66 lines
1.5 KiB
C
66 lines
1.5 KiB
C
/*
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nextafterl.c
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Contributed by Danny Smith <dannysmith@users.sourceforge.net>
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No copyright claimed, absolutely no warranties.
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2005-05-09
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*/
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#include <math.h>
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long double
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nextafterl (long double x, long double y)
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{
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union {
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long double ld;
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struct {
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unsigned long long mantissa;
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unsigned short expn;
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unsigned short pad;
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} __attribute__ ((packed)) parts;
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} u;
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/* The normal bit is explicit for long doubles, unlike
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float and double. */
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static const unsigned long long normal_bit = 0x8000000000000000ull;
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if (isnan (y) || isnan (x))
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return x + y;
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if (x == y )
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/* nextafter (0.0, -O.0) should return -0.0. */
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return y;
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u.ld = x;
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if (x == 0.0L)
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{
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u.parts.mantissa = 1ull;
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return y > 0.0L ? u.ld : -u.ld;
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}
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if (((x > 0.0L) ^ (y > x)) == 0)
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{
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u.parts.mantissa++;
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if ((u.parts.mantissa & ~normal_bit) == 0ull)
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u.parts.expn++;
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}
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else
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{
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if ((u.parts.mantissa & ~normal_bit) == 0ull)
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u.parts.expn--;
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u.parts.mantissa--;
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}
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/* If we have updated the expn of a normal number,
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or moved from denormal to normal, [re]set the normal bit. */
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if (u.parts.expn & 0x7fff)
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u.parts.mantissa |= normal_bit;
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return u.ld;
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}
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/* nexttowardl is the same function with a different name. */
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long double
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nexttowardl (long double, long double) __attribute__ ((alias("nextafterl")));
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