cosmopolitan/libc/tinymath/fmaxl.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
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│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
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│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/tinymath/tinymath.h"

/**
 * Returns maximum of two long doubles.
 *
 * If one argument is NAN then the other is returned.
 * This function is designed to do the right thing with
 * signed zeroes.
 */
long double fmaxl(long double x, long double y) {
  if (__builtin_isnan(x)) return y;
  if (__builtin_isnan(y)) return x;
  if (__builtin_signbitl(x) != __builtin_signbitl(y)) {
    return __builtin_signbitl(x) ? y : x; /* C99 Annex F.9.9.2 */
  }
  return x < y ? y : x;
}