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authorDenys Vlasenko <vda.linux@googlemail.com>2009-10-09 18:59:04 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2009-10-09 18:59:04 (GMT)
commit3ea2e82dc7b32703f5043c3b30b049905a0d07aa (patch)
treeeae992a986a4ce66efa32845ecccc204a0c4c0e1
parenta05b2b856bf095dfd5f575c106d1a9e5ac6edd3c (diff)
downloadbusybox-3ea2e82dc7b32703f5043c3b30b049905a0d07aa.tar.gz
busybox-3ea2e82dc7b32703f5043c3b30b049905a0d07aa.tar.bz2
ash: factor out $RANDOM support
function old new delta next_random - 46 +46 ash_main 1361 1356 -5 change_random 132 97 -35 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 0/2 up/down: 46/-40) Total: 6 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--shell/Kbuild3
-rw-r--r--shell/ash.c46
-rw-r--r--shell/random.c37
-rw-r--r--shell/random.h19
4 files changed, 77 insertions, 28 deletions
diff --git a/shell/Kbuild b/shell/Kbuild
index 4d4741e..03960a8 100644
--- a/shell/Kbuild
+++ b/shell/Kbuild
@@ -8,4 +8,7 @@ lib-y:=
lib-$(CONFIG_ASH) += ash.o ash_ptr_hack.o
lib-$(CONFIG_HUSH) += hush.o match.o
lib-$(CONFIG_CTTYHACK) += cttyhack.o
+
lib-$(CONFIG_SH_MATH_SUPPORT) += math.o
+lib-$(CONFIG_ASH_RANDOM_SUPPORT) += random.o
+lib-$(CONFIG_HUSH_RANDOM_SUPPORT) += random.o
diff --git a/shell/ash.c b/shell/ash.c
index f2d372f..6ce6215 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -51,16 +51,19 @@
#include <setjmp.h>
#include <fnmatch.h>
#include "math.h"
+#if ENABLE_ASH_RANDOM_SUPPORT
+# include "random.h"
+#endif
#if defined SINGLE_APPLET_MAIN
/* STANDALONE does not make sense, and won't compile */
-#undef CONFIG_FEATURE_SH_STANDALONE
-#undef ENABLE_FEATURE_SH_STANDALONE
-#undef IF_FEATURE_SH_STANDALONE
-#undef IF_NOT_FEATURE_SH_STANDALONE(...)
-#define ENABLE_FEATURE_SH_STANDALONE 0
-#define IF_FEATURE_SH_STANDALONE(...)
-#define IF_NOT_FEATURE_SH_STANDALONE(...) __VA_ARGS__
+# undef CONFIG_FEATURE_SH_STANDALONE
+# undef ENABLE_FEATURE_SH_STANDALONE
+# undef IF_FEATURE_SH_STANDALONE
+# undef IF_NOT_FEATURE_SH_STANDALONE(...)
+# define ENABLE_FEATURE_SH_STANDALONE 0
+# define IF_FEATURE_SH_STANDALONE(...)
