vfpsingle.c

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/*
 *  linux/arch/arm/vfp/vfpsingle.c
 *
 * This code is derived in part from John R. Housers softfloat library, which
 * carries the following notice:
 *
 * ===========================================================================
 * This C source file is part of the SoftFloat IEC/IEEE Floating-point
 * Arithmetic Package, Release 2.
 *
 * Written by John R. Hauser.  This work was made possible in part by the
 * International Computer Science Institute, located at Suite 600, 1947 Center
 * Street, Berkeley, California 94704.  Funding was partially provided by the
 * National Science Foundation under grant MIP-9311980.  The original version
 * of this code was written as part of a project to build a fixed-point vector
 * processor in collaboration with the University of California at Berkeley,
 * overseen by Profs. Nelson Morgan and John Wawrzynek.  More information
 * is available through the web page `http://HTTP.CS.Berkeley.EDU/~jhauser/
 * arithmetic/softfloat.html'.
 *
 * THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE.  Although reasonable effort
 * has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
 * TIMES RESULT IN INCORRECT BEHAVIOR.  USE OF THIS SOFTWARE IS RESTRICTED TO
 * PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
 * AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
 *
 * Derivative works are acceptable, even for commercial purposes, so long as
 * (1) they include prominent notice that the work is derivative, and (2) they
 * include prominent notice akin to these three paragraphs for those parts of
 * this code that are retained.
 * ===========================================================================
 */
#include <linux/kernel.h>
#include <linux/bitops.h>

#include <asm/div64.h>
#include <asm/vfp.h>

#include "vfpinstr.h"
#include "vfp.h"

static struct vfp_single vfp_single_default_qnan = {
    .exponent   = 255,
    .sign       = 0,
    .significand    = VFP_SINGLE_SIGNIFICAND_QNAN,
};

static void vfp_single_dump(const char *str, struct vfp_single *s)
{
    pr_debug("VFP: %s: sign=%d exponent=%d significand=%08x\n",
         str, s->sign != 0, s->exponent, s->significand);
}

static void vfp_single_normalise_denormal(struct vfp_single *vs)
{
    int bits = 31 - fls(vs->significand);

    vfp_single_dump("normalise_denormal: in", vs);

    if (bits) {
        vs->exponent -= bits - 1;
        vs->significand <<= bits;
    }

    vfp_single_dump("normalise_denormal: out", vs);
}

#ifndef DEBUG
#define vfp_single_normaliseround(sd,vsd,fpscr,except,func) __vfp_single_normaliseround(sd,vsd,fpscr,except)
u32 __vfp_single_normaliseround(int sd, struct vfp_single *vs, u32 fpscr, u32 exceptions)
#else
u32 vfp_single_normaliseround(int sd, struct vfp_single *vs, u32 fpscr, u32 exceptions, const char *func)
#endif
{
    u32 significand, incr, rmode;
    int exponent, shift, underflow;

    vfp_single_dump("pack: in", vs);

    /*
     * Infinities and NaNs are a special case.
     */
    if (vs->exponent == 255 && (vs->significand == 0 || exceptions))
        goto pack;

    /*
     * Special-case zero.
     */
    if (vs->significand == 0) {
        vs->exponent = 0;
        goto pack;
    }

    exponent = vs->exponent;
    significand = vs->significand;

    /*
     * Normalise first.  Note that we shift the significand up to
     * bit 31, so we have VFP_SINGLE_LOW_BITS + 1 below the least
     * significant bit.
     */
    shift = 32 - fls(significand);
    if (shift < 32 && shift) {
        exponent -= shift;
        significand <<= shift;
    }

#ifdef DEBUG
    vs->exponent = exponent;
    vs->significand = significand;
    vfp_single_dump("pack: normalised", vs);
#endif

    /*
     * Tiny number?
     */
    underflow = exponent < 0;
    if (underflow) {
        significand = vfp_shiftright32jamming(significand, -exponent);
        exponent = 0;
#ifdef DEBUG
        vs->exponent = exponent;
        vs->significand = significand;
        vfp_single_dump("pack: tiny number", vs);
#endif
        if (!(significand & ((1 << (VFP_SINGLE_LOW_BITS + 1)) - 1)))
            underflow = 0;
    }

    /*
     * Select rounding increment.
     */
    incr = 0;
    rmode = fpscr & FPSCR_RMODE_MASK;

    if (rmode == FPSCR_ROUND_NEAREST) {
        incr = 1 << VFP_SINGLE_LOW_BITS;
        if ((significand & (1 << (VFP_SINGLE_LOW_BITS + 1))) == 0)
            incr -= 1;
    } else if (rmode == FPSCR_ROUND_TOZERO) {
        incr = 0;
    } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vs->sign != 0))
        incr = (1 << (VFP_SINGLE_LOW_BITS + 1)) - 1;

    pr_debug("VFP: rounding increment = 0x%08x\n", incr);

    /*
     * Is our rounding going to overflow?
     */
    if ((significand + incr) < significand) {
        exponent += 1;
        significand = (significand >> 1) | (significand & 1);
        incr >>= 1;
#ifdef DEBUG
        vs->exponent = exponent;
        vs->significand = significand;
        vfp_single_dump("pack: overflow", vs);
#endif
    }

