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/*
* Argyll Color Correction System
*
* Random index routines.
*
* Author: Graeme W. Gill
* Date: 5/10/96
*
* Copyright 1996, Graeme W. Gill
* All rights reserved.
*
* This material is licenced under the GNU AFFERO GENERAL PUBLIC LICENSE Version 3 :-
* see the License.txt file for licencing details.
*/
#include <stdio.h>
#include <stdlib.h>
#include "randix.h"
#include <stdarg.h>
void error(char *fmt, ...), warning(char *fmt, ...), verbose(int level, char *fmt, ...);
/* A table entry structure */
typedef struct {
int bits; /* Number of bits */
int length; /* Length of sequence */
int xorm; /* Xor mask */
} tabe;
static tabe table[] = {
{ 1, (1<<1)-1, 0x1},
{ 2, (1<<2)-1, 0x3},
{ 3, (1<<3)-1, 0x3},
{ 4, (1<<4)-1, 0x13},
{ 5, (1<<5)-1, 0x1b},
{ 6, (1<<6)-1, 0x1b},
{ 7, (1<<7)-1, 0x65},
{ 8, (1<<8)-1, 0xc3},
{ 9, (1<<9)-1, 0x1b5},
{ 10, (1<<10)-1, 0x1c7},
{ 11, (1<<11)-1, 0x6bb},
{ 12, (1<<12)-1, 0x5c5},
{ 13, (1<<13)-1, 0x15b9},
{ 14, (1<<14)-1, 0x36d1},
{ 15, (1<<15)-1, 0x376b},
{ 16, (1<<16)-1, 0x5bab},
{ 17, (1<<17)-1, 0x1b5c5},
{ 18, (1<<18)-1, 0x15561},
{ 19, (1<<19)-1, 0x5b4db},
{ 20, (1<<20)-1, 0xf6e01},
{ 21, (1<<21)-1, 0x186517},
{ 22, (1<<22)-1, 0x6bf4f},
{ 23, (1<<23)-1, 0x376623},
{ 24, (1<<24)-1, 0xf54e35},
{ 0, 0, 0}
};
#define PSRAND(S, XOV, TBIT, MASK) ((((S) & TBIT) ? (((S) << 1) ^ (XOV)) : ((S) << 1)) & MASK)
static int
randix_next(struct _randix *p) {
int rv = p->ss-1; /* Return start value first */
do {
p->ss = PSRAND(p->ss, p->xorm, p->tbit, p->mask);
} while(p->ss >= p->length);
return rv;
}
/* Destroy ourselves */
static void
randix_del(randix *p) {
free (p);
}
/* Creator */
randix *new_randix(int length, int start)
{
int i;
randix *p;
if ((p = (randix *)malloc(sizeof(randix))) == NULL)
error ("randix: malloc failed");
p->next = randix_next;
p->del = randix_del;
if (length == 0)
error ("randix: Can't handle length %d",length);
start %= length;
p->length = length+1;
for (i = 0; table[i].bits != 0; i++) {
if (length <= table[i].length) {
p->tbit = 1 << (table[i].bits-1);
p->mask = (p->tbit << 1)-1;
p->xorm = table[i].xorm;
p->ss = start + 1;
return p;
break;
}
}
error ("randix: Can't handle length %d",length);
return NULL;
}
#ifdef NEVER
main(argc,argv)
int argc;
char *argv[];
{
int length = 11;
int i, iv, cv;
randix *r;
if (argc > 1)
length = atoi(argv[1]);
r = new_randix(length, 0);
iv = r->next(r);
printf("First Val = %d\n",iv);
i = 0;
do {
cv = r->next(r);
i++;
} while (cv != iv);
printf("Last Val = %d\n",cv);
printf("Count for length %d = %d\n",length,i);
return 0;
}
/* Basic printf type error() and warning() routines */
void
error(char *fmt, ...)
{
va_list args;
fprintf(stderr,"targen: Error - ");
va_start(args, fmt);
vfprintf(stderr, fmt, args);
va_end(args);
fprintf(stderr, "\n");
fflush(stdout);
exit (-1);
}
#endif /* NEVER */
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