ref: e2e4a46f26ff7268a696a45d82414fb992b648d5
dir: /sys/src/9/teg2/v7-arch.c/
/*
* arm arch v7 routines other than cache-related ones.
*
* calling this arch-v7.c would confuse the mk scripts,
* to which a filename arch*.c is magic.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "io.h"
#include "arm.h"
/*
* these routines should be cheap enough that there will
* be no hesitation to use them.
*
* once 5c in-lines vlong ops, just use the vlong versions.
*/
/* see Hacker's Delight if this isn't obvious */
#define ISPOW2(i) (((i) & ((i) - 1)) == 0)
int
ispow2(uvlong uvl)
{
/* see Hacker's Delight if this isn't obvious */
return ISPOW2(uvl);
}
static int
isulpow2(ulong ul) /* temporary speed hack */
{
return ISPOW2(ul);
}
/*
* return exponent of smallest power of 2 ≥ n
*/
int
log2(ulong n)
{
int i;
i = BI2BY*BY2WD - 1 - clz(n);
if (n == 0 || !ISPOW2(n))
i++;
return i;
}