drygdryg/calc
1
0
Fork 0
mirror of https://github.com/lcn2/calc.git synced 2025-08-16 01:03:29 +03:00
Code Issues Packages Projects Releases Wiki Activity

Improve seed()

Browse Source 
Added charbit.h to define CALC_CHARBIT which is either CHAR_BIT
from <limits.h> or 8 or a value set by the Makefile variable
CALC_CHARBIT.  Added have_limits.h to determine if <limits.h>
is a system include file.
This commit is contained in:
Landon Curt Noll
2021-12-07 21:41:28 -08:00
parent a02f8aa9f9
commit 177a5d00d1
8 changed files with 208 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
seed.c
View File

@@ -80,7 +80,8 @@
#endif
#if defined(HAVE_STDLIB_H)
# include <stdlib.h>
# define RANDOM_CNT (16) /* random() call repeat count */
/* NOTE: RANDOM_CNT should remain 32 to circular shift 31-bit returns */
# define RANDOM_CNT (32) /* random() call repeat and circular shift */
# define INITSTATE_SIZE (256) /* initstate pool size */
#endif
#include <setjmp.h>
@@ -464,6 +465,7 @@ pseudo_seed(void)
/**/
#if defined(HAVE_STDLIB_H)
unsigned long tmp; /* temp holder of 31-bit random() */
unsigned past_hash; /* prev hash or xor-folded prev hash */
long random_before[RANDOM_CNT]; /* random() pre initstate() */
char *initstate_ret; /* return from initstate() call */
@@ -642,9 +644,10 @@ pseudo_seed(void)
/* classic 31-bit random seeded with time of day, count, prev hash */
srandom((unsigned)(sdata.time) ^ (unsigned)call_count ^ past_hash);
for (j=0; j < RANDOM_CNT; j += 2) {
random_before[j] = random();
random_before[j+1] = (random() << 1);
for (j=0; j < RANDOM_CNT; ++j) {
tmp = random(); /* 31-bit value */
/* we 32-bit circular shift to spread 31-bit returns around */
random_before[j] = (tmp << j) | (tmp >> (RANDOM_CNT-j));
}
/* initialize random state with the FNV hash of sdata */
@@ -659,9 +662,10 @@ pseudo_seed(void)
#endif /* HAVE_B64 */
/* use 31-bit random some more with the new random state */
for (j=0; j < RANDOM_CNT; j += 2) {
random_after[j] = random();
random_after[j+1] = (random() << 1);
for (j=0; j < RANDOM_CNT; ++j) {
tmp = random(); /* 31-bit value */
/* we 32-bit circular shift to spread 31-bit returns around */
random_after[j] = (tmp << j) | (tmp >> (RANDOM_CNT-j));
}
/* restore previous state */