    /*
     * If any of the low bits (which will be shifted out of the
     * number) are non-zero, the result is inexact.
     */
    if (significand & ((1 << (VFP_SINGLE_LOW_BITS + 1)) - 1))
        exceptions |= FPSCR_IXC;

    /*
     * Do our rounding.
     */
    significand += incr;

    /*
     * Infinity?
     */
    if (exponent >= 254) {
        exceptions |= FPSCR_OFC | FPSCR_IXC;
        if (incr == 0) {
            vs->exponent = 253;
            vs->significand = 0x7fffffff;
        } else {
            vs->exponent = 255;     /* infinity */
            vs->significand = 0;
        }
    } else {
        if (significand >> (VFP_SINGLE_LOW_BITS + 1) == 0)
            exponent = 0;
        if (exponent || significand > 0x80000000)
            underflow = 0;
        if (underflow)
            exceptions |= FPSCR_UFC;
        vs->exponent = exponent;
        vs->significand = significand >> 1;
    }

 pack:
    vfp_single_dump("pack: final", vs);
    {
        s32 d = vfp_single_pack(vs);
#ifdef DEBUG
        pr_debug("VFP: %s: d(s%d)=%08x exceptions=%08x\n", func,
             sd, d, exceptions);
#endif
        vfp_put_float(d, sd);
    }

    return exceptions;
}

/*
 * Propagate the NaN, setting exceptions if it is signalling.
 * 'n' is always a NaN.  'm' may be a number, NaN or infinity.
 */
static u32
vfp_propagate_nan(struct vfp_single *vsd, struct vfp_single *vsn,
          struct vfp_single *vsm, u32 fpscr)
{
    struct vfp_single *nan;
    int tn, tm = 0;

    tn = vfp_single_type(vsn);

    if (vsm)
        tm = vfp_single_type(vsm);

    if (fpscr & FPSCR_DEFAULT_NAN)
        /*
         * Default NaN mode - always returns a quiet NaN
         */
        nan = &vfp_single_default_qnan;
    else {
        /*
         * Contemporary mode - select the first signalling
         * NAN, or if neither are signalling, the first
         * quiet NAN.
         */
        if (tn == VFP_SNAN || (tm != VFP_SNAN && tn == VFP_QNAN))
            nan = vsn;
        else
            nan = vsm;
        /*
         * Make the NaN quiet.
         */
        nan->significand |= VFP_SINGLE_SIGNIFICAND_QNAN;
    }

    *vsd = *nan;

    /*
     * If one was a signalling NAN, raise invalid operation.
     */
    return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : VFP_NAN_FLAG;
}


/*
 * Extended operations
 */
static u32 vfp_single_fabs(int sd, int unused, s32 m, u32 fpscr)
{
    vfp_put_float(vfp_single_packed_abs(m), sd);
    return 0;
}

static u32 vfp_single_fcpy(int sd, int unused, s32 m, u32 fpscr)
{
    vfp_put_float(m, sd);
    return 0;
}

static u32 vfp_single_fneg(int sd, int unused, s32 m, u32 fpscr)
{
    vfp_put_float(vfp_single_packed_negate(m), sd);
    return 0;
}

static const u16 sqrt_oddadjust[] = {
    0x0004, 0x0022, 0x005d, 0x00b1, 0x011d, 0x019f, 0x0236, 0x02e0,
    0x039c, 0x0468, 0x0545, 0x0631, 0x072b, 0x0832, 0x0946, 0x0a67
};

static const u16 sqrt_evenadjust[] = {
    0x0a2d, 0x08af, 0x075a, 0x0629, 0x051a, 0x0429, 0x0356, 0x029e,
    0x0200, 0x0179, 0x0109, 0x00af, 0x0068, 0x0034, 0x0012, 0x0002
};

u32 vfp_estimate_sqrt_significand(u32 exponent, u32 significand)
{
    int index;
    u32 z, a;

    if ((significand & 0xc0000000) != 0x40000000) {
        printk(KERN_WARNING "VFP: estimate_sqrt: invalid significand\n");
    }

    a = significand << 1;
    index = (a >> 27) & 15;
    if (exponent & 1) {
        z = 0x4000 + (a >> 17) - sqrt_oddadjust[index];
        z = ((a / z) << 14) + (z << 15);
        a >>= 1;
    } else {
        z = 0x8000 + (a >> 17) - sqrt_evenadjust[index];
        z = a / z + z;
        z = (z >= 0x20000) ? 0xffff8000 : (z << 15);
        if (z <= a)
            return (s32)a >> 1;
    }
    {
        u64 v = (u64)a << 31;
        do_div(v, z);
        return v + (z >> 1);
    }
}

static u32 vfp_single_fsqrt(int sd, int unused, s32 m, u32 fpscr)
{
    struct vfp_single vsm, vsd;
    int ret, tm;

    vfp_single_unpack(&vsm, m);
    tm = vfp_single_type(&vsm);
    if (tm & (VFP_NAN|VFP_INFINITY)) {
        struct vfp_single *vsp = &vsd;

        if (tm & VFP_NAN)
            ret = vfp_propagate_nan(vsp, &vsm, NULL, fpscr);
        else if (vsm.sign == 0) {
 sqrt_copy:
            vsp = &vsm;
            ret = 0;
        } else {
 sqrt_invalid:
            vsp = &vfp_single_default_qnan;
            ret = FPSCR_IOC;
        }
        vfp_put_float(vfp_single_pack(vsp), sd);
        return ret;
    }

