libgcc/dfp-bit.c

   1 /* This is a software decimal floating point library.
   2    Copyright (C) 2005-2016 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 Under Section 7 of GPL version 3, you are granted additional
  17 permissions described in the GCC Runtime Library Exception, version
  18 3.1, as published by the Free Software Foundation.
  19
  20 You should have received a copy of the GNU General Public License and
  21 a copy of the GCC Runtime Library Exception along with this program;
  22 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 <http://www.gnu.org/licenses/>.  */
  24
  25 /* This implements IEEE 754 decimal floating point arithmetic, but
  26    does not provide a mechanism for setting the rounding mode, or for
  27    generating or handling exceptions.  Conversions between decimal
  28    floating point types and other types depend on C library functions.
  29
  30    Contributed by Ben Elliston  <bje@au.ibm.com>.  */
  31
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 /* FIXME: compile with -std=gnu99 to get these from stdlib.h */
  35 extern float strtof (const char *, char **);
  36 extern long double strtold (const char *, char **);
  37 #include <string.h>
  38 #include <limits.h>
  39
  40 #include "dfp-bit.h"
  41
  42 /* Forward declarations.  */
  43 #if WIDTH == 32 || WIDTH_TO == 32
  44 void __host_to_ieee_32 (_Decimal32 in, decimal32 *out);
  45 void __ieee_to_host_32 (decimal32 in, _Decimal32 *out);
  46 #endif
  47 #if WIDTH == 64 || WIDTH_TO == 64
  48 void __host_to_ieee_64 (_Decimal64 in, decimal64 *out);
  49 void __ieee_to_host_64 (decimal64 in, _Decimal64 *out);
  50 #endif
  51 #if WIDTH == 128 || WIDTH_TO == 128
  52 void __host_to_ieee_128 (_Decimal128 in, decimal128 *out);
  53 void __ieee_to_host_128 (decimal128 in, _Decimal128 *out);
  54 #endif
  55
  56 /* A pointer to a binary decFloat operation.  */
  57 typedef decFloat* (*dfp_binary_func)
  58      (decFloat *, const decFloat *, const decFloat *, decContext *);
  59 \f
  60 /* Binary operations.  */
  61
  62 /* Use a decFloat (decDouble or decQuad) function to perform a DFP
  63    binary operation.  */
  64 static inline decFloat
  65 dfp_binary_op (dfp_binary_func op, decFloat arg_a, decFloat arg_b)
  66 {
  67   decFloat result;
  68   decContext context;
  69
  70   decContextDefault (&context, CONTEXT_INIT);
  71   DFP_INIT_ROUNDMODE (context.round);
  72
  73   /* Perform the operation.  */
  74   op (&result, &arg_a, &arg_b, &context);
  75
  76   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
  77     {
  78       /* decNumber exception flags we care about here.  */
  79       int ieee_flags;
  80       int dec_flags = DEC_IEEE_854_Division_by_zero | DEC_IEEE_854_Inexact
  81                       | DEC_IEEE_854_Invalid_operation | DEC_IEEE_854_Overflow
  82                       | DEC_IEEE_854_Underflow;
  83       dec_flags &= context.status;
  84       ieee_flags = DFP_IEEE_FLAGS (dec_flags);
  85       if (ieee_flags != 0)
  86         DFP_HANDLE_EXCEPTIONS (ieee_flags);
  87     }
  88
  89   return result;
  90 }
  91
  92 #if WIDTH == 32
  93 /* The decNumber package doesn't provide arithmetic for decSingle (32 bits);
