libgcc/config/libbid/bid128_rem.c

   1 /* Copyright (C) 2007-2013 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 #define BID_128RES
  25 #include "bid_div_macros.h"
  26
  27
  28 BID128_FUNCTION_ARG2_NORND_CUSTOMRESTYPE (UINT128, bid128_rem, x, y)
  29
  30      UINT256 P256;
  31      UINT128 CX, CY, CX2, CQ, CR, T, CXS, P128, res;
  32      UINT64 sign_x, sign_y, valid_y;
  33      SINT64 D;
  34      int_float f64, fx;
  35      int exponent_x, exponent_y, diff_expon, bin_expon_cx, scale,
  36        scale0;
  37
  38   // unpack arguments, check for NaN or Infinity
  39
  40 valid_y = unpack_BID128_value (&sign_y, &exponent_y, &CY, y);
  41
  42 if (!unpack_BID128_value (&sign_x, &exponent_x, &CX, x)) {
  43 #ifdef SET_STATUS_FLAGS
  44 if ((y.w[1] & SNAN_MASK64) == SNAN_MASK64)      // y is sNaN
  45   __set_status_flags (pfpsf, INVALID_EXCEPTION);
  46 #endif
  47     // test if x is NaN
  48 if ((x.w[1] & 0x7c00000000000000ull) == 0x7c00000000000000ull) {
  49 #ifdef SET_STATUS_FLAGS
  50   if ((x.w[1] & SNAN_MASK64) == SNAN_MASK64)    // y is sNaN
  51     __set_status_flags (pfpsf, INVALID_EXCEPTION);
  52 #endif
  53   res.w[1] = CX.w[1] & QUIET_MASK64;
  54   res.w[0] = CX.w[0];
  55   BID_RETURN (res);
  56 }
  57     // x is Infinity?
  58 if ((x.w[1] & 0x7800000000000000ull) == 0x7800000000000000ull) {
  59   // check if y is Inf.
  60   if (((y.w[1] & 0x7c00000000000000ull) != 0x7c00000000000000ull))
  61     // return NaN
  62   {
  63 #ifdef SET_STATUS_FLAGS
  64     // set status flags
  65     __set_status_flags (pfpsf, INVALID_EXCEPTION);
  66 #endif
  67     res.w[1] = 0x7c00000000000000ull;
  68     res.w[0] = 0;
  69     BID_RETURN (res);
  70   }
  71
  72 }
  73     // x is 0
  74 if ((!CY.w[1]) && (!CY.w[0])) {
  75 #ifdef SET_STATUS_FLAGS
  76   // set status flags
  77   __set_status_flags (pfpsf, INVALID_EXCEPTION);
  78 #endif
  79   // x=y=0, return NaN
  80   res.w[1] = 0x7c00000000000000ull;
  81   res.w[0] = 0;
  82   BID_RETURN (res);
  83 }
  84 if (valid_y || ((y.w[1] & NAN_MASK64) == INFINITY_MASK64)) {
  85   // return 0
  86   if ((exponent_x > exponent_y)
  87       && ((y.w[1] & NAN_MASK64) != INFINITY_MASK64))
  88     exponent_x = exponent_y;
  89
  90   res.w[1] = sign_x | (((UINT64) exponent_x) << 49);
  91   res.w[0] = 0;
  92   BID_RETURN (res);
  93 }
  94 }
  95 if (!valid_y) {
  96   // y is Inf. or NaN
  97
  98   // test if y is NaN
  99   if ((y.w[1] & 0x7c00000000000000ull) == 0x7c00000000000000ull) {
 100 #ifdef SET_STATUS_FLAGS
 101     if ((y.w[1] & SNAN_MASK64) == SNAN_MASK64)  // y is sNaN
 102       __set_status_flags (pfpsf, INVALID_EXCEPTION);
 103 #endif
 104     res.w[1] = CY.w[1] & QUIET_MASK64;
 105     res.w[0] = CY.w[0];
 106     BID_RETURN (res);
 107   }
 108   // y is Infinity?
