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;
        }
}