 num, GncInt128 den, GncInt128 rem,
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RT2T<RoundType::bankers>)
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{
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@ -162,7 +217,7 @@ round<GncInt128>(GncInt128 num, GncInt128 den, GncInt128 rem,
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return num;
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if (rem.abs() * 2 > den.abs() ||
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(rem.abs() * 2 == den.abs() && num % 2))
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return num += (num < 0 ? -1 : 1);
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return num + (num.isNeg() ? -1 : 1);
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return num;
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}
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#endif //__GNC_RATIONAL_ROUNDING_HPP__
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@ -432,7 +432,7 @@ TEST(GncInt128_functions, divide)
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GncInt128 big (sarg, barg);
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GncInt128 bigger (static_cast<uint64_t>(sarg), uarg);
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GncInt128 nsmall = -small;
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GncInt128 nbig = -bigger;
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GncInt128 nbigger = -bigger;
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EXPECT_EQ (GncInt128(INT64_C(0)), zero /= smallest);
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EXPECT_EQ (GncInt128(INT64_C(0)), zero %= smallest);
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@ -451,11 +451,20 @@ TEST(GncInt128_functions, divide)
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nsmall.div (smaller, q, r);
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EXPECT_EQ (-two, q);
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EXPECT_EQ (GncInt128(INT64_C(3810195028972355394)), r);
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EXPECT_EQ (GncInt128(INT64_C(-3810195028972355394)), r);
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nsmall.div (-smaller, q, r);
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EXPECT_EQ (two, q);
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EXPECT_EQ (GncInt128(INT64_C(3810195028972355394)), r);
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EXPECT_EQ (GncInt128(INT64_C(-3810195028972355394)), r);
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smaller.div (small, q, r);
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EXPECT_EQ (zero, q);
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EXPECT_EQ (smaller, r);
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smaller.div (nsmall, q, r);
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EXPECT_EQ (zero, q);
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EXPECT_TRUE (q.isNeg());
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EXPECT_EQ (smaller, r);
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bigger.div (bigger, q, r);
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EXPECT_EQ (one, q);
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@ -477,18 +486,23 @@ TEST(GncInt128_functions, divide)
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EXPECT_EQ (-two, q);
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EXPECT_EQ (GncInt128(UINT64_C(3810195028972355394)), r);
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nbig.div (-big, q, r);
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nbigger.div (-big, q, r);
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EXPECT_EQ (two, q);
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EXPECT_EQ (GncInt128(UINT64_C(3810195028972355394)), r);
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EXPECT_EQ (GncInt128(0, UINT64_C(3810195028972355394), GncInt128::neg), r);
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nbig.div (-big, q, r);
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nbigger.div (-big, q, r);
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EXPECT_EQ (two, q);
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EXPECT_EQ (GncInt128(UINT64_C(3810195028972355394)), r);
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EXPECT_EQ (GncInt128(0, UINT64_C(3810195028972355394), GncInt128::neg), r);
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big.div (bigger, q, r);
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EXPECT_EQ (zero, q);
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EXPECT_EQ (big, r);
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big.div (nbigger, q, r);
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EXPECT_EQ (zero, q);
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EXPECT_TRUE (q.isNeg());
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EXPECT_EQ (big, r);
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big.div (big - 1, q, r);
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EXPECT_EQ(one, q);
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EXPECT_EQ(one, r);
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@ -411,7 +411,7 @@ TEST(gncnumeric_functions, test_convert)
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EXPECT_EQ(3465453, c.num());
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EXPECT_EQ(128, c.denom());
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ASSERT_NO_THROW(c = b.convert<RoundType::floor>(128));
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EXPECT_EQ(-3465452, c.num());
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EXPECT_EQ(-3465454, c.num());
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EXPECT_EQ(128, c.denom());
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ASSERT_NO_THROW(c = a.convert<RoundType::ceiling>(128));
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EXPECT_EQ(3465454, c.num());
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