    /*
     * sqrt(+/- 0) == +/- 0
     */
    if (tm & VFP_ZERO)
        goto sqrt_copy;

    /*
     * Normalise a denormalised number
     */
    if (tm & VFP_DENORMAL)
        vfp_single_normalise_denormal(&vsm);

    /*
     * sqrt(<0) = invalid
     */
    if (vsm.sign)
        goto sqrt_invalid;

    vfp_single_dump("sqrt", &vsm);

    /*
     * Estimate the square root.
     */
    vsd.sign = 0;
    vsd.exponent = ((vsm.exponent - 127) >> 1) + 127;
    vsd.significand = vfp_estimate_sqrt_significand(vsm.exponent, vsm.significand) + 2;

    vfp_single_dump("sqrt estimate", &vsd);

    /*
     * And now adjust.
     */
    if ((vsd.significand & VFP_SINGLE_LOW_BITS_MASK) <= 5) {
        if (vsd.significand < 2) {
            vsd.significand = 0xffffffff;
        } else {
            u64 term;
            s64 rem;
            vsm.significand <<= !(vsm.exponent & 1);
            term = (u64)vsd.significand * vsd.significand;
            rem = ((u64)vsm.significand << 32) - term;

            pr_debug("VFP: term=%016llx rem=%016llx\n", term, rem);

            while (rem < 0) {
                vsd.significand -= 1;
                rem += ((u64)vsd.significand << 1) | 1;
            }
            vsd.significand |= rem != 0;
        }
    }
    vsd.significand = vfp_shiftright32jamming(vsd.significand, 1);

    return vfp_single_normaliseround(sd, &vsd, fpscr, 0, "fsqrt");
}

/*
 * Equal    := ZC
 * Less than    := N
 * Greater than := C
 * Unordered    := CV
 */
static u32 vfp_compare(int sd, int signal_on_qnan, s32 m, u32 fpscr)
{
    s32 d;
    u32 ret = 0;

    d = vfp_get_float(sd);
    if (vfp_single_packed_exponent(m) == 255 && vfp_single_packed_mantissa(m)) {
        ret |= FPSCR_C | FPSCR_V;
        if (signal_on_qnan || !(vfp_single_packed_mantissa(m) & (1 << (VFP_SINGLE_MANTISSA_BITS - 1))))
            /*
             * Signalling NaN, or signalling on quiet NaN
             */
            ret |= FPSCR_IOC;
    }

    if (vfp_single_packed_exponent(d) == 255 && vfp_single_packed_mantissa(d)) {
        ret |= FPSCR_C | FPSCR_V;
        if (signal_on_qnan || !(vfp_single_packed_mantissa(d) & (1 << (VFP_SINGLE_MANTISSA_BITS - 1))))
            /*
             * Signalling NaN, or signalling on quiet NaN
             */
            ret |= FPSCR_IOC;
    }

    if (ret == 0) {
        if (d == m || vfp_single_packed_abs(d | m) == 0) {
            /*
             * equal
             */
            ret |= FPSCR_Z | FPSCR_C;
        } else if (vfp_single_packed_sign(d ^ m)) {
            /*
             * different signs
             */
            if (vfp_single_packed_sign(d))
                /*
                 * d is negative, so d < m
                 */
                ret |= FPSCR_N;
            else
                /*
                 * d is positive, so d > m
                 */
                ret |= FPSCR_C;
        } else if ((vfp_single_packed_sign(d) != 0) ^ (d < m)) {
            /*
             * d < m
             */
            ret |= FPSCR_N;
        } else if ((vfp_single_packed_sign(d) != 0) ^ (d > m)) {
            /*
             * d > m
             */
            ret |= FPSCR_C;
        }
    }
    return ret;
}

static u32 vfp_single_fcmp(int sd, int unused, s32 m, u32 fpscr)
{
    return vfp_compare(sd, 0, m, fpscr);
}

static u32 vfp_single_fcmpe(int sd, int unused, s32 m, u32 fpscr)
{
    return vfp_compare(sd, 1, m, fpscr);
}

static u32 vfp_single_fcmpz(int sd, int unused, s32 m, u32 fpscr)
{
    return vfp_compare(sd, 0, 0, fpscr);
}

static u32 vfp_single_fcmpez(int sd, int unused, s32 m, u32 fpscr)
{
    return vfp_compare(sd, 1, 0, fpscr);
}

static u32 vfp_single_fcvtd(int dd, int unused, s32 m, u32 fpscr)
{
    struct vfp_single vsm;
    struct vfp_double vdd;
    int tm;
    u32 exceptions = 0;

    vfp_single_unpack(&vsm, m);

    tm = vfp_single_type(&vsm);

