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
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23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 /* Many of these implementations are rather fake, but good enough. */
37 typedef u_int32_t atomic_t;
39 #define atomic_set(p, v) (*(p) = (v))
40 #define atomic_read(p) (*(p))
41 #define atomic_inc(p) atomic_add_int(p, 1)
42 #define atomic_dec(p) atomic_subtract_int(p, 1)
43 #define atomic_add(n, p) atomic_add_int(p, n)
44 #define atomic_sub(n, p) atomic_subtract_int(p, n)
46 static __inline atomic_t
47 test_and_set_bit(int b, volatile void *p)
50 unsigned int m = 1<<b;
51 unsigned int r = *(volatile int *)p & m;
52 *(volatile int *)p |= m;
58 clear_bit(int b, volatile void *p)
60 atomic_clear_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
64 set_bit(int b, volatile void *p)
66 atomic_set_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
70 test_bit(int b, volatile void *p)
72 return ((volatile int *)p)[b >> 5] & (1 << (b & 0x1f));
76 find_first_zero_bit(volatile void *p, int max)
79 volatile int *ptr = (volatile int *)p;
81 for (b = 0; b < max; b += 32) {
82 if (ptr[b >> 5] != ~0) {
84 if ((ptr[b >> 5] & (1 << (b & 0x1f))) == 0)