Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/cmd/unix/drawterm/libsec/nfastrand.c

Copyright © 2021 Plan 9 Foundation.
Distributed under the MIT License.
Download the Plan 9 distribution.


#include <u.h>
#include <libc.h>
#include <libsec.h>

#define Maxrand	((1UL<<31)-1)

ulong
nfastrand(ulong n)
{
	ulong m, r;
	
	/*
	 * set m to the maximum multiple of n <= 2^31-1
	 * so we want a random number < m.
	 */
	if(n > Maxrand)
		abort();

	m = Maxrand - Maxrand % n;
	while((r = fastrand()) >= m)
		;
	return r%n;
}

Bell Labs OSI certified Powered by Plan 9

(Return to Plan 9 Home Page)

Copyright © 2021 Plan 9 Foundation. All Rights Reserved.
Comments to [email protected].