1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
/*
* Copyright (c) 1994 The University of Utah and
* the Center for Software Science (CSS). All rights reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* THE UNIVERSITY OF UTAH AND CSS ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
* IS" CONDITION. THE UNIVERSITY OF UTAH AND CSS DISCLAIM ANY LIABILITY OF
* ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* CSS requests users of this software to return to css-dist@cs.utah.edu any
* improvements that they make and grant CSS redistribution rights.
*
* Author: Bryan Ford, University of Utah CSS
*/
/*
* Simple operations that don't exist as primitives in C,
* but which processors often implement directly.
* This file contains default, "dumb" implementations;
* machine-independent code can override these with smarter implementations.
*/
#ifndef _MACH_PROC_OPS_H_
#define _MACH_PROC_OPS_H_
#include <mach/machine/vm_types.h>
#include <mach/inline.h>
/* Returns the bit number of the most-significant set bit in `val',
e.g. 0 for 1, 1 for 2-3, 2 for 4-7, etc.
If `val' is 0 (i.e. no bits are set), the behavior is undefined. */
MACH_INLINE int find_msb_set(natural_t val)
{
int msb;
for (msb = sizeof(val)*8-1; (val & ((natural_t)1 << msb)) == 0; msb--);
return msb;
}
/* Returns the bit number of the least-significant set bit in `val'.
If `val' is 0 (i.e. no bits are set), the behavior is undefined. */
MACH_INLINE int find_lsb_set(natural_t val)
{
int lsb;
for (lsb = 0; (val & ((natural_t)1 << lsb)) == 0; lsb++);
return lsb;
}
#endif _MACH_PROC_OPS_H_
|