 109   if ((y.w[1] & 0x7800000000000000ull) == 0x7800000000000000ull) {
 110     // return x
 111     res.w[1] = x.w[1];
 112     res.w[0] = x.w[0];
 113     BID_RETURN (res);
 114   }
 115   // y is 0
 116 #ifdef SET_STATUS_FLAGS
 117   // set status flags
 118   __set_status_flags (pfpsf, INVALID_EXCEPTION);
 119 #endif
 120   res.w[1] = 0x7c00000000000000ull;
 121   res.w[0] = 0;
 122   BID_RETURN (res);
 123 }
 124
 125 diff_expon = exponent_x - exponent_y;
 126
 127 if (diff_expon <= 0) {
 128   diff_expon = -diff_expon;
 129
 130   if (diff_expon > 34) {
 131     // |x|<|y| in this case
 132     res = x;
 133     BID_RETURN (res);
 134   }
 135   // set exponent of y to exponent_x, scale coefficient_y
 136   T = power10_table_128[diff_expon];
 137   __mul_128x128_to_256 (P256, CY, T);
 138
 139   if (P256.w[2] || P256.w[3]) {
 140     // |x|<|y| in this case
 141     res = x;
 142     BID_RETURN (res);
 143   }
 144
 145   CX2.w[1] = (CX.w[1] << 1) | (CX.w[0] >> 63);
 146   CX2.w[0] = CX.w[0] << 1;
 147   if (__unsigned_compare_ge_128 (P256, CX2)) {
 148     // |x|<|y| in this case
 149     res = x;
 150     BID_RETURN (res);
 151   }
 152
 153   P128.w[0] = P256.w[0];
 154   P128.w[1] = P256.w[1];
 155   __div_128_by_128 (&CQ, &CR, CX, P128);
 156
 157   CX2.w[1] = (CR.w[1] << 1) | (CR.w[0] >> 63);
 158   CX2.w[0] = CR.w[0] << 1;
 159   if ((__unsigned_compare_gt_128 (CX2, P256))
 160       || (CX2.w[1] == P256.w[1] && CX2.w[0] == P256.w[0]
 161           && (CQ.w[0] & 1))) {
 162     __sub_128_128 (CR, P256, CR);
 163     sign_x ^= 0x8000000000000000ull;
 164   }
 165
 166   get_BID128_very_fast (&res, sign_x, exponent_x, CR);
 167   BID_RETURN (res);
 168 }
 169   // 2^64
 170 f64.i = 0x5f800000;
 171
 172 scale0 = 38;
 173 if (!CY.w[1])
 174   scale0 = 34;
 175
 176 while (diff_expon > 0) {
 177   // get number of digits in CX and scale=38-digits
 178   // fx ~ CX
 179   fx.d = (float) CX.w[1] * f64.d + (float) CX.w[0];
 180   bin_expon_cx = ((fx.i >> 23) & 0xff) - 0x7f;
 181   scale = scale0 - estimate_decimal_digits[bin_expon_cx];
 182   // scale = 38-estimate_decimal_digits[bin_expon_cx];
 183   D = CX.w[1] - power10_index_binexp_128[bin_expon_cx].w[1];
 184   if (D > 0
 185       || (!D && CX.w[0] >= power10_index_binexp_128[bin_expon_cx].w[0]))
 186     scale--;
 187
 188   if (diff_expon >= scale)
 189     diff_expon -= scale;
 190   else {
 191     scale = diff_expon;
 192     diff_expon = 0;
 193   }
 194
 195   T = power10_table_128[scale];
 196   __mul_128x128_low (CXS, CX, T);
 197
 198   __div_128_by_128 (&CQ, &CX, CXS, CY);
 199
 200   // check for remainder == 0
 201   if (!CX.w[1] && !CX.w[0]) {
 202     get_BID128_very_fast (&res, sign_x, exponent_y, CX);
 203     BID_RETURN (res);
 204   }
 205 }
 206
 207 CX2.w[1] = (CX.w[1] << 1) | (CX.w[0] >> 63);
 208 CX2.w[0] = CX.w[0] << 1;
 209 if ((__unsigned_compare_gt_128 (CX2, CY))
 210     || (CX2.w[1] == CY.w[1] && CX2.w[0] == CY.w[0] && (CQ.w[0] & 1))) {
 211   __sub_128_128 (CX, CY, CX);
 212   sign_x ^= 0x8000000000000000ull;
 213 }
 214
 215 get_BID128_very_fast (&res, sign_x, exponent_y, CX);
 216 BID_RETURN (res);
 217 }