cosmopolitan/third_party/gdtoa/gmisc.c

/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8   -*-│
│vi: set et ft=c ts=8 tw=8 fenc=utf-8                                       :vi│
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│  The author of this software is David M. Gay.                                │
│  Please send bug reports to David M. Gay <dmg@acm.org>                       │
│                          or Justine Tunney <jtunney@gmail.com>               │
│                                                                              │
│  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.                                                              │
│                                                                              │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "third_party/gdtoa/gdtoa.internal.h"
/* clang-format off */

void
__gdtoa_rshift(Bigint *b, int k)
{
	ULong *x, *x1, *xe, y;
	int n;
	x = x1 = b->x;
	n = k >> kshift;
	if (n < b->wds) {
		xe = x + b->wds;
		x += n;
		if (k &= kmask) {
			n = ULbits - k;
			y = *x++ >> k;
			while(x < xe) {
				*x1++ = (y | (*x << n)) & ALL_ON;
				y = *x++ >> k;
			}
			if ((*x1 = y) !=0)
				x1++;
		}
		else
			while(x < xe)
				*x1++ = *x++;
	}
	if ((b->wds = x1 - b->x) == 0)
		b->x[0] = 0;
}

int
__gdtoa_trailz(Bigint *b)
{
	ULong L, *x, *xe;
	int n = 0;
	x = b->x;
	xe = x + b->wds;
	for(n = 0; x < xe && !*x; x++)
		n += ULbits;
	if (x < xe) {
		L = *x;
		n += lo0bits(&L);
	}
	return n;
}