ref: f8a582a7a0f38958ba8fdfcb32fd95e55b7bd6e6 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