/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 */

/* This is optimized primarily for the ARC700.
   It would be possible to speed up the loops by one cycle / word
   respective one cycle / byte by forcing double source 1 alignment, unrolling
   by a factor of two, and speculatively loading the second word / byte of
   source 1; however, that would increase the overhead for loop setup / finish,
   and strcmp might often terminate early.  */

#include <linux/linkage.h>

ENTRY_CFI(strcmp)
        or      r2,r0,r1
        bmsk_s  r2,r2,1
        brne    r2,0,.Lcharloop
        mov_s   r12,0x01010101
        ror     r5,r12
.Lwordloop:
        ld.ab   r2,[r0,4]
        ld.ab   r3,[r1,4]
        nop_s
        sub     r4,r2,r12
        bic     r4,r4,r2
        and     r4,r4,r5
        brne    r4,0,.Lfound0
        breq    r2,r3,.Lwordloop
#ifdef  __LITTLE_ENDIAN__
        xor     r0,r2,r3        ; mask for difference
        sub_s   r1,r0,1
        bic_s   r0,r0,r1        ; mask for least significant difference bit
        sub     r1,r5,r0
        xor     r0,r5,r1        ; mask for least significant difference byte
        and_s   r2,r2,r0
        and_s   r3,r3,r0
#endif /* LITTLE ENDIAN */
        cmp_s   r2,r3
        mov_s   r0,1
        j_s.d   [blink]
        bset.lo r0,r0,31

        .balign 4
#ifdef __LITTLE_ENDIAN__
.Lfound0:
        xor     r0,r2,r3        ; mask for difference
        or      r0,r0,r4        ; or in zero indicator
        sub_s   r1,r0,1
        bic_s   r0,r0,r1        ; mask for least significant difference bit
        sub     r1,r5,r0
        xor     r0,r5,r1        ; mask for least significant difference byte
        and_s   r2,r2,r0
        and_s   r3,r3,r0
        sub.f   r0,r2,r3
        mov.hi  r0,1
        j_s.d   [blink]
        bset.lo r0,r0,31
#else /* BIG ENDIAN */
        /* The zero-detection above can mis-detect 0x01 bytes as zeroes
           because of carry-propagateion from a lower significant zero byte.
           We can compensate for this by checking that bit0 is zero.
           This compensation is not necessary in the step where we
           get a low estimate for r2, because in any affected bytes
           we already have 0x00 or 0x01, which will remain unchanged
           when bit 7 is cleared.  */
        .balign 4
.Lfound0:
        lsr     r0,r4,8
        lsr_s   r1,r2
        bic_s   r2,r2,r0        ; get low estimate for r2 and get ...
        bic_s   r0,r0,r1        ; <this is the adjusted mask for zeros>
        or_s    r3,r3,r0        ; ... high estimate r3 so that r2 > r3 will ...
        cmp_s   r3,r2           ; ... be independent of trailing garbage
        or_s    r2,r2,r0        ; likewise for r3 > r2
        bic_s   r3,r3,r0
        rlc     r0,0            ; r0 := r2 > r3 ? 1 : 0
        cmp_s   r2,r3
        j_s.d   [blink]
        bset.lo r0,r0,31
#endif /* ENDIAN */

        .balign 4
.Lcharloop:
        ldb.ab  r2,[r0,1]
        ldb.ab  r3,[r1,1]
        nop_s
        breq    r2,0,.Lcmpend
        breq    r2,r3,.Lcharloop
.Lcmpend:
        j_s.d   [blink]
        sub     r0,r2,r3
END_CFI(strcmp)