// SPDX-License-Identifier: GPL-2.0-only
/*
 * IEEE754 floating point arithmetic
 * single precision: MAX{,A}.f
 * MAX : Scalar Floating-Point Maximum
 * MAXA: Scalar Floating-Point argument with Maximum Absolute Value
 *
 * MAX.S : FPR[fd] = maxNum(FPR[fs],FPR[ft])
 * MAXA.S: FPR[fd] = maxNumMag(FPR[fs],FPR[ft])
 *
 * MIPS floating point support
 * Copyright (C) 2015 Imagination Technologies, Ltd.
 * Author: Markos Chandras <markos.chandras@imgtec.com>
 */

#include "ieee754sp.h"

union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y)
{
        COMPXSP;
        COMPYSP;

        EXPLODEXSP;
        EXPLODEYSP;

        FLUSHXSP;
        FLUSHYSP;

        ieee754_clearcx();

        switch (CLPAIR(xc, yc)) {
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
                return ieee754sp_nanxcpt(y);

        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);

        /*
         * Quiet NaN handling
         */

        /*
         *    The case of both inputs quiet NaNs
         */
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
                return x;

        /*
         *    The cases of exactly one input quiet NaN (numbers
         *    are here preferred as returned values to NaNs)
         */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;

        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
                return y;

        /*
         * Infinity and zero handling
         */
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
                return xs ? y : x;

        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
                return ys ? x : y;

        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
                return ieee754sp_zero(xs & ys);

        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
                SPDNORMX;
                fallthrough;
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
                SPDNORMY;
                break;

        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
                SPDNORMX;
        }

        /* Finally get to do some computation */

        assert(xm & SP_HIDDEN_BIT);
        assert(ym & SP_HIDDEN_BIT);

        /* Compare signs */
        if (xs > ys)
                return y;
        else if (xs < ys)
                return x;

        /* Signs of inputs are equal, let's compare exponents */
        if (xs == 0) {
                /* Inputs are both positive */
                if (xe > ye)
                        return x;
                else if (xe < ye)
                        return y;
        } else {
                /* Inputs are both negative */
                if (xe > ye)
                        return y;
                else if (xe < ye)
                        return x;
        }

        /* Signs and exponents of inputs are equal, let's compare mantissas */
        if (xs == 0) {
                /* Inputs are both positive, with equal signs and exponents */
                if (xm <= ym)
                        return y;
                return x;
        }
        /* Inputs are both negative, with equal signs and exponents */
        if (xm <= ym)
                return x;
        return y;
}

union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
{
        COMPXSP;
        COMPYSP;

        EXPLODEXSP;
        EXPLODEYSP;

        FLUSHXSP;
        FLUSHYSP;

        ieee754_clearcx();

        switch (CLPAIR(xc, yc)) {
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
                return ieee754sp_nanxcpt(y);

        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);

        /*
         * Quiet NaN handling
         */

        /*
         *    The case of both inputs quiet NaNs
         */
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
                return x;

        /*
         *    The cases of exactly one input quiet NaN (numbers
         *    are here preferred as returned values to NaNs)
         */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;

        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
                return y;

        /*
         * Infinity and zero handling
         */
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
                return ieee754sp_inf(xs & ys);

        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
                return x;

        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
                return y;

        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
                return ieee754sp_zero(xs & ys);

        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
                SPDNORMX;
                fallthrough;
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
                SPDNORMY;
                break;

        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
                SPDNORMX;
        }

        /* Finally get to do some computation */

        assert(xm & SP_HIDDEN_BIT);
        assert(ym & SP_HIDDEN_BIT);

        /* Compare exponent */
        if (xe > ye)
                return x;
        else if (xe < ye)
                return y;

        /* Compare mantissa */
        if (xm < ym)
                return y;
        else if (xm > ym)
                return x;
        else if (xs == 0)
                return x;
        return y;
}