  94    convert to decDouble, use the operation for that, and convert back.  */
  95 static inline _Decimal32
  96 d32_binary_op (dfp_binary_func op, _Decimal32 arg_a, _Decimal32 arg_b)
  97 {
  98   union { _Decimal32 c; decSingle f; } a32, b32, res32;
  99   decDouble a, b, res;
 100   decContext context;
 101
 102   /* Widen the operands and perform the operation.  */
 103   a32.c = arg_a;
 104   b32.c = arg_b;
 105   decSingleToWider (&a32.f, &a);
 106   decSingleToWider (&b32.f, &b);
 107   res = dfp_binary_op (op, a, b);
 108
 109   /* Narrow the result, which might result in an underflow or overflow.  */
 110   decContextDefault (&context, CONTEXT_INIT);
 111   DFP_INIT_ROUNDMODE (context.round);
 112   decSingleFromWider (&res32.f, &res, &context);
 113   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 114     {
 115       /* decNumber exception flags we care about here.  */
 116       int ieee_flags;
 117       int dec_flags = DEC_IEEE_854_Inexact | DEC_IEEE_854_Overflow
 118                       | DEC_IEEE_854_Underflow;
 119       dec_flags &= context.status;
 120       ieee_flags = DFP_IEEE_FLAGS (dec_flags);
 121       if (ieee_flags != 0)
 122         DFP_HANDLE_EXCEPTIONS (ieee_flags);
 123     }
 124
 125   return res32.c;
 126 }
 127 #else
 128 /* decFloat operations are supported for decDouble (64 bits) and
 129    decQuad (128 bits).  The bit patterns for the types are the same.  */
 130 static inline DFP_C_TYPE
 131 dnn_binary_op (dfp_binary_func op, DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 132 {
 133   union { DFP_C_TYPE c; decFloat f; } a, b, result;
 134
 135   a.c = arg_a;
 136   b.c = arg_b;
 137   result.f = dfp_binary_op (op, a.f, b.f);
 138   return result.c;
 139 }
 140 #endif
 141
 142 /* Comparison operations.  */
 143
 144 /* Use a decFloat (decDouble or decQuad) function to perform a DFP
 145    comparison.  */
 146 static inline CMPtype
 147 dfp_compare_op (dfp_binary_func op, decFloat arg_a, decFloat arg_b)
 148 {
 149   decContext context;
 150   decFloat res;
 151   int result;
 152
 153   decContextDefault (&context, CONTEXT_INIT);
 154   DFP_INIT_ROUNDMODE (context.round);
 155
 156   /* Perform the comparison.  */
 157   op (&res, &arg_a, &arg_b, &context);
 158
 159   if (DEC_FLOAT_IS_SIGNED (&res))
 160     result = -1;
 161   else if (DEC_FLOAT_IS_ZERO (&res))
 162     result = 0;
 163   else if (DEC_FLOAT_IS_NAN (&res))
 164     result = -2;
 165   else
 166     result = 1;
 167
 168   return (CMPtype) result;
 169 }
 170
 171 #if WIDTH == 32
 172 /* The decNumber package doesn't provide comparisons for decSingle (32 bits);
 173    convert to decDouble, use the operation for that, and convert back.  */
 174 static inline CMPtype
 175 d32_compare_op (dfp_binary_func op, _Decimal32 arg_a, _Decimal32 arg_b)
 176 {
 177   union { _Decimal32 c; decSingle f; } a32, b32;
 178   decDouble a, b;
 179
 180   a32.c = arg_a;
 181   b32.c = arg_b;
 182   decSingleToWider (&a32.f, &a);
 183   decSingleToWider (&b32.f, &b);
 184   return dfp_compare_op (op, a, b);
 185 }
 186 #else
 187 /* decFloat comparisons are supported for decDouble (64 bits) and
 188    decQuad (128 bits).  The bit patterns for the types are the same.  */
