compiler-rt/lib/builtins/floatunsisf.c

   1 //===-- lib/floatunsisf.c - uint -> single-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 single-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 SINGLE_PRECISION
  16 #include "fp_lib.h"
  17
  18 #include "int_lib.h"
  19
  20 COMPILER_RT_ABI fp_t __floatunsisf(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, rounding if it is a right-shift
  33   if (exponent <= significandBits) {
  34     const int shift = significandBits - exponent;
  35     result = (rep_t)a << shift ^ implicitBit;
  36   } else {
  37     const int shift = exponent - significandBits;
  38     result = (rep_t)a >> shift ^ implicitBit;
  39     rep_t round = (rep_t)a << (typeWidth - shift);
  40     if (round > signBit)
  41       result++;
  42     if (round == signBit)
  43       result += result & 1;
  44   }
  45
  46   // Insert the exponent
  47   result += (rep_t)(exponent + exponentBias) << significandBits;
  48   return fromRep(result);
  49 }
  50
  51 #if defined(__ARM_EABI__)
  52 #if defined(COMPILER_RT_ARMHF_TARGET)
  53 AEABI_RTABI fp_t __aeabi_ui2f(unsigned int a) { return __floatunsisf(a); }
  54 #else
  55 COMPILER_RT_ALIAS(__floatunsisf, __aeabi_ui2f)
  56 #endif
  57 #endif