    /*
     * If we have a signalling NaN, signal invalid operation.
     */
    if (tm == VFP_SNAN)
        exceptions = FPSCR_IOC;

    if (tm & VFP_DENORMAL)
        vfp_single_normalise_denormal(&vsm);

    vdd.sign = vsm.sign;
    vdd.significand = (u64)vsm.significand << 32;

    /*
     * If we have an infinity or NaN, the exponent must be 2047.
     */
    if (tm & (VFP_INFINITY|VFP_NAN)) {
        vdd.exponent = 2047;
        if (tm == VFP_QNAN)
            vdd.significand |= VFP_DOUBLE_SIGNIFICAND_QNAN;
        goto pack_nan;
    } else if (tm & VFP_ZERO)
        vdd.exponent = 0;
    else
        vdd.exponent = vsm.exponent + (1023 - 127);

    return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fcvtd");

 pack_nan:
    vfp_put_double(vfp_double_pack(&vdd), dd);
    return exceptions;
}

static u32 vfp_single_fuito(int sd, int unused, s32 m, u32 fpscr)
{
    struct vfp_single vs;

    vs.sign = 0;
    vs.exponent = 127 + 31 - 1;
    vs.significand = (u32)m;

    return vfp_single_normaliseround(sd, &vs, fpscr, 0, "fuito");
}

static u32 vfp_single_fsito(int sd, int unused, s32 m, u32 fpscr)
{
    struct vfp_single vs;

    vs.sign = (m & 0x80000000) >> 16;
    vs.exponent = 127 + 31 - 1;
    vs.significand = vs.sign ? -m : m;

    return vfp_single_normaliseround(sd, &vs, fpscr, 0, "fsito");
}

static u32 vfp_single_ftoui(int sd, int unused, s32 m, u32 fpscr)
{
    struct vfp_single vsm;
    u32 d, exceptions = 0;
    int rmode = fpscr & FPSCR_RMODE_MASK;
    int tm;

    vfp_single_unpack(&vsm, m);
    vfp_single_dump("VSM", &vsm);

    /*
     * Do we have a denormalised number?
     */
    tm = vfp_single_type(&vsm);
    if (tm & VFP_DENORMAL)
        exceptions |= FPSCR_IDC;

    if (tm & VFP_NAN)
        vsm.sign = 0;

    if (vsm.exponent >= 127 + 32) {
        d = vsm.sign ? 0 : 0xffffffff;
        exceptions = FPSCR_IOC;
    } else if (vsm.exponent >= 127 - 1) {
        int shift = 127 + 31 - vsm.exponent;
        u32 rem, incr = 0;

        /*
         * 2^0 <= m < 2^32-2^8
         */
        d = (vsm.significand << 1) >> shift;
        rem = vsm.significand << (33 - shift);

        if (rmode == FPSCR_ROUND_NEAREST) {
            incr = 0x80000000;
            if ((d & 1) == 0)
                incr -= 1;
        } else if (rmode == FPSCR_ROUND_TOZERO) {
            incr = 0;
        } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vsm.sign != 0)) {
            incr = ~0;
        }

        if ((rem + incr) < rem) {
            if (d < 0xffffffff)
                d += 1;
            else
                exceptions |= FPSCR_IOC;
        }

        if (d && vsm.sign) {
            d = 0;
            exceptions |= FPSCR_IOC;
        } else if (rem)
            exceptions |= FPSCR_IXC;
    } else {
        d = 0;
        if (vsm.exponent | vsm.significand) {
            exceptions |= FPSCR_IXC;
            if (rmode == FPSCR_ROUND_PLUSINF && vsm.sign == 0)
                d = 1;
            else if (rmode == FPSCR_ROUND_MINUSINF && vsm.sign) {
                d = 0;
                exceptions |= FPSCR_IOC;
            }
        }
    }

    pr_debug("VFP: ftoui: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);

    vfp_put_float(d, sd);

    return exceptions;
}

static u32 vfp_single_ftouiz(int sd, int unused, s32 m, u32 fpscr)
{
    return vfp_single_ftoui(sd, unused, m, FPSCR_ROUND_TOZERO);
}

static u32 vfp_single_ftosi(int sd, int unused, s32 m, u32 fpscr)
{
    struct vfp_single vsm;
    u32 d, exceptions = 0;
    int rmode = fpscr & FPSCR_RMODE_MASK;
    int tm;

    vfp_single_unpack(&vsm, m);
    vfp_single_dump("VSM", &vsm);

    /*
     * Do we have a denormalised number?
     */
    tm = vfp_single_type(&vsm);
    if (vfp_single_type(&vsm) & VFP_DENORMAL)
        exceptions |= FPSCR_IDC;

    if (tm & VFP_NAN) {
        d = 0;
        exceptions |= FPSCR_IOC;
    } else if (vsm.exponent >= 127 + 32) {
        /*
         * m >= 2^31-2^7: invalid
         */
        d = 0x7fffffff;
        if (vsm.sign)
            d = ~d;
        exceptions |= FPSCR_IOC;
    } else if (vsm.exponent >= 127 - 1) {
        int shift = 127 + 31 - vsm.exponent;
        u32 rem, incr = 0;

