From mboxrd@z Thu Jan  1 00:00:00 1970
X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/72
Path: news.gmane.org!not-for-mail
From: Szabolcs Nagy <nsz@port70.net>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: Completeness status of musl
Date: Thu, 23 Jun 2011 20:50:41 +0200
Message-ID: <20110623185041.GQ27421@port70.net>
References: <4DE28333.9040900@int3.at>
 <20110529180854.GC6142@port70.net>
 <20110530103009.GE6142@port70.net>
 <20110530154741.GB277@brightrain.aerifal.cx>
 <20110530172735.GF6142@port70.net>
 <20110608235810.GJ191@brightrain.aerifal.cx>
 <20110621014640.GL27421@port70.net>
 <20110623065452.GU12592@brightrain.aerifal.cx>
 <20110623132517.GO27421@port70.net>
 <20110623141608.GP27421@port70.net>
Reply-To: musl@lists.openwall.com
NNTP-Posting-Host: lo.gmane.org
Mime-Version: 1.0
Content-Type: multipart/mixed; boundary="gneEPciiIl/aKvOT"
X-Trace: dough.gmane.org 1308855069 10834 80.91.229.12 (23 Jun 2011 18:51:09 GMT)
X-Complaints-To: usenet@dough.gmane.org
NNTP-Posting-Date: Thu, 23 Jun 2011 18:51:09 +0000 (UTC)
To: musl@lists.openwall.com
Original-X-From: musl-return-156-gllmg-musl=m.gmane.org@lists.openwall.com Thu Jun 23 20:51:05 2011
Return-path: <musl-return-156-gllmg-musl=m.gmane.org@lists.openwall.com>
Envelope-to: gllmg-musl@lo.gmane.org
Original-Received: from mother.openwall.net ([195.42.179.200])
	by lo.gmane.org with smtp (Exim 4.69)
	(envelope-from <musl-return-156-gllmg-musl=m.gmane.org@lists.openwall.com>)
	id 1QZozY-0002Ws-C8
	for gllmg-musl@lo.gmane.org; Thu, 23 Jun 2011 20:51:04 +0200
Original-Received: (qmail 5436 invoked by uid 550); 23 Jun 2011 18:51:04 -0000
Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm
Precedence: bulk
List-Post: <mailto:musl@lists.openwall.com>
List-Help: <mailto:musl-help@lists.openwall.com>
List-Unsubscribe: <mailto:musl-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:musl-subscribe@lists.openwall.com>
Original-Received: (qmail 5428 invoked from network); 23 Jun 2011 18:51:03 -0000
Content-Disposition: inline
In-Reply-To: <20110623141608.GP27421@port70.net>
User-Agent: Mutt/1.5.20 (2009-06-14)
Xref: news.gmane.org gmane.linux.lib.musl.general:72
Archived-At: <http://permalink.gmane.org/gmane.linux.lib.musl.general/72>


--gneEPciiIl/aKvOT
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

* Szabolcs Nagy <nsz@port70.net> [2011-06-23 16:16:08 +0200]:
> modified a bit to use uint32_t and uint64_t

i changed the seeding

--gneEPciiIl/aKvOT
Content-Type: text/x-csrc; charset=us-ascii
Content-Disposition: attachment; filename="random.c"

#include <stdlib.h>
#include <stdint.h>

/*
this code uses the same lagged fibonacci generator as the
original bsd random implementation except for the seeding

different seeds produce different sequences with long period
(other libcs seed the state with a park-miller generator
when seed=0 some fail to produce good random sequence
others produce the same sequence as another seed)
*/

static uint32_t init[] = {
0x00000000,0x5851f42d,0xc0b18ccf,0xcbb5f646,
0xc7033129,0x30705b04,0x20fd5db4,0x9a8b7f78,
0x502959d8,0xab894868,0x6c0356a7,0x88cdb7ff,
0xb477d43f,0x70a3a52b,0xa8e4baf1,0xfd8341fc,
0x8ae16fd9,0x742d2f7a,0x0d1f0796,0x76035e09,
0x40f7702c,0x6fa72ca5,0xaaa84157,0x58a0df74,
0xc74a0364,0xae533cc4,0x04185faf,0x6de3b115,
0x0cab8628,0xf043bfa4,0x398150e9,0x37521657};

static int n = 31;
static int i = 3;
static int j = 0;
static uint32_t *x = init+1;

static uint32_t lcg31(uint32_t x) {
	return (1103515245*x + 12345) & 0x7fffffff;
}

static uint64_t lcg64(uint64_t x) {
	return 6364136223846793005ull*x + 1;
}

static void *savestate() {
	x[-1] = (n<<16)|(i<<8)|j;
	return x-1;
}

static void loadstate(uint32_t *state) {
	x = state+1;
	n = x[-1]>>16;
	i = (x[-1]>>8)&0xff;
	j = x[-1]&0xff;
}

void srandom(unsigned seed) {
	int k;
	uint64_t s = seed;

	if (n == 0) {
		x[0] = s;
		return;
	}
	i = n == 31 || n == 7 ? 3 : 1;
	j = 0;
	for (k = 0; k < n; k++) {
		s = lcg64(s);
		x[k] = s>>32;
	}
	/* make sure x contains at least one odd number */
	x[0] |= 1;
}

char *initstate(unsigned seed, char *state, size_t size) {
	void *old = savestate();
	if (size < 8)
		return 0;
	else if (size < 32)
		n = 0;
	else if (size < 64)
		n = 7;
	else if (size < 128)
		n = 15;
	else if (size < 256)
		n = 31;
	else
		n = 63;
	x = (uint32_t*)state + 1;
	srandom(seed);
	return old;
}

char *setstate(char *state) {
	void *old = savestate();
	loadstate((uint32_t*)state);
	return old;
}

long random(void) {
	long k;

	if (n == 0)
		return x[0] = lcg31(x[0]);
	x[i] += x[j];
	k = x[i]>>1;
	if (++i == n)
		i = 0;
	if (++j == n)
		j = 0;
	return k;
}

--gneEPciiIl/aKvOT--