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authorRoland McGrath <roland@gnu.org>1995-02-22 05:47:15 +0000
committerRoland McGrath <roland@gnu.org>1995-02-22 05:47:15 +0000
commit50843ff068aae5b1ff58581eddd3bd107e99114b (patch)
tree0c72d59f78d63861d4a901fafd90cf6c3c822193 /stdlib/random.c
parent23ad311df0e01caa58b54afb8ae999a3ffc1ba7a (diff)
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Wed Feb 22 00:44:41 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu>
* sysdeps/mach/hurd/i386/sigreturn.c: Restore the FPU state. * stdlib/random.c (__srandom): Change algorithm used to populate the state array. (randtbl): Recomputed with new algorithm.
Diffstat (limited to 'stdlib/random.c')
-rw-r--r--stdlib/random.c26
1 files changed, 18 insertions, 8 deletions
diff --git a/stdlib/random.c b/stdlib/random.c
index fb32b36b87..473a5b13d3 100644
--- a/stdlib/random.c
+++ b/stdlib/random.c
@@ -122,12 +122,14 @@ static int seps[MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 };
static long int randtbl[DEG_3 + 1] =
{
TYPE_3,
- -851904987, -43806228, -2029755270, 1390239686, -1912102820,
- -485608943, 1969813258, -1590463333, -1944053249, 455935928, 508023712,
- -1714531963, 1800685987, -2015299881, 654595283, -1149023258,
- -1470005550, -1143256056, -1325577603, -1568001885, 1275120390,
- -607508183, -205999574, -1696891592, 1492211999, -1528267240,
- -952028296, -189082757, 362343714, 1424981831, 2039449641,
+
+ -1726662223, 379960547, 1735697613, 1040273694, 1313901226,
+ 1627687941, -179304937, -2073333483, 1780058412, -1989503057,
+ -615974602, 344556628, 939512070, -1249116260, 1507946756,
+ -812545463, 154635395, 1388815473, -1926676823, 525320961,
+ -1009028674, 968117788, -123449607, 1284210865, 435012392,
+ -2017506339, -911064859, -370259173, 1132637927, 1398500161,
+ -205601318,
};
/* FPTR and RPTR are two pointers into the state info, a front and a rear
@@ -179,11 +181,19 @@ DEFUN(__srandom, (x), unsigned int x)
{
register long int i;
for (i = 1; i < rand_deg; ++i)
- state[i] = (1103515145 * state[i - 1]) + 12345;
+ {
+ /* This does:
+ state[i] = (16807 * state[i - 1]) % 2147483647;
+ but avoids overflowing 31 bits. */
+ long int hi = state[i - 1] / 127773;
+ long int lo = state[i - 1] % 127773;
+ long int test = 16807 * lo - 2836 * hi;
+ state[i] = test + (test < 0 ? 2147483647 : 0);
+ }
fptr = &state[rand_sep];
rptr = &state[0];
for (i = 0; i < 10 * rand_deg; ++i)
- (void) __random();
+ (void) __random ();
}
}