154 lines
4.3 KiB
C++
154 lines
4.3 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2011 Danny Robson <danny@nerdcruft.net>
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*/
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#include "float.hpp"
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#include "debug/assert.hpp"
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#include <cmath>
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using cruft::ieee_float;
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///////////////////////////////////////////////////////////////////////////////
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template <unsigned int E, unsigned int S>
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ieee_float<E, S>::ieee_float (void)
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{ ; }
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//-----------------------------------------------------------------------------
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template <unsigned int E, unsigned int S>
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ieee_float<E, S>::ieee_float (floating_t _floating):
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m_floating (_floating)
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{ ; }
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//-----------------------------------------------------------------------------
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template <unsigned int E, unsigned int S>
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ieee_float<E, S>::ieee_float (const ieee_float &rhs):
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m_bits (rhs.m_bits)
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{ ; }
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///////////////////////////////////////////////////////////////////////////////
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template <unsigned int E, unsigned int S>
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bool
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ieee_float<E, S>::is_zero (void) const
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{
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return m_components.exponent == 0 &&
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m_components.significand == 0;
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}
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//-----------------------------------------------------------------------------
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template <unsigned int E, unsigned int S>
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bool
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ieee_float<E, S>::is_subnormal (void) const
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{
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return m_components.exponent == 0 &&
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m_components.significand != 0;
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}
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//-----------------------------------------------------------------------------
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template <unsigned int E, unsigned int S>
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bool
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ieee_float<E, S>::is_inifinity (void) const {
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return m_components.exponent == (1 << EXPONENT_BITS) - 1 &&
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m_components.significand == 0;
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}
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//-----------------------------------------------------------------------------
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template <unsigned int E, unsigned int S>
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bool
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ieee_float<E, S>::is_nan (void) const {
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return m_components.exponent == (1 << EXPONENT_BITS) - 1 &&
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m_components.significand != 0;
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}
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///////////////////////////////////////////////////////////////////////////////
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template <unsigned int E, unsigned int S>
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bool
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ieee_float<E, S>::operator==(floating_t _floating) const {
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// TODO: This method really shouldn't be generated if there's no
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// representative native floating point type. But I'm sick of
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// C++'s template bullshit for tonight.
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CHECK (bits_type<TOTAL_BITS>::has_floating);
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union {
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floating_t _floating;
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uint_t _uint;
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} convertor;
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convertor._floating = _floating;
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return m_bits == convertor._uint;
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}
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///////////////////////////////////////////////////////////////////////////////
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template <unsigned int E, unsigned int S>
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bool
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ieee_float<E, S>::almost_equal (floating_t a,
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floating_t b)
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{
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return almost_equal (a, b, 128u);
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}
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//-----------------------------------------------------------------------------
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// Based on the Cygnus `AlmostEqual2sComplement` function
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template <unsigned int E, unsigned int S>
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bool
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ieee_float<E, S>::almost_equal (floating_t _a,
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floating_t _b,
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unsigned ulps)
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{
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// Ensure ULPs is small enough that the default NaNs won't compare as
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// equal to anything else.
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CHECK_LE (ulps, 4 * 1024 * 1024u);
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union {
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floating_t f;
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sint_t s;
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uint_t u;
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} a, b;
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a.f = _a;
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b.f = _b;
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// Special case the NaNs early so simplify diffs
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if (std::isnan (a.f) || std::isnan (b.f))
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return false;
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// Early out, as identity comparisons are reasonably common
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if (a.s == b.s)
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return true;
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// Re-base negative floats to be continuous against +ve/-ve 0
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static const union {
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floating_t f;
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sint_t s;
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} NEG_ZERO { -floating_t {0} };
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if (a.s < 0)
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a.s = NEG_ZERO.s - a.s;
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if (b.s < 0)
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b.s = NEG_ZERO.s - b.s;
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// Calculate ULP difference, but don't use abs(a.s - b.s) as it may cause
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// signed overflow
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uint_t diff = a.u > b.u ? a.u - b.u : b.u - a.u;
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return diff <= ulps;
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}
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///////////////////////////////////////////////////////////////////////////////
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template class cruft::ieee_float< 5, 10>; // ieee_half
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template class cruft::ieee_float< 8, 23>; // ieee_single;
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template class cruft::ieee_float<11, 52>; // ieee_double;
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