Subversion Repositories HelenOS

Rev

Rev 112 | Rev 341 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
1 jermar 1 
/*
112 jermar 2 
 * Copyright (C) 2005 Ondrej Palkovsky
1 jermar 3 
 * All rights reserved.
4 
 *
5 
 * Redistribution and use in source and binary forms, with or without
6 
 * modification, are permitted provided that the following conditions
7 
 * are met:
8 
 *
9 
 * - Redistributions of source code must retain the above copyright
10 
 *   notice, this list of conditions and the following disclaimer.
11 
 * - Redistributions in binary form must reproduce the above copyright
12 
 *   notice, this list of conditions and the following disclaimer in the
13 
 *   documentation and/or other materials provided with the distribution.
14 
 * - The name of the author may not be used to endorse or promote products
15 
 *   derived from this software without specific prior written permission.
16 
 *
17 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 
 */
28 
 
29 
#ifndef __MIPS_ATOMIC_H__
30 
#define __MIPS_ATOMIC_H__
31 
 
111 palkovsky 32 
#define atomic_inc(x)   (a_add(x,1))
33 
#define atomic_dec(x)   (a_sub(x,1))
1 jermar 34 
 
111 palkovsky 35 
/*
36 
 * Atomic addition
37 
 *
38 
 * This case is harder, and we have to use the special LL and SC operations
39 
 * to achieve atomicity. The instructions are similar to LW (load) and SW
40 
 * (store), except that the LL (load-linked) instruction loads the address
41 
 * of the variable to a special register and if another process writes to
42 
 * the same location, the SC (store-conditional) instruction fails.
43 
 */
44 
static inline int a_add( volatile int *val, int i)
45 
{
46 
    int tmp, tmp2;
47 
 
48 
    asm volatile (
49 
        "   .set    push\n"
50 
        "   .set    noreorder\n"
51 
        "   nop\n"
52 
        "1:\n"
53 
        "   ll  %0, %1\n"
240 palkovsky 54 
        "   addu    %0, %0, %3\n"
55 
        "       move    %2, %0\n"
111 palkovsky 56 
        "   sc  %0, %1\n"
57 
        "   beq %0, 0x0, 1b\n"
240 palkovsky 58 
        "   move    %0, %2\n"
111 palkovsky 59 
        "   .set    pop\n"
240 palkovsky 60 
        : "=&r" (tmp), "=o" (*val), "=r" (tmp2)
61 
        : "r" (i)
111 palkovsky 62 
        );
63 
    return tmp;
64 
}
65 
 
66 
 
67 
/*
68 
 * Atomic subtraction
69 
 *
70 
 * Implemented in the same manner as a_add, except we substract the value.
71 
 */
72 
static inline int a_sub( volatile int *val, int i)
73 
 
74 
{
75 
    int tmp, tmp2;
76 
 
77 
    asm volatile (
78 
        "   .set    push\n"
79 
        "   .set    noreorder\n"
80 
        "   nop\n"
81 
        "1:\n"
82 
        "   ll  %0, %1\n"
240 palkovsky 83 
        "   subu    %0, %0, %3\n"
84 
        "       move    %2, %0\n"
111 palkovsky 85 
        "   sc  %0, %1\n"
86 
        "   beq %0, 0x0, 1b\n"
240 palkovsky 87 
        "       move    %0, %2\n"
111 palkovsky 88 
        "   .set    pop\n"
240 palkovsky 89 
        : "=&r" (tmp), "=o" (*val), "=r" (tmp2)
90 
        : "r" (i)
111 palkovsky 91 
        );
92 
    return tmp;
93 
}
94 
 
95 
 
1 jermar 96 
#endif