aboutsummaryrefslogtreecommitdiff
path: root/shell/random.h
diff options
context:
space:
mode:
authorDenys Vlasenko <vda.linux@googlemail.com>2014-03-13 12:52:43 +0100
committerDenys Vlasenko <vda.linux@googlemail.com>2014-03-13 12:52:43 +0100
commitfb183076a3a6580a4aba435c53ce033ef89e7fe6 (patch)
tree72e36e623d7b8841825a8d82aabe5ac7b7654cab /shell/random.h
parent69f9567de28976cfbc7b216c46aa391ce82bd3b7 (diff)
downloadbusybox-w32-fb183076a3a6580a4aba435c53ce033ef89e7fe6.tar.gz
busybox-w32-fb183076a3a6580a4aba435c53ce033ef89e7fe6.tar.bz2
busybox-w32-fb183076a3a6580a4aba435c53ce033ef89e7fe6.zip
ash,hush: improve randomness of $RANDOM, add easy-ish way to test it
function old new delta next_random 68 113 +45 change_random 103 121 +18 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to '')
-rw-r--r--shell/random.h16
1 files changed, 12 insertions, 4 deletions
diff --git a/shell/random.h b/shell/random.h
index 180c48abb..c4eb44c13 100644
--- a/shell/random.h
+++ b/shell/random.h
@@ -12,16 +12,24 @@
12PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN 12PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
13 13
14typedef struct random_t { 14typedef struct random_t {
15 /* Random number generators */ 15 /* State of random number generators: */
16 int32_t galois_LFSR; /* Galois LFSR (fast but weak). signed! */ 16
17 uint32_t LCG; /* LCG (fast but weak) */ 17 /* Galois LFSR (fast but weak) */
18 int32_t galois_LFSR; /* must be signed! */
19
20 /* LCG (fast but weak) */
21 uint32_t LCG;
22
23 /* 64-bit xorshift (fast, moderate strength) */
24 uint32_t xs64_x;
25 uint32_t xs64_y;
18} random_t; 26} random_t;
19 27
20#define UNINITED_RANDOM_T(rnd) \ 28#define UNINITED_RANDOM_T(rnd) \
21 ((rnd)->galois_LFSR == 0) 29 ((rnd)->galois_LFSR == 0)
22 30
23#define INIT_RANDOM_T(rnd, nonzero, v) \ 31#define INIT_RANDOM_T(rnd, nonzero, v) \
24 ((rnd)->galois_LFSR = (nonzero), (rnd)->LCG = (v)) 32 ((rnd)->galois_LFSR = (rnd)->xs64_x = (nonzero), (rnd)->LCG = (rnd)->xs64_y = (v))
25 33
26#define CLEAR_RANDOM_T(rnd) \ 34#define CLEAR_RANDOM_T(rnd) \
27 ((rnd)->galois_LFSR = 0) 35 ((rnd)->galois_LFSR = 0)