ref: e61060a5fe59b10d8f68e75eb5e5380d8a1b29e4 dir: /sys/src/libc/arm/tas.s/
TEXT _tas(SB), $-4 MOVW R0,R1 MOVW $1,R0 SWPW R0,(R1) /* fix: deprecated in armv7 */ RET