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Diffstat (limited to 'sys/kern/subr_rand.c')
| -rw-r--r-- | sys/kern/subr_rand.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/sys/kern/subr_rand.c b/sys/kern/subr_rand.c new file mode 100644 index 000000000000..09f36a7d630a --- /dev/null +++ b/sys/kern/subr_rand.c @@ -0,0 +1,100 @@ +/* + * Copyright (c) 1993 Regents of the University of California. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the Computer Systems + * Engineering Group at Lawrence Berkeley Laboratory. + * 4. Neither the name of the University nor of the Laboratory may be used + * to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + * LBL BSD kernel random number generator (used by statclock). + * + * Written by Steve McCanne & Chris Torek (mccanne@ee.lbl.gov, + * torek@ee.lbl.gov), November, 1992. + * + * This implementation is based on ``Two Fast Implementations of + * the "Minimal Standard" Random Number Generator", David G. Carta, + * Communications of the ACM, Jan 1990, Vol 33 No 1. + */ + +#ifdef sparc +asm("\ + .global _kernrand ;\ +_kernrand: ;\ + sethi %hi(16807), %o1 ;\ + wr %o1, %lo(16807), %y ;\ + set 0xffff, %o4 ;\ + andcc %g0, 0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %o0, %o2 ;\ + mulscc %o2, %g0, %o2 ;\ + rd %y, %o3 ;\ + srl %o2, 16, %o1 ;\ + and %o4, %o2, %o0 ;\ + sll %o0, 15, %o0 ;\ + srl %o3, 17, %o3 ;\ + or %o3, %o0, %o0 ;\ + addcc %o0, %o1, %o0 ;\ + bl 1f ;\ + sethi %hi(0x7fffffff), %o1 ;\ + retl ;\ + nop ;\ +1: ;\ + or %o1, %lo(0x7fffffff), %o1 ;\ + add %o0, 1, %o0 ;\ + retl ;\ + and %o1, %o0, %o0 "); +#else +long +kernrand(x) + register long x; +{ + register long hi, lo, t; + + hi = x / 127773; + lo = x % 127773; + t = 16807 * lo - 2836 * hi; + if (t > 0) + return (t); + else + return (t + 0x7fffffff); +} +#endif |