Subversion Repositories planix.SVN

#include "u.h"

#include "libc.h"

int

tas(long *x)

{

	int     v, t, i = 1;

#if ARMv5

	__asm__(

		"swp  %0, %1, [%2]"

		: "=&r" (v)

		: "r" (1), "r" (x)

		: "memory"

	);

#else

	__asm__ (

		"1:	ldrex	%0, [%2]\n"

		"	strex	%1, %3, [%2]\n"

		"	teq	%1, #0\n"

		"	bne	1b"

		: "=&r" (v), "=&r" (t)

		: "r" (x), "r" (i)

		: "cc");

#endif

	switch(v) {

	case 0:

	case 1:

		return v;

	default:

		print("canlock: corrupted 0x%lux\n", v);

		return 1;

	}

}