        /* 2^0 <= m <= 2^31-2^7 */
        d = (vsm.significand << 1) >> shift;
        rem = vsm.significand << (33 - shift);

        if (rmode == FPSCR_ROUND_NEAREST) {
            incr = 0x80000000;
            if ((d & 1) == 0)
                incr -= 1;
        } else if (rmode == FPSCR_ROUND_TOZERO) {
            incr = 0;
        } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vsm.sign != 0)) {
            incr = ~0;
        }

        if ((rem + incr) < rem && d < 0xffffffff)
            d += 1;
        if (d > 0x7fffffff + (vsm.sign != 0)) {
            d = 0x7fffffff + (vsm.sign != 0);
            exceptions |= FPSCR_IOC;
        } else if (rem)
            exceptions |= FPSCR_IXC;

        if (vsm.sign)
            d = -d;
    } else {
        d = 0;
        if (vsm.exponent | vsm.significand) {
            exceptions |= FPSCR_IXC;
            if (rmode == FPSCR_ROUND_PLUSINF && vsm.sign == 0)
                d = 1;
            else if (rmode == FPSCR_ROUND_MINUSINF && vsm.sign)
                d = -1;
        }
    }

    pr_debug("VFP: ftosi: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);

    vfp_put_float((s32)d, sd);

    return exceptions;
}

static u32 vfp_single_ftosiz(int sd, int unused, s32 m, u32 fpscr)
{
    return vfp_single_ftosi(sd, unused, m, FPSCR_ROUND_TOZERO);
}

static struct op fops_ext[32] = {
    [FEXT_TO_IDX(FEXT_FCPY)]    = { vfp_single_fcpy,   0 },
    [FEXT_TO_IDX(FEXT_FABS)]    = { vfp_single_fabs,   0 },
    [FEXT_TO_IDX(FEXT_FNEG)]    = { vfp_single_fneg,   0 },
    [FEXT_TO_IDX(FEXT_FSQRT)]   = { vfp_single_fsqrt,  0 },
    [FEXT_TO_IDX(FEXT_FCMP)]    = { vfp_single_fcmp,   OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FCMPE)]   = { vfp_single_fcmpe,  OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FCMPZ)]   = { vfp_single_fcmpz,  OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FCMPEZ)]  = { vfp_single_fcmpez, OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FCVT)]    = { vfp_single_fcvtd,  OP_SCALAR|OP_DD },
    [FEXT_TO_IDX(FEXT_FUITO)]   = { vfp_single_fuito,  OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FSITO)]   = { vfp_single_fsito,  OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FTOUI)]   = { vfp_single_ftoui,  OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FTOUIZ)]  = { vfp_single_ftouiz, OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FTOSI)]   = { vfp_single_ftosi,  OP_SCALAR },
    [FEXT_TO_IDX(FEXT_FTOSIZ)]  = { vfp_single_ftosiz, OP_SCALAR },
};





static u32
vfp_single_fadd_nonnumber(struct vfp_single *vsd, struct vfp_single *vsn,
              struct vfp_single *vsm, u32 fpscr)
{
    struct vfp_single *vsp;
    u32 exceptions = 0;
    int tn, tm;

    tn = vfp_single_type(vsn);
    tm = vfp_single_type(vsm);

    if (tn & tm & VFP_INFINITY) {
        /*
         * Two infinities.  Are they different signs?
         */
        if (vsn->sign ^ vsm->sign) {
            /*
             * different signs -> invalid
             */
            exceptions = FPSCR_IOC;
            vsp = &vfp_single_default_qnan;
        } else {
            /*
             * same signs -> valid
             */
            vsp = vsn;
        }
    } else if (tn & VFP_INFINITY && tm & VFP_NUMBER) {
        /*
         * One infinity and one number -> infinity
         */
        vsp = vsn;
    } else {
        /*
         * 'n' is a NaN of some type
         */
        return vfp_propagate_nan(vsd, vsn, vsm, fpscr);
    }
    *vsd = *vsp;
    return exceptions;
}

static u32
vfp_single_add(struct vfp_single *vsd, struct vfp_single *vsn,
           struct vfp_single *vsm, u32 fpscr)
{
    u32 exp_diff, m_sig;

    if (vsn->significand & 0x80000000 ||
        vsm->significand & 0x80000000) {
        pr_info("VFP: bad FP values in %s\n", __func__);
        vfp_single_dump("VSN", vsn);
        vfp_single_dump("VSM", vsm);
    }

    /*
     * Ensure that 'n' is the largest magnitude number.  Note that
     * if 'n' and 'm' have equal exponents, we do not swap them.
     * This ensures that NaN propagation works correctly.
     */
    if (vsn->exponent < vsm->exponent) {
        struct vfp_single *t = vsn;
        vsn = vsm;
        vsm = t;
    }

    /*
     * Is 'n' an infinity or a NaN?  Note that 'm' may be a number,
     * infinity or a NaN here.
     */
    if (vsn->exponent == 255)
        return vfp_single_fadd_nonnumber(vsd, vsn, vsm, fpscr);

    /*
     * We have two proper numbers, where 'vsn' is the larger magnitude.
     *
     * Copy 'n' to 'd' before doing the arithmetic.
     */
    *vsd = *vsn;

