source: trunk/libs/newlib/src/newlib/libc/machine/arc/strchr-bs-norm.S @ 444

/*
   Copyright (c) 2015, Synopsys, Inc. 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) Neither the name of the Synopsys, Inc., nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
*/

/* This implementation is optimized for performance.  For code size a generic
   implementation of this function from newlib/libc/string/strchr.c will be
   used.  */
#if !defined (__OPTIMIZE_SIZE__) && !defined (PREFER_SIZE_OVER_SPEED)

/* ARC700 has a relatively long pipeline and branch prediction, so we want
   to avoid branches that are hard to predict.  On the other hand, the
   presence of the norm instruction makes it easier to operate on whole
   words branch-free.  */
#include "asm.h"

#if (defined (__ARC700__) || defined (__ARCEM__) || defined (__ARCHS__)) \
    && defined (__ARC_NORM__) && defined (__ARC_BARREL_SHIFTER__)

ENTRY (strchr)
        extb_s  r1,r1
        asl     r5,r1,8
        bmsk    r2,r0,1
        or      r5,r5,r1
        mov_s   r3,0x01010101
        breq.d  r2,r0,.Laligned
        asl     r4,r5,16
        sub_s   r0,r0,r2
        asl     r7,r2,3
        ld_s    r2,[r0]
#ifdef __LITTLE_ENDIAN__
        asl     r7,r3,r7
#else
        lsr     r7,r3,r7
#endif
        or      r5,r5,r4
        ror     r4,r3
        sub     r12,r2,r7
        bic_s   r12,r12,r2
        and     r12,r12,r4
        brne.d  r12,0,.Lfound0_ua
        xor     r6,r2,r5
        ld.a    r2,[r0,4]
        sub     r12,r6,r7
        bic     r12,r12,r6
#ifdef __LITTLE_ENDIAN__
        and     r7,r12,r4
        breq    r7,0,.Loop ; For speed, we want this branch to be unaligned.
        b_l     .Lfound_char ; Likewise this one.
#else
        and     r12,r12,r4
        breq_l  r12,0,.Loop ; For speed, we want this branch to be unaligned.
        lsr_s   r12,r12,7
        bic     r2,r7,r6
        b.d     .Lfound_char_b
        and_s   r2,r2,r12
#endif
; /* We require this code address to be unaligned for speed...  */
.Laligned:
        ld_s    r2,[r0]
        or      r5,r5,r4
        ror     r4,r3
; /* ... so that this code address is aligned, for itself and ...  */
.Loop:
        sub     r12,r2,r3
        bic_s   r12,r12,r2
        and     r12,r12,r4
        brne.d  r12,0,.Lfound0
        xor     r6,r2,r5
        ld.a    r2,[r0,4]
        sub     r12,r6,r3
        bic     r12,r12,r6
        and     r7,r12,r4
        breq    r7,0,.Loop /* ... so that this branch is unaligned.  */
        ; Found searched-for character.  r0 has already advanced to next word.
#ifdef __LITTLE_ENDIAN__
/* We only need the information about the first matching byte
   (i.e. the least significant matching byte) to be exact,
   hence there is no problem with carry effects.  */
.Lfound_char:
        sub     r3,r7,1
        bic     r3,r3,r7
        norm    r2,r3
        sub_s   r0,r0,1
        asr_s   r2,r2,3
        j_l.d   [blink]
        sub_s   r0,r0,r2

        .balign 4
.Lfound0_ua:
        mov_l   r3,r7
.Lfound0:
        sub     r3,r6,r3
        bic     r3,r3,r6
        and     r2,r3,r4
        or_s    r12,r12,r2
        sub_s   r3,r12,1
        bic_s   r3,r3,r12
        norm    r3,r3
        add_s   r0,r0,3
        asr_s   r12,r3,3
        asl.f   0,r2,r3
        sub_s   r0,r0,r12
        j_s.d   [blink]
        mov.pl  r0,0
#else /* BIG ENDIAN */
.Lfound_char:
        lsr     r7,r7,7

        bic     r2,r7,r6
.Lfound_char_b:
        norm    r2,r2
        sub_s   r0,r0,4
        asr_s   r2,r2,3
        j_l.d   [blink]
        add_s   r0,r0,r2

.Lfound0_ua:
        mov_s   r3,r7
.Lfound0:
        asl_s   r2,r2,7
        or      r7,r6,r4
        bic_s   r12,r12,r2
        sub     r2,r7,r3
        or      r2,r2,r6
        bic     r12,r2,r12
        bic.f   r3,r4,r12
        norm    r3,r3

        add.pl  r3,r3,1
        asr_s   r12,r3,3
        asl.f   0,r2,r3
        add_s   r0,r0,r12
        j_s.d   [blink]
        mov.mi  r0,0
#endif /* ENDIAN */
ENDFUNC (strchr)
#endif /* (__ARC700__ || __ARCEM__ || __ARCHS__) && __ARC_NORM__
    && __ARC_BARREL_SHIFTER__ */

#endif /* !__OPTIMIZE_SIZE__ && !PREFER_SIZE_OVER_SPEED */