include/asm-i386/atomic.h

   1 #ifndef __ARCH_I386_ATOMIC__
   2 #define __ARCH_I386_ATOMIC__
   3
   4 #include <linux/config.h>
   5 #include <linux/compiler.h>
   6 #include <asm/processor.h>
   7
   8 /*
   9  * Atomic operations that C can't guarantee us.  Useful for
  10  * resource counting etc..
  11  */
  12
  13 #ifdef CONFIG_SMP
  14 #define LOCK "lock ; "
  15 #else
  16 #define LOCK ""
  17 #endif
  18
  19 /*
  20  * Make sure gcc doesn't try to be clever and move things around
  21  * on us. We need to use _exactly_ the address the user gave us,
  22  * not some alias that contains the same information.
  23  */
  24 typedef struct { volatile int counter; } atomic_t;
  25
  26 #define ATOMIC_INIT(i)  { (i) }
  27
  28 /**
  29  * atomic_read - read atomic variable
  30  * @v: pointer of type atomic_t
  31  *
  32  * Atomically reads the value of @v.
  33  */
  34 #define atomic_read(v)          ((v)->counter)
  35
  36 /**
  37  * atomic_set - set atomic variable
  38  * @v: pointer of type atomic_t
  39  * @i: required value
  40  *
  41  * Atomically sets the value of @v to @i.
  42  */
  43 #define atomic_set(v,i)         (((v)->counter) = (i))
  44
  45 /**
  46  * atomic_add - add integer to atomic variable
  47  * @i: integer value to add
  48  * @v: pointer of type atomic_t
  49  *
  50  * Atomically adds @i to @v.
  51  */
  52 static __inline__ void atomic_add(int i, atomic_t *v)
  53 {
  54         __asm__ __volatile__(
  55                 LOCK "addl %1,%0"
  56                 :"=m" (v->counter)
  57                 :"ir" (i), "m" (v->counter));
  58 }
  59
  60 /**
  61  * atomic_sub - subtract the atomic variable
  62  * @i: integer value to subtract
  63  * @v: pointer of type atomic_t
  64  *
  65  * Atomically subtracts @i from @v.
  66  */
  67 static __inline__ void atomic_sub(int i, atomic_t *v)
  68 {
  69         __asm__ __volatile__(
  70                 LOCK "subl %1,%0"
  71                 :"=m" (v->counter)
  72                 :"ir" (i), "m" (v->counter));
  73 }
  74
  75 /**
  76  * atomic_sub_and_test - subtract value from variable and test result
  77  * @i: integer value to subtract
  78  * @v: pointer of type atomic_t
  79  *
  80  * Atomically subtracts @i from @v and returns
  81  * true if the result is zero, or false for all
  82  * other cases.
  83  */
  84 static __inline__ int atomic_sub_and_test(int i, atomic_t *v)
  85 {
  86         unsigned char c;
  87
  88         __asm__ __volatile__(
  89                 LOCK "subl %2,%0; sete %1"
  90                 :"=m" (v->counter), "=qm" (c)
  91                 :"ir" (i), "m" (v->counter) : "memory");
  92         return c;
  93 }
  94
  95 /**
  96  * atomic_inc - increment atomic variable
  97  * @v: pointer of type atomic_t
  98  *
  99  * Atomically increments @v by 1.
 100  */
 101 static __inline__ void atomic_inc(atomic_t *v)
 102 {
 103         __asm__ __volatile__(
 104                 LOCK "incl %0"
 105                 :"=m" (v->counter)
 106                 :"m" (v->counter));
 107 }
 108
 109 /**
 110  * atomic_dec - decrement atomic variable
 111  * @v: pointer of type atomic_t
 112  *
 113  * Atomically decrements @v by 1.
 114  */
 115 static __inline__ void atomic_dec(atomic_t *v)
 116 {
 117         __asm__ __volatile__(
 118                 LOCK "decl %0"
 119                 :"=m" (v->counter)
 120                 :"m" (v->counter));
 121 }
 122
 123 /**
 124  * atomic_dec_and_test - decrement and test
 125  * @v: pointer of type atomic_t
 126  *
 127  * Atomically decrements @v by 1 and
 128  * returns true if the result is 0, or false for all other
 129  * cases.
