libgo/runtime/go-cdiv.c

   1 /* go-cdiv.c -- complex division routines
   2
   3    Copyright 2013 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 /* Calls to these functions are generated by the Go frontend for
   8    division of complex64 or complex128.  We use these because Go's
   9    complex division expects slightly different results from the GCC
  10    default.  When dividing NaN+1.0i / 0+0i, Go expects NaN+NaNi but
  11    GCC generates NaN+Infi.  NaN+Infi seems wrong seems the rules of
  12    C99 Annex G specify that if either side of a complex number is Inf,
  13    the the whole number is Inf, but an operation involving NaN ought
  14    to result in NaN, not Inf.  */
  15
  16 __complex float
  17 __go_complex64_div (__complex float a, __complex float b)
  18 {
  19   if (__builtin_expect (b == 0+0i, 0))
  20     {
  21       if (!__builtin_isinff (__real__ a)
  22           && !__builtin_isinff (__imag__ a)
  23           && (__builtin_isnanf (__real__ a) || __builtin_isnanf (__imag__ a)))
  24         {
  25           /* Pass "1" to nanf to match math/bits.go.  */
  26           return __builtin_nanf("1") + __builtin_nanf("1")*1i;
  27         }
  28     }
  29   return a / b;
  30 }
  31
  32 __complex double
  33 __go_complex128_div (__complex double a, __complex double b)
  34 {
  35   if (__builtin_expect (b == 0+0i, 0))
  36     {
  37       if (!__builtin_isinf (__real__ a)
  38           && !__builtin_isinf (__imag__ a)
  39           && (__builtin_isnan (__real__ a) || __builtin_isnan (__imag__ a)))
  40         {
  41           /* Pass "1" to nan to match math/bits.go.  */
  42           return __builtin_nan("1") + __builtin_nan("1")*1i;
  43         }
  44     }
  45   return a / b;
  46 }