forked from Telodendria/Telodendria
[#48] Add Rand API and make StrRandom() use it.
This commit is contained in:
parent
fdecac576f
commit
6a593ab8a0
3 changed files with 129 additions and 9 deletions
83
src/Rand.c
Normal file
83
src/Rand.c
Normal file
|
@ -0,0 +1,83 @@
|
||||||
|
/*
|
||||||
|
* Copyright (C) 2022-2023 Jordan Bancino <@jordan:bancino.net>
|
||||||
|
*
|
||||||
|
* Permission is hereby granted, free of charge, to any person
|
||||||
|
* obtaining a copy of this software and associated documentation files
|
||||||
|
* (the "Software"), to deal in the Software without restriction,
|
||||||
|
* including without limitation the rights to use, copy, modify, merge,
|
||||||
|
* publish, distribute, sublicense, and/or sell copies of the Software,
|
||||||
|
* and to permit persons to whom the Software is furnished to do so,
|
||||||
|
* subject to the following conditions:
|
||||||
|
*
|
||||||
|
* The above copyright notice and this permission notice shall be
|
||||||
|
* included in all copies or portions of the Software.
|
||||||
|
*
|
||||||
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
|
||||||
|
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
||||||
|
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
|
||||||
|
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
|
||||||
|
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
|
||||||
|
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
|
||||||
|
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
||||||
|
* SOFTWARE.
|
||||||
|
*/
|
||||||
|
#include <Rand.h>
|
||||||
|
|
||||||
|
#include <Util.h>
|
||||||
|
|
||||||
|
#include <stdlib.h>
|
||||||
|
#include <pthread.h>
|
||||||
|
#include <unistd.h>
|
||||||
|
|
||||||
|
/* Generate random numbers using rejection sampling.
|
||||||
|
* The basic idea is to "reroll" if a number happens to be
|
||||||
|
* outside the range. However this could be extremely inefficient.
|
||||||
|
*
|
||||||
|
* Another idea would just be to "reroll" if the generated number
|
||||||
|
* ends up in the previously "biased" range, and THEN do a modulo.
|
||||||
|
*
|
||||||
|
* This would be far more efficient for small values of max,
|
||||||
|
* and fixes the bias issue. */
|
||||||
|
|
||||||
|
/* This algorithm therefore computes N random numbers generally in
|
||||||
|
* O(N) time, while being less biased. */
|
||||||
|
void
|
||||||
|
RandIntN(int * buf, size_t size, unsigned int max)
|
||||||
|
{
|
||||||
|
static pthread_mutex_t seedLock = PTHREAD_MUTEX_INITIALIZER;
|
||||||
|
static unsigned int seed = 0;
|
||||||
|
int tmp;
|
||||||
|
/* Limit the range to banish all previously biased results */
|
||||||
|
const int allowed = RAND_MAX - RAND_MAX % max;
|
||||||
|
|
||||||
|
size_t i;
|
||||||
|
|
||||||
|
pthread_mutex_lock(&seedLock);
|
||||||
|
if (!seed)
|
||||||
|
{
|
||||||
|
/* Generate a seed from the system time, PID, and TID */
|
||||||
|
seed = UtilServerTs() ^ getpid() ^ (unsigned long) pthread_self();
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Generate {size} random numbers. */
|
||||||
|
for (i = 0; i < size; i++)
|
||||||
|
{
|
||||||
|
/* Most of the time, this will take about 1 loop */
|
||||||
|
do
|
||||||
|
{
|
||||||
|
tmp = rand_r(&seed);
|
||||||
|
} while (tmp >= allowed);
|
||||||
|
/* Since a generated number here is never in the biased range,
|
||||||
|
* we can now safely use modulo. */
|
||||||
|
buf[i] = tmp % max;
|
||||||
|
}
|
||||||
|
pthread_mutex_unlock(&seedLock);
|
||||||
|
}
|
||||||
|
/* Generate just 1 random number */
|
||||||
|
int
|
||||||
|
RandInt(unsigned int max)
|
||||||
|
{
|
||||||
