mirror of git://git.psyced.org/git/psyclpc
121 lines
4.1 KiB
C
121 lines
4.1 KiB
C
/*------------------------------------------------------------------
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* Wrapper for the 'SIMD oriented Fast Mersenne Twister.
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*
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* SFMT was developed by Mutsuo Saito and Makoto Matsumoto,
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* Hiroshima University,
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* http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index.html)
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* SFMT was integrated to LDMud by Zesstra@MorgenGrauen (http://mg.mud.de)
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*------------------------------------------------------------------
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*/
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#include "driver.h"
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#include "random.h"
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#include "backend.h"
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/* This is included on purpose so that the compiler may inline some functions.
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* They are anyway never used anywhere else, all other parts of the driver use
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* only the wrapper functions in this file.
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*/
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#include "random/SFMT.c"
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const unsigned int INIT_ARRAY_SIZE = 156U; // 4*156 == 624 bytes
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// Name of the device/file to seed the PRNG from
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char * prng_device_name = NULL;
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/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
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/* Driver interface functions */
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/*-------------------------------------------------------------------------*/
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/* random_number() is in random.h to be inlined. */
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/* Return a random number in the range 0..n-1.
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*
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* The MT FAQ suggests:
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* If the application is not sensitive to the rounding off error, then please
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* multiply N to [0,1)-real uniform random numbers and take the integer part
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* (this is sufficient for most applications).
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* I use the appropriate functions from the SFMT to generate random numbers on
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* the [0,1) interval and multiply with N.
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*/
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#if SIZEOF_LONG == SIZEOF_CHAR_P
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uint64_t random_number(uint64_t n) {
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return genrand_res53() * n;
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}
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#elif SIZEOF_INT == SIZEOF_CHAR_P
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uint32_t random_number(uint32 n) {
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return genrand_real2() * n;
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}
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#else
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#error We currently do not yet support a 128 bit integer type used as \
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svalue number type.
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#endif
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void seed_random_from_int (uint32_t seed)
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/* Initialize the generator */
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{
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#ifdef USE_LDMUD_COMPATIBILITY
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# ifdef VERBOSE
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printf("%s Seeding PRNG with: 0x%lx\n"
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, time_stamp(), (unsigned long)seed);
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# endif
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debug_message("%s Seeding PRNG with: 0x%lx\n"
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, time_stamp(), (unsigned long)seed);
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#endif
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init_gen_rand(seed);
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} /* seed_random_from_int() */
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/*-------------------------------------------------------------------------*/
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void
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seed_random(const char *filename)
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/* Opens the file given by filename and reads 156 uint32_t (624
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* bytes) from it (most often the file is probably /dev/urandom or
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* /dev/random). If successful the random number generator will be seeded
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* by an array of 624 bytes. Otherwise the driver clock will be used as
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* fallback.
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*/
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{
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FILE *seedsrc = NULL; // Filepointer
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// If we got a NULL pointer or an empty string, don't try to open some
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// device/file.
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if (filename != NULL && strlen(filename))
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seedsrc = fopen(filename,"rb");
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// if we have a file descriptor try to get a suitable amount of 32-bit
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// values from a file (right now 156 uint32_t / 624 bytes)
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if (seedsrc) {
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uint32_t seeddata[INIT_ARRAY_SIZE];
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size_t count = fread( seeddata, sizeof(uint32), INIT_ARRAY_SIZE,
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seedsrc );
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fclose(seedsrc);
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if( count == INIT_ARRAY_SIZE ) {
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init_by_array(seeddata, INIT_ARRAY_SIZE ); // seed PRNG
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#ifdef USE_LDMUD_COMPATIBILITY
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# ifdef VERBOSE
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printf("%s Seeding PRNG from %s.\n", time_stamp(),
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filename);
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# endif
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debug_message("%s Seeding PRNG from %s.\n", time_stamp(),
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filename);
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#endif
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return;
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} // if (count == INIT_ARRAY_SIZE)
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} // if (seedsrc)
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// Fall-back: driver clock
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#ifdef USE_LDMUD_COMPATIBILITY
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# ifdef VERBOSE
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printf("%s Seeding PRNG with current driver time\n"
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, time_stamp());
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# endif
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debug_message("%s Seeding PRNG with current driver time\n"
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, time_stamp());
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#endif
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seed_random_from_int((uint32_t)current_time);
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} /* seed_random() */
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/***************************************************************************/
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