ref: 4a1d005a9a2318b99df31c92b2c8bcd11cffdb5a 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