harvey/sys/src/libmp/port/mptouv.c

/*
 * This file is part of the UCB release of Plan 9. It is subject to the license
 * terms in the LICENSE file found in the top-level directory of this
 * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
 * part of the UCB release of Plan 9, including this file, may be copied,
 * modified, propagated, or distributed except according to the terms contained
 * in the LICENSE file.
 */

#include "os.h"
#include <mp.h>
#include "dat.h"

#define VLDIGITS (sizeof(int64_t)/sizeof(mpdigit))

/*
 *  this code assumes that a vlong is an integral number of
 *  mpdigits long.
 */
mpint*
uvtomp(uint64_t v, mpint *b)
{
	int s;

	if(b == nil)
		b = mpnew(VLDIGITS*sizeof(mpdigit));
	else
		mpbits(b, VLDIGITS*sizeof(mpdigit));
	mpassign(mpzero, b);
	if(v == 0)
		return b;
	for(s = 0; s < VLDIGITS && v != 0; s++){
		b->p[s] = v;
		v >>= sizeof(mpdigit)*8;
	}
	b->top = s;
	return b;
}

uint64_t
mptouv(mpint *b)
{
	uint64_t v;
	int s;

	if(b->top == 0)
		return 0LL;

	mpnorm(b);
	if(b->top > VLDIGITS)
		return MAXVLONG;

	v = 0ULL;
	for(s = 0; s < b->top; s++)
		v |= (uint64_t)b->p[s]<<(s*sizeof(mpdigit)*8);

	return v;
}