+# define IF_NOT_FEATURE_SH_STANDALONE(...) __VA_ARGS__
#endif
#ifndef PIPE_BUF
@@ -197,9 +200,7 @@ struct globals_misc {
/* Rarely referenced stuff */
#if ENABLE_ASH_RANDOM_SUPPORT
- /* Random number generators */
- int32_t random_galois_LFSR; /* Galois LFSR (fast but weak). signed! */
- uint32_t random_LCG; /* LCG (fast but weak) */
+ random_t random_gen;
#endif
pid_t backgndpid; /* pid of last background process */
smallint job_warning; /* user was warned about stopped jobs (can be 2, 1 or 0). */
@@ -224,8 +225,7 @@ extern struct globals_misc *const ash_ptr_to_globals_misc;
#define gotsig (G_misc.gotsig )
#define trap (G_misc.trap )
#define trap_ptr (G_misc.trap_ptr )
-#define random_galois_LFSR (G_misc.random_galois_LFSR)
-#define random_LCG (G_misc.random_LCG )
+#define random_gen (G_misc.random_gen )
#define backgndpid (G_misc.backgndpid )
#define job_warning (G_misc.job_warning)
#define INIT_G_misc() do { \
@@ -10075,28 +10075,18 @@ change_random(const char *value)
/* Another example - taps at 32 31 30 10: */
/* MASK = 0x00400007 */
+ uint32_t t;
+
if (value == NULL) {
/* "get", generate */
- uint32_t t;
-
- /* LCG has period of 2^32 and alternating lowest bit */
- random_LCG = 1664525 * random_LCG + 1013904223;
- /* Galois LFSR has period of 2^32-1 = 3 * 5 * 17 * 257 * 65537 */
- t = (random_galois_LFSR << 1);
- if (random_galois_LFSR < 0) /* if we just shifted 1 out of msb... */
- t ^= MASK;
- random_galois_LFSR = t;
- /* Both are weak, combining them gives better randomness
- * and ~2^64 period. & 0x7fff is probably bash compat
- * for $RANDOM range. Combining with subtraction is
- * just for fun. + and ^ would work equally well. */
- t = (t - random_LCG) & 0x7fff;
+ t = next_random(&random_gen);
/* set without recursion */
setvar(vrandom.text, utoa(t), VNOFUNC);
vrandom.flags &= ~VNOFUNC;
} else {
/* set/reset */
- random_galois_LFSR = random_LCG = strtoul(value, NULL, 10);
+ t = strtoul(value, NULL, 10);
+ INIT_RANDOM_T(&random_gen, (t ? t : 1), t);
}
}
#endif
@@ -13271,7 +13261,7 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
#if ENABLE_ASH_RANDOM_SUPPORT
/* Can use monotonic_ns() for better randomness but for now it is
* not used anywhere else in busybox... so avoid bloat */
- random_galois_LFSR = random_LCG = rootpid + monotonic_us();
+ INIT_RANDOM_T(&random_gen, rootpid, monotonic_us());
#endif
init();
setstackmark(&smark);
diff --git a/shell/random.c b/shell/random.c
new file mode 100644
index 0000000..a4dce84
--- /dev/null
+++ b/shell/random.c
@@ -0,0 +1,37 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * $RANDOM support.
+ *
+ * Copyright (C) 2008 Denys Vlasenko
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ */
+#include "libbb.h"
+#include "random.h"
+
+uint32_t FAST_FUNC
+next_random(random_t *rnd)
+{
+ /* Galois LFSR parameter */
+ /* Taps at 32 31 29 1: */
+ enum { MASK = 0x8000000b };
+ /* Another example - taps at 32 31 30 10: */
+ /* MASK = 0x00400007 */
+
+ uint32_t t;
+
+ /* LCG has period of 2^32 and alternating lowest bit */
+ rnd->LCG = 1664525 * rnd->LCG + 1013904223;
+ /* Galois LFSR has period of 2^32-1 = 3 * 5 * 17 * 257 * 65537 */
+ t = (rnd->galois_LFSR << 1);
+ if (rnd->galois_LFSR < 0) /* if we just shifted 1 out of msb... */
+ t ^= MASK;
+ rnd->galois_LFSR = t;
+ /* Both are weak, combining them gives better randomness
+ * and ~2^64 period. & 0x7fff is probably bash compat
+ * for $RANDOM range. Combining with subtraction is
+ * just for fun. + and ^ would work equally well. */
+ t = (t - rnd->LCG) & 0x7fff;
+
+ return t;
+}
diff --git a/shell/random.h b/shell/random.h
new file mode 100644
index 0000000..2d29a60
--- /dev/null
+++ b/shell/random.h
@@ -0,0 +1,19 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * $RANDOM support.
+ *
+ * Copyright (C) 2008 Denys Vlasenko
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ */
+
+typedef struct random_t {
+ /* Random number generators */
+ int32_t galois_LFSR; /* Galois LFSR (fast but weak). signed! */
+ uint32_t LCG; /* LCG (fast but weak) */
+} random_t;
+
+#define INIT_RANDOM_T(rnd, nonzero, v) \
+ ((rnd)->galois_LFSR = (nonzero), (rnd)->LCG = (v))
+
+uint32_t next_random(random_t *rnd) FAST_FUNC;