mirror of
https://github.com/ganelson/inform.git
synced 2024-07-16 22:14:23 +03:00
70 lines
1.1 KiB
C
70 lines
1.1 KiB
C
/*
|
|
* random.c
|
|
*
|
|
* Z-machine random number generator
|
|
*
|
|
*/
|
|
|
|
#include "frotz.h"
|
|
|
|
static long A = 1;
|
|
|
|
static interval = 0;
|
|
static counter = 0;
|
|
|
|
/*
|
|
* seed_random
|
|
*
|
|
* Set the seed value for the random number generator.
|
|
*
|
|
*/
|
|
|
|
void seed_random (int value)
|
|
{
|
|
|
|
if (value == 0) { /* ask interface for seed value */
|
|
A = os_random_seed ();
|
|
interval = 0;
|
|
} else if (value < 1000) { /* special seed value */
|
|
counter = 0;
|
|
interval = value;
|
|
} else { /* standard seed value */
|
|
A = value;
|
|
interval = 0;
|
|
}
|
|
|
|
}/* seed_random */
|
|
|
|
/*
|
|
* z_random, store a random number or set the random number seed.
|
|
*
|
|
* zargs[0] = range (positive) or seed value (negative)
|
|
*
|
|
*/
|
|
|
|
void z_random ()
|
|
{
|
|
|
|
if ((short) zargs[0] <= 0) { /* set random seed */
|
|
|
|
seed_random (- (short) zargs[0]);
|
|
store (0);
|
|
|
|
} else { /* generate random number */
|
|
|
|
zword result;
|
|
|
|
if (interval != 0) { /* ...in special mode */
|
|
result = counter++;
|
|
if (counter == interval) counter = 0;
|
|
} else { /* ...in standard mode */
|
|
A = 0x015a4e35L * A + 1;
|
|
result = (A >> 16) & 0x7fff;
|
|
}
|
|
|
|
store ((zword) (result % zargs[0] + 1));
|
|
|
|
}
|
|
|
|
}/* z_random */
|