ref: 2ae2e5f856f8f95f8d780f9ffe0a0ebb634ffb1a 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