source: vendor/FreeBSD-libc/current/gdtoa/smisc.c

/****************************************************************

The author of this software is David M. Gay.

Copyright (C) 1998, 1999 by Lucent Technologies
All Rights Reserved

Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name of Lucent or any of its entities
not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.

****************************************************************/

/* Please send bug reports to
        David M. Gay
        Bell Laboratories, Room 2C-463
        600 Mountain Avenue
        Murray Hill, NJ 07974-0636
        U.S.A.
        dmg@bell-labs.com
 */

#include "gdtoaimp.h"

 Bigint *
s2b
#ifdef KR_headers
        (s, nd0, nd, y9) CONST char *s; int nd0, nd; ULong y9;
#else
        (CONST char *s, int nd0, int nd, ULong y9)
#endif
{
        Bigint *b;
        int i, k;
        Long x, y;

        x = (nd + 8) / 9;
        for(k = 0, y = 1; x > y; y <<= 1, k++) ;
#ifdef Pack_32
        b = Balloc(k);
        b->x[0] = y9;
        b->wds = 1;
#else
        b = Balloc(k+1);
        b->x[0] = y9 & 0xffff;
        b->wds = (b->x[1] = y9 >> 16) ? 2 : 1;
#endif

        i = 9;
        if (9 < nd0) {
                s += 9;
                do b = multadd(b, 10, *s++ - '0');
                        while(++i < nd0);
                s++;
                }
        else
                s += 10;
        for(; i < nd; i++)
                b = multadd(b, 10, *s++ - '0');
        return b;
        }

 double
ratio
#ifdef KR_headers
        (a, b) Bigint *a, *b;
#else
        (Bigint *a, Bigint *b)
#endif
{
        double da, db;
        int k, ka, kb;

        dval(da) = b2d(a, &ka);
        dval(db) = b2d(b, &kb);
        k = ka - kb + ULbits*(a->wds - b->wds);
#ifdef IBM
        if (k > 0) {
                word0(da) += (k >> 2)*Exp_msk1;
                if (k &= 3)
                        dval(da) *= 1 << k;
                }
        else {
                k = -k;
                word0(db) += (k >> 2)*Exp_msk1;
                if (k &= 3)
                        dval(db) *= 1 << k;
                }
#else
        if (k > 0)
                word0(da) += k*Exp_msk1;
        else {
                k = -k;
                word0(db) += k*Exp_msk1;
                }
#endif
        return dval(da) / dval(db);
        }

#ifdef INFNAN_CHECK

 int
match
#ifdef KR_headers
        (sp, t) char **sp, *t;
#else
        (CONST char **sp, char *t)
#endif
{
        int c, d;
        CONST char *s = *sp;

        while( (d = *t++) !=0) {
                if ((c = *++s) >= 'A' && c <= 'Z')
                        c += 'a' - 'A';
                if (c != d)
                        return 0;
                }
        *sp = s + 1;
        return 1;
        }
#endif /* INFNAN_CHECK */

 void
#ifdef KR_headers
copybits(c, n, b) ULong *c; int n; Bigint *b;
#else
copybits(ULong *c, int n, Bigint *b)
#endif
{
        ULong *ce, *x, *xe;
#ifdef Pack_16
        int nw, nw1;
#endif

        ce = c + ((n-1) >> kshift) + 1;
        x = b->x;
#ifdef Pack_32
        xe = x + b->wds;
        while(x < xe)
                *c++ = *x++;
#else
        nw = b->wds;
        nw1 = nw & 1;
        for(xe = x + (nw - nw1); x < xe; x += 2)
                Storeinc(c, x[1], x[0]);
        if (nw1)
                *c++ = *x;
#endif
        while(c < ce)
                *c++ = 0;
        }

 ULong
#ifdef KR_headers
any_on(b, k) Bigint *b; int k;
#else
any_on(Bigint *b, int k)
#endif
{
        int n, nwds;
        ULong *x, *x0, x1, x2;

        x = b->x;
        nwds = b->wds;
        n = k >> kshift;
        if (n > nwds)
                n = nwds;
        else if (n < nwds && (k &= kmask)) {
                x1 = x2 = x[n];
                x1 >>= k;
                x1 <<= k;
                if (x1 != x2)
                        return 1;
                }
        x0 = x;
        x += n;
        while(x > x0)
                if (*--x)
                        return 1;
        return 0;
        }