/* Test for strtod handling of arguments that may cause floating-point

   underflow.

   Copyright (C) 2012-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <fenv.h>

#include <float.h>

#include <stdbool.h>

#include <stdio.h>

#include <stdlib.h>

#include <tininess.h>

enum underflow_case

  {

    /* Result is exact or outside the subnormal range.  */

    UNDERFLOW_NONE,

    /* Result has magnitude at most half way between the largest

       subnormal value and the smallest positive normal value, and is

       not exact, so underflows in all rounding modes and independent

       of how tininess is detected.  */

    UNDERFLOW_ALWAYS,

    /* Result is positive, with magnitude larger than half way between

       the largest subnormal value and the least positive normal

       value, but would underflow when rounded to nearest to normal

       precision, so underflows after rounding in all modes except

       rounding upward.  */

    UNDERFLOW_EXCEPT_UPWARD,

    /* Likewise, for a negative result, underflowing after rounding

       except when rounding downward.  */

    UNDERFLOW_EXCEPT_DOWNWARD,

    /* Result is positive, with magnitude at least three quarters of

       the way from the largest subnormal value to the smallest

       positive normal value, so underflows after rounding only when

       rounding downward or toward zero.  */

    UNDERFLOW_ONLY_DOWNWARD_ZERO,

    /* Likewise, for a negative result, underflowing after rounding

       only when rounding upward or toward zero.  */

    UNDERFLOW_ONLY_UPWARD_ZERO,

  };

struct test

{

  const char *s;

  enum underflow_case c;

};

static const struct test tests[] =

  {

    { "0x1p-1022", UNDERFLOW_NONE },

    { "-0x1p-1022", UNDERFLOW_NONE },

    { "0x0p-10000000000000000000000000", UNDERFLOW_NONE },

    { "-0x0p-10000000000000000000000000", UNDERFLOW_NONE },

    { "0x1p-10000000000000000000000000", UNDERFLOW_ALWAYS },

    { "-0x1p-10000000000000000000000000", UNDERFLOW_ALWAYS },

    { "0x1.000000000000000000001p-1022", UNDERFLOW_NONE },

    { "-0x1.000000000000000000001p-1022", UNDERFLOW_NONE },

    { "0x1p-1075", UNDERFLOW_ALWAYS },

    { "-0x1p-1075", UNDERFLOW_ALWAYS },

    { "0x1p-1023", UNDERFLOW_NONE },

    { "-0x1p-1023", UNDERFLOW_NONE },

    { "0x1p-1074", UNDERFLOW_NONE },

    { "-0x1p-1074", UNDERFLOW_NONE },

    { "0x1.ffffffffffffep-1023", UNDERFLOW_NONE },

    { "-0x1.ffffffffffffep-1023", UNDERFLOW_NONE },

    { "0x1.fffffffffffffp-1023", UNDERFLOW_ALWAYS },

    { "-0x1.fffffffffffffp-1023", UNDERFLOW_ALWAYS },

    { "0x1.fffffffffffff0001p-1023", UNDERFLOW_EXCEPT_UPWARD },

    { "-0x1.fffffffffffff0001p-1023", UNDERFLOW_EXCEPT_DOWNWARD },

    { "0x1.fffffffffffff7fffp-1023", UNDERFLOW_EXCEPT_UPWARD },

    { "-0x1.fffffffffffff7fffp-1023", UNDERFLOW_EXCEPT_DOWNWARD },

    { "0x1.fffffffffffff8p-1023", UNDERFLOW_ONLY_DOWNWARD_ZERO },

    { "-0x1.fffffffffffff8p-1023", UNDERFLOW_ONLY_UPWARD_ZERO },

    { "0x1.fffffffffffffffffp-1023", UNDERFLOW_ONLY_DOWNWARD_ZERO },

    { "-0x1.fffffffffffffffffp-1023", UNDERFLOW_ONLY_UPWARD_ZERO },

  };

/* Return whether to expect underflow from a particular testcase, in a

   given rounding mode.  */

static bool

expect_underflow (enum underflow_case c, int rm)

