gcc/libgcc/config/libbid/bid32_to_bid64.c

/* Copyright (C) 2007  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 2, or (at your option) any later
version.

In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file.  (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)

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.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

#include "bid_internal.h"

/*
 * Takes a BID32 as input and converts it to a BID64 and returns it.
 */
TYPE0_FUNCTION_ARGTYPE1_NORND(UINT64, __bid32_to_bid64, UINT32, x)

  UINT64 res;
  UINT32 sign_x;
  int exponent_x = 0;
  UINT32 coefficient_x = 0;

  if (!unpack_BID32 (&sign_x, &exponent_x, &coefficient_x, x)) {
    // Inf, NaN, 0
    if (((x) & 0x78000000) == 0x78000000) {
      res = ((UINT64) (x)) << 32;
      BID_RETURN (res);
    }
  }

  res =
    very_fast_get_BID64_small_mantissa (((UINT64) sign_x) << 32,
					exponent_x +
					DECIMAL_EXPONENT_BIAS -
					DECIMAL_EXPONENT_BIAS_32,
					(UINT64) coefficient_x);
  BID_RETURN (res);
} // convert_bid32_to_bid64


/*
 * Takes a BID64 as input and converts it to a BID32 and returns it.
 */
#if DECIMAL_CALL_BY_REFERENCE

void
__bid64_to_bid32 (UINT32 * pres,
		UINT64 *
		px _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
		_EXC_INFO_PARAM) {
  UINT64 x;
#else

UINT32
__bid64_to_bid32 (UINT64 x _RND_MODE_PARAM _EXC_FLAGS_PARAM
		_EXC_MASKS_PARAM _EXC_INFO_PARAM) {
#endif
  UINT128 Q;
  UINT64 sign_x, coefficient_x, remainder_h, carry, Stemp;
  UINT32 res;
  int_float tempx;
  int exponent_x, bin_expon_cx, extra_digits, rmode, amount;
  unsigned status=0;

#if DECIMAL_CALL_BY_REFERENCE
#if !DECIMAL_GLOBAL_ROUNDING
  _IDEC_round rnd_mode = *prnd_mode;
#endif
  x = *px;
#endif

  // unpack arguments, check for NaN or Infinity, 0
  if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
    if (((x) & 0x7800000000000000ull) == 0x7800000000000000ull) {
      res = ((UINT32) ((x) >> 32)) & 0xfc000000;
      BID_RETURN (res);
    }
    exponent_x =
      exponent_x - DECIMAL_EXPONENT_BIAS + DECIMAL_EXPONENT_BIAS_32;
    if (exponent_x < 0)
      exponent_x = 0;
    if (exponent_x > DECIMAL_MAX_EXPON_32)
      exponent_x = DECIMAL_MAX_EXPON_32;
    res = (sign_x >> 32) | (exponent_x << 23);
    BID_RETURN (res);
  }

	exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS + DECIMAL_EXPONENT_BIAS_32;

  // check number of digits
  if (coefficient_x >= 10000000) {
    tempx.d = (float) coefficient_x;
    bin_expon_cx = ((tempx.i >> 23) & 0xff) - 0x7f;
    extra_digits = __bid_estimate_decimal_digits[bin_expon_cx] - 7;
    // add test for range
    if (coefficient_x >= __bid_power10_index_binexp[bin_expon_cx])
      extra_digits++;

#ifndef IEEE_ROUND_NEAREST_TIES_AWAY
#ifndef IEEE_ROUND_NEAREST
    rmode = rnd_mode;
    if (sign_x && (unsigned) (rmode - 1) < 2)
      rmode = 3 - rmode;
#else
    rmode = 0;
#endif
#else
    rmode = 0;
#endif

    coefficient_x += __bid_round_const_table[rmode][extra_digits];
    exponent_x += extra_digits;
	if((exponent_x<0) && (exponent_x + MAX_FORMAT_DIGITS_32 >= 0)) {
		extra_digits -= exponent_x;
		exponent_x = 0;
		status = UNDERFLOW_EXCEPTION;
	}
    __mul_64x64_to_128 (Q, coefficient_x,
			__bid_reciprocals10_64[extra_digits]);

    // now get P/10^extra_digits: shift Q_high right by M[extra_digits]-128
    amount = __bid_short_recip_scale[extra_digits];

    coefficient_x = Q.w[1] >> amount;

#ifndef IEEE_ROUND_NEAREST_TIES_AWAY
#ifndef IEEE_ROUND_NEAREST
    if (rmode == 0)	//ROUNDING_TO_NEAREST
#endif
      if (coefficient_x & 1) {
	// check whether fractional part of initial_P/10^extra_digits 
        // is exactly .5

	// get remainder
	remainder_h = Q.w[1] << (64 - amount);

	if (!remainder_h && (Q.w[0] < __bid_reciprocals10_64[extra_digits]))
	  coefficient_x--;
      }
#endif

#ifdef SET_STATUS_FLAGS

    {
      status |= INEXACT_EXCEPTION;
      // get remainder
      remainder_h = Q.w[1] << (64 - amount);

      switch (rmode) {
      case ROUNDING_TO_NEAREST:
      case ROUNDING_TIES_AWAY:
	// test whether fractional part is 0
	if (remainder_h == 0x8000000000000000ull
	    && (Q.w[0] < __bid_reciprocals10_64[extra_digits]))
	  status = EXACT_STATUS;
	break;
      case ROUNDING_DOWN:
      case ROUNDING_TO_ZERO:
	if (!remainder_h && (Q.w[0] < __bid_reciprocals10_64[extra_digits]))
	  status = EXACT_STATUS;
	break;
      default:
	// round up
	__add_carry_out (Stemp, carry, Q.w[0],
			 __bid_reciprocals10_64[extra_digits]);
	if ((remainder_h >> (64 - amount)) + carry >=
	    (((UINT64) 1) << amount))
	  status = EXACT_STATUS;
      }

      if (status != EXACT_STATUS)
	__set_status_flags (pfpsf, status);
    }

#endif

  }

  res =
    get_BID32 ((UINT32) (sign_x >> 32),
	       exponent_x,
	       coefficient_x, rnd_mode,
	       pfpsf);
  BID_RETURN (res);

}