kaguya
32 lines
634 B
C
32 lines
634 B
C
#include "libm.h"
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double nextafter(double x, double y)
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{
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union {double f; uint64_t i;} ux={x}, uy={y};
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uint64_t ax, ay;
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int e;
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if (isnan(x) || isnan(y))
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return x + y;
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if (ux.i == uy.i)
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return y;
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ax = ux.i & -1ULL/2;
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ay = uy.i & -1ULL/2;
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if (ax == 0) {
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if (ay == 0)
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return y;
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ux.i = (uy.i & 1ULL<<63) | 1;
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} else if (ax > ay || ((ux.i ^ uy.i) & 1ULL<<63))
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ux.i--;
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else
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ux.i++;
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e = ux.i >> 52 & 0x7ff;
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/* raise overflow if ux.f is infinite and x is finite */
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if (e == 0x7ff)
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FORCE_EVAL(x+x);
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/* raise underflow if ux.f is subnormal or zero */
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if (e == 0)
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FORCE_EVAL(x*x + ux.f*ux.f);
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return ux.f;
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}
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