 189 static inline CMPtype
 190 dnn_compare_op (dfp_binary_func op, DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 191 {
 192   union { DFP_C_TYPE c; decFloat f; } a, b;
 193
 194   a.c = arg_a;
 195   b.c = arg_b;
 196   return dfp_compare_op (op, a.f, b.f);
 197 }
 198 #endif
 199 \f
 200 #if defined(L_conv_sd)
 201 void
 202 __host_to_ieee_32 (_Decimal32 in, decimal32 *out)
 203 {
 204   memcpy (out, &in, 4);
 205 }
 206
 207 void
 208 __ieee_to_host_32 (decimal32 in, _Decimal32 *out)
 209 {
 210   memcpy (out, &in, 4);
 211 }
 212 #endif /* L_conv_sd */
 213
 214 #if defined(L_conv_dd)
 215 void
 216 __host_to_ieee_64 (_Decimal64 in, decimal64 *out)
 217 {
 218   memcpy (out, &in, 8);
 219 }
 220
 221 void
 222 __ieee_to_host_64 (decimal64 in, _Decimal64 *out)
 223 {
 224   memcpy (out, &in, 8);
 225 }
 226 #endif /* L_conv_dd */
 227
 228 #if defined(L_conv_td)
 229 void
 230 __host_to_ieee_128 (_Decimal128 in, decimal128 *out)
 231 {
 232   memcpy (out, &in, 16);
 233 }
 234
 235 void
 236 __ieee_to_host_128 (decimal128 in, _Decimal128 *out)
 237 {
 238   memcpy (out, &in, 16);
 239 }
 240 #endif /* L_conv_td */
 241
 242 #if defined(L_addsub_sd) || defined(L_addsub_dd) || defined(L_addsub_td)
 243 DFP_C_TYPE
 244 DFP_ADD (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 245 {
 246   return DFP_BINARY_OP (DEC_FLOAT_ADD, arg_a, arg_b);
 247 }
 248
 249 DFP_C_TYPE
 250 DFP_SUB (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 251 {
 252   return DFP_BINARY_OP (DEC_FLOAT_SUBTRACT, arg_a, arg_b);
 253 }
 254 #endif /* L_addsub */
 255
 256 #if defined(L_mul_sd) || defined(L_mul_dd) || defined(L_mul_td)
 257 DFP_C_TYPE
 258 DFP_MULTIPLY (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 259 {
 260   return DFP_BINARY_OP (DEC_FLOAT_MULTIPLY, arg_a, arg_b);
 261 }
 262 #endif /* L_mul */
 263
 264 #if defined(L_div_sd) || defined(L_div_dd) || defined(L_div_td)
 265 DFP_C_TYPE
 266 DFP_DIVIDE (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 267 {
 268   return DFP_BINARY_OP (DEC_FLOAT_DIVIDE, arg_a, arg_b);
 269 }
 270 #endif /* L_div */
 271
 272 #if defined (L_eq_sd) || defined (L_eq_dd) || defined (L_eq_td)
 273 CMPtype
 274 DFP_EQ (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 275 {
 276   CMPtype stat;
 277   stat = DFP_COMPARE_OP (DEC_FLOAT_COMPARE, arg_a, arg_b);
 278   /* For EQ return zero for true, nonzero for false.  */
 279   return stat != 0;
 280 }
 281 #endif /* L_eq */
 282
 283 #if defined (L_ne_sd) || defined (L_ne_dd) || defined (L_ne_td)
 284 CMPtype
 285 DFP_NE (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 286 {
 287   int stat;
 288   stat = DFP_COMPARE_OP (DEC_FLOAT_COMPARE, arg_a, arg_b);
 289   /* For NE return zero for true, nonzero for false.  */
 290   if (__builtin_expect (stat == -2, 0))  /* An operand is NaN.  */
 291     return 1;
 292   return stat != 0;
 293 }
 294 #endif /* L_ne */
 295
 296 #if defined (L_lt_sd) || defined (L_lt_dd) || defined (L_lt_td)
 297 CMPtype
 298 DFP_LT (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 299 {
 300   int stat;
 301   stat = DFP_COMPARE_OP (DEC_FLOAT_COMPARE, arg_a, arg_b);
 302   /* For LT return -1 (<0) for true, 1 for false.  */