    /*
     * Align both numbers.
     */
    exp_diff = vsn->exponent - vsm->exponent;
    m_sig = vfp_shiftright32jamming(vsm->significand, exp_diff);

    /*
     * If the signs are different, we are really subtracting.
     */
    if (vsn->sign ^ vsm->sign) {
        m_sig = vsn->significand - m_sig;
        if ((s32)m_sig < 0) {
            vsd->sign = vfp_sign_negate(vsd->sign);
            m_sig = -m_sig;
        } else if (m_sig == 0) {
            vsd->sign = (fpscr & FPSCR_RMODE_MASK) ==
                      FPSCR_ROUND_MINUSINF ? 0x8000 : 0;
        }
    } else {
        m_sig = vsn->significand + m_sig;
    }
    vsd->significand = m_sig;

    return 0;
}

static u32
vfp_single_multiply(struct vfp_single *vsd, struct vfp_single *vsn, struct vfp_single *vsm, u32 fpscr)
{
    vfp_single_dump("VSN", vsn);
    vfp_single_dump("VSM", vsm);

    /*
     * Ensure that 'n' is the largest magnitude number.  Note that
     * if 'n' and 'm' have equal exponents, we do not swap them.
     * This ensures that NaN propagation works correctly.
     */
    if (vsn->exponent < vsm->exponent) {
        struct vfp_single *t = vsn;
        vsn = vsm;
        vsm = t;
        pr_debug("VFP: swapping M <-> N\n");
    }

    vsd->sign = vsn->sign ^ vsm->sign;

    /*
     * If 'n' is an infinity or NaN, handle it.  'm' may be anything.
     */
    if (vsn->exponent == 255) {
        if (vsn->significand || (vsm->exponent == 255 && vsm->significand))
            return vfp_propagate_nan(vsd, vsn, vsm, fpscr);
        if ((vsm->exponent | vsm->significand) == 0) {
            *vsd = vfp_single_default_qnan;
            return FPSCR_IOC;
        }
        vsd->exponent = vsn->exponent;
        vsd->significand = 0;
        return 0;
    }

    /*
     * If 'm' is zero, the result is always zero.  In this case,
     * 'n' may be zero or a number, but it doesn't matter which.
     */
    if ((vsm->exponent | vsm->significand) == 0) {
        vsd->exponent = 0;
        vsd->significand = 0;
        return 0;
    }

    /*
     * We add 2 to the destination exponent for the same reason as
     * the addition case - though this time we have +1 from each
     * input operand.
     */
    vsd->exponent = vsn->exponent + vsm->exponent - 127 + 2;
    vsd->significand = vfp_hi64to32jamming((u64)vsn->significand * vsm->significand);

    vfp_single_dump("VSD", vsd);
    return 0;
}

#define NEG_MULTIPLY    (1 << 0)
#define NEG_SUBTRACT    (1 << 1)

static u32
vfp_single_multiply_accumulate(int sd, int sn, s32 m, u32 fpscr, u32 negate, char *func)
{
    struct vfp_single vsd, vsp, vsn, vsm;
    u32 exceptions;
    s32 v;

    v = vfp_get_float(sn);
    pr_debug("VFP: s%u = %08x\n", sn, v);
    vfp_single_unpack(&vsn, v);
    if (vsn.exponent == 0 && vsn.significand)
        vfp_single_normalise_denormal(&vsn);

    vfp_single_unpack(&vsm, m);
    if (vsm.exponent == 0 && vsm.significand)
        vfp_single_normalise_denormal(&vsm);

    exceptions = vfp_single_multiply(&vsp, &vsn, &vsm, fpscr);
    if (negate & NEG_MULTIPLY)
        vsp.sign = vfp_sign_negate(vsp.sign);

    v = vfp_get_float(sd);
    pr_debug("VFP: s%u = %08x\n", sd, v);
    vfp_single_unpack(&vsn, v);
    if (negate & NEG_SUBTRACT)
        vsn.sign = vfp_sign_negate(vsn.sign);

    exceptions |= vfp_single_add(&vsd, &vsn, &vsp, fpscr);

    return vfp_single_normaliseround(sd, &vsd, fpscr, exceptions, func);
}

/*
 * Standard operations
 */

/*
 * sd = sd + (sn * sm)
 */
static u32 vfp_single_fmac(int sd, int sn, s32 m, u32 fpscr)
{
    return vfp_single_multiply_accumulate(sd, sn, m, fpscr, 0, "fmac");
}

/*
 * sd = sd - (sn * sm)
 */
static u32 vfp_single_fnmac(int sd, int sn, s32 m, u32 fpscr)
{
    return vfp_single_multiply_accumulate(sd, sn, m, fpscr, NEG_MULTIPLY, "fnmac");
}

/*
 * sd = -sd + (sn * sm)
 */
static u32 vfp_single_fmsc(int sd, int sn, s32 m, u32 fpscr)
{
    return vfp_single_multiply_accumulate(sd, sn, m, fpscr, NEG_SUBTRACT, "fmsc");
}

