#ifndef __ASM_SYSTEM_H
#define __ASM_SYSTEM_H

#include <linux/config.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#include <linux/bitops.h> /* for LOCK_PREFIX */

#ifdef __KERNEL__

struct task_struct;     /* one of the stranger aspects of C forward declarations.. */
extern void FASTCALL(__switch_to(struct task_struct *prev, struct task_struct *next));

#define prepare_to_switch()     do { } while(0)
#define switch_to(prev,next,last) do {                                  \
        asm volatile("pushl %%esi\n\t"                                  \
                     "pushl %%edi\n\t"                                  \
                     "pushl %%ebp\n\t"                                  \
                     "movl %%esp,%0\n\t"        /* save ESP */          \
                     "movl %3,%%esp\n\t"        /* restore ESP */       \
                     "movl $1f,%1\n\t"          /* save EIP */          \
                     "pushl %4\n\t"             /* restore EIP */       \
                     "jmp __switch_to\n"                                \
                     "1:\t"                                             \
                     "popl %%ebp\n\t"                                   \
                     "popl %%edi\n\t"                                   \
                     "popl %%esi\n\t"                                   \
                     :"=m" (prev->thread.esp),"=m" (prev->thread.eip),  \
                      "=b" (last)                                       \
                     :"m" (next->thread.esp),"m" (next->thread.eip),    \
                      "a" (prev), "d" (next),                           \
                      "b" (prev));                                      \
} while (0)

#define _set_base(addr,base) do { unsigned long __pr; \
__asm__ __volatile__ ("movw %%dx,%1\n\t" \
        "rorl $16,%%edx\n\t" \
        "movb %%dl,%2\n\t" \
        "movb %%dh,%3" \
        :"=&d" (__pr) \
        :"m" (*((addr)+2)), \
         "m" (*((addr)+4)), \
         "m" (*((addr)+7)), \
         "0" (base) \
        ); } while(0)

#define _set_limit(addr,limit) do { unsigned long __lr; \
__asm__ __volatile__ ("movw %%dx,%1\n\t" \
        "rorl $16,%%edx\n\t" \
        "movb %2,%%dh\n\t" \
        "andb $0xf0,%%dh\n\t" \
        "orb %%dh,%%dl\n\t" \
        "movb %%dl,%2" \
        :"=&d" (__lr) \
        :"m" (*(addr)), \
         "m" (*((addr)+6)), \
         "0" (limit) \
        ); } while(0)

#define set_base(ldt,base) _set_base( ((char *)&(ldt)) , (base) )
#define set_limit(ldt,limit) _set_limit( ((char *)&(ldt)) , ((limit)-1)>>12 )

static inline unsigned long _get_base(char * addr)
{
        unsigned long __base;
        __asm__("movb %3,%%dh\n\t"
                "movb %2,%%dl\n\t"
                "shll $16,%%edx\n\t"
                "movw %1,%%dx"
                :"=&d" (__base)
                :"m" (*((addr)+2)),
                 "m" (*((addr)+4)),
                 "m" (*((addr)+7)));
        return __base;
}

#define get_base(ldt) _get_base( ((char *)&(ldt)) )

/*
 * Load a segment. Fall back on loading the zero
 * segment if something goes wrong..
 */
#define loadsegment(seg,value)                  \
        asm volatile("\n"                       \
                "1:\t"                          \
                "movl %0,%%" #seg "\n"          \
                "2:\n"                          \
                ".section .fixup,\"ax\"\n"      \
                "3:\t"                          \
                "pushl $0\n\t"                  \
                "popl %%" #seg "\n\t"           \
                "jmp 2b\n"                      \
                ".previous\n"                   \
                ".section __ex_table,\"a\"\n\t" \
                ".align 4\n\t"                  \
                ".long 1b,3b\n"                 \
                ".previous"                     \
                : :"m" (*(unsigned int *)&(value)))

/*
 * Clear and set 'TS' bit respectively
 */
#define clts() __asm__ __volatile__ ("clts")
#define read_cr0() ({ \
        unsigned int __dummy; \
        __asm__( \
                "movl %%cr0,%0\n\t" \
                :"=r" (__dummy)); \
        __dummy; \
})
#define write_cr0(x) \
        __asm__("movl %0,%%cr0": :"r" (x));
#define stts() write_cr0(8 | read_cr0())

#endif  /* __KERNEL__ */

static inline unsigned long get_limit(unsigned long segment)
{
        unsigned long __limit;
        __asm__("lsll %1,%0"
                :"=r" (__limit):"r" (segment));
        return __limit+1;
}

#define nop() __asm__ __volatile__ ("nop")

#define xchg(ptr,v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v),(ptr),sizeof(*(ptr))))

#define tas(ptr) (xchg((ptr),1))

struct __xchg_dummy { unsigned long a[100]; };
#define __xg(x) ((struct __xchg_dummy *)(x))


/*
 * The semantics of XCHGCMP8B are a bit strange, this is why
 * there is a loop and the loading of %%eax and %%edx has to
 * be inside. This inlines well in most cases, the cached
 * cost is around ~38 cycles. (in the future we might want
 * to do an SIMD/3DNOW!/MMX/FPU 64-bit store here, but that
 * might have an implicit FPU-save as a cost, so it's not
 * clear which path to go.)
 */
extern inline void __set_64bit (unsigned long long * ptr,
                unsigned int low, unsigned int high)
{
__asm__ __volatile__ (
        "1:     movl (%0), %%eax;
                movl 4(%0), %%edx;
                cmpxchg8b (%0);
                jnz 1b"
        ::              "D"(ptr),
                        "b"(low),
                        "c"(high)
        :
                        "ax","dx","memory");
}

extern void inline __set_64bit_constant (unsigned long long *ptr,
                                                 unsigned long long value)
{
        __set_64bit(ptr,(unsigned int)(value), (unsigned int)((value)>>32ULL));
}
#define ll_low(x)       *(((unsigned int*)&(x))+0)
#define ll_high(x)      *(((unsigned int*)&(x))+1)

extern void inline __set_64bit_var (unsigned long long *ptr,
                         unsigned long long value)
{
        __set_64bit(ptr,ll_low(value), ll_high(value));
}

