32 lines
653 B
C
32 lines
653 B
C
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#include "libm.h"
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#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
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#define EPS DBL_EPSILON
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#elif FLT_EVAL_METHOD==2
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#define EPS LDBL_EPSILON
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#endif
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static const double_t toint = 1/EPS;
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double floor(double x)
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{
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union {double f; uint64_t i;} u = {x};
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int e = u.i >> 52 & 0x7ff;
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double_t y;
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if (e >= 0x3ff+52 || x == 0)
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return x;
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/* y = int(x) - x, where int(x) is an integer neighbor of x */
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if (u.i >> 63)
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y = x - toint + toint - x;
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else
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y = x + toint - toint - x;
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/* special case because of non-nearest rounding modes */
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if (e <= 0x3ff-1) {
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FORCE_EVAL(y);
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return u.i >> 63 ? -1 : 0;
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}
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if (y > 0)
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return x + y - 1;
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return x + y;
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}
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