compiler-rt/lib/builtins/powidf2.c

   1 //===-- powidf2.cpp - Implement __powidf2 ---------------------------------===//
   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 __powidf2 for the compiler_rt library.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "int_lib.h"
  14
  15 // Returns: a ^ b
  16
  17 COMPILER_RT_ABI double __powidf2(double a, int b) {
  18   const int recip = b < 0;
  19   double r = 1;
  20   while (1) {
  21     if (b & 1)
  22       r *= a;
  23     b /= 2;
  24     if (b == 0)
  25       break;
  26     a *= a;
  27   }
  28   return recip ? 1 / r : r;
  29 }