|
int val = 0;
|
||||||
|
RandIntN(&val, 1, max);
|
||||||
|
return val;
|
||||||
|
}
|
20
src/Str.c
20
src/Str.c
|
@ -25,6 +25,7 @@
|
||||||
|
|
||||||
#include <Memory.h>
|
#include <Memory.h>
|
||||||
#include <Util.h>
|
#include <Util.h>
|
||||||
|
#include <Rand.h>
|
||||||
|
|
||||||
#include <stdlib.h>
|
#include <stdlib.h>
|
||||||
#include <string.h>
|
#include <string.h>
|
||||||
|
@ -153,10 +154,9 @@ char *
|
||||||
StrRandom(size_t len)
|
StrRandom(size_t len)
|
||||||
{
|
{
|
||||||
static const char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
|
static const char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
|
||||||
static pthread_mutex_t seedLock = PTHREAD_MUTEX_INITIALIZER;
|
|
||||||
static unsigned int seed = 0;
|
|
||||||
|
|
||||||
char *str;
|
char *str;
|
||||||
|
int * nums;
|
||||||
size_t i;
|
size_t i;
|
||||||
|
|
||||||
if (!len)
|
if (!len)
|
||||||
|
@ -165,25 +165,27 @@ StrRandom(size_t len)
|
||||||
}
|
}
|
||||||
|
|
||||||
str = Malloc(len + 1);
|
str = Malloc(len + 1);
|
||||||
|
|
||||||
if (!str)
|
if (!str)
|
||||||
{
|
{
|
||||||
return NULL;
|
return NULL;
|
||||||
}
|
}
|
||||||
|
|
||||||
pthread_mutex_lock(&seedLock);
|
nums = Malloc(len);
|
||||||
|
if (!nums)
|
||||||
if (!seed)
|
|
||||||
{
|
{
|
||||||
seed = UtilServerTs() ^ getpid() ^ (unsigned long) pthread_self();
|
Free(str);
|
||||||
|
return NULL;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
/* TODO: This seems slow. */
|
||||||
|
RandIntN(nums, len, sizeof(charset) - 1);
|
||||||
for (i = 0; i < len; i++)
|
for (i = 0; i < len; i++)
|
||||||
{
|
{
|
||||||
str[i] = charset[rand_r(&seed) % (sizeof(charset) - 1)];
|
str[i] = charset[nums[i]];
|
||||||
}
|
}
|
||||||
|
|
||||||
pthread_mutex_unlock(&seedLock);
|
Free(nums);
|
||||||
|
|
||||||
str[len] = '\0';
|
str[len] = '\0';
|
||||||
return str;
|
return str;
|
||||||
}
|
}
|
||||||
|
|
35
src/include/Rand.h
Normal file
35
src/include/Rand.h
Normal file
|
@ -0,0 +1,35 @@
|
||||||
|
/*
|
||||||
|
* Copyright (C) 2022-2023 Jordan Bancino <@jordan:bancino.net>
|
||||||
|
*
|
||||||
|
* Permission is hereby granted, free of charge, to any person
|
||||||
|
* obtaining a copy of this software and associated documentation files
|
||||||
|
* (the "Software"), to deal in the Software without restriction,
|
||||||
|
* including without limitation the rights to use, copy, modify, merge,
|
||||||
|
* publish, distribute, sublicense, and/or sell copies of the Software,
|
||||||
|
* and to permit persons to whom the Software is furnished to do so,
|
||||||
|
* subject to the following conditions:
|
||||||
|
*
|
||||||
|
* The above copyright notice and this permission notice shall be
|
||||||
|
* included in all copies or portions of the Software.
|
||||||
|
*
|
||||||
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
|
||||||
|
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
||||||
|
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
|
||||||
|
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
|
||||||
|
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
|
||||||
|
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
|
||||||
|
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
||||||
|
* SOFTWARE.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#ifndef TELODENDRIA_RAND_H
|
||||||
|
#define TELODENDRIA_RAND_H
|
||||||
|
#include <stddef.h>
|
||||||
|
|
||||||
|
extern int
|
||||||
|
RandInt(unsigned int);
|
||||||
|
|
||||||
|
extern void
|
||||||
|
RandIntN(int *, size_t, unsigned int);
|
||||||
|
|
||||||
|
#endif /* TELODENDRIA_RAND_H */
|
Loading…
Reference in a new issue