#include <glib.h>

#if defined(__GNUC__) && (__GNUC__ >= 4)

# define TEST_BUILTINS 1

#else

# define TEST_BUILTINS 0

#endif

#if TEST_BUILTINS

static gint

builtin_bit_nth_lsf1 (gulong mask, gint nth_bit)

{

  if (nth_bit >= 0)

    {

      if (G_LIKELY (nth_bit < GLIB_SIZEOF_LONG * 8 - 1))

	mask &= -(1UL<<(nth_bit+1));

      else

	mask = 0;

    }

  return __builtin_ffsl(mask) - 1;

}

static gint

builtin_bit_nth_lsf2 (gulong mask, gint nth_bit)

{

  if (nth_bit >= 0)

    {

      if (G_LIKELY (nth_bit < GLIB_SIZEOF_LONG * 8 - 1))

	mask &= -(1UL<<(nth_bit+1));

      else

	mask = 0;

    }

  return mask ? __builtin_ctzl(mask) : -1;

}

static gint

builtin_bit_nth_msf (gulong mask, gint nth_bit)

{

  if (nth_bit >= 0 && nth_bit < GLIB_SIZEOF_LONG * 8)

    mask &= (1UL<

  return mask ? GLIB_SIZEOF_LONG * 8 - 1 - __builtin_clzl(mask) : -1;

}

static guint

builtin_bit_storage (gulong number)

{

  return number ? GLIB_SIZEOF_LONG * 8 - __builtin_clzl(number) : 1;

}

#endif

static gint

naive_bit_nth_lsf (gulong mask, gint   nth_bit)

{

  if (G_UNLIKELY (nth_bit < -1))

    nth_bit = -1;

  while (nth_bit < ((GLIB_SIZEOF_LONG * 8) - 1))

    {

      nth_bit++;

      if (mask & (1UL << nth_bit))

	return nth_bit;

    }

  return -1;

}

static gint

naive_bit_nth_msf (gulong mask, gint   nth_bit)

{

  if (nth_bit < 0 || G_UNLIKELY (nth_bit > GLIB_SIZEOF_LONG * 8))

    nth_bit = GLIB_SIZEOF_LONG * 8;

  while (nth_bit > 0)

    {

      nth_bit--;

      if (mask & (1UL << nth_bit))

	return nth_bit;

    }

  return -1;

}

static guint

naive_bit_storage (gulong number)

{

  guint n_bits = 0;

  do

    {

      n_bits++;

      number >>= 1;

    }

  while (number);

  return n_bits;

}

#define TEST(f1, f2, i) \

	if (f1 (i) != f2 (i)) { \

		g_error (G_STRINGIFY (f1) " (%lu) = %d; " \

			 G_STRINGIFY (f2) " (%lu) = %d; ", \

			 i, f1 (i), \

			 i, f2 (i)); \

		return 1; \

	}

#define TEST2(f1, f2, i, n) \

	if (f1 (i, n) != f2 (i, n)) { \

		g_error (G_STRINGIFY (f1) " (%lu, %d) = %d; " \

			 G_STRINGIFY (f2) " (%lu, %d) = %d; ", \

			 i, n, f1 (i, n), \

			 i, n, f2 (i, n)); \

		return 1; \

	}

int

main (void)

{

  gulong i;

  gint nth_bit;

  /* we loop like this: 0, -1, 1, -2, 2, -3, 3, ... */

  for (i = 0; (glong)i < 1500 ; i = -(i+((glong)i>=0))) {

#if TEST_BUILTINS

    TEST (naive_bit_storage, builtin_bit_storage, i);

#endif

    TEST (naive_bit_storage, g_bit_storage, i);

    for (nth_bit = -3; nth_bit <= 2 + GLIB_SIZEOF_LONG * 8; nth_bit++) {

#if TEST_BUILTINS

      TEST2 (naive_bit_nth_lsf, builtin_bit_nth_lsf1, i, nth_bit);

      TEST2 (naive_bit_nth_lsf, builtin_bit_nth_lsf2, i, nth_bit);

#endif

      TEST2 (naive_bit_nth_lsf, g_bit_nth_lsf, i, nth_bit);

#if TEST_BUILTINS

      TEST2 (naive_bit_nth_msf, builtin_bit_nth_msf, i, nth_bit);

#endif

      TEST2 (naive_bit_nth_msf, g_bit_nth_msf, i, nth_bit);

    }

  }

  return 0;

}