 303   return (stat == -1) ? -1 : 1;
 304 }
 305 #endif /* L_lt */
 306
 307 #if defined (L_gt_sd) || defined (L_gt_dd) || defined (L_gt_td)
 308 CMPtype
 309 DFP_GT (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 310 {
 311   int stat;
 312   stat = DFP_COMPARE_OP (DEC_FLOAT_COMPARE, arg_a, arg_b);
 313   /* For GT return 1 (>0) for true, -1 for false.  */
 314   return (stat == 1) ? 1 : -1;
 315 }
 316 #endif
 317
 318 #if defined (L_le_sd) || defined (L_le_dd) || defined (L_le_td)
 319 CMPtype
 320 DFP_LE (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 321 {
 322   int stat;
 323   stat = DFP_COMPARE_OP (DEC_FLOAT_COMPARE, arg_a, arg_b);
 324   /* For LE return 0 (<= 0) for true, 1 for false.  */
 325   if (__builtin_expect (stat == -2, 0))  /* An operand is NaN.  */
 326     return 1;
 327   return stat == 1;
 328 }
 329 #endif /* L_le */
 330
 331 #if defined (L_ge_sd) || defined (L_ge_dd) || defined (L_ge_td)
 332 CMPtype
 333 DFP_GE (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 334 {
 335   int stat;
 336   stat = DFP_COMPARE_OP (DEC_FLOAT_COMPARE, arg_a, arg_b);
 337   /* For GE return 1 (>=0) for true, -1 for false.  */
 338   if (__builtin_expect (stat == -2, 0))  /* An operand is NaN.  */
 339     return -1;
 340   return (stat != -1) ? 1 : -1;
 341 }
 342 #endif /* L_ge */
 343
 344 #define BUFMAX 128
 345
 346 /* Check for floating point exceptions that are relevant for conversions
 347    between decimal float values and handle them.  */
 348 static inline void
 349 dfp_conversion_exceptions (const int status)
 350 {
 351   /* decNumber exception flags we care about here.  */
 352   int ieee_flags;
 353   int dec_flags = DEC_IEEE_854_Inexact | DEC_IEEE_854_Invalid_operation
 354                   | DEC_IEEE_854_Overflow;
 355   dec_flags &= status;
 356   ieee_flags = DFP_IEEE_FLAGS (dec_flags);
 357   if (ieee_flags != 0)
 358     DFP_HANDLE_EXCEPTIONS (ieee_flags);
 359 }
 360
 361 #if defined (L_sd_to_dd)
 362 /* Use decNumber to convert directly from _Decimal32 to _Decimal64.  */
 363 _Decimal64
 364 DFP_TO_DFP (_Decimal32 f_from)
 365 {
 366   union { _Decimal32 c; decSingle f; } from;
 367   union { _Decimal64 c; decDouble f; } to;
 368
 369   from.c = f_from;
 370   to.f = *decSingleToWider (&from.f, &to.f);
 371   return to.c;
 372 }
 373 #endif
 374
 375 #if defined (L_sd_to_td)
 376 /* Use decNumber to convert directly from _Decimal32 to _Decimal128.  */
 377 _Decimal128
 378 DFP_TO_DFP (_Decimal32 f_from)
 379 {
 380   union { _Decimal32 c; decSingle f; } from;
 381   union { _Decimal128 c; decQuad f; } to;
 382   decDouble temp;
 383
 384   from.c = f_from;
 385   temp = *decSingleToWider (&from.f, &temp);
 386   to.f = *decDoubleToWider (&temp, &to.f);
 387   return to.c;
 388 }
 389 #endif
 390
 391 #if defined (L_dd_to_td)
 392 /* Use decNumber to convert directly from _Decimal64 to _Decimal128.  */
 393 _Decimal128
 394 DFP_TO_DFP (_Decimal64 f_from)
 395 {
 396   union { _Decimal64 c; decDouble f; } from;
 397   union { _Decimal128 c; decQuad f; } to;
 398
 399   from.c = f_from;
 400   to.f = *decDoubleToWider (&from.f, &to.f);
 401   return to.c;
 402 }
 403 #endif
 404
 405 #if defined (L_dd_to_sd)
