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/* Copyright (C) 2007, 2009  Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 3, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

Under Section 7 of GPL version 3, you are granted additional

permissions described in the GCC Runtime Library Exception, version

3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and

a copy of the GCC Runtime Library Exception along with this program;

see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

<http://www.gnu.org/licenses/>.  */

#include "bid_internal.h"

/*****************************************************************************

 *  BID64_to_int64_rnint

 ****************************************************************************/

#if DECIMAL_CALL_BY_REFERENCE

void

bid64_to_int64_rnint (SINT64 * pres, UINT64 * px

                      _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

                      _EXC_INFO_PARAM) {

  UINT64 x = *px;

#else

SINT64

bid64_to_int64_rnint (UINT64 x

                      _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

                      _EXC_INFO_PARAM) {

#endif

  SINT64 res;

  UINT64 x_sign;

  UINT64 x_exp;

  int exp;                      // unbiased exponent

  // Note: C1 represents x_significand (UINT64)

  BID_UI64DOUBLE tmp1;

  unsigned int x_nr_bits;

  int q, ind, shift;

  UINT64 C1;

  UINT128 C;

  UINT64 Cstar;                 // C* represents up to 16 decimal digits ~ 54 bits

  UINT128 fstar;

  UINT128 P128;

  // check for NaN or Infinity

  if ((x & MASK_NAN) == MASK_NAN || (x & MASK_INF) == MASK_INF) {

    // set invalid flag

    *pfpsf |= INVALID_EXCEPTION;

    // return Integer Indefinite

    res = 0x8000000000000000ull;

    BID_RETURN (res);

  }

  // unpack x

  x_sign = x & MASK_SIGN;       // 0 for positive, MASK_SIGN for negative

  // if steering bits are 11 (condition will be 0), then exponent is G[0:w+1] =>

  if ((x & MASK_STEERING_BITS) == MASK_STEERING_BITS) {

    x_exp = (x & MASK_BINARY_EXPONENT2) >> 51;  // biased

    C1 = (x & MASK_BINARY_SIG2) | MASK_BINARY_OR2;

    if (C1 > 9999999999999999ull) {     // non-canonical

      x_exp = 0;

      C1 = 0;

    }

  } else {

    x_exp = (x & MASK_BINARY_EXPONENT1) >> 53;  // biased

    C1 = x & MASK_BINARY_SIG1;

  }

  // check for zeros (possibly from non-canonical values)

  if (C1 == 0x0ull) {

    // x is 0

    res = 0x00000000;

    BID_RETURN (res);

  }

  // x is not special and is not zero

  // q = nr. of decimal digits in x (1 <= q <= 54)

  //  determine first the nr. of bits in x

  if (C1 >= 0x0020000000000000ull) {    // x >= 2^53

    // split the 64-bit value in two 32-bit halves to avoid rounding errors

    if (C1 >= 0x0000000100000000ull) {  // x >= 2^32

      tmp1.d = (double) (C1 >> 32);     // exact conversion

      x_nr_bits =

        33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

    } else {    // x < 2^32

      tmp1.d = (double) C1;     // exact conversion

      x_nr_bits =

        1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

    }

  } else {      // if x < 2^53

    tmp1.d = (double) C1;       // exact conversion

    x_nr_bits =

      1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

  }

  q = nr_digits[x_nr_bits - 1].digits;

  if (q == 0) {

    q = nr_digits[x_nr_bits - 1].digits1;

    if (C1 >= nr_digits[x_nr_bits - 1].threshold_lo)

      q++;

  }

  exp = x_exp - 398;    // unbiased exponent

  if ((q + exp) > 19) { // x >= 10^19 ~= 2^63.11... (cannot fit in SINT64)

    // set invalid flag

    *pfpsf |= INVALID_EXCEPTION;

    // return Integer Indefinite

    res = 0x8000000000000000ull;

    BID_RETURN (res);

  } else if ((q + exp) == 19) { // x = c(0)c(1)...c(18).c(19)...c(q-1)

    // in this case 2^63.11... ~= 10^19 <= x < 10^20 ~= 2^66.43...

