lib/powidf2.c

   1 /* ===-- powidf2.cpp - Implement __powidf2 ---------------------------------===
   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 __powidf2 for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 /* Returns: a ^ b */
  18
  19 COMPILER_RT_ABI double
  20 __powidf2(double a, si_int b)
  21 {
  22     const int recip = b < 0;
  23     double r = 1;
  24     while (1)
  25     {
  26         if (b & 1)
  27             r *= a;
  28         b /= 2;
  29         if (b == 0)
  30             break;
  31         a *= a;
  32     }
  33     return recip ? 1/r : r;
  34 }