 406 /* Use decNumber to convert directly from _Decimal64 to _Decimal32.  */
 407 _Decimal32
 408 DFP_TO_DFP (_Decimal64 f_from)
 409 {
 410   union { _Decimal32 c; decSingle f; } to;
 411   union { _Decimal64 c; decDouble f; } from;
 412   decContext context;
 413
 414   decContextDefault (&context, CONTEXT_INIT);
 415   DFP_INIT_ROUNDMODE (context.round);
 416   from.c = f_from;
 417   to.f = *decSingleFromWider (&to.f, &from.f, &context);
 418   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 419     dfp_conversion_exceptions (context.status);
 420   return to.c;
 421 }
 422 #endif
 423
 424 #if defined (L_td_to_sd)
 425 /* Use decNumber to convert directly from _Decimal128 to _Decimal32.  */
 426 _Decimal32
 427 DFP_TO_DFP (_Decimal128 f_from)
 428 {
 429   union { _Decimal32 c; decSingle f; } to;
 430   union { _Decimal128 c; decQuad f; } from;
 431   decDouble temp;
 432   decContext context;
 433
 434   decContextDefault (&context, CONTEXT_INIT);
 435   DFP_INIT_ROUNDMODE (context.round);
 436   from.c = f_from;
 437   temp = *decDoubleFromWider (&temp, &from.f, &context);
 438   to.f = *decSingleFromWider (&to.f, &temp, &context);
 439   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 440     dfp_conversion_exceptions (context.status);
 441   return to.c;
 442 }
 443 #endif
 444
 445 #if defined (L_td_to_dd)
 446 /* Use decNumber to convert directly from _Decimal128 to _Decimal64.  */
 447 _Decimal64
 448 DFP_TO_DFP (_Decimal128 f_from)
 449 {
 450   union { _Decimal64 c; decDouble f; } to;
 451   union { _Decimal128 c; decQuad f; } from;
 452   decContext context;
 453
 454   decContextDefault (&context, CONTEXT_INIT);
 455   DFP_INIT_ROUNDMODE (context.round);
 456   from.c = f_from;
 457   to.f = *decDoubleFromWider (&to.f, &from.f, &context);
 458   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 459     dfp_conversion_exceptions (context.status);
 460   return to.c;
 461 }
 462 #endif
 463
 464 #if defined (L_dd_to_si) || defined (L_td_to_si) \
 465   || defined (L_dd_to_usi) || defined (L_td_to_usi)
 466 /* Use decNumber to convert directly from decimal float to integer types.  */
 467 INT_TYPE
 468 DFP_TO_INT (DFP_C_TYPE x)
 469 {
 470   union { DFP_C_TYPE c; decFloat f; } u;
 471   decContext context;
 472   INT_TYPE i;
 473
 474   decContextDefault (&context, DEC_INIT_DECIMAL128);
 475   context.round = DEC_ROUND_DOWN;
 476   u.c = x;
 477   i = DEC_FLOAT_TO_INT (&u.f, &context, context.round);
 478   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 479     dfp_conversion_exceptions (context.status);
 480   return i;
 481 }
 482 #endif
 483
 484 #if defined (L_sd_to_si) || (L_sd_to_usi)
 485 /* Use decNumber to convert directly from decimal float to integer types.  */
 486 INT_TYPE
 487 DFP_TO_INT (_Decimal32 x)
 488 {
 489   union { _Decimal32 c; decSingle f; } u32;
 490   decDouble f64;
 491   decContext context;
 492   INT_TYPE i;
 493
 494   decContextDefault (&context, DEC_INIT_DECIMAL128);
 495   context.round = DEC_ROUND_DOWN;
 496   u32.c = x;
 497   f64 = *decSingleToWider (&u32.f, &f64);
 498   i = DEC_FLOAT_TO_INT (&f64, &context, context.round);
 499   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 500     dfp_conversion_exceptions (context.status);
