libgcc/config/libbid/bid32_to_bid64.c

   1 /* Copyright (C) 2007-2017 Free Software Foundation, Inc.
   2
   3 This file is part of GCC.
   4
   5 GCC is free software; you can redistribute it and/or modify it under
   6 the terms of the GNU General Public License as published by the Free
   7 Software Foundation; either version 3, or (at your option) any later
   8 version.
   9
  10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  11 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13 for more details.
  14
  15 Under Section 7 of GPL version 3, you are granted additional
  16 permissions described in the GCC Runtime Library Exception, version
  17 3.1, as published by the Free Software Foundation.
  18
  19 You should have received a copy of the GNU General Public License and
  20 a copy of the GCC Runtime Library Exception along with this program;
  21 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22 <http://www.gnu.org/licenses/>.  */
  23
  24 #include "bid_internal.h"
  25
  26 /*
  27  * Takes a BID32 as input and converts it to a BID64 and returns it.
  28  */
  29 TYPE0_FUNCTION_ARGTYPE1_NORND (UINT64, bid32_to_bid64, UINT32, x)
  30
  31      UINT64 res;
  32      UINT32 sign_x;
  33      int exponent_x;
  34      UINT32 coefficient_x;
  35
  36 if (!unpack_BID32 (&sign_x, &exponent_x, &coefficient_x, x)) {
  37     // Inf, NaN, 0
  38 if (((x) & 0x78000000) == 0x78000000) {
  39   if (((x) & 0x7e000000) == 0x7e000000) {       // sNaN
  40 #ifdef SET_STATUS_FLAGS
  41     __set_status_flags (pfpsf, INVALID_EXCEPTION);
  42 #endif
  43   }
  44   res = (coefficient_x & 0x000fffff);
  45   res *= 1000000000;
  46   res |= ((((UINT64) coefficient_x) << 32) & 0xfc00000000000000ull);
  47
  48   BID_RETURN (res);
  49 }
  50 }
  51
  52 res =
  53 very_fast_get_BID64_small_mantissa (((UINT64) sign_x) << 32,
  54                                     exponent_x +
  55                                     DECIMAL_EXPONENT_BIAS -
  56                                     DECIMAL_EXPONENT_BIAS_32,
  57                                     (UINT64) coefficient_x);
  58 BID_RETURN (res);
  59 }       // convert_bid32_to_bid64
  60
  61
  62 /*
  63  * Takes a BID64 as input and converts it to a BID32 and returns it.
  64  */
  65 #if DECIMAL_CALL_BY_REFERENCE
  66
  67 void
  68 bid64_to_bid32 (UINT32 * pres,
  69                 UINT64 *
  70                 px _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
  71                 _EXC_INFO_PARAM) {
  72   UINT64 x;
  73 #else
  74
  75 UINT32
  76 bid64_to_bid32 (UINT64 x _RND_MODE_PARAM _EXC_FLAGS_PARAM
  77                 _EXC_MASKS_PARAM _EXC_INFO_PARAM) {
  78 #endif
  79   UINT128 Q;
  80   UINT64 sign_x, coefficient_x, remainder_h, carry, Stemp;
  81   UINT32 res;
  82   int_float tempx;
  83   int exponent_x, bin_expon_cx, extra_digits, rmode = 0, amount;
  84   unsigned status = 0;
  85
  86 #if DECIMAL_CALL_BY_REFERENCE
  87 #if !DECIMAL_GLOBAL_ROUNDING
  88   _IDEC_round rnd_mode = *prnd_mode;
  89 #endif
  90   x = *px;
  91 #endif
  92
  93   // unpack arguments, check for NaN or Infinity, 0
  94   if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
  95     if (((x) & 0x7800000000000000ull) == 0x7800000000000000ull) {
  96       res = (coefficient_x & 0x0003ffffffffffffull);
  97       res /= 1000000000ull;
  98       res |= ((coefficient_x >> 32) & 0xfc000000);
  99 #ifdef SET_STATUS_FLAGS
 100       if ((x & SNAN_MASK64) == SNAN_MASK64)     // sNaN
 101         __set_status_flags (pfpsf, INVALID_EXCEPTION);
 102 #endif
 103       BID_RETURN (res);
 104     }
 105     exponent_x =
