43 lines
748 B
C
43 lines
748 B
C
#include "libc/math/libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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double nexttoward(double x, long double y)
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{
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return nextafter(x, y);
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}
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#else
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double nexttoward(double x, long double y)
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{
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union {double f; uint64_t i;} ux = {x};
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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 (x == y)
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return y;
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if (x == 0) {
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ux.i = 1;
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if (signbit(y))
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ux.i |= 1ULL<<63;
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} else if (x < y) {
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if (signbit(x))
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ux.i--;
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else
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ux.i++;
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} else {
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if (signbit(x))
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ux.i++;
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else
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ux.i--;
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}
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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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#endif
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