| /** @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; |
| } |