    // so x rounded to an integer may or may not fit in a signed 64-bit int

    // the cases that do not fit are identified here; the ones that fit

    // fall through and will be handled with other cases further,

    // under '1 <= q + exp <= 19'

    if (x_sign) {       // if n < 0 and q + exp = 19

      // if n < -2^63 - 1/2 then n is too large

      // too large if c(0)c(1)...c(18).c(19)...c(q-1) > 2^63+1/2

      // <=> 0.c(0)c(1)...c(q-1) * 10^20 > 5*(2^64+1), 1<=q<=16

      // <=> 0.c(0)c(1)...c(q-1) * 10^20 > 0x50000000000000005, 1<=q<=16

      // <=> C * 10^(20-q) > 0x50000000000000005, 1<=q<=16

      // 1 <= q <= 16 => 4 <= 20-q <= 19 => 10^(20-q) is 64-bit, and so is C1

      __mul_64x64_to_128MACH (C, C1, ten2k64[20 - q]);

      // Note: C1 * 10^(11-q) has 19 or 20 digits; 0x50000000000000005, has 20

      if (C.w[1] > 0x05ull || (C.w[1] == 0x05ull && C.w[0] > 0x05ull)) {

        // set invalid flag

        *pfpsf |= INVALID_EXCEPTION;

        // return Integer Indefinite

        res = 0x8000000000000000ull;

        BID_RETURN (res);

      }

      // else cases that can be rounded to a 64-bit int fall through

      // to '1 <= q + exp <= 19'

    } else {    // if n > 0 and q + exp = 19

      // if n >= 2^63 - 1/2 then n is too large

      // too large if c(0)c(1)...c(18).c(19)...c(q-1) >= 2^63-1/2

      // <=> if 0.c(0)c(1)...c(q-1) * 10^20 >= 5*(2^64-1), 1<=q<=16

      // <=> if 0.c(0)c(1)...c(q-1) * 10^20 >= 0x4fffffffffffffffb, 1<=q<=16

      // <=> if C * 10^(20-q) >= 0x4fffffffffffffffb, 1<=q<=16

      C.w[1] = 0x0000000000000004ull;

      C.w[0] = 0xfffffffffffffffbull;

      // 1 <= q <= 16 => 4 <= 20-q <= 19 => 10^(20-q) is 64-bit, and so is C1

      __mul_64x64_to_128MACH (C, C1, ten2k64[20 - q]);

      if (C.w[1] > 0x04ull ||

          (C.w[1] == 0x04ull && C.w[0] >= 0xfffffffffffffffbull)) {

        // set invalid flag

        *pfpsf |= INVALID_EXCEPTION;

        // return Integer Indefinite

        res = 0x8000000000000000ull;

        BID_RETURN (res);

      }

      // else cases that can be rounded to a 64-bit int fall through

      // to '1 <= q + exp <= 19'

    }   // end else if n > 0 and q + exp = 19

  }     // end else if ((q + exp) == 19)

  // n is not too large to be converted to int64: -2^63-1/2 <= n < 2^63-1/2

  // Note: some of the cases tested for above fall through to this point

  if ((q + exp) < 0) {   // n = +/-0.0...c(0)c(1)...c(q-1)

    // return 0

    res = 0x0000000000000000ull;

    BID_RETURN (res);

  } else if ((q + exp) == 0) {   // n = +/-0.c(0)c(1)...c(q-1)

    // if 0.c(0)c(1)...c(q-1) <= 0.5 <=> c(0)c(1)...c(q-1) <= 5 * 10^(q-1)

    //   res = 0

    // else

    //   res = +/-1

    ind = q - 1;        // 0 <= ind <= 15

    if (C1 <= midpoint64[ind]) {

      res = 0x0000000000000000ull;      // return 0

    } else if (x_sign) {        // n < 0

      res = 0xffffffffffffffffull;      // return -1

    } else {    // n > 0

      res = 0x0000000000000001ull;      // return +1

    }

  } else {      // if (1 <= q + exp <= 19, 1 <= q <= 16, -15 <= exp <= 18)

    // -2^63-1/2 <= x <= -1 or 1 <= x < 2^63-1/2 so x can be rounded

    // to nearest to a 64-bit signed integer

    if (exp < 0) {       // 2 <= q <= 16, -15 <= exp <= -1, 1 <= q + exp <= 19

      ind = -exp;       // 1 <= ind <= 15; ind is a synonym for 'x'

      // chop off ind digits from the lower part of C1

      // C1 = C1 + 1/2 * 10^ind where the result C1 fits in 64 bits

      C1 = C1 + midpoint64[ind - 1];

      // calculate C* and f*

      // C* is actually floor(C*) in this case

      // C* and f* need shifting and masking, as shown by

      // shiftright128[] and maskhigh128[]