{

  if (c == UNDERFLOW_NONE)

    return false;

  if (c == UNDERFLOW_ALWAYS)

    return true;

  if (TININESS_AFTER_ROUNDING)

    {

      switch (rm)

	{

#ifdef FE_DOWNWARD

	case FE_DOWNWARD:

	  return (c == UNDERFLOW_EXCEPT_UPWARD

		  || c == UNDERFLOW_ONLY_DOWNWARD_ZERO);

#endif

#ifdef FE_TOWARDZERO

	case FE_TOWARDZERO:

	  return true;

#endif

#ifdef FE_UPWARD

	case FE_UPWARD:

	  return (c == UNDERFLOW_EXCEPT_DOWNWARD

		  || c == UNDERFLOW_ONLY_UPWARD_ZERO);

#endif

	default:

	  return (c == UNDERFLOW_EXCEPT_UPWARD

		  || c == UNDERFLOW_EXCEPT_DOWNWARD);

	}

    }

  else

    return true;

}

static bool support_underflow_exception = false;

volatile double d = DBL_MIN;

volatile double dd;

static int

test_in_one_mode (const char *s, enum underflow_case c, int rm,

		  const char *mode_name)

{

  int result = 0;

  feclearexcept (FE_ALL_EXCEPT);

  errno = 0;

  double d = strtod (s, NULL);

  int got_errno = errno;

#ifdef FE_UNDERFLOW

  bool got_fe_underflow = fetestexcept (FE_UNDERFLOW) != 0;

#else

  bool got_fe_underflow = false;

#endif

  printf ("strtod (%s) (%s) returned %a, errno = %d, %sunderflow exception\n",

	  s, mode_name, d, got_errno, got_fe_underflow ? "" : "no ");

  bool this_expect_underflow = expect_underflow (c, rm);

  if (got_errno != 0 && got_errno != ERANGE)

    {

      puts ("FAIL: errno neither 0 nor ERANGE");

      result = 1;

    }

  else if (this_expect_underflow != (errno == ERANGE))

    {

      puts ("FAIL: underflow from errno differs from expectations");

      result = 1;

    }

  if (support_underflow_exception && got_fe_underflow != this_expect_underflow)

    {

      puts ("FAIL: underflow from exceptions differs from expectations");

      result = 1;

    }

  return result;

}

static int

do_test (void)

{

  int save_round_mode __attribute__ ((unused)) = fegetround ();

  int result = 0;

#ifdef FE_TONEAREST

  const int fe_tonearest = FE_TONEAREST;

#else

  const int fe_tonearest = 0;

# if defined FE_DOWNWARD || defined FE_TOWARDZERO || defined FE_UPWARD

#  error "FE_TONEAREST not defined, but another rounding mode is"

# endif

#endif

#ifdef FE_UNDERFLOW

  feclearexcept (FE_ALL_EXCEPT);

  dd = d * d;

  if (fetestexcept (FE_UNDERFLOW))

    support_underflow_exception = true;

  else

    puts ("underflow exception not supported at runtime, only testing errno");

#endif

  for (size_t i = 0; i < sizeof (tests) / sizeof (tests[0]); i++)

    {

      result |= test_in_one_mode (tests[i].s, tests[i].c, fe_tonearest,

				  "default rounding mode");

#ifdef FE_DOWNWARD

      if (!fesetround (FE_DOWNWARD))

	{

	  result |= test_in_one_mode (tests[i].s, tests[i].c, FE_DOWNWARD,

				      "FE_DOWNWARD");

	  fesetround (save_round_mode);

	}

#endif

#ifdef FE_TOWARDZERO

      if (!fesetround (FE_TOWARDZERO))

	{

	  result |= test_in_one_mode (tests[i].s, tests[i].c, FE_TOWARDZERO,

				      "FE_TOWARDZERO");

	  fesetround (save_round_mode);

	}

#endif

#ifdef FE_UPWARD

      if (!fesetround (FE_UPWARD))

	{

	  result |= test_in_one_mode (tests[i].s, tests[i].c, FE_UPWARD,

				      "FE_UPWARD");

	  fesetround (save_round_mode);

	}

#endif

    }

  return result;

}

#define TEST_FUNCTION do_test ()

#include "../test-skeleton.c"