3 * Atomic operations used in the DRM which may or may not be provided by the OS.
5 * \author Eric Anholt <anholt@FreeBSD.org>
9 * Copyright 2004 Eric Anholt
10 * All Rights Reserved.
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13 * copy of this software and associated documentation files (the "Software"),
14 * to deal in the Software without restriction, including without limitation
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16 * and/or sell copies of the Software, and to permit persons to whom the
17 * Software is furnished to do so, subject to the following conditions:
19 * The above copyright notice and this permission notice (including the next
20 * paragraph) shall be included in all copies or substantial portions of the
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
24 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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26 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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31 * $FreeBSD: src/sys/dev/drm2/drm_atomic.h,v 1.1 2012/05/22 11:07:44 kib Exp $
34 /* Many of these implementations are rather fake, but good enough. */
36 typedef u_int32_t atomic_t;
38 #define atomic_set(p, v) (*(p) = (v))
39 #define atomic_read(p) (*(p))
40 #define atomic_inc(p) atomic_add_int(p, 1)
41 #define atomic_dec(p) atomic_subtract_int(p, 1)
42 #define atomic_add(n, p) atomic_add_int(p, n)
43 #define atomic_sub(n, p) atomic_subtract_int(p, n)
45 static __inline atomic_t
46 test_and_set_bit(int b, volatile void *p)
48 unsigned int mask = 1 << b;
52 v = *(volatile unsigned int *)p;
54 if (atomic_cmpset_int(p, v, v | mask))
61 clear_bit(int b, volatile void *p)
63 atomic_clear_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
67 set_bit(int b, volatile void *p)
69 atomic_set_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
73 test_bit(int b, volatile void *p)
75 return ((volatile int *)p)[b >> 5] & (1 << (b & 0x1f));
79 find_first_zero_bit(volatile void *p, int max)
82 volatile int *ptr = (volatile int *)p;
84 for (b = 0; b < max; b += 32) {
85 if (ptr[b >> 5] != ~0) {
87 if ((ptr[b >> 5] & (1 << (b & 0x1f))) == 0)
96 #define BITS_TO_LONGS(x) (howmany((x), NBBY * sizeof(long)))