compiler-rt/lib/builtins/floatunsitf.c

   1 //===-- lib/floatunsitf.c - uint -> quad-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 quad-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 QUAD_PRECISION
  16 #include "fp_lib.h"
  17
  18 #if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
  19 COMPILER_RT_ABI fp_t __floatunsitf(su_int a) {
  20
  21   const int aWidth = sizeof a * CHAR_BIT;
  22
  23   // Handle zero as a special case to protect clz
  24   if (a == 0)
  25     return fromRep(0);
  26
  27   // Exponent of (fp_t)a is the width of abs(a).
  28   const int exponent = (aWidth - 1) - clzsi(a);
  29   rep_t result;
  30
  31   // Shift a into the significand field and clear the implicit bit.
  32   const int shift = significandBits - exponent;
  33   result = (rep_t)a << shift ^ implicitBit;
  34
  35   // Insert the exponent
  36   result += (rep_t)(exponent + exponentBias) << significandBits;
  37   return fromRep(result);
  38 }
  39
  40 #endif