      // 1 <= x <= 15 

      // kx = 10^(-x) = ten2mk64[ind - 1]

      // C* = (C1 + 1/2 * 10^x) * 10^(-x)

      // the approximation of 10^(-x) was rounded up to 54 bits

      __mul_64x64_to_128MACH (P128, C1, ten2mk64[ind - 1]);

      Cstar = P128.w[1];

      fstar.w[1] = P128.w[1] & maskhigh128[ind - 1];

      fstar.w[0] = P128.w[0];

      // the top Ex bits of 10^(-x) are T* = ten2mk128trunc[ind].w[0], e.g.

      // if x=1, T*=ten2mk128trunc[0].w[0]=0x1999999999999999

      // if (0 < f* < 10^(-x)) then the result is a midpoint

      //   if floor(C*) is even then C* = floor(C*) - logical right

      //       shift; C* has p decimal digits, correct by Prop. 1)

      //   else if floor(C*) is odd C* = floor(C*)-1 (logical right

      //       shift; C* has p decimal digits, correct by Pr. 1)

      // else

      //   C* = floor(C*) (logical right shift; C has p decimal digits,

      //       correct by Property 1)

      // n = C* * 10^(e+x)

      // shift right C* by Ex-64 = shiftright128[ind]

      shift = shiftright128[ind - 1];   // 0 <= shift <= 39

      Cstar = Cstar >> shift;

      // if the result was a midpoint it was rounded away from zero, so

      // it will need a correction

      // check for midpoints

      if ((fstar.w[1] == 0) && fstar.w[0] &&

          (fstar.w[0] <= ten2mk128trunc[ind - 1].w[1])) {

        // ten2mk128trunc[ind -1].w[1] is identical to 

        // ten2mk128[ind -1].w[1]

        // the result is a midpoint; round to nearest

        if (Cstar & 0x01) {     // Cstar is odd; MP in [EVEN, ODD]

          // if floor(C*) is odd C = floor(C*) - 1; the result >= 1

          Cstar--;      // Cstar is now even

        }       // else MP in [ODD, EVEN]

      }

      if (x_sign)

        res = -Cstar;

      else

        res = Cstar;

    } else if (exp == 0) {

      // 1 <= q <= 16

      // res = +/-C (exact)

      if (x_sign)

        res = -C1;

      else

        res = C1;

    } else {    // if (exp > 0) => 1 <= exp <= 18, 1 <= q <= 16, 2 <= q + exp <= 20

      // (the upper limit of 20 on q + exp is due to the fact that 

      // +/-C * 10^exp is guaranteed to fit in 64 bits) 

      // res = +/-C * 10^exp (exact)

      if (x_sign)

        res = -C1 * ten2k64[exp];

      else

        res = C1 * ten2k64[exp];

    }

  }

  BID_RETURN (res);

}

/*****************************************************************************

 *  BID64_to_int64_xrnint

 ****************************************************************************/

#if DECIMAL_CALL_BY_REFERENCE

void

bid64_to_int64_xrnint (SINT64 * pres, UINT64 * px

                       _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

                       _EXC_INFO_PARAM) {

  UINT64 x = *px;

#else

SINT64

bid64_to_int64_xrnint (UINT64 x

                       _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

                       _EXC_INFO_PARAM) {

#endif

  SINT64 res;

  UINT64 x_sign;

  UINT64 x_exp;

  int exp;                      // unbiased exponent

  // Note: C1 represents x_significand (UINT64)

  UINT64 tmp64;

  BID_UI64DOUBLE tmp1;

  unsigned int x_nr_bits;

  int q, ind, shift;

  UINT64 C1;

  UINT128 C;

  UINT64 Cstar;                 // C* represents up to 16 decimal digits ~ 54 bits

  UINT128 fstar;

  UINT128 P128;

  // check for NaN or Infinity

  if ((x & MASK_NAN) == MASK_NAN || (x & MASK_INF) == MASK_INF) {

    // set invalid flag

    *pfpsf |= INVALID_EXCEPTION;

    // return Integer Indefinite

    res = 0x8000000000000000ull;

    BID_RETURN (res);

