ref: 6bb619c8db2867ddd9cd19c0aec05065f5ee0cae
dir: /libkern/memset-thumb.s/
TO = 1 TOE = 2 N = 3 TMP = 3 /* N and TMP don't overlap */ TEXT memset(SB), $0 MOVW R0, R(TO) MOVW data+4(FP), R(4) MOVW n+8(FP), R(N) ADD R(N), R(TO), R(TOE) /* to end pointer */ CMP $4, R(N) /* need at least 4 bytes to copy */ BLT _1tail AND $0xFF, R(4) /* it's a byte */ SLL $8, R(4), R(TMP) /* replicate to a word */ ORR R(TMP), R(4) SLL $16, R(4), R(TMP) ORR R(TMP), R(4) _4align: /* align on 4 */ AND.S $3, R(TO), R(TMP) BEQ _4aligned MOVBU.P R(4), 1(R(TO)) /* implicit write back */ B _4align _4aligned: SUB $31, R(TOE), R(TMP) /* do 32-byte chunks if possible */ CMP R(TMP), R(TO) BHS _4tail MOVW R4, R5 /* replicate */ MOVW R4, R6 MOVW R4, R7 MOVW R4, R8 MOVW R4, R9 MOVW R4, R10 MOVW R4, R11 _f32loop: CMP R(TMP), R(TO) BHS _4tail MOVM.IA.W [R4-R11], (R(TO)) B _f32loop _4tail: SUB $3, R(TOE), R(TMP) /* do remaining words if possible */ _4loop: CMP R(TMP), R(TO) BHS _1tail MOVW.P R(4), 4(R(TO)) /* implicit write back */ B _4loop _1tail: CMP R(TO), R(TOE) BEQ _return MOVBU.P R(4), 1(R(TO)) /* implicit write back */ B _1tail _return: RET