ref: 5b50d2da070cc4155ef09853cd088c69a9cbb220
dir: /posix-arm/tas.c/
#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; } }