vendor/compiler_builtins/compiler-rt/lib/builtins/floatunsidf.c

   1 //===-- lib/floatunsidf.c - uint -> double-precision conversion ---*- C -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is dual licensed under the MIT and the University of Illinois Open
   6 // Source Licenses. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements unsigned integer to double-precision conversion for the
  11 // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
  12 // mode.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #define DOUBLE_PRECISION
  17 #include "fp_lib.h"
  18
  19 #include "int_lib.h"
  20
  21 COMPILER_RT_ABI fp_t
  22 __floatunsidf(unsigned int a) {
  23
  24     const int aWidth = sizeof a * CHAR_BIT;
  25
  26     // Handle zero as a special case to protect clz
  27     if (a == 0) return fromRep(0);
  28
  29     // Exponent of (fp_t)a is the width of abs(a).
  30     const int exponent = (aWidth - 1) - __builtin_clz(a);
  31     rep_t result;
  32
  33     // Shift a into the significand field and clear the implicit bit.
  34     const int shift = significandBits - exponent;
  35     result = (rep_t)a << shift ^ implicitBit;
  36
  37     // Insert the exponent
  38     result += (rep_t)(exponent + exponentBias) << significandBits;
  39     return fromRep(result);
  40 }
  41
  42 #if defined(__ARM_EABI__)
  43 #if defined(COMPILER_RT_ARMHF_TARGET)
  44 AEABI_RTABI fp_t __aeabi_ui2d(unsigned int a) {
  45   return __floatunsidf(a);
  46 }
  47 #else
  48 AEABI_RTABI fp_t __aeabi_ui2d(unsigned int a) COMPILER_RT_ALIAS(__floatunsidf);
  49 #endif
  50 #endif