  }

  // unpack x

  x_sign = x & MASK_SIGN;       // 0 for positive, MASK_SIGN for negative

  // if steering bits are 11 (condition will be 0), then exponent is G[0:w+1] =>

  if ((x & MASK_STEERING_BITS) == MASK_STEERING_BITS) {

    x_exp = (x & MASK_BINARY_EXPONENT2) >> 51;  // biased

    C1 = (x & MASK_BINARY_SIG2) | MASK_BINARY_OR2;

    if (C1 > 9999999999999999ull) {     // non-canonical

      x_exp = 0;

      C1 = 0;

    }

  } else {

    x_exp = (x & MASK_BINARY_EXPONENT1) >> 53;  // biased

    C1 = x & MASK_BINARY_SIG1;

  }

  // check for zeros (possibly from non-canonical values)

  if (C1 == 0x0ull) {

    // x is 0

    res = 0x00000000;

    BID_RETURN (res);

  }

  // x is not special and is not zero

  // q = nr. of decimal digits in x (1 <= q <= 54)

  //  determine first the nr. of bits in x

  if (C1 >= 0x0020000000000000ull) {    // x >= 2^53

    // split the 64-bit value in two 32-bit halves to avoid rounding errors

    if (C1 >= 0x0000000100000000ull) {  // x >= 2^32

      tmp1.d = (double) (C1 >> 32);     // exact conversion

      x_nr_bits =

        33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

    } else {    // x < 2^32

      tmp1.d = (double) C1;     // exact conversion

      x_nr_bits =

        1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

    }

  } else {      // if x < 2^53

    tmp1.d = (double) C1;       // exact conversion

    x_nr_bits =

      1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

  }

  q = nr_digits[x_nr_bits - 1].digits;

  if (q == 0) {

    q = nr_digits[x_nr_bits - 1].digits1;

    if (C1 >= nr_digits[x_nr_bits - 1].threshold_lo)

      q++;

  }

  exp = x_exp - 398;    // unbiased exponent

  if ((q + exp) > 19) { // x >= 10^19 ~= 2^63.11... (cannot fit in SINT64)

    // set invalid flag

    *pfpsf |= INVALID_EXCEPTION;

    // return Integer Indefinite

    res = 0x8000000000000000ull;

    BID_RETURN (res);

  } else if ((q + exp) == 19) { // x = c(0)c(1)...c(18).c(19)...c(q-1)

    // in this case 2^63.11... ~= 10^19 <= x < 10^20 ~= 2^66.43...

    // so x rounded to an integer may or may not fit in a signed 64-bit int

    // the cases that do not fit are identified here; the ones that fit

    // fall through and will be handled with other cases further,

    // under '1 <= q + exp <= 19'

    if (x_sign) {       // if n < 0 and q + exp = 19

      // if n < -2^63 - 1/2 then n is too large

      // too large if c(0)c(1)...c(18).c(19)...c(q-1) > 2^63+1/2

      // <=> 0.c(0)c(1)...c(q-1) * 10^20 > 5*(2^64+1), 1<=q<=16

      // <=> 0.c(0)c(1)...c(q-1) * 10^20 > 0x50000000000000005, 1<=q<=16

      // <=> C * 10^(20-q) > 0x50000000000000005, 1<=q<=16

      // 1 <= q <= 16 => 4 <= 20-q <= 19 => 10^(20-q) is 64-bit, and so is C1

      __mul_64x64_to_128MACH (C, C1, ten2k64[20 - q]);

      // Note: C1 * 10^(11-q) has 19 or 20 digits; 0x50000000000000005, has 20

      if (C.w[1] > 0x05ull || (C.w[1] == 0x05ull && C.w[0] > 0x05ull)) {

        // set invalid flag

        *pfpsf |= INVALID_EXCEPTION;

        // return Integer Indefinite

        res = 0x8000000000000000ull;

        BID_RETURN (res);

      }

      // else cases that can be rounded to a 64-bit int fall through

      // to '1 <= q + exp <= 19'

    } else {    // if n > 0 and q + exp = 19

      // if n >= 2^63 - 1/2 then n is too large

      // too large if c(0)c(1)...c(18).c(19)...c(q-1) >= 2^63-1/2

      // <=> if 0.c(0)c(1)...c(q-1) * 10^20 >= 5*(2^64-1), 1<=q<=16

      // <=> if 0.c(0)c(1)...c(q-1) * 10^20 >= 0x4fffffffffffffffb, 1<=q<=16

      // <=> if C * 10^(20-q) >= 0x4fffffffffffffffb, 1<=q<=16

      C.w[1] = 0x0000000000000004ull;

