diff options
Diffstat (limited to 'mysys/my_rnd.c')
-rw-r--r-- | mysys/my_rnd.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/mysys/my_rnd.c b/mysys/my_rnd.c new file mode 100644 index 00000000000..e1aca222954 --- /dev/null +++ b/mysys/my_rnd.c @@ -0,0 +1,55 @@ +/* Copyright (C) 2007 MySQL AB & Michael Widenius + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; version 2 of the License. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ + +#include <mysys_priv.h> +#include <m_string.h> + +/* + Initialize random generator + + NOTES + MySQL's password checks depends on this, so don't do any changes + that changes the random numbers that are generated! +*/ + +void my_rnd_init(struct my_rnd_struct *rand_st, ulong seed1, ulong seed2) +{ +#ifdef HAVE_purify + bzero((char*) rand_st,sizeof(*rand_st)); /* Avoid UMC varnings */ +#endif + rand_st->max_value= 0x3FFFFFFFL; + rand_st->max_value_dbl=(double) rand_st->max_value; + rand_st->seed1=seed1%rand_st->max_value ; + rand_st->seed2=seed2%rand_st->max_value; +} + + +/* + Generate random number. + + SYNOPSIS + my_rnd() + rand_st INOUT Structure used for number generation + + RETURN VALUE + generated pseudo random number +*/ + +double my_rnd(struct my_rnd_struct *rand_st) +{ + rand_st->seed1=(rand_st->seed1*3+rand_st->seed2) % rand_st->max_value; + rand_st->seed2=(rand_st->seed1+rand_st->seed2+33) % rand_st->max_value; + return (((double) rand_st->seed1)/rand_st->max_value_dbl); +} |