compiler-rt/lib/builtins/floatunsidf.c

   1 //===-- lib/floatunsidf.c - uint -> double-precision conversion ---*- C -*-===//
   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 unsigned integer to double-precision conversion for the
  10 // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
  11 // mode.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #define DOUBLE_PRECISION
  16 #include "fp_lib.h"
  17
  18 #include "int_lib.h"
  19
  20 COMPILER_RT_ABI fp_t __floatunsidf(su_int a) {
  21
  22   const int aWidth = sizeof a * CHAR_BIT;
  23
  24   // Handle zero as a special case to protect clz
  25   if (a == 0)
  26     return fromRep(0);
  27
  28   // Exponent of (fp_t)a is the width of abs(a).
  29   const int exponent = (aWidth - 1) - clzsi(a);
  30   rep_t result;
  31
  32   // Shift a into the significand field and clear the implicit bit.
  33   const int shift = significandBits - exponent;
  34   result = (rep_t)a << shift ^ implicitBit;
  35
  36   // Insert the exponent
  37   result += (rep_t)(exponent + exponentBias) << significandBits;
  38   return fromRep(result);
  39 }
  40
  41 #if defined(__ARM_EABI__)
  42 #if defined(COMPILER_RT_ARMHF_TARGET)
  43 AEABI_RTABI fp_t __aeabi_ui2d(su_int a) { return __floatunsidf(a); }
  44 #else
  45 COMPILER_RT_ALIAS(__floatunsidf, __aeabi_ui2d)
  46 #endif
  47 #endif