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      1 //===-- lib/floatsidf.c - integer -> 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 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 __floatsidf(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)
     28         return fromRep(0);
     29 
     30     // All other cases begin by extracting the sign and absolute value of a
     31     rep_t sign = 0;
     32     if (a < 0) {
     33         sign = signBit;
     34         a = -a;
     35     }
     36 
     37     // Exponent of (fp_t)a is the width of abs(a).
     38     const int exponent = (aWidth - 1) - __builtin_clz(a);
     39     rep_t result;
     40 
     41     // Shift a into the significand field and clear the implicit bit.  Extra
     42     // cast to unsigned int is necessary to get the correct behavior for
     43     // the input INT_MIN.
     44     const int shift = significandBits - exponent;
     45     result = (rep_t)(unsigned int)a << shift ^ implicitBit;
     46 
     47     // Insert the exponent
     48     result += (rep_t)(exponent + exponentBias) << significandBits;
     49     // Insert the sign bit and return
     50     return fromRep(result | sign);
     51 }
     52 
     53 #if defined(__ARM_EABI__)
     54 #if defined(COMPILER_RT_ARMHF_TARGET)
     55 AEABI_RTABI fp_t __aeabi_i2d(int a) {
     56   return __floatsidf(a);
     57 }
     58 #else
     59 AEABI_RTABI fp_t __aeabi_i2d(int a) COMPILER_RT_ALIAS(__floatsidf);
     60 #endif
     61 #endif
     62