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      1 //===-- lib/floatunsisf.c - uint -> single-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 single-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 SINGLE_PRECISION
     17 #include "fp_lib.h"
     18 
     19 #include "int_lib.h"
     20 
     21 ARM_EABI_FNALIAS(ui2f, floatunsisf)
     22 
     23 COMPILER_RT_ABI fp_t
     24 __floatunsisf(unsigned int a) {
     25 
     26     const int aWidth = sizeof a * CHAR_BIT;
     27 
     28     // Handle zero as a special case to protect clz
     29     if (a == 0) return fromRep(0);
     30 
     31     // Exponent of (fp_t)a is the width of abs(a).
     32     const int exponent = (aWidth - 1) - __builtin_clz(a);
     33     rep_t result;
     34 
     35     // Shift a into the significand field, rounding if it is a right-shift
     36     if (exponent <= significandBits) {
     37         const int shift = significandBits - exponent;
     38         result = (rep_t)a << shift ^ implicitBit;
     39     } else {
     40         const int shift = exponent - significandBits;
     41         result = (rep_t)a >> shift ^ implicitBit;
     42         rep_t round = (rep_t)a << (typeWidth - shift);
     43         if (round > signBit) result++;
     44         if (round == signBit) result += result & 1;
     45     }
     46 
     47     // Insert the exponent
     48     result += (rep_t)(exponent + exponentBias) << significandBits;
     49     return fromRep(result);
     50 }
     51