/*
* Initialize the default Mersenne Twist PRNG from a 32-bit seed.
*
* See mts_seed32new for full commentary.
*/
void mt_seed32new(
uint32_t seed) /* 32-bit seed to start from */
{
mts_seed32new(&mt_default_state, seed);
}
/*
* Choose a seed based on a random-number device given by the caller.
* If that device can't be opened, use the lower 32 bits from the
* current time.
*/
static void mts_devseed(
mt_state* state, /* State vector to seed */
char* seed_dev) /* Device to seed from */
{
int bytesread; /* Byte count read from device */
int nextbyte; /* Index of next byte to read */
FILE* ranfile; /* Access to device */
union
{
char ranbuffer[sizeof (uint32_t)];
/* Space for reading random int */
uint32_t randomvalue; /* Random value for initialization */
}
randomunion; /* Union for reading random int */
#ifdef WIN32
struct _timeb tb; /* Time of day (Windows mode) */
#else /* WIN32 */
struct timeval tv; /* Time of day */
struct timezone tz; /* Dummy for gettimeofday */
#endif /* WIN32 */
ranfile = fopen(seed_dev, "rb");
if (ranfile != NULL)
{
for (nextbyte = 0;
nextbyte < (int)sizeof randomunion.ranbuffer;
nextbyte += bytesread)
{
bytesread = fread(&randomunion.ranbuffer[nextbyte], 1,
sizeof randomunion.ranbuffer - nextbyte, ranfile);
if (bytesread == 0)
break;
}
fclose(ranfile);
if (nextbyte == sizeof randomunion.ranbuffer)
{
mts_seed32new(state, randomunion.randomvalue);
return;
}
}
/*
* The device isn't available. Use the time. We will
* assume that the time of day is accurate to microsecond
* resolution, which is true on most modern machines.
*/
#ifdef WIN32
(void) _ftime (&tb);
#else /* WIN32 */
(void) gettimeofday (&tv, &tz);
#endif /* WIN32 */
/*
* We just let the excess part of the seconds field overflow
*/
#ifdef WIN32
randomunion.randomvalue = tb.time * 1000 + tb.millitm;
#else /* WIN32 */
randomunion.randomvalue = tv.tv_sec * 1000000 + tv.tv_usec;
#endif /* WIN32 */
mts_seed32new(state, randomunion.randomvalue);
}
/*
* Choose a seed based on a random-number device given by the caller.
* If that device can't be opened, use the lower 32 bits from the
* current time.
*/
static uint32_t mts_devseed(
mt_state* state, /* State vector to seed */
char* seed_dev) /* Device to seed from */
{
#ifdef WIN32
dTHX;
#endif
int bytesread; /* Byte count read from device */
int nextbyte; /* Index of next byte to read */
FILE* ranfile; /* Access to device */
union
{
char ranbuffer[sizeof (uint32_t)];
/* Space for reading random int */
uint32_t randomvalue; /* Random value for initialization */
}
randomunion; /* Union for reading random int */
#ifdef WIN32
struct _timeb tb; /* Time of day (Windows mode) */
#else /* WIN32 */
struct timeval tv; /* Time of day */
#endif /* WIN32 */
ranfile = fopen(seed_dev, "rb");
/*
* Some machines have /dev/random but not /dev/urandom. On those
* machines, /dev/random is nonblocking, so we'll try it before we
* fall back to using the time.
*/
if (ranfile == NULL)
ranfile = fopen(DEVRANDOM, "rb");
if (ranfile != NULL)
{
setbuf(ranfile, NULL);
for (nextbyte = 0;
nextbyte < (int)sizeof randomunion.ranbuffer;
nextbyte += bytesread)
{
bytesread = fread(&randomunion.ranbuffer[nextbyte], (size_t)1,
sizeof randomunion.ranbuffer - nextbyte, ranfile);
if (bytesread == 0)
break;
}
fclose(ranfile);
if (nextbyte == sizeof randomunion.ranbuffer)
{
mts_seed32new(state, randomunion.randomvalue);
return randomunion.randomvalue;
}
}
/*
* The device isn't available. Use the time. We will
* assume that the time of day is accurate to microsecond
* resolution, which is true on most modern machines.
*/
#ifdef WIN32
(void) _ftime (&tb);
#else /* WIN32 */
(void) gettimeofday (&tv, NULL);
#endif /* WIN32 */
/*
* We just let the excess part of the seconds field overflow
*/
#ifdef WIN32
randomunion.randomvalue = tb.time * 1000 + tb.millitm;
#else /* WIN32 */
randomunion.randomvalue = tv.tv_sec * 1000000 + tv.tv_usec;
#endif /* WIN32 */
mts_seed32new(state, randomunion.randomvalue);
return randomunion.randomvalue;
}
/*
* Initialize the default Mersenne Twist PRNG from a 32-bit seed.
*
* See mts_seed32new for full commentary.
*/
void mt_seed32new(
unsigned long seed) /* 32-bit seed to start from */
{
mts_seed32new(&mt_default_state, seed);
}
