/** @file * * Random number generation * */ FILE_LICENCE ( GPL2_OR_LATER ); #include <stdlib.h> #include <gpxe/timer.h> static int32_t rnd_seed = 0; /** * Seed the pseudo-random number generator * * @v seed Seed value */ void srandom ( unsigned int seed ) { rnd_seed = seed; } /** * Generate a pseudo-random number between 0 and 2147483647L or 2147483562? * * @ret rand Pseudo-random number */ long int random ( void ) { int32_t q; if ( ! rnd_seed ) /* Initialize linear congruential generator */ srandom ( currticks() ); /* simplified version of the LCG given in Bruce Schneier's "Applied Cryptography" */ q = ( rnd_seed / 53668 ); rnd_seed = ( 40014 * ( rnd_seed - 53668 * q ) - 12211 * q ); if ( rnd_seed < 0 ) rnd_seed += 2147483563L; return rnd_seed; }