/*
 * sd = -sd - (sn * sm)
 */
static u32 vfp_single_fnmsc(int sd, int sn, s32 m, u32 fpscr)
{
    return vfp_single_multiply_accumulate(sd, sn, m, fpscr, NEG_SUBTRACT | NEG_MULTIPLY, "fnmsc");
}

/*
 * sd = sn * sm
 */
static u32 vfp_single_fmul(int sd, int sn, s32 m, u32 fpscr)
{
    struct vfp_single vsd, vsn, vsm;
    u32 exceptions;
    s32 n = vfp_get_float(sn);

    pr_debug("VFP: s%u = %08x\n", sn, n);

    vfp_single_unpack(&vsn, n);
    if (vsn.exponent == 0 && vsn.significand)
        vfp_single_normalise_denormal(&vsn);

    vfp_single_unpack(&vsm, m);
    if (vsm.exponent == 0 && vsm.significand)
        vfp_single_normalise_denormal(&vsm);

    exceptions = vfp_single_multiply(&vsd, &vsn, &vsm, fpscr);
    return vfp_single_normaliseround(sd, &vsd, fpscr, exceptions, "fmul");
}

/*
 * sd = -(sn * sm)
 */
static u32 vfp_single_fnmul(int sd, int sn, s32 m, u32 fpscr)
{
    struct vfp_single vsd, vsn, vsm;
    u32 exceptions;
    s32 n = vfp_get_float(sn);

    pr_debug("VFP: s%u = %08x\n", sn, n);

    vfp_single_unpack(&vsn, n);
    if (vsn.exponent == 0 && vsn.significand)
        vfp_single_normalise_denormal(&vsn);

    vfp_single_unpack(&vsm, m);
    if (vsm.exponent == 0 && vsm.significand)
        vfp_single_normalise_denormal(&vsm);

    exceptions = vfp_single_multiply(&vsd, &vsn, &vsm, fpscr);
    vsd.sign = vfp_sign_negate(vsd.sign);
    return vfp_single_normaliseround(sd, &vsd, fpscr, exceptions, "fnmul");
}

/*
 * sd = sn + sm
 */
static u32 vfp_single_fadd(int sd, int sn, s32 m, u32 fpscr)
{
    struct vfp_single vsd, vsn, vsm;
    u32 exceptions;
    s32 n = vfp_get_float(sn);

    pr_debug("VFP: s%u = %08x\n", sn, n);

    /*
     * Unpack and normalise denormals.
     */
    vfp_single_unpack(&vsn, n);
    if (vsn.exponent == 0 && vsn.significand)
        vfp_single_normalise_denormal(&vsn);

    vfp_single_unpack(&vsm, m);
    if (vsm.exponent == 0 && vsm.significand)
        vfp_single_normalise_denormal(&vsm);

    exceptions = vfp_single_add(&vsd, &vsn, &vsm, fpscr);

    return vfp_single_normaliseround(sd, &vsd, fpscr, exceptions, "fadd");
}

/*
 * sd = sn - sm
 */
static u32 vfp_single_fsub(int sd, int sn, s32 m, u32 fpscr)
{
    /*
     * Subtraction is addition with one sign inverted.
     */
    return vfp_single_fadd(sd, sn, vfp_single_packed_negate(m), fpscr);
}

/*
 * sd = sn / sm
 */
static u32 vfp_single_fdiv(int sd, int sn, s32 m, u32 fpscr)
{
    struct vfp_single vsd, vsn, vsm;
    u32 exceptions = 0;
    s32 n = vfp_get_float(sn);
    int tm, tn;

    pr_debug("VFP: s%u = %08x\n", sn, n);

    vfp_single_unpack(&vsn, n);
    vfp_single_unpack(&vsm, m);

    vsd.sign = vsn.sign ^ vsm.sign;

    tn = vfp_single_type(&vsn);
    tm = vfp_single_type(&vsm);

    /*
     * Is n a NAN?
     */
    if (tn & VFP_NAN)
        goto vsn_nan;

    /*
     * Is m a NAN?
     */
    if (tm & VFP_NAN)
        goto vsm_nan;

    /*
     * If n and m are infinity, the result is invalid
     * If n and m are zero, the result is invalid
     */
    if (tm & tn & (VFP_INFINITY|VFP_ZERO))
        goto invalid;

    /*
     * If n is infinity, the result is infinity
     */
    if (tn & VFP_INFINITY)
        goto infinity;

    /*
     * If m is zero, raise div0 exception
     */
    if (tm & VFP_ZERO)
        goto divzero;

    /*
     * If m is infinity, or n is zero, the result is zero
     */
    if (tm & VFP_INFINITY || tn & VFP_ZERO)
        goto zero;

    if (tn & VFP_DENORMAL)
        vfp_single_normalise_denormal(&vsn);
    if (tm & VFP_DENORMAL)
        vfp_single_normalise_denormal(&vsm);

