This repository has been archived on 2023-08-20. You can view files and clone it, but cannot push or open issues or pull requests.
yap-6.3/OPTYap/x86_locks.h
ricroc b8546491fc copyright header in OPTYap files
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1315 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
2005-05-31 08:24:24 +00:00

101 lines
3.2 KiB
C

/**********************************************************************
The OPTYap Prolog system
OPTYap extends the Yap Prolog system to support or-parallel tabling
Copyright: R. Rocha and NCC - University of Porto, Portugal
File: x86_locks.h
version: $Id: x86_locks.h,v 1.3 2005-05-31 08:24:24 ricroc Exp $
**********************************************************************/
/* ----------------------------- **
** Atomic lock for X86 **
** ----------------------------- */
#define swap(reg,adr) \
({ \
char _ret; \
asm volatile ("xchgb %0,%1" \
: "=q" (_ret), "=m" (*(adr)) /* Output %0,%1 */ \
: "m" (*(adr)), "0" (reg)); /* Input (%2),%0 */ \
_ret; \
})
#define TRY_LOCK(LOCK_VAR) (swap(1,(LOCK_VAR))==0)
#define INIT_LOCK(LOCK_VAR) ((LOCK_VAR) = 0)
#define LOCK(LOCK_VAR) do { \
if (TRY_LOCK(&(LOCK_VAR))) break; \
while (IS_LOCKED(LOCK_VAR)) continue; \
} while (1)
#define IS_LOCKED(LOCK_VAR) ((LOCK_VAR) != 0)
#define IS_UNLOCKED(LOCK_VAR) ((LOCK_VAR) == 0)
#define UNLOCK(LOCK_VAR) ((LOCK_VAR) = 0)
/* This code has been copied from the sources of the Linux kernel */
/*
* On x86, we implement read-write locks as a 32-bit counter
* with the high bit (sign) being the "contended" bit.
*
* The inline assembly is non-obvious. Think about it.
*
* Changed to use the same technique as rw semaphores. See
* semaphore.h for details. -ben
*/
/* the spinlock helpers are in arch/i386/kernel/semaphore.S */
typedef struct { unsigned long a[100]; } __dummy_lock_t;
#define __dummy_lock(lock) (*(__dummy_lock_t *)(lock))
typedef struct { volatile unsigned int lock; } rwlock_t;
#define RW_LOCK_BIAS 0x01000000
#define RW_LOCK_BIAS_STR "0x01000000"
#define RW_LOCK_UNLOCKED RW_LOCK_BIAS
#define __build_read_lock(rw, helper) \
asm volatile("lock\n" \
"subl $1,(%0)\n\t" \
"js 2f\n" \
"1:\n" \
".section .text.lock,\"ax\"\n" \
"2:\tcall __read_lock_failed\n\t" \
"jmp 1b\n" \
".previous" \
::"a" (rw) : "memory")
#define __build_write_lock(rw, helper) \
asm volatile("lock\n"\
"subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
"jnz 2f\n" \
"1:\n" \
".section .text.lock,\"ax\"\n" \
"2:\tcall __write_lock_failed\n\t" \
"jmp 1b\n" \
".previous" \
::"a" (rw) : "memory")
static inline void read_lock(rwlock_t *rw)
{
__build_read_lock(rw, "__read_lock_failed");
}
static inline void write_lock(rwlock_t *rw)
{
__build_write_lock(rw, "__write_lock_failed");
}
#define READ_LOCK(X) read_lock(&(X))
#define WRITE_LOCK(X) write_lock(&(X))
#define READ_UNLOCK(rw) asm volatile("lock ; incl %0" :"=m" (__dummy_lock(&(rw))))
#define WRITE_UNLOCK(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" (__dummy_lock(&(rw))))
#define INIT_RWLOCK(RW) (RW).lock = RW_LOCK_UNLOCKED