ref: 3fbd9f07c8ce1a8fe1910d2edf71cda3dcf5703e 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