martin/emacs
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

(seed_random): Renamed from srandom.

Browse Source 
(get_random): Renamed from random.  Return VALBITS random bits.
This commit is contained in:
Karl Heuer
1995-01-19 23:37:10 +00:00
parent 99175c23d3
commit 4bb8c8b792
1 changed files with 65 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

90
src/sysdep.c
View File

@@ -2699,38 +2699,79 @@ bcmp (b1, b2, length) /* This could be a macro! */
#endif /* not BSTRING */
#ifndef HAVE_RANDOM
#ifndef random
long
random ()
{
#ifdef HAVE_LRAND48
return lrand48 ();
#else
/* The BSD rand returns numbers in the range of 0 to 2e31 - 1,
with unusable least significant bits. The USG rand returns
numbers in the range of 0 to 2e15 - 1, all usable. Let us
build a usable 30 bit number from either. */
#ifdef USG
return (rand () << 15) + rand ();
#else
return (rand () & 0x3fff8000) + (rand () >> 16);
#ifdef random
#define HAVE_RANDOM
#endif
#endif
}
srandom (arg)
int arg;
/* Figure out how many bits the system's random number generator uses.
`random' and `lrand48' are assumed to return 31 usable bits.
BSD `rand' returns a 31 bit value but the low order bits are unusable;
so we'll shift it and treat it like the 15-bit USG `rand'. */
#ifndef RAND_BITS
# ifdef HAVE_RANDOM
# define RAND_BITS 31
# else /* !HAVE_RANDOM */
# ifdef HAVE_LRAND48
# define RAND_BITS 31
# define random lrand48
# else /* !HAVE_LRAND48 */
# define RAND_BITS 15
# if RAND_MAX == 32767
# define random rand
# else /* RAND_MAX != 32767 */
# if RAND_MAX == 2147483647
# define random() (rand () >> 16)
# else /* RAND_MAX != 2147483647 */
# ifdef USG
# define random rand
# else
# define random() (rand () >> 16)
# endif /* !BSD */
# endif /* RAND_MAX != 2147483647 */
# endif /* RAND_MAX != 32767 */
# endif /* !HAVE_LRAND48 */
# endif /* !HAVE_RANDOM */
#endif /* !RAND_BITS */
void
seed_random (arg)
long arg;
{
#ifdef HAVE_LRAND48
#ifdef HAVE_RANDOM
srandom ((unsigned int)arg);
#else
# ifdef HAVE_LRAND48
srand48 (arg);
#else
srand (arg);
# else
srand ((unsigned int)arg);
# endif
#endif
}
#endif /* no random */
#endif /* not HAVE_RANDOM */
/*
* Build a full Emacs-sized word out of whatever we've got.
* This suffices even for a 64-bit architecture with a 15-bit rand.
*/
long
get_random ()
{
long val = random ();
#if VALBITS > RAND_BITS
val = (val << RAND_BITS) ^ random ();
#if VALBITS > 2*RAND_BITS
val = (val << RAND_BITS) ^ random ();
#if VALBITS > 3*RAND_BITS
val = (val << RAND_BITS) ^ random ();
#if VALBITS > 4*RAND_BITS
val = (val << RAND_BITS) ^ random ();
#endif /* need at least 5 */
#endif /* need at least 4 */
#endif /* need at least 3 */
#endif /* need at least 2 */
return val & ((1L << VALBITS) - 1);
}
#ifdef WRONG_NAME_INSQUE
@@ -4977,4 +5018,3 @@ dlclose ()
}
#endif /* USE_DL_STUBS */