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vfpsingle.c

/*
 *  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;
}

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