the_lib.c

阿基米德操作系统的源代码

///////////////////////////////////////////////////////////////////

char * strcpy(char * dest, const char * src)
{
	__asm__ ("cld\n"
			 "1:\tlodsb\n\t"
			 "stosb\n\t"
			 "testb %%al,%%al\n\t"
			 "jne 1b"
		    :
		    :"S" (src),"D" (dest));
	return dest;
}

int strcmp(const char * cs, const char * ct)
{
	int __res;

	__asm__ ("cld\n"
			 "1:\tlodsb\n\t"
			 "scasb\n\t"
			 "jne 2f\n\t"
			 "testb %%al,%%al\n\t"
			 "jne 1b\n\t"
			 "xorl %%eax,%%eax\n\t"
			 "jmp 3f\n"
			 "2:\tmovl $1,%%eax\n\t"
			 "ja 3f\n\t"
			 "negl %%eax\n"
			 "3:"
		    :"=a" (__res)
		    :"S" (cs),"D" (ct));
	return __res;
}

void * memset(void * s, char c, int count)
{
	__asm__ ("cld\n\t"
			 "rep\n\t"
			 "stosb"
		    :
	        :"a" (c),"D" (s),"c" (count));
	return s;
}

unsigned char get_gs_byte(const char * addr)
{
	unsigned char _v;

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

void put_gs_byte(char val,char * addr)
{
	__asm__ ("movb %0,%%gs:%1"
			:
			:"r" (val),"m" (*addr));
	return;
}

///////////////////////////////////////////////////////////////////
unsigned long get_gs_long(const unsigned long * addr)
{
	unsigned long _v;

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

void put_gs_long(unsigned long val,unsigned long * addr)
{
	__asm__ ("movl %0,%%gs:%1"
			:
			:"r" (val),"m" (*addr));
	return;
}