ref: 3e7ad6ef67711cbf73c61d1ab2d77c82a2ff7b3c 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