s_modff.c

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/* s_modff.c -- float version of s_modf.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice 
 * is preserved.
 * ====================================================
 */

#include "math.h"
#include "math_private.h"

static const float one = 1.0;

float
modff(float x, float *iptr)
{
    int32_t i0,jj0;
    u_int32_t i;
    GET_FLOAT_WORD(i0,x);
    jj0 = ((i0>>23)&0xff)-0x7f; /* exponent of x */
    if(jj0<23) {            /* integer part in x */
        if(jj0<0) {         /* |x|<1 */
            SET_FLOAT_WORD(*iptr,i0&0x80000000);    /* *iptr = +-0 */
        return x;
        } else {
        i = (0x007fffff)>>jj0;
        if((i0&i)==0) {         /* x is integral */
            u_int32_t ix;
            *iptr = x;
            GET_FLOAT_WORD(ix,x);
            SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
            return x;
        } else {
            SET_FLOAT_WORD(*iptr,i0&(~i));
            return x - *iptr;
        }
        }
    } else {            /* no fraction part */
        u_int32_t ix;
        *iptr = x*one;
        GET_FLOAT_WORD(ix,x);
        SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
        return x;
    }
}