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/*
* HT Editor
* htanaly.cc
*
* Copyright (C) 1999, 2000, 2001 Sebastian Biallas (sb@web-productions.de)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "tools.h"
#include "htdebug.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
int *random_permutation(int max)
{
if (!max) return NULL;
int *table= (int *)smalloc(max * sizeof(int));
int i,j,k,l,m;
for (i=0; i<max; i++) table[i] = i;
for (i=0; i<max; i++) {
k=rand()%(max);
l=rand()%(max);
m=rand()%(max);
j=table[k];
table[k]=table[l];
table[l]=j;
j=table[i];
table[i]=table[m];
table[m]=j;
}
return table;
}
#define LN2 0.693147180559945309417232121458177
double calc_entropy(byte *buf, int size)
{
int p[256];
if (!size) return 0.0;
memset(p, 0, sizeof p);
for (int i=0; i<size; i++) {
p[*buf]++;
buf++;
}
double result = 0.0;
for (int i=0; i<256; i++) {
if (p[i]) {
double pi = p[i];
pi /= size;
result += pi * log(pi) / LN2;
}
}
return -result;
}
/*
* buffer size must be 64 bytes
* return value will be in range from 0 to 100
*/
int calc_entropy2(byte *buf, int size)
{
int p[256];
int result = 0;
if (size<3) return 0;
memset(p, 0, sizeof p);
// pass1
byte *b = buf;
for (int i=0; i < size; i++) {
if (p[*b]++ == 0) {
result ++;
}
b++;
}
memset(p, 0, sizeof p);
b = buf;
// pass2
size--;
for (int i=0; i < size; i++) {
int d = b[0]-b[1];
if (d<0) d = -d;
if (p[d]++ == 0) {
result ++;
}
b++;
}
memset(p, 0, sizeof p);
b = buf;
// pass3
size--;
for (int i=0; i < size; i++) {
int d = b[0]-b[1];
int e = b[1]-b[2];
if (d<0) d = -d;
if (e<0) e = -e;
d = d-e;
if (d<0) d = -d;
if (p[d]++ == 0) {
result ++;
}
b++;
}
return (result-3)*100/(size*3+3);
}
/*
* "out of memory" - handlers
*/
int out_of_memory(int size)
{
printf("Out of memory.");
exit(1);
return OUT_OF_MEMORY_FAIL;
}
int (*out_of_memory_func)(int size)=&out_of_memory;
void *smalloc(size_t size)
{
void *p;
retry:
if ((p=malloc(size))) return p;
switch (out_of_memory_func(size)) {
case OUT_OF_MEMORY_IGNORE:
return NULL;
case OUT_OF_MEMORY_RETRY:
goto retry;
default:
exit(666);
}
}
void *smalloc0(size_t size)
{
void *p;
retry0:
if ((p=malloc(size))) return memset(p, 0, size);
switch (out_of_memory_func(size)) {
case OUT_OF_MEMORY_IGNORE:
return NULL;
case OUT_OF_MEMORY_RETRY:
goto retry0;
default:
exit(666);
}
}
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