      C.w[0] = 0xfffffffffffffffbull;

      // 1 <= q <= 16 => 4 <= 20-q <= 19 => 10^(20-q) is 64-bit, and so is C1

      __mul_64x64_to_128MACH (C, C1, ten2k64[20 - q]);

      if (C.w[1] > 0x04ull ||

          (C.w[1] == 0x04ull && C.w[0] >= 0xfffffffffffffffbull)) {

        // set invalid flag

        *pfpsf |= INVALID_EXCEPTION;

        // return Integer Indefinite

        res = 0x8000000000000000ull;

        BID_RETURN (res);

      }

      // else cases that can be rounded to a 64-bit int fall through

      // to '1 <= q + exp <= 19'

    }   // end else if n > 0 and q + exp = 19

  }     // end else if ((q + exp) == 19)

  // n is not too large to be converted to int64: -2^63-1/2 <= n < 2^63-1/2

  // Note: some of the cases tested for above fall through to this point

  if ((q + exp) < 0) {   // n = +/-0.0...c(0)c(1)...c(q-1)

    // set inexact flag

    *pfpsf |= INEXACT_EXCEPTION;

    // return 0

    res = 0x0000000000000000ull;

    BID_RETURN (res);

  } else if ((q + exp) == 0) {   // n = +/-0.c(0)c(1)...c(q-1)

    // if 0.c(0)c(1)...c(q-1) <= 0.5 <=> c(0)c(1)...c(q-1) <= 5 * 10^(q-1)

    //   res = 0

    // else

    //   res = +/-1

    ind = q - 1;        // 0 <= ind <= 15

    if (C1 <= midpoint64[ind]) {

      res = 0x0000000000000000ull;      // return 0

    } else if (x_sign) {        // n < 0

      res = 0xffffffffffffffffull;      // return -1

    } else {    // n > 0

      res = 0x0000000000000001ull;      // return +1

    }

    // set inexact flag

    *pfpsf |= INEXACT_EXCEPTION;

  } else {      // if (1 <= q + exp <= 19, 1 <= q <= 16, -15 <= exp <= 18)

    // -2^63-1/2 <= x <= -1 or 1 <= x < 2^63-1/2 so x can be rounded

    // to nearest to a 64-bit signed integer

    if (exp < 0) {       // 2 <= q <= 16, -15 <= exp <= -1, 1 <= q + exp <= 19

      ind = -exp;       // 1 <= ind <= 15; ind is a synonym for 'x'

      // chop off ind digits from the lower part of C1

      // C1 = C1 + 1/2 * 10^ind where the result C1 fits in 64 bits

      C1 = C1 + midpoint64[ind - 1];

      // calculate C* and f*

      // C* is actually floor(C*) in this case

      // C* and f* need shifting and masking, as shown by

      // shiftright128[] and maskhigh128[]

      // 1 <= x <= 15 

      // kx = 10^(-x) = ten2mk64[ind - 1]

      // C* = (C1 + 1/2 * 10^x) * 10^(-x)

      // the approximation of 10^(-x) was rounded up to 54 bits

      __mul_64x64_to_128MACH (P128, C1, ten2mk64[ind - 1]);

      Cstar = P128.w[1];

      fstar.w[1] = P128.w[1] & maskhigh128[ind - 1];

      fstar.w[0] = P128.w[0];

      // the top Ex bits of 10^(-x) are T* = ten2mk128trunc[ind].w[0], e.g.

      // if x=1, T*=ten2mk128trunc[0].w[0]=0x1999999999999999

      // if (0 < f* < 10^(-x)) then the result is a midpoint

      //   if floor(C*) is even then C* = floor(C*) - logical right

      //       shift; C* has p decimal digits, correct by Prop. 1)

      //   else if floor(C*) is odd C* = floor(C*)-1 (logical right

      //       shift; C* has p decimal digits, correct by Pr. 1)

      // else

      //   C* = floor(C*) (logical right shift; C has p decimal digits,

      //       correct by Property 1)

      // n = C* * 10^(e+x)

      // shift right C* by Ex-64 = shiftright128[ind]

      shift = shiftright128[ind - 1];   // 0 <= shift <= 39

      Cstar = Cstar >> shift;

