segment.h

fairysky系统,是一个小型的内核,模拟linux原始版本的

/*文件名: segment.h
  说明:   段寄存器处理函数
  作者:   marsinfan
  日期:   2005/12/20
*/

extern inline unsigned char get_fs_byte(const char * addr)
{
	unsigned register char _v;

    __asm__ ("movb %%fs:%1,%0":"=q" (_v):"m" (*addr));
    return _v;
}

extern inline unsigned short get_fs_word(const unsigned short *addr)
{
    unsigned short _v;

    __asm__ ("movw %%fs:%1,%0":"=r" (_v):"m" (*addr));
    return _v;
}

extern inline unsigned long get_fs_long(const unsigned long *addr)
{
    unsigned long _v;

    __asm__ ("movl %%fs:%1,%0":"=r" (_v):"m" (*addr)); \
    return _v;
}

extern inline void put_fs_byte(char val,char *addr)
{
    __asm__ ("movb %0,%%fs:%1"::"q" (val),"m" (*addr));
}

extern inline void put_fs_word(short val,short * addr)
{
    __asm__ ("movw %0,%%fs:%1"::"r" (val),"m" (*addr));
}

extern inline void put_fs_long(unsigned long val,unsigned long * addr)
{
    __asm__ ("movl %0,%%fs:%1"::"r" (val),"m" (*addr));
}

extern inline void memcpy_tofs(void * to, void * from, unsigned long n)
{
__asm__("cld\n\t"
    "push %%es\n\t"
    "push %%fs\n\t"
    "pop %%es\n\t"
    "testb $1,%%cl\n\t"
    "je 1f\n\t"
    "movsb\n"
    "1:\ttestb $2,%%cl\n\t"
    "je 2f\n\t"
    "movsw\n"
    "2:\tshrl $2,%%ecx\n\t"
    "rep ; movsl\n\t"
    "pop %%es"
    ::"c" (n),"D" ((long) to),"S" ((long) from)
    );
}

extern inline void memcpy_fromfs(void * to, void * from, unsigned long n)
{
__asm__("cld\n\t"
    "testb $1,%%cl\n\t"
    "je 1f\n\t"
    "fs ; movsb\n"
    "1:\ttestb $2,%%cl\n\t"
    "je 2f\n\t"
    "fs ; movsw\n"
    "2:\tshrl $2,%%ecx\n\t"
    "rep ; fs ; movsl"
    ::"c" (n),"D" ((long) to),"S" ((long) from)
    );
}

/*
 * Someone who knows GNU asm better than I should double check the followig.
 * It seems to work, but I don't know if I'm doing something subtly wrong.
 * --- TYT, 11/24/91
 * [ nothing wrong here, Linus: I just changed the ax to be any reg ]
 */

extern inline unsigned long get_fs() 
{
    u32 _v;
    __asm__("movl %%fs, %0":"=r" (_v):);
    return _v;
}

extern inline unsigned long get_ds() 
{
    u32 _v;
    __asm__("movl %%ds, %0":"=r" (_v):);
    return _v;
}

extern inline void set_fs(u32 val)
{
    __asm__ __volatile__("movl %0, %%fs"::"r" ((u32) val));
}

extern inline unsigned long get_cr2() 
{
    u32 _v;
    __asm__("movl %%cr2, %0":"=r" (_v):);
    return _v;
}

extern inline void set_esp(u32 val)
{
    __asm__ __volatile__("movl %0, %%esp"::"r" ((u32) val));
}

extern inline unsigned long get_esp() 
{
    u32 _v;
    __asm__("movl %%esp, %0":"=r" (_v):);
    return _v;
}