 106       exponent_x - DECIMAL_EXPONENT_BIAS + DECIMAL_EXPONENT_BIAS_32;
 107     if (exponent_x < 0)
 108       exponent_x = 0;
 109     if (exponent_x > DECIMAL_MAX_EXPON_32)
 110       exponent_x = DECIMAL_MAX_EXPON_32;
 111     res = (sign_x >> 32) | (exponent_x << 23);
 112     BID_RETURN (res);
 113   }
 114
 115   exponent_x =
 116     exponent_x - DECIMAL_EXPONENT_BIAS + DECIMAL_EXPONENT_BIAS_32;
 117
 118   // check number of digits
 119   if (coefficient_x >= 10000000) {
 120     tempx.d = (float) coefficient_x;
 121     bin_expon_cx = ((tempx.i >> 23) & 0xff) - 0x7f;
 122     extra_digits = estimate_decimal_digits[bin_expon_cx] - 7;
 123     // add test for range
 124     if (coefficient_x >= power10_index_binexp[bin_expon_cx])
 125       extra_digits++;
 126
 127 #ifndef IEEE_ROUND_NEAREST_TIES_AWAY
 128 #ifndef IEEE_ROUND_NEAREST
 129     rmode = rnd_mode;
 130     if (sign_x && (unsigned) (rmode - 1) < 2)
 131       rmode = 3 - rmode;
 132 #else
 133     rmode = 0;
 134 #endif
 135 #else
 136     rmode = 0;
 137 #endif
 138
 139     exponent_x += extra_digits;
 140     if ((exponent_x < 0) && (exponent_x + MAX_FORMAT_DIGITS_32 >= 0)) {
 141       status = UNDERFLOW_EXCEPTION;
 142       if (exponent_x == -1)
 143         if (coefficient_x + round_const_table[rmode][extra_digits] >=
 144             power10_table_128[extra_digits + 7].w[0])
 145           status = 0;
 146       extra_digits -= exponent_x;
 147       exponent_x = 0;
 148     }
 149     coefficient_x += round_const_table[rmode][extra_digits];
 150     __mul_64x64_to_128 (Q, coefficient_x,
 151                         reciprocals10_64[extra_digits]);
 152
 153     // now get P/10^extra_digits: shift Q_high right by M[extra_digits]-128
 154     amount = short_recip_scale[extra_digits];
 155
 156     coefficient_x = Q.w[1] >> amount;
 157
 158 #ifndef IEEE_ROUND_NEAREST_TIES_AWAY
 159 #ifndef IEEE_ROUND_NEAREST
 160     if (rmode == 0)     //ROUNDING_TO_NEAREST
 161 #endif
 162       if (coefficient_x & 1) {
 163         // check whether fractional part of initial_P/10^extra_digits
 164         // is exactly .5
 165
 166         // get remainder
 167         remainder_h = Q.w[1] << (64 - amount);
 168
 169         if (!remainder_h && (Q.w[0] < reciprocals10_64[extra_digits]))
 170           coefficient_x--;
 171       }
 172 #endif
 173
 174 #ifdef SET_STATUS_FLAGS
 175
 176     {
 177       status |= INEXACT_EXCEPTION;
 178       // get remainder
 179       remainder_h = Q.w[1] << (64 - amount);
 180
 181       switch (rmode) {
 182       case ROUNDING_TO_NEAREST:
 183       case ROUNDING_TIES_AWAY:
 184         // test whether fractional part is 0
 185         if (remainder_h == 0x8000000000000000ull
 186             && (Q.w[0] < reciprocals10_64[extra_digits]))
 187           status = EXACT_STATUS;
 188         break;
 189       case ROUNDING_DOWN:
 190       case ROUNDING_TO_ZERO:
 191         if (!remainder_h && (Q.w[0] < reciprocals10_64[extra_digits]))
 192           status = EXACT_STATUS;
 193         break;
 194       default:
 195         // round up
 196         __add_carry_out (Stemp, carry, Q.w[0],
 197                          reciprocals10_64[extra_digits]);
 198         if ((remainder_h >> (64 - amount)) + carry >=
 199             (((UINT64) 1) << amount))
 200           status = EXACT_STATUS;
 201       }
 202
 203       if (status != EXACT_STATUS)
 204         __set_status_flags (pfpsf, status);
 205     }
 206
 207 #endif
 208
 209   }
 210
 211   res =
 212     get_BID32 ((UINT32) (sign_x >> 32),
 213                exponent_x, coefficient_x, rnd_mode, pfpsf);
 214   BID_RETURN (res);
 215
 216 }