 130  */
 131 static __inline__ int atomic_dec_and_test(atomic_t *v)
 132 {
 133         unsigned char c;
 134
 135         __asm__ __volatile__(
 136                 LOCK "decl %0; sete %1"
 137                 :"=m" (v->counter), "=qm" (c)
 138                 :"m" (v->counter) : "memory");
 139         return c != 0;
 140 }
 141
 142 /**
 143  * atomic_inc_and_test - increment and test
 144  * @v: pointer of type atomic_t
 145  *
 146  * Atomically increments @v by 1
 147  * and returns true if the result is zero, or false for all
 148  * other cases.
 149  */
 150 static __inline__ int atomic_inc_and_test(atomic_t *v)
 151 {
 152         unsigned char c;
 153
 154         __asm__ __volatile__(
 155                 LOCK "incl %0; sete %1"
 156                 :"=m" (v->counter), "=qm" (c)
 157                 :"m" (v->counter) : "memory");
 158         return c != 0;
 159 }
 160
 161 /**
 162  * atomic_add_negative - add and test if negative
 163  * @v: pointer of type atomic_t
 164  * @i: integer value to add
 165  *
 166  * Atomically adds @i to @v and returns true
 167  * if the result is negative, or false when
 168  * result is greater than or equal to zero.
 169  */
 170 static __inline__ int atomic_add_negative(int i, atomic_t *v)
 171 {
 172         unsigned char c;
 173
 174         __asm__ __volatile__(
 175                 LOCK "addl %2,%0; sets %1"
 176                 :"=m" (v->counter), "=qm" (c)
 177                 :"ir" (i), "m" (v->counter) : "memory");
 178         return c;
 179 }
 180
 181 /**
 182  * atomic_add_return - add and return
 183  * @v: pointer of type atomic_t
 184  * @i: integer value to add
 185  *
 186  * Atomically adds @i to @v and returns @i + @v
 187  */
 188 static __inline__ int atomic_add_return(int i, atomic_t *v)
 189 {
 190         int __i;
 191 #ifdef CONFIG_M386
 192         if(unlikely(boot_cpu_data.x86==3))
 193                 goto no_xadd;
 194 #endif
 195         /* Modern 486+ processor */
 196         __i = i;
 197         __asm__ __volatile__(
 198                 LOCK "xaddl %0, %1;"
 199                 :"=r"(i)
 200                 :"m"(v->counter), "0"(i));
 201         return i + __i;
 202
 203 #ifdef CONFIG_M386
 204 no_xadd: /* Legacy 386 processor */
 205         local_irq_disable();
 206         __i = atomic_read(v);
 207         atomic_set(v, i + __i);
 208         local_irq_enable();
 209         return i + __i;
 210 #endif
 211 }
 212
 213 static __inline__ int atomic_sub_return(int i, atomic_t *v)
 214 {
 215         return atomic_add_return(-i,v);
 216 }
 217
 218 #define atomic_inc_return(v)  (atomic_add_return(1,v))
 219 #define atomic_dec_return(v)  (atomic_sub_return(1,v))
 220
 221 /* These are x86-specific, used by some header files */
 222 #define atomic_clear_mask(mask, addr) \
 223 __asm__ __volatile__(LOCK "andl %0,%1" \
 224 : : "r" (~(mask)),"m" (*addr) : "memory")
 225
 226 #define atomic_set_mask(mask, addr) \
 227 __asm__ __volatile__(LOCK "orl %0,%1" \
 228 : : "r" (mask),"m" (*(addr)) : "memory")
 229
 230 /* Atomic operations are already serializing on x86 */
 231 #define smp_mb__before_atomic_dec()     barrier()
 232 #define smp_mb__after_atomic_dec()      barrier()
 233 #define smp_mb__before_atomic_inc()     barrier()
 234 #define smp_mb__after_atomic_inc()      barrier()
 235
 236 #endif