ref: 2c5dfc8dbd6cf36adedf1b4be35e49f8a8d5f3cf 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