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Updated rand.c with a newer version from FreeBSD (version 1.17). This

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also removes the advertising clause.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25023 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2008-04-18 14:24:10 +00:00
parent dc1ffc79ef
commit 25010b8723
1 changed files with 70 additions and 10 deletions
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80
src/system/libroot/posix/stdlib/rand.c
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@ -10,10 +10,6 @@
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
@ -33,12 +29,14 @@
* Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93";
#endif /* LIBC_SCCS and not lint */
//#include "namespace.h"
//#include <sys/time.h> /* for sranddev() */
#include <sys/types.h>
//#include <fcntl.h> /* for sranddev() */
#include <stdlib.h>
//#include <unistd.h> /* for sranddev() */
//#include "un-namespace.h"
#ifdef TEST
#include <stdio.h>
@ -47,7 +45,34 @@ static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93";
static int
do_rand(unsigned long *ctx)
{
#ifdef USE_WEAK_SEEDING
/*
* Historic implementation compatibility.
* The random sequences do not vary much with the seed,
* even with overflowing.
*/
return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
#else /* !USE_WEAK_SEEDING */
/*
* Compute x = (7^5 * x) mod (2^31 - 1)
* without overflowing 31 bits:
* (2^31 - 1) = 127773 * (7^5) + 2836
* From "Random number generators: good ones are hard to find",
* Park and Miller, Communications of the ACM, vol. 31, no. 10,
* October 1988, p. 1195.
*/
long hi, lo, x;
/* Can't be initialized with 0, so use another value. */
if (*ctx == 0)
*ctx = 123459876;
hi = *ctx / 127773;
lo = *ctx % 127773;
x = 16807 * lo - 2836 * hi;
if (x < 0)
x += 0x7fffffff;
return ((*ctx = x) % ((u_long)RAND_MAX + 1));
#endif /* !USE_WEAK_SEEDING */
}
@ -55,8 +80,10 @@ int
rand_r(unsigned int *ctx)
{
u_long val = (u_long) *ctx;
*ctx = do_rand(&val);
return (int) *ctx;
int r = do_rand(&val);
*ctx = (unsigned int) val;
return (r);
}
@ -65,7 +92,7 @@ static u_long next = 1;
int
rand()
{
return do_rand(&next);
return (do_rand(&next));
}
void
@ -75,6 +102,39 @@ u_int seed;
next = seed;
}
#if 0
/*
* sranddev:
*
* Many programs choose the seed value in a totally predictable manner.
* This often causes problems. We seed the generator using the much more
* secure random(4) interface.
*/
void
sranddev()
{
int fd, done;
done = 0;
fd = _open("/dev/random", O_RDONLY, 0);
if (fd >= 0) {
if (_read(fd, (void *) &next, sizeof(next)) == sizeof(next))
done = 1;
_close(fd);
}
if (!done) {
struct timeval tv;
unsigned long junk;
gettimeofday(&tv, NULL);
srand((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk);
}
}
#endif // 0
#ifdef TEST
main()