/*      $NetBSD: memcmp.S,v 1.5 2015/03/26 13:34:51 justin 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>

RCSID("$NetBSD: memcmp.S,v 1.5 2015/03/26 13:34:51 justin Exp $")

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
       RETc(eq)                        /* 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
       RETc(ne)
       subs    r2, r2, #0x01
       RETc(eq)

       /* Compare up to 2 bytes */
       ldrb    r0, [ip], #0x01
       ldrb    r3, [r1], #0x01
       subs    r0, r0, r3
       RETc(ne)
       subs    r2, r2, #0x01
       RETc(eq)

       /* Compare 1 byte */
       ldrb    r0, [ip], #0x01
       ldrb    r3, [r1], #0x01
       subs    r0, r0, r3
       RETc(ne)
       subs    r2, r2, #0x01
       RETc(eq)

       /* 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? */
       RETc(eq)                        /* 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 */
       ldrbeq  r3, [ip, #0x01]         /* r3 = b1#1 */
       RETc(ne)                        /* Return if mismatch on #0 */
       subs    r0, r3, r2              /* r0 = b1#1 - b2#1 */
       ldrbeq  r3, [r1, #0x02]         /* r3 = b2#2 */
       ldrbeq  r0, [ip, #0x02]         /* r0 = b1#2 */
       RETc(ne)                        /* Return if mismatch on #1 */
       ldrb    r2, [r1, #0x03]         /* r2 = b2#3 */
       subs    r0, r0, r3              /* r0 = b1#2 - b2#2 */
       ldrbeq  r3, [ip, #0x03]         /* r3 = b1#3 */
       RETc(ne)                        /* Return if mismatch on #2 */
       subs    r0, r3, r2              /* r0 = b1#3 - b2#3 */
       ldrbeq  r3, [r1, #0x04]         /* r3 = b2#4 */
       ldrbeq  r0, [ip, #0x04]         /* r0 = b1#4 */
       RETc(ne)                        /* Return if mismatch on #3 */
       ldrb    r2, [r1, #0x05]         /* r2 = b2#5 */
       subs    r0, r0, r3              /* r0 = b1#4 - b2#4 */
       ldrbeq  r3, [ip, #0x05]         /* r3 = b1#5 */
       RETc(ne)                        /* Return if mismatch on #4 */
       sub     r0, r3, r2              /* r0 = b1#5 - b2#5 */
       RET
#endif
END(memcmp)

#if defined(__ARM_EABI__) && !defined(_RUMPKERNEL)
STRONG_ALIAS(__aeabi_memcmp, memcmp)
#endif