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42 lines
1,019 B
C
42 lines
1,019 B
C
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/*
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* PROJECT: ReactOS CRT
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* LICENSE: MIT (https://spdx.org/licenses/MIT)
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* PURPOSE: Implementation of nextafter.
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* COPYRIGHT: Imported from musl libc
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* https://git.musl-libc.org/cgit/musl/tree/src/math/nextafter.c
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* blob: ab5795a47a93e36c8c461d8a4be6621b582ae077
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* See https://git.musl-libc.org/cgit/musl/tree/COPYRIGHT
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*/
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#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 & ~0ULL/2;
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ay = uy.i & ~0ULL/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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