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/****************************************************************************
**
** Copyright (C) 2016 by Southwest Research Institute (R)
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qfloat16_p.h"
#include "private/qsimd_p.h"

QT_BEGIN_NAMESPACE

/*!
    \headerfile <QFloat16>
    \title 16-bit Floating Point Support
    \ingroup funclists
    \brief The <QFloat16> header file provides 16-bit floating point support.

    This header file provides support for half-precision (16-bit) floating
    point data with the class \c qfloat16.  It is fully compliant with IEEE
    754 as a storage type.  This implies that any arithmetic operation on a
    \c qfloat16 instance results in the value first being converted to a
    \c float.  This conversion to and from \c float is performed by hardware
    when possible, but on processors that do not natively support half-precision,
    the conversion is performed through a sequence of lookup table operations.

    \c qfloat16 should be treated as if it were a POD (plain old data) type.
    Consequently, none of the supported operations need any elaboration beyond
    stating that it supports all arithmetic operators incident to floating point
    types.

    \since 5.9
*/

/*!
    Returns true if the \c qfloat16 \a {f} is equivalent to infinity.
    \relates <QFloat16>

    \sa qIsInf
*/
Q_REQUIRED_RESULT bool qIsInf(qfloat16 f) Q_DECL_NOTHROW { return qt_is_inf(f); }

/*!
    Returns true if the \c qfloat16 \a {f} is not a number (NaN).
    \relates <QFloat16>

    \sa qIsNaN
*/
Q_REQUIRED_RESULT bool qIsNaN(qfloat16 f) Q_DECL_NOTHROW { return qt_is_nan(f); }

/*!
    Returns true if the \c qfloat16 \a {f} is a finite number.
    \relates <QFloat16>

    \sa qIsFinite
*/
Q_REQUIRED_RESULT bool qIsFinite(qfloat16 f) Q_DECL_NOTHROW { return qt_is_finite(f); }

/*! \fn int qRound(qfloat16 value)
    \relates <QFloat16>

    Rounds \a value to the nearest integer.

    \sa qRound
*/

/*! \fn qint64 qRound64(qfloat16 value)
    \relates <QFloat16>

    Rounds \a value to the nearest 64-bit integer.

    \sa qRound64
*/

/*! \fn bool qFuzzyCompare(qfloat16 p1, qfloat16 p2)
    \relates <QFloat16>

    Compares the floating point value \a p1 and \a p2 and
    returns \c true if they are considered equal, otherwise \c false.

    The two numbers are compared in a relative way, where the
    exactness is stronger the smaller the numbers are.
 */

#if QT_COMPILER_SUPPORTS(F16C)
static inline bool hasFastF16()
{
    // All processors with F16C also support AVX, but YMM registers
    // might not be supported by the OS, or they might be disabled.
    return qCpuHasFeature(F16C) && qCpuHasFeature(AVX);
}

extern "C" {
#ifdef QFLOAT16_INCLUDE_FAST
#  define f16cextern    static
#else
#  define f16cextern    extern
#endif

f16cextern void qFloatToFloat16_fast(quint16 *out, const float *in, qsizetype len) Q_DECL_NOTHROW;
f16cextern void qFloatFromFloat16_fast(float *out, const quint16 *in, qsizetype len) Q_DECL_NOTHROW;

#undef f16cextern
}

#elif defined(__ARM_FP16_FORMAT_IEEE) && defined(__ARM_NEON__)
static inline bool hasFastF16()
{
    return true;
}

static void qFloatToFloat16_fast(quint16 *out, const float *in, qsizetype len) Q_DECL_NOTHROW
{
    __fp16 *out_f16 = reinterpret_cast<__fp16 *>(out);
    qsizetype i = 0;
    for (; i < len - 3; i += 4)
        vst1_f16(out_f16 + i, vcvt_f16_f32(vld1q_f32(in + i)));
    SIMD_EPILOGUE(i, len, 3)
        out_f16[i] = __fp16(in[i]);
}

static void qFloatFromFloat16_fast(float *out, const quint16 *in, qsizetype len) Q_DECL_NOTHROW
{
    const __fp16 *in_f16 = reinterpret_cast<const __fp16 *>(in);
    qsizetype i = 0;
    for (; i < len - 3; i += 4)
        vst1q_f32(out + i, vcvt_f32_f16(vld1_f16(in_f16 + i)));
    SIMD_EPILOGUE(i, len, 3)
        out[i] = float(in_f16[i]);
}
#else
static inline bool hasFastF16()
{
    return false;
}

static void qFloatToFloat16_fast(quint16 *, const float *, qsizetype) Q_DECL_NOTHROW
{
    Q_UNREACHABLE();
}

static void qFloatFromFloat16_fast(float *, const quint16 *, qsizetype) Q_DECL_NOTHROW
{
    Q_UNREACHABLE();
}
#endif
/*!
    \since 5.11
    \relates <QFloat16>

    Converts \a len floats from \a in to qfloat16 and stores them in \a out.
    Both \a in and \a out must have \a len allocated entries.
*/
Q_CORE_EXPORT void qFloatToFloat16(qfloat16 *out, const float *in, qsizetype len) Q_DECL_NOTHROW
{
    if (hasFastF16())
        return qFloatToFloat16_fast(reinterpret_cast<quint16 *>(out), in, len);

    for (qsizetype i = 0; i < len; ++i)
        out[i] = qfloat16(in[i]);
}

/*!
    \since 5.11
    \relates <QFloat16>

    Converts \a len qfloat16 from \a in to floats and stores them in \a out.
    Both \a in and \a out must have \a len allocated entries.
*/
Q_CORE_EXPORT void qFloatFromFloat16(float *out, const qfloat16 *in, qsizetype len) Q_DECL_NOTHROW
{
    if (hasFastF16())
        return qFloatFromFloat16_fast(out, reinterpret_cast<const quint16 *>(in), len);

    for (qsizetype i = 0; i < len; ++i)
        out[i] = float(in[i]);
}

QT_END_NAMESPACE

#ifdef QFLOAT16_INCLUDE_FAST
#  include "qfloat16_f16c.c"
#endif