      // determine inexactness of the rounding of C*

      // if (0 < f* - 1/2 < 10^(-x)) then

      //   the result is exact

      // else // if (f* - 1/2 > T*) then

      //   the result is inexact

      if (ind - 1 <= 2) {

        if (fstar.w[0] > 0x8000000000000000ull) {

          // f* > 1/2 and the result may be exact

          tmp64 = fstar.w[0] - 0x8000000000000000ull;    // f* - 1/2

          if ((tmp64 > ten2mk128trunc[ind - 1].w[1])) {

            // ten2mk128trunc[ind -1].w[1] is identical to 

            // ten2mk128[ind -1].w[1]

            // set the inexact flag

            *pfpsf |= INEXACT_EXCEPTION;

          }     // else the result is exact

        } else {        // the result is inexact; f2* <= 1/2

          // set the inexact flag

          *pfpsf |= INEXACT_EXCEPTION;

        }

      } else {  // if 3 <= ind - 1 <= 14

        if (fstar.w[1] > onehalf128[ind - 1] ||

            (fstar.w[1] == onehalf128[ind - 1] && fstar.w[0])) {

          // f2* > 1/2 and the result may be exact

          // Calculate f2* - 1/2

          tmp64 = fstar.w[1] - onehalf128[ind - 1];

          if (tmp64 || fstar.w[0] > ten2mk128trunc[ind - 1].w[1]) {

            // ten2mk128trunc[ind -1].w[1] is identical to 

            // ten2mk128[ind -1].w[1]

            // set the inexact flag

            *pfpsf |= INEXACT_EXCEPTION;

          }     // else the result is exact

        } else {        // the result is inexact; f2* <= 1/2

          // set the inexact flag

          *pfpsf |= INEXACT_EXCEPTION;

        }

      }

      // if the result was a midpoint it was rounded away from zero, so

      // it will need a correction

      // check for midpoints

      if ((fstar.w[1] == 0) && fstar.w[0] &&

          (fstar.w[0] <= ten2mk128trunc[ind - 1].w[1])) {

        // ten2mk128trunc[ind -1].w[1] is identical to 

        // ten2mk128[ind -1].w[1]

        // the result is a midpoint; round to nearest

        if (Cstar & 0x01) {     // Cstar is odd; MP in [EVEN, ODD]

          // if floor(C*) is odd C = floor(C*) - 1; the result >= 1

          Cstar--;      // Cstar is now even

        }       // else MP in [ODD, EVEN]

      }

      if (x_sign)

        res = -Cstar;

      else

        res = Cstar;

    } else if (exp == 0) {

      // 1 <= q <= 16

      // res = +/-C (exact)

      if (x_sign)

        res = -C1;

      else

        res = C1;

    } else {    // if (exp > 0) => 1 <= exp <= 18, 1 <= q <= 16, 2 <= q + exp <= 20

      // (the upper limit of 20 on q + exp is due to the fact that 

      // +/-C * 10^exp is guaranteed to fit in 64 bits) 

      // res = +/-C * 10^exp (exact)

      if (x_sign)

        res = -C1 * ten2k64[exp];

      else

        res = C1 * ten2k64[exp];

    }

  }

  BID_RETURN (res);

}

/*****************************************************************************

 *  BID64_to_int64_floor

 ****************************************************************************/

#if DECIMAL_CALL_BY_REFERENCE

void

bid64_to_int64_floor (SINT64 * pres, UINT64 * px

                      _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

                      _EXC_INFO_PARAM) {

  UINT64 x = *px;

#else

SINT64

bid64_to_int64_floor (UINT64 x

                      _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

                      _EXC_INFO_PARAM) {

#endif

  SINT64 res;

  UINT64 x_sign;

  UINT64 x_exp;

  int exp;                      // unbiased exponent

  // Note: C1 represents x_significand (UINT64)

  BID_UI64DOUBLE tmp1;

  unsigned int x_nr_bits;

  int q, ind, shift;

  UINT64 C1;

  UINT128 C;

  UINT64 Cstar;                 // C* represents up to 16 decimal digits ~ 54 bits

  UINT128 fstar;

  UINT128 P128;

  // check for NaN or Infinity

  if ((x & MASK_NAN) == MASK_NAN || (x & MASK_INF) == MASK_INF) {

    // set invalid flag

    *pfpsf |= INVALID_EXCEPTION;

    // return Integer Indefinite

    res = 0x8000000000000000ull;

    BID_RETURN (res);

