diff options
Diffstat (limited to 'libkern/memset-thumb.s')
| -rw-r--r-- | libkern/memset-thumb.s | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/libkern/memset-thumb.s b/libkern/memset-thumb.s new file mode 100644 index 00000000..92355c11 --- /dev/null +++ b/libkern/memset-thumb.s @@ -0,0 +1,66 @@ +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 |