compiler-rt/lib/builtins/floatdidf.c

   1 //===-- floatdidf.c - Implement __floatdidf -------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements __floatdidf for the compiler_rt library.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "int_lib.h"
  14
  15 // Returns: convert a to a double, rounding toward even.
  16
  17 // Assumption: double is a IEEE 64 bit floating point type
  18 //             di_int is a 64 bit integral type
  19
  20 // seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm
  21 // mmmm
  22
  23 #ifndef __SOFTFP__
  24 // Support for systems that have hardware floating-point; we'll set the inexact
  25 // flag as a side-effect of this computation.
  26
  27 COMPILER_RT_ABI double __floatdidf(di_int a) {
  28   static const double twop52 = 4503599627370496.0; // 0x1.0p52
  29   static const double twop32 = 4294967296.0;       // 0x1.0p32
  30
  31   union {
  32     int64_t x;
  33     double d;
  34   } low = {.d = twop52};
  35
  36   const double high = (int32_t)(a >> 32) * twop32;
  37   low.x |= a & INT64_C(0x00000000ffffffff);
  38
  39   const double result = (high - twop52) + low.d;
  40   return result;
  41 }
  42
  43 #else
  44 // Support for systems that don't have hardware floating-point; there are no
  45 // flags to set, and we don't want to code-gen to an unknown soft-float
  46 // implementation.
  47
  48 #define SRC_I64
  49 #define DST_DOUBLE
  50 #include "int_to_fp_impl.inc"
  51
  52 COMPILER_RT_ABI double __floatdidf(di_int a) { return __floatXiYf__(a); }
  53 #endif
  54
  55 #if defined(__ARM_EABI__)
  56 #if defined(COMPILER_RT_ARMHF_TARGET)
  57 AEABI_RTABI double __aeabi_l2d(di_int a) { return __floatdidf(a); }
  58 #else
  59 COMPILER_RT_ALIAS(__floatdidf, __aeabi_l2d)
  60 #endif
  61 #endif
  62
  63 #if defined(__MINGW32__) && defined(__arm__)
  64 COMPILER_RT_ALIAS(__floatdidf, __i64tod)
  65 #endif