#define set_64bit(ptr,value) \
(__builtin_constant_p(value) ? \
 __set_64bit_constant(ptr, value) : \
 __set_64bit_var(ptr, value) )

#define _set_64bit(ptr,value) \
(__builtin_constant_p(value) ? \
 __set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \
 __set_64bit(ptr, ll_low(value), ll_high(value)) )

/*
 * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
 * Note 2: xchg has side effect, so that attribute volatile is necessary,
 *        but generally the primitive is invalid, *ptr is output argument. --ANK
 */
static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
{
        switch (size) {
                case 1:
                        __asm__ __volatile__("xchgb %b0,%1"
                                :"=q" (x)
                                :"m" (*__xg(ptr)), "0" (x)
                                :"memory");
                        break;
                case 2:
                        __asm__ __volatile__("xchgw %w0,%1"
                                :"=r" (x)
                                :"m" (*__xg(ptr)), "0" (x)
                                :"memory");
                        break;
                case 4:
                        __asm__ __volatile__("xchgl %0,%1"
                                :"=r" (x)
                                :"m" (*__xg(ptr)), "0" (x)
                                :"memory");
                        break;
        }
        return x;
}

/*
 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 * store NEW in MEM.  Return the initial value in MEM.  Success is
 * indicated by comparing RETURN with OLD.
 */

#ifdef CONFIG_X86_CMPXCHG
#define __HAVE_ARCH_CMPXCHG 1

static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
                                      unsigned long new, int size)
{
        unsigned long prev;
        switch (size) {
        case 1:
                __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
                                     : "=a"(prev)
                                     : "q"(new), "m"(*__xg(ptr)), "0"(old)
                                     : "memory");
                return prev;
        case 2:
                __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
                                     : "=a"(prev)
                                     : "q"(new), "m"(*__xg(ptr)), "0"(old)
                                     : "memory");
                return prev;
        case 4:
                __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
                                     : "=a"(prev)
                                     : "q"(new), "m"(*__xg(ptr)), "0"(old)
                                     : "memory");
                return prev;
        }
        return old;
}

#define cmpxchg(ptr,o,n)\
        ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
                                        (unsigned long)(n),sizeof(*(ptr))))
    
#else
/* Compiling for a 386 proper.  Is it worth implementing via cli/sti?  */
#endif

/*
 * Force strict CPU ordering.
 * And yes, this is required on UP too when we're talking
 * to devices.
 *
 * For now, "wmb()" doesn't actually do anything, as all
 * Intel CPU's follow what Intel calls a *Processor Order*,
 * in which all writes are seen in the program order even
 * outside the CPU.
 *
 * I expect future Intel CPU's to have a weaker ordering,
 * but I'd also expect them to finally get their act together
 * and add some real memory barriers if so.
 *
 * The Pentium III does add a real memory barrier with the
 * sfence instruction, so we use that where appropriate.
 */
#ifndef CONFIG_X86_XMM
#define mb()    __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
#else
#define mb()    __asm__ __volatile__ ("sfence": : :"memory")
#endif
#define rmb()   mb()
#define wmb()   __asm__ __volatile__ ("": : :"memory")

#ifdef CONFIG_SMP
#define smp_mb()        mb()
#define smp_rmb()       rmb()
#define smp_wmb()       wmb()
#else
#define smp_mb()        barrier()
#define smp_rmb()       barrier()
#define smp_wmb()       barrier()
#endif

#define set_mb(var, value) do { xchg(&var, value); } while (0)
#define set_wmb(var, value) do { var = value; wmb(); } while (0)

/* interrupt control.. */
#define __save_flags(x)         __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */)
#define __restore_flags(x)      __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory")
#define __cli()                 __asm__ __volatile__("cli": : :"memory")
#define __sti()                 __asm__ __volatile__("sti": : :"memory")
/* used in the idle loop; sti takes one instruction cycle to complete */
#define safe_halt()             __asm__ __volatile__("sti; hlt": : :"memory")

/* For spinlocks etc */
#define local_irq_save(x)       __asm__ __volatile__("pushfl ; popl %0 ; cli":"=g" (x): /* no input */ :"memory")
#define local_irq_restore(x)    __restore_flags(x)
#define local_irq_disable()     __cli()
#define local_irq_enable()      __sti()

#ifdef CONFIG_SMP

extern void __global_cli(void);
extern void __global_sti(void);
extern unsigned long __global_save_flags(void);
extern void __global_restore_flags(unsigned long);
#define cli() __global_cli()
#define sti() __global_sti()
#define save_flags(x) ((x)=__global_save_flags())
#define restore_flags(x) __global_restore_flags(x)

#else

#define cli() __cli()
#define sti() __sti()
#define save_flags(x) __save_flags(x)
#define restore_flags(x) __restore_flags(x)

#endif

/*
 * disable hlt during certain critical i/o operations
 */
#define HAVE_DISABLE_HLT
void disable_hlt(void);
void enable_hlt(void);

#endif