FreeBSD/Linux Kernel Cross Reference
sys/dev/drm/drm_atomic.h

     /**
      * \file drm_atomic.h
      * Atomic operations used in the DRM which may or may not be provided by the OS.
      * 
      * \author Eric Anholt <anholt@FreeBSD.org>
      */
     
     /*-
      * Copyright 2004 Eric Anholt
     * All Rights Reserved.
     *
     * Permission is hereby granted, free of charge, to any person obtaining a
     * copy of this software and associated documentation files (the "Software"),
     * to deal in the Software without restriction, including without limitation
     * the rights to use, copy, modify, merge, publish, distribute, sublicense,
     * and/or sell copies of the Software, and to permit persons to whom the
     * Software is furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice (including the next
     * paragraph) shall be included in all copies or substantial portions of the
     * Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
     * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
     * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
     * OTHER DEALINGS IN THE SOFTWARE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/6.4/sys/dev/drm/drm_atomic.h 153401 2005-12-14 00:52:59Z anholt $");
    
    /* Many of these implementations are rather fake, but good enough. */
    
    typedef u_int32_t atomic_t;
    
    #ifdef __FreeBSD__
    #define atomic_set(p, v)        (*(p) = (v))
    #define atomic_read(p)          (*(p))
    #define atomic_inc(p)           atomic_add_int(p, 1)
    #define atomic_dec(p)           atomic_subtract_int(p, 1)
    #define atomic_add(n, p)        atomic_add_int(p, n)
    #define atomic_sub(n, p)        atomic_subtract_int(p, n)
    #else /* __FreeBSD__ */
    /* FIXME */
    #define atomic_set(p, v)        (*(p) = (v))
    #define atomic_read(p)          (*(p))
    #define atomic_inc(p)           (*(p) += 1)
    #define atomic_dec(p)           (*(p) -= 1)
    #define atomic_add(n, p)        (*(p) += (n))
    #define atomic_sub(n, p)        (*(p) -= (n))
    /* FIXME */
    #define atomic_add_int(p, v)      *(p) += v
    #define atomic_subtract_int(p, v) *(p) -= v
    #define atomic_set_int(p, bits)   *(p) |= (bits)
    #define atomic_clear_int(p, bits) *(p) &= ~(bits)
    #endif /* !__FreeBSD__ */
    
    #if !defined(__FreeBSD_version) || (__FreeBSD_version < 500000)
    #if defined(__i386__)
    /* The extra atomic functions from 5.0 haven't been merged to 4.x */
    static __inline int
    atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
    {
            int res = exp;
    
            __asm __volatile (
            "       lock ;                  "
            "       cmpxchgl %1,%2 ;        "
            "       setz    %%al ;          "
            "       movzbl  %%al,%0 ;       "
            "1:                             "
            "# atomic_cmpset_int"
            : "+a" (res)                    /* 0 (result) */
            : "r" (src),                    /* 1 */
              "m" (*(dst))                  /* 2 */
            : "memory");                             
    
            return (res);
    }
    #else /* __i386__ */
    static __inline int
    atomic_cmpset_int(__volatile__ int *dst, int old, int new)
    {
            int s = splhigh();
            if (*dst==old) {
                    *dst = new;
                    splx(s);
                    return 1;
            }
            splx(s);
            return 0;
    }
    #endif /* !__i386__ */
    #endif /* !__FreeBSD_version || __FreeBSD_version < 500000 */
    
    static __inline atomic_t
   test_and_set_bit(int b, volatile void *p)
   {
           int s = splhigh();
           unsigned int m = 1<<b;
           unsigned int r = *(volatile int *)p & m;
           *(volatile int *)p |= m;
           splx(s);
           return r;
   }
   
   static __inline void
   clear_bit(int b, volatile void *p)
   {
           atomic_clear_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
   }
   
   static __inline void
   set_bit(int b, volatile void *p)
   {
           atomic_set_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
   }
   
   static __inline int
   test_bit(int b, volatile void *p)
   {
           return ((volatile int *)p)[b >> 5] & (1 << (b & 0x1f));
   }
   
   static __inline int
   find_first_zero_bit(volatile void *p, int max)
   {
           int b;
           volatile int *ptr = (volatile int *)p;
   
           for (b = 0; b < max; b += 32) {
                   if (ptr[b >> 5] != ~0) {
                           for (;;) {
                                   if ((ptr[b >> 5] & (1 << (b & 0x1f))) == 0)
                                           return b;
                                   b++;
                           }
                   }
           }
           return max;
   }

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