    /*
     * Ok, we have two numbers, we can perform division.
     */
    vsd.exponent = vsn.exponent - vsm.exponent + 127 - 1;
    vsm.significand <<= 1;
    if (vsm.significand <= (2 * vsn.significand)) {
        vsn.significand >>= 1;
        vsd.exponent++;
    }
    {
        u64 significand = (u64)vsn.significand << 32;
        do_div(significand, vsm.significand);
        vsd.significand = significand;
    }
    if ((vsd.significand & 0x3f) == 0)
        vsd.significand |= ((u64)vsm.significand * vsd.significand != (u64)vsn.significand << 32);

    return vfp_single_normaliseround(sd, &vsd, fpscr, 0, "fdiv");

 vsn_nan:
    exceptions = vfp_propagate_nan(&vsd, &vsn, &vsm, fpscr);
 pack:
    vfp_put_float(vfp_single_pack(&vsd), sd);
    return exceptions;

 vsm_nan:
    exceptions = vfp_propagate_nan(&vsd, &vsm, &vsn, fpscr);
    goto pack;

 zero:
    vsd.exponent = 0;
    vsd.significand = 0;
    goto pack;

 divzero:
    exceptions = FPSCR_DZC;
 infinity:
    vsd.exponent = 255;
    vsd.significand = 0;
    goto pack;

 invalid:
    vfp_put_float(vfp_single_pack(&vfp_single_default_qnan), sd);
    return FPSCR_IOC;
}

static struct op fops[16] = {
    [FOP_TO_IDX(FOP_FMAC)]  = { vfp_single_fmac,  0 },
    [FOP_TO_IDX(FOP_FNMAC)] = { vfp_single_fnmac, 0 },
    [FOP_TO_IDX(FOP_FMSC)]  = { vfp_single_fmsc,  0 },
    [FOP_TO_IDX(FOP_FNMSC)] = { vfp_single_fnmsc, 0 },
    [FOP_TO_IDX(FOP_FMUL)]  = { vfp_single_fmul,  0 },
    [FOP_TO_IDX(FOP_FNMUL)] = { vfp_single_fnmul, 0 },
    [FOP_TO_IDX(FOP_FADD)]  = { vfp_single_fadd,  0 },
    [FOP_TO_IDX(FOP_FSUB)]  = { vfp_single_fsub,  0 },
    [FOP_TO_IDX(FOP_FDIV)]  = { vfp_single_fdiv,  0 },
};

#define FREG_BANK(x)    ((x) & 0x18)
#define FREG_IDX(x) ((x) & 7)

u32 vfp_single_cpdo(u32 inst, u32 fpscr)
{
    u32 op = inst & FOP_MASK;
    u32 exceptions = 0;
    unsigned int dest;
    unsigned int sn = vfp_get_sn(inst);
    unsigned int sm = vfp_get_sm(inst);
    unsigned int vecitr, veclen, vecstride;
    struct op *fop;

    vecstride = 1 + ((fpscr & FPSCR_STRIDE_MASK) == FPSCR_STRIDE_MASK);

    fop = (op == FOP_EXT) ? &fops_ext[FEXT_TO_IDX(inst)] : &fops[FOP_TO_IDX(op)];

    /*
     * fcvtsd takes a dN register number as destination, not sN.
     * Technically, if bit 0 of dd is set, this is an invalid
     * instruction.  However, we ignore this for efficiency.
     * It also only operates on scalars.
     */
    if (fop->flags & OP_DD)
        dest = vfp_get_dd(inst);
    else
        dest = vfp_get_sd(inst);

    /*
     * If destination bank is zero, vector length is always '1'.
     * ARM DDI0100F C5.1.3, C5.3.2.
     */
    if ((fop->flags & OP_SCALAR) || FREG_BANK(dest) == 0)
        veclen = 0;
    else
        veclen = fpscr & FPSCR_LENGTH_MASK;

    pr_debug("VFP: vecstride=%u veclen=%u\n", vecstride,
         (veclen >> FPSCR_LENGTH_BIT) + 1);

    if (!fop->fn)
        goto invalid;

    for (vecitr = 0; vecitr <= veclen; vecitr += 1 << FPSCR_LENGTH_BIT) {
        s32 m = vfp_get_float(sm);
        u32 except;
        char type;

        type = fop->flags & OP_DD ? 'd' : 's';
        if (op == FOP_EXT)
            pr_debug("VFP: itr%d (%c%u) = op[%u] (s%u=%08x)\n",
                 vecitr >> FPSCR_LENGTH_BIT, type, dest, sn,
                 sm, m);
        else
            pr_debug("VFP: itr%d (%c%u) = (s%u) op[%u] (s%u=%08x)\n",
                 vecitr >> FPSCR_LENGTH_BIT, type, dest, sn,
                 FOP_TO_IDX(op), sm, m);

        except = fop->fn(dest, sn, m, fpscr);
        pr_debug("VFP: itr%d: exceptions=%08x\n",
             vecitr >> FPSCR_LENGTH_BIT, except);

        exceptions |= except;

        /*
         * CHECK: It appears to be undefined whether we stop when
         * we encounter an exception.  We continue.
         */
        dest = FREG_BANK(dest) + ((FREG_IDX(dest) + vecstride) & 7);
        sn = FREG_BANK(sn) + ((FREG_IDX(sn) + vecstride) & 7);
        if (FREG_BANK(sm) != 0)
            sm = FREG_BANK(sm) + ((FREG_IDX(sm) + vecstride) & 7);
    }
    return exceptions;

 invalid:
    return (u32)-1;
}