src/libcompiler_builtins/compiler-rt/lib/builtins/floatsidf.c

   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