scalbn.c File Reference

#include "prim.h"

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Functions
double	scalbn (double x, int32_t n)

Variables
static const double	two54 = 1.80143985094819840000e+16
static const double	twom54 = 5.55111512312578270212e-17
static const double	huge = 1.0e+300
static const double	tiny = 1.0e-300

Function Documentation

scalbn()

double scalbn	(	double	x,
		int32_t	n
	)

Definition at line 56 of file scalbn.c.

References copysign(), huge, tiny, two54, and twom54.

Referenced by __kernel_rem_pio2(), and pow().

{
    int32_t k, hx, lx;
    EXTRACT_WORDS(hx, lx, x);
    k = (hx & 0x7ff00000) >> 20; /* extract exponent */
    if (k == 0)
    { /* 0 or subnormal x */
        if ((lx | (hx & 0x7fffffff)) == 0)
            return x; /* +-0 */
        x *= two54;
        GET_HIGH_WORD(hx, x);
        k = ((hx & 0x7ff00000) >> 20) - 54;
        if (n < -50000)
            return tiny * x; /*underflow*/
    }
    if (k == 0x7ff)
        return x + x; /* NaN or Inf */
    k = k + n;
    if (k > 0x7fe)
        return huge * copysign(huge, x); /* overflow  */
    if (k > 0)                           /* normal result */
    {
        SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
        return x;
    }
    if (k <= -54)
    {
        if (n > 50000)                       /* in case integer overflow in n+k */
            return huge * copysign(huge, x); /*overflow*/
        else
            return tiny * copysign(tiny, x); /*underflow*/
    }
    k += 54; /* subnormal result */
    SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
    return x * twom54;
}

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Variable Documentation

huge

const double huge = 1.0e+300

static

Definition at line 53 of file scalbn.c.

Referenced by scalbn().

tiny

const double tiny = 1.0e-300

static

Definition at line 54 of file scalbn.c.

Referenced by scalbn().

two54

const double two54 = 1.80143985094819840000e+16

static

Definition at line 51 of file scalbn.c.

Referenced by scalbn().

twom54

const double twom54 = 5.55111512312578270212e-17

static

Definition at line 52 of file scalbn.c.

Referenced by scalbn().