 501   return i;
 502 }
 503 #endif
 504
 505 #if defined (L_sd_to_di) || defined (L_dd_to_di) || defined (L_td_to_di) \
 506   || defined (L_sd_to_udi) || defined (L_dd_to_udi) || defined (L_td_to_udi)
 507 /* decNumber doesn't provide support for conversions to 64-bit integer
 508    types, so do it the hard way.  */
 509 INT_TYPE
 510 DFP_TO_INT (DFP_C_TYPE x)
 511 {
 512   /* decNumber's decimal* types have the same format as C's _Decimal*
 513      types, but they have different calling conventions.  */
 514
 515   /* TODO: Decimal float to integer conversions should raise FE_INVALID
 516      if the result value does not fit into the result type.  */
 517
 518   IEEE_TYPE s;
 519   char buf[BUFMAX];
 520   char *pos;
 521   decNumber qval, n1, n2;
 522   decContext context;
 523
 524   /* Use a large context to avoid losing precision.  */
 525   decContextDefault (&context, DEC_INIT_DECIMAL128);
 526   /* Need non-default rounding mode here.  */
 527   context.round = DEC_ROUND_DOWN;
 528
 529   HOST_TO_IEEE (x, &s);
 530   TO_INTERNAL (&s, &n1);
 531   /* Rescale if the exponent is less than zero.  */
 532   decNumberToIntegralValue (&n2, &n1, &context);
 533   /* Get a value to use for the quantize call.  */
 534   decNumberFromString (&qval, "1.", &context);
 535   /* Force the exponent to zero.  */
 536   decNumberQuantize (&n1, &n2, &qval, &context);
 537   /* Get a string, which at this point will not include an exponent.  */
 538   decNumberToString (&n1, buf);
 539   /* Ignore the fractional part.  */
 540   pos = strchr (buf, '.');
 541   if (pos)
 542     *pos = 0;
 543   /* Use a C library function to convert to the integral type.  */
 544   return STR_TO_INT (buf, NULL, 10);
 545 }
 546 #endif
 547
 548 #if defined (L_si_to_dd) || defined (L_si_to_td) \
 549   || defined (L_usi_to_dd) || defined (L_usi_to_td)
 550 /* Use decNumber to convert directly from integer to decimal float types.  */
 551 DFP_C_TYPE
 552 INT_TO_DFP (INT_TYPE i)
 553 {
 554   union { DFP_C_TYPE c; decFloat f; } u;
 555
 556   u.f = *DEC_FLOAT_FROM_INT (&u.f, i);
 557   return u.c;
 558 }
 559 #endif
 560
 561 #if defined (L_si_to_sd) || defined (L_usi_to_sd)
 562 _Decimal32
 563 /* Use decNumber to convert directly from integer to decimal float types.  */
 564 INT_TO_DFP (INT_TYPE i)
 565 {
 566   union { _Decimal32 c; decSingle f; } u32;
 567   decDouble f64;
 568   decContext context;
 569
 570   decContextDefault (&context, DEC_INIT_DECIMAL128);
 571   f64 = *DEC_FLOAT_FROM_INT (&f64, i);
 572   u32.f = *decSingleFromWider (&u32.f, &f64, &context);
 573   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 574     dfp_conversion_exceptions (context.status);
 575   return u32.c;
 576 }
 577 #endif
 578
 579 #if defined (L_di_to_sd) || defined (L_di_to_dd) || defined (L_di_to_td) \
 580   || defined (L_udi_to_sd) || defined (L_udi_to_dd) || defined (L_udi_to_td)
 581 /* decNumber doesn't provide support for conversions from 64-bit integer
 582    types, so do it the hard way.  */
 583 DFP_C_TYPE
 584 INT_TO_DFP (INT_TYPE i)
 585 {
 586   DFP_C_TYPE f;
 587   IEEE_TYPE s;
 588   char buf[BUFMAX];
 589   decContext context;
 590