  }

  // unpack x

  x_sign = x & MASK_SIGN;       // 0 for positive, MASK_SIGN for negative

  // if steering bits are 11 (condition will be 0), then exponent is G[0:w+1] =>

  if ((x & MASK_STEERING_BITS) == MASK_STEERING_BITS) {

    x_exp = (x & MASK_BINARY_EXPONENT2) >> 51;  // biased

    C1 = (x & MASK_BINARY_SIG2) | MASK_BINARY_OR2;

    if (C1 > 9999999999999999ull) {     // non-canonical

      x_exp = 0;

      C1 = 0;

    }

  } else {

    x_exp = (x & MASK_BINARY_EXPONENT1) >> 53;  // biased

    C1 = x & MASK_BINARY_SIG1;

  }

  // check for zeros (possibly from non-canonical values)

  if (C1 == 0x0ull) {

    // x is 0

    res = 0x0000000000000000ull;

    BID_RETURN (res);

  }

  // x is not special and is not zero

  // q = nr. of decimal digits in x (1 <= q <= 54)

  //  determine first the nr. of bits in x

  if (C1 >= 0x0020000000000000ull) {    // x >= 2^53

    // split the 64-bit value in two 32-bit halves to avoid rounding errors

    if (C1 >= 0x0000000100000000ull) {  // x >= 2^32

      tmp1.d = (double) (C1 >> 32);     // exact conversion

      x_nr_bits =

        33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

    } else {    // x < 2^32

      tmp1.d = (double) C1;     // exact conversion

      x_nr_bits =

        1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

    }

  } else {      // if x < 2^53

    tmp1.d = (double) C1;       // exact conversion

    x_nr_bits =

      1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff);

  }

  q = nr_digits[x_nr_bits - 1].digits;

  if (q == 0) {

    q = nr_digits[x_nr_bits - 1].digits1;

    if (C1 >= nr_digits[x_nr_bits - 1].threshold_lo)

      q++;

  }

  exp = x_exp - 398;    // unbiased exponent

  if ((q + exp) > 19) { // x >= 10^19 ~= 2^63.11... (cannot fit in SINT64)

    // set invalid flag

    *pfpsf |= INVALID_EXCEPTION;

    // return Integer Indefinite

    res = 0x8000000000000000ull;

    BID_RETURN (res);

  } else if ((q + exp) == 19) { // x = c(0)c(1)...c(18).c(19)...c(q-1)

    // in this case 2^63.11... ~= 10^19 <= x < 10^20 ~= 2^66.43...

    // so x rounded to an integer may or may not fit in a signed 64-bit int

    // the cases that do not fit are identified here; the ones that fit

    // fall through and will be handled with other cases further,

    // under '1 <= q + exp <= 19'

    if (x_sign) {       // if n < 0 and q + exp = 19

      // if n < -2^63 then n is too large

      // too large if c(0)c(1)...c(18).c(19)...c(q-1) > 2^63

      // <=> 0.c(0)c(1)...c(q-1) * 10^20 >= 5*2^64, 1<=q<=16

      // <=> 0.c(0)c(1)...c(q-1) * 10^20 > 0x50000000000000000, 1<=q<=16

      // <=> C * 10^(20-q) > 0x50000000000000000, 1<=q<=16

      // 1 <= q <= 16 => 4 <= 20-q <= 19 => 10^(20-q) is 64-bit, and so is C1

      __mul_64x64_to_128MACH (C, C1, ten2k64[20 - q]);

      // Note: C1 * 10^(11-q) has 19 or 20 digits; 0x5000000000000000a, has 20

      if (C.w[1] > 0x05ull || (C.w[1] == 0x05ull && C.w[0] != 0)) {

        // set invalid flag

        *pfpsf |= INVALID_EXCEPTION;

        // return Integer Indefinite

        res = 0x8000000000000000ull;

        BID_RETURN (res);

      }

      // else cases that can be rounded to a 64-bit int fall through

      // to '1 <= q + exp <= 19'

    } else {    // if n > 0 and q + exp = 19

      // if n >= 2^63 then n is too large

      // too large if c(0)c(1)...c(18).c(19)...c(q-1) >= 2^63

      // <=> if 0.c(0)c(1)...c(q-1) * 10^20 >= 5*2^64, 1<=q<=16

      // <=> if 0.c(0)c(1)...c(q-1) * 10^20 >= 0x50000000000000000, 1<=q<=16

      // <=> if C * 10^(20-q) >= 0x50000000000000000, 1<=q<=16