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libbb: shrink monotonic_XXX functions, introduce monotonic_ns

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(unused for now)

function                                             old     new   delta
get_mono                                               -      31     +31
sv_main                                             1228    1234      +6
expand                                              1693    1697      +4
get_address                                          178     181      +3
utoa_to_buf                                          108     110      +2
builtin_exit                                          46      48      +2
qrealloc                                              36      33      -3
qgravechar                                           109     106      -3
ash_main                                            1383    1380      -3
grep_file                                            850     846      -4
popstring                                            140     134      -6
monotonic_us                                          85      60     -25
monotonic_sec                                         41      16     -25
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 5/7 up/down: 48/-69)            Total: -21 bytes
This commit is contained in:
Denis Vlasenko 2008-06-29 02:25:53 +00:00
parent 540ab7097c
commit ce13b76002
3 changed files with 31 additions and 11 deletions
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1
include/libbb.h
View File

@ -237,6 +237,7 @@ extern int *const bb_errno;
#define errno (*bb_errno)
#endif
unsigned long long monotonic_ns(void) FAST_FUNC;
unsigned long long monotonic_us(void) FAST_FUNC;
unsigned monotonic_sec(void) FAST_FUNC;

29
libbb/time.c
View File

@ -10,8 +10,8 @@
#include "libbb.h"
#if ENABLE_MONOTONIC_SYSCALL
#include <sys/syscall.h>
#include <sys/syscall.h>
/* Old glibc (< 2.3.4) does not provide this constant. We use syscall
* directly so this definition is safe. */
#ifndef CLOCK_MONOTONIC
@ -20,30 +20,47 @@
/* libc has incredibly messy way of doing this,
* typically requiring -lrt. We just skip all this mess */
static void get_mono(struct timespec *ts)
{
if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, ts))
bb_error_msg_and_die("clock_gettime(MONOTONIC) failed");
}
unsigned long long FAST_FUNC monotonic_ns(void)
{
struct timespec ts;
get_mono(&ts);
return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
}
unsigned long long FAST_FUNC monotonic_us(void)
{
struct timespec ts;
if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts))
bb_error_msg_and_die("clock_gettime(MONOTONIC) failed");
get_mono(&ts);
return ts.tv_sec * 1000000ULL + ts.tv_nsec/1000;
}
unsigned FAST_FUNC monotonic_sec(void)
{
struct timespec ts;
if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts))
bb_error_msg_and_die("clock_gettime(MONOTONIC) failed");
get_mono(&ts);
return ts.tv_sec;
}
#else
unsigned long long FAST_FUNC monotonic_ns(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_sec * 1000000000ULL + tv.tv_usec * 1000;
}
unsigned long long FAST_FUNC monotonic_us(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_sec * 1000000ULL + tv.tv_usec;
}
unsigned FAST_FUNC monotonic_sec(void)
{
return time(NULL);
}
#endif

12
shell/ash.c
View File

@ -9615,7 +9615,6 @@ setcmd(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED)
}
#if ENABLE_ASH_RANDOM_SUPPORT
/* Roughly copied from bash.. */
static void
change_random(const char *value)
{
@ -9636,10 +9635,11 @@ change_random(const char *value)
if (random_galois_LFSR < 0) /* if we just shifted 1 out of msb... */
t ^= MASK;
random_galois_LFSR = t;
/* Both are weak, xoring them gives better randomness
/* Both are weak, combining them gives better randomness
* and ~2^64 period. & 0x7fff is probably bash compat
* for $RANDOM range. */
t = (t ^ random_LCG) & 0x7fff;
* for $RANDOM range. Combining with subtraction is
* just for fun. + and ^ would work equally well. */
t = (t - random_LCG) & 0x7fff;
/* set without recursion */
setvar(vrandom.text, utoa(t), VNOFUNC);
vrandom.flags &= ~VNOFUNC;
@ -13432,7 +13432,9 @@ int ash_main(int argc ATTRIBUTE_UNUSED, char **argv)
rootpid = getpid();
#if ENABLE_ASH_RANDOM_SUPPORT
random_galois_LFSR = random_LCG = rootpid + time(NULL);
/* 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();
#endif
init();
setstackmark(&smark);