floor.c File Reference

Floor function. More...

#include "prim.h"

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Functions
double	floor (double x)
	Floor function. More...

Variables
static const double	huge = 1.0e300

Detailed Description

Floor function.

Definition in file floor.c.

Function Documentation

floor()

double floor

(

double

x

)

Floor function.

Returns

x rounded toward -inf to integral value

Method:
    Bit twiddling

Exception:
    Inexact flag raised if x not equal to floor(x)

Definition at line 62 of file floor.c.

References huge.

Referenced by __kernel_rem_pio2(), cfloor(), RealNumber::Floor(), round(), and trunc().

{
    int32_t i0, i1, j0;
    uint32_t i, j;
    EXTRACT_WORDS(i0, i1, x);
    j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
    if (j0 < 20)
    {
        if (j0 < 0)
        { /* raise inexact if x != 0 */
            if (huge + x > 0.0)
            { /* return 0*sign(x) if |x|<1 */
                if (i0 >= 0)
                {
                    i0 = i1 = 0;
                }
                else if (((i0 & 0x7fffffff) | i1) != 0)
                {
                    i0 = 0xbff00000;
                    i1 = 0;
                }
            }
        }
        else
        {
            i = (0x000fffff) >> j0;
            if (((i0 & i) | i1) == 0)
                return x; /* x is integral */
            if (huge + x > 0.0)
            { /* raise inexact flag */
                if (i0 < 0)
                    i0 += (0x00100000) >> j0;
                i0 &= (~i);
                i1 = 0;
            }
        }
    }
    else if (j0 > 51)
    {
        if (j0 == 0x400)
            return x + x; /* inf or NaN */
        else
            return x; /* x is integral */
    }
    else
    {
        i = ((uint32_t)(0xffffffff)) >> (j0 - 20);
        if ((i1 & i) == 0)
            return x; /* x is integral */
        if (huge + x > 0.0)
        { /* raise inexact flag */
            if (i0 < 0)
            {
                if (j0 == 20)
                    i0 += 1;
                else
                {
                    j = i1 + (1 << (52 - j0));
                    if (j < (uint32_t)i1)
                        i0 += 1; /* got a carry */
                    i1 = j;
                }
            }
            i1 &= (~i);
        }
    }
    INSERT_WORDS(x, i0, i1);
    return x;
}

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Variable Documentation

huge

const double huge = 1.0e300

static

Definition at line 48 of file floor.c.

Referenced by floor().