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add simple15 shift to randomize tests

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This commit is contained in:
Radim Kolar 2024-07-13 12:22:08 +02:00
parent ca1abea3ea
commit 848368274c
2 changed files with 31 additions and 3 deletions
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2
ChangeLog
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@ -30,6 +30,8 @@ Version NEXT
dependant. classic fsp algo seems to produce best results.
randomcheck: added skip8 method. skips 8 lowest bits from
random() output
randomcheck: added simple15 method. its currently used random
number generator in 2.8.1 beta 29 code
Version 2.8.1b29 - 24 Aug 2019
added scons command line argument without-fspscan=yes for building

32
tests/randomcheck.c
View File

@ -4,7 +4,7 @@
#include "my-string.h"
#include <math.h>
#define GROUPS 5
#define GROUPS 6
static int group[GROUPS];
static int bitcount[16];
static int rounds;
@ -35,6 +35,15 @@ static unsigned short simple (void)
return random();
}
/*
shift random() 15 times to get higher bits.
used in fsp beta 29 as production random code.
*/
static unsigned short simple15 (void)
{
return ( random() >> 15 );
}
/* get high bits from random() result.
In most classic random implementations used in libc
@ -45,11 +54,16 @@ In modern random() generators there should be no difference.
static unsigned short simple2 (void)
{
/* we assume that our return value is 16 bits long
and random() returns only positive long integers
and random() returns only positive long integers.
Original code used >> 15
*/
/* TODO: this needs to be checked on 64-bit systems because
I am not sure if random returns 31 bits or 63 bits of
randomness there.
Current status:
32-bit: 17 shifts
64-bit: 49 shifts
*/
return ( random() >> (SIZEOF_LONG*8 - 16 - 1) );
}
@ -148,6 +162,9 @@ static void run_one(void)
run_randomtest(skip8);
worst[4] = worst_bitcount();
run_randomtest(simple15);
worst[5] = worst_bitcount();
/* fimd the best algo */
float minValue = worst[0];
int minIndex = 0;
@ -208,9 +225,17 @@ int main(int argc,const char *argv[])
run_randomtest(simple2);
print_bitcount();
printf("Generator: simple15 (high bits legacy)\n");
run_randomtest(simple15);
print_bitcount();
printf("Generator: Numerical Recipes\n");
run_randomtest(nr);
print_bitcount();
printf("Generator: skip8\n");
run_randomtest(skip8);
print_bitcount();
} else {
int i;
for (i=0; i< groups; i++)
@ -219,10 +244,11 @@ int main(int argc,const char *argv[])
run_one();
}
printf("Winning generators\n\n");
printf("Winning generators:\n\n");
printf("Generator: classic %d\n", group[0]);
printf("Generator: simple (low bits) %d\n", group[1]);
printf("Generator: simple2 (high bits) %d\n", group[2]);
printf("Generator: simple15 (shift by 15) %d\n", group[5]);
printf("Generator: Numerical Recipes %d\n", group[3]);
printf("Generator: skip8 (skip 8 lower bits) %d\n", group[4]);
}