diff --git a/common/lib/libc/arch/arm/string/memset_naive.S b/common/lib/libc/arch/arm/string/memset_naive.S new file mode 100644 index 000000000000..78b339480060 --- /dev/null +++ b/common/lib/libc/arch/arm/string/memset_naive.S @@ -0,0 +1,86 @@ +/*- + * Copyright (c) 2013 The NetBSD Foundation, Inc. + * All rights reserved. + * + * This code is derived from software contributed to The NetBSD Foundation + * by Matt Thomas of 3am Software Foundry. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED + * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS + * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include + +RCSID("$NetBSD: memset_naive.S,v 1.1 2013/01/08 20:15:00 matt Exp $") + +/* + * This isn't quite as simple/short as it could be but the truly trivial + * memset was an order of magnitude slower than this. + */ + +ENTRY(memset) +/* LINTSTUB: void *memset(void *, int, size_t) */ + mov ip, r0 /* need to preserve r0 */ + cmp r2, #10 /* 10 bytes or less? */ + ble .Lbyte_by_byte /* yes, bytewise is faster */ + ands r3, r1, #0xff /* we are dealing with bytes */ + orrne r3, r3, r3, lsl #8 /* move value into 2nd byte lane */ + orrne r3, r3, r3, lsl #16 /* move value into all byte lanes */ + mov r1, r2 /* move count */ + ands r2, ip, #7 /* are we dword aligned? */ + beq 1f /* yes we are */ + rsb r2, r2, #8 /* how many bytes until aligned? */ + sub r1, r1, r2 /* subtract from count */ + tst ip, #1 /* halfword aligned? */ + strneb r3, [ip], #1 /* nope, write a byte */ + tst ip, #2 /* word aligned? */ + strneh r3, [ip], #2 /* nope, write a halfword */ + tst ip, #4 /* dword aligned? */ + strne r3, [ip], #4 /* nope, write a word */ + /* + * At this point, we are dword aligned. + */ +1: mov r2, r3 /* duplicate fill value */ +2: subs r1, r1, #16 /* can we write 16 bytes? */ + stmgeia ip!, {r2,r3} /* yes, write the first 8 of them */ + stmgeia ip!, {r2,r3} /* yes, write the second 8 of them */ + bgt 2b /* more left to fill */ + RETc(eq) /* no, return */ + /* + * Our count went negative but the bits below 16 haven't changed. + * So we are effectively testing modulo 16. + */ + tst r1, #8 /* can we write at least 8 bytes? */ + stmneia ip!, {r2,r3} /* so do it */ + tst r1, #4 /* can we write at least 4 bytes? */ + strne r3, [ip], #4 /* so do it */ + tst r1, #2 /* can we write at least 2 bytes? */ + strneh r3, [ip], #2 /* so do it */ + tst r1, #1 /* can we write 1 bytes? */ + strneb r3, [ip], #1 /* so do it */ + RET /* return */ + +.Lbyte_by_byte: + subs r2, r2, #1 /* can we write a byte? */ + RETc(lt) /* no, return */ + strb r3, [ip], #1 /* write a byte */ + b .Lbyte_by_byte /* do next byte */ +END(memset)