diff options
Diffstat (limited to 'lib/libc/arm/string/memcmp.S')
| -rw-r--r-- | lib/libc/arm/string/memcmp.S | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/lib/libc/arm/string/memcmp.S b/lib/libc/arm/string/memcmp.S new file mode 100644 index 0000000..6fd8130 --- /dev/null +++ b/lib/libc/arm/string/memcmp.S @@ -0,0 +1,183 @@ +/* $NetBSD: memcmp.S,v 1.3 2003/10/14 07:51:45 scw Exp $ */ + +/* + * Copyright 2003 Wasabi Systems, Inc. + * All rights reserved. + * + * Written by Steve C. Woodford for Wasabi Systems, Inc. + * + * 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. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed for the NetBSD Project by + * Wasabi Systems, Inc. + * 4. The name of Wasabi Systems, Inc. may not be used to endorse + * or promote products derived from this software without specific prior + * written permission. + * + * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC + * 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. + */ +/* + * Copyright (c) 2002 ARM Ltd + * All rights reserved. + * + * 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. + * 3. The name of the company may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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 <machine/asm.h> + +__FBSDID("$FreeBSD$"); + +.syntax unified + +ENTRY(memcmp) + mov ip, r0 +#if defined(_KERNEL) && !defined(_STANDALONE) + cmp r2, #0x06 + beq .Lmemcmp_6bytes +#endif + mov r0, #0x00 + + /* Are both addresses aligned the same way? */ + cmp r2, #0x00 + eorsne r3, ip, r1 + RETeq /* len == 0, or same addresses! */ + tst r3, #0x03 + subne r2, r2, #0x01 + bne .Lmemcmp_bytewise2 /* Badly aligned. Do it the slow way */ + + /* Word-align the addresses, if necessary */ + sub r3, r1, #0x05 + ands r3, r3, #0x03 + add r3, r3, r3, lsl #1 + addne pc, pc, r3, lsl #3 + nop + + /* Compare up to 3 bytes */ + ldrb r0, [ip], #0x01 + ldrb r3, [r1], #0x01 + subs r0, r0, r3 + RETne + subs r2, r2, #0x01 + RETeq + + /* Compare up to 2 bytes */ + ldrb r0, [ip], #0x01 + ldrb r3, [r1], #0x01 + subs r0, r0, r3 + RETne + subs r2, r2, #0x01 + RETeq + + /* Compare 1 byte */ + ldrb r0, [ip], #0x01 + ldrb r3, [r1], #0x01 + subs r0, r0, r3 + RETne + subs r2, r2, #0x01 + RETeq + + /* Compare 4 bytes at a time, if possible */ + subs r2, r2, #0x04 + bcc .Lmemcmp_bytewise +.Lmemcmp_word_aligned: + ldr r0, [ip], #0x04 + ldr r3, [r1], #0x04 + subs r2, r2, #0x04 + cmpcs r0, r3 + beq .Lmemcmp_word_aligned + sub r0, r0, r3 + + /* Correct for extra subtraction, and check if done */ + adds r2, r2, #0x04 + cmpeq r0, #0x00 /* If done, did all bytes match? */ + RETeq /* Yup. Just return */ + + /* Re-do the final word byte-wise */ + sub ip, ip, #0x04 + sub r1, r1, #0x04 + +.Lmemcmp_bytewise: + add r2, r2, #0x03 +.Lmemcmp_bytewise2: + ldrb r0, [ip], #0x01 + ldrb r3, [r1], #0x01 + subs r2, r2, #0x01 + cmpcs r0, r3 + beq .Lmemcmp_bytewise2 + sub r0, r0, r3 + RET + +#if defined(_KERNEL) && !defined(_STANDALONE) + /* + * 6 byte compares are very common, thanks to the network stack. + * This code is hand-scheduled to reduce the number of stalls for + * load results. Everything else being equal, this will be ~32% + * faster than a byte-wise memcmp. + */ + .align 5 +.Lmemcmp_6bytes: + ldrb r3, [r1, #0x00] /* r3 = b2#0 */ + ldrb r0, [ip, #0x00] /* r0 = b1#0 */ + ldrb r2, [r1, #0x01] /* r2 = b2#1 */ + subs r0, r0, r3 /* r0 = b1#0 - b2#0 */ + ldreqb r3, [ip, #0x01] /* r3 = b1#1 */ + RETne /* Return if mismatch on #0 */ + subs r0, r3, r2 /* r0 = b1#1 - b2#1 */ + ldreqb r3, [r1, #0x02] /* r3 = b2#2 */ + ldreqb r0, [ip, #0x02] /* r0 = b1#2 */ + RETne /* Return if mismatch on #1 */ + ldrb r2, [r1, #0x03] /* r2 = b2#3 */ + subs r0, r0, r3 /* r0 = b1#2 - b2#2 */ + ldreqb r3, [ip, #0x03] /* r3 = b1#3 */ + RETne /* Return if mismatch on #2 */ + subs r0, r3, r2 /* r0 = b1#3 - b2#3 */ + ldreqb r3, [r1, #0x04] /* r3 = b2#4 */ + ldreqb r0, [ip, #0x04] /* r0 = b1#4 */ + RETne /* Return if mismatch on #3 */ + ldrb r2, [r1, #0x05] /* r2 = b2#5 */ + subs r0, r0, r3 /* r0 = b1#4 - b2#4 */ + ldreqb r3, [ip, #0x05] /* r3 = b1#5 */ + RETne /* Return if mismatch on #4 */ + sub r0, r3, r2 /* r0 = b1#5 - b2#5 */ + RET +#endif +END(memcmp) |
