ref: 14c8343e86d3dfe01c939df550846741c2c9c31b
dir: /sys/src/libc/arm/tas.s/
TEXT _tas(SB), 1, $-4 MOVW $1, R2 _tas1: LDREX (R0), R1 STREX R2, (R0), R3 CMP.S $0, R3 BNE _tas1 MOVW R1, R0 MOVW _barrier(SB), R4 B (R4) TEXT _dmb(SB), 1, $-4 WORD $0xf57ff05f RET