ref: 7aceac32e8fae763634f28cfccd9ce2356fccab5
dir: /sys/src/ape/lib/ap/arm/memset.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) ORR R(4)<<8, R(4) ORR R(4)<<16, R(4) /* replicate to word */ _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 $15, R(TOE), R(TMP) /* do 16-byte chunks if possible */ CMP R(TMP), R(TO) BHS _4tail MOVW R4, R5 /* replicate */ MOVW R4, R6 MOVW R4, R7 _f16loop: CMP R(TMP), R(TO) BHS _4tail MOVM.IA.W [R4-R7], (R(TO)) B _f16loop _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