 591   decContextDefault (&context, CONTEXT_INIT);
 592   DFP_INIT_ROUNDMODE (context.round);
 593
 594   /* Use a C library function to get a floating point string.  */
 595   sprintf (buf, INT_FMT ".", CAST_FOR_FMT(i));
 596   /* Convert from the floating point string to a decimal* type.  */
 597   FROM_STRING (&s, buf, &context);
 598   IEEE_TO_HOST (s, &f);
 599
 600   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 601     dfp_conversion_exceptions (context.status);
 602
 603   return f;
 604 }
 605 #endif
 606
 607 #if defined (L_sd_to_sf) || defined (L_dd_to_sf) || defined (L_td_to_sf) \
 608  || defined (L_sd_to_df) || defined (L_dd_to_df) || defined (L_td_to_df) \
 609  || ((defined (L_sd_to_xf) || defined (L_dd_to_xf) || defined (L_td_to_xf)) \
 610      && LONG_DOUBLE_HAS_XF_MODE) \
 611  || ((defined (L_sd_to_tf) || defined (L_dd_to_tf) || defined (L_td_to_tf)) \
 612      && LONG_DOUBLE_HAS_TF_MODE)
 613 BFP_TYPE
 614 DFP_TO_BFP (DFP_C_TYPE f)
 615 {
 616   IEEE_TYPE s;
 617   char buf[BUFMAX];
 618
 619   HOST_TO_IEEE (f, &s);
 620   /* Write the value to a string.  */
 621   TO_STRING (&s, buf);
 622   /* Read it as the binary floating point type and return that.  */
 623   return STR_TO_BFP (buf, NULL);
 624 }
 625 #endif
 626
 627 #if defined (L_sf_to_sd) || defined (L_sf_to_dd) || defined (L_sf_to_td) \
 628  || defined (L_df_to_sd) || defined (L_df_to_dd) || defined (L_df_to_td) \
 629  || ((defined (L_xf_to_sd) || defined (L_xf_to_dd) || defined (L_xf_to_td)) \
 630      && LONG_DOUBLE_HAS_XF_MODE) \
 631  || ((defined (L_tf_to_sd) || defined (L_tf_to_dd) || defined (L_tf_to_td)) \
 632      && LONG_DOUBLE_HAS_TF_MODE)
 633 DFP_C_TYPE
 634 BFP_TO_DFP (BFP_TYPE x)
 635 {
 636   DFP_C_TYPE f;
 637   IEEE_TYPE s;
 638   char buf[BUFMAX];
 639   decContext context;
 640
 641   decContextDefault (&context, CONTEXT_INIT);
 642   DFP_INIT_ROUNDMODE (context.round);
 643
 644   /* Use a C library function to write the floating point value to a string.  */
 645   sprintf (buf, BFP_FMT, (BFP_VIA_TYPE) x);
 646
 647   /* Convert from the floating point string to a decimal* type.  */
 648   FROM_STRING (&s, buf, &context);
 649   IEEE_TO_HOST (s, &f);
 650
 651   if (DFP_EXCEPTIONS_ENABLED && context.status != 0)
 652     {
 653       /* decNumber exception flags we care about here.  */
 654       int ieee_flags;
 655       int dec_flags = DEC_IEEE_854_Inexact | DEC_IEEE_854_Invalid_operation
 656                       | DEC_IEEE_854_Overflow | DEC_IEEE_854_Underflow;
 657       dec_flags &= context.status;
 658       ieee_flags = DFP_IEEE_FLAGS (dec_flags);
 659       if (ieee_flags != 0)
 660         DFP_HANDLE_EXCEPTIONS (ieee_flags);
 661     }
 662
 663   return f;
 664 }
 665 #endif
 666
 667 #if defined (L_unord_sd) || defined (L_unord_dd) || defined (L_unord_td)
 668 CMPtype
 669 DFP_UNORD (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
 670 {
 671   decNumber arg1, arg2;
 672   IEEE_TYPE a, b;
 673
 674   HOST_TO_IEEE (arg_a, &a);
 675   HOST_TO_IEEE (arg_b, &b);
 676   TO_INTERNAL (&a, &arg1);
 677   TO_INTERNAL (&b, &arg2);
 678   return (decNumberIsNaN (&arg1) || decNumberIsNaN (&arg2));
 679 }
 680 #endif /* L_unord_sd || L_unord_dd || L_unord_td */