// SPDX-License-Identifier: GPL-2.0-only
/* IEEE754 floating point arithmetic
 * double precision: common utilities
 */
/*
 * MIPS floating point support
 * Copyright (C) 1994-2000 Algorithmics Ltd.
 * Copyright (C) 2017 Imagination Technologies, Ltd.
 * Author: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
 */

#include "ieee754dp.h"

union ieee754dp ieee754dp_rint(union ieee754dp x)
{
        union ieee754dp ret;
        u64 residue;
        int sticky;
        int round;
        int odd;

        COMPXDP;

        ieee754_clearcx();

        EXPLODEXDP;
        FLUSHXDP;

        if (xc == IEEE754_CLASS_SNAN)
                return ieee754dp_nanxcpt(x);

        if ((xc == IEEE754_CLASS_QNAN) ||
            (xc == IEEE754_CLASS_INF) ||
            (xc == IEEE754_CLASS_ZERO))
                return x;

        if (xe >= DP_FBITS)
                return x;

        if (xe < -1) {
                residue = xm;
                round = 0;
                sticky = residue != 0;
                xm = 0;
        } else {
                residue = xm << (64 - DP_FBITS + xe);
                round = (residue >> 63) != 0;
                sticky = (residue << 1) != 0;
                xm >>= DP_FBITS - xe;
        }

        odd = (xm & 0x1) != 0x0;

        switch (ieee754_csr.rm) {
        case FPU_CSR_RN:        /* toward nearest */
                if (round && (sticky || odd))
                        xm++;
                break;
        case FPU_CSR_RZ:        /* toward zero */
                break;
        case FPU_CSR_RU:        /* toward +infinity */
                if ((round || sticky) && !xs)
                        xm++;
                break;
        case FPU_CSR_RD:        /* toward -infinity */
                if ((round || sticky) && xs)
                        xm++;
                break;
        }

        if (round || sticky)
                ieee754_setcx(IEEE754_INEXACT);

        ret = ieee754dp_flong(xm);
        DPSIGN(ret) = xs;

        return ret;
}