source: trunk/libs/newlib/src/newlib/libc/machine/arc/strlen.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/strlen.c will be
   used.  */
#if !defined (__OPTIMIZE_SIZE__) && !defined (PREFER_SIZE_OVER_SPEED)

#include "asm.h"

#if defined(__ARC601__) || !defined (__ARC_BARREL_SHIFTER__)
/* This code is optimized for the ARC601 pipeline without barrel shifter.  */

ENTRY (strlen)
        or      r3,r0,7
        ld      r2,[r3,-7]
        ld.a    r6,[r3,-3]
        mov     r4,0x01010101
        ; uses long immediate
#ifdef __LITTLE_ENDIAN__
        bmsk.f  0,r0,1
        mov_s   r1,31
        add3_s  r1,r1,r0
        bmsk    r7,r4,r1
        xor.ne  r7,r7,r4
        btst_s  r0,2
        ror     r5,r4
        sub     r1,r2,r7
        bic_s   r1,r1,r2
        mov.eq  r7,r4
        sub     r12,r6,r7
        bic     r12,r12,r6
        or.eq   r12,r12,r1
        and     r12,r12,r5
        brne    r12,0,.Learly_end
#else /* BIG ENDIAN */
        add.f   r1,r4,30 ; r1 mod 31 := -1; clear carry
        ror     r5,r4
        sub3    r7,r1,r0
        btst_s  r0,2
        sub     r1,r2,r4
        bic_s   r1,r1,r2
        bmsk    r1,r1,r7
        sub     r12,r6,r4
        bic     r12,r12,r6
        bmsk.ne r12,r12,r7
        or.eq   r12,r12,r1
        and     r12,r12,r5
        brne    r12,0,.Learly_end
#endif /* ENDIAN */

.Loop:
        ld_s    r2,[r3,4]
        ld.a    r6,[r3,8]
        ; stall for load result
        sub     r1,r2,r4
        bic_s   r1,r1,r2
        sub     r12,r6,r4
        bic     r12,r12,r6
        or_s    r12,r12,r1
        and     r12,r12,r5
        breq_s  r12,0,.Loop
.Lend:
        and.f   r1,r1,r5
        sub.ne  r3,r3,4
#ifdef __LITTLE_ENDIAN__
        mov.eq  r1,r12
        btst_s  r1,7
        sub     r0,r3,r0
        add.eq  r0,r0,1
        bmsk.f  0,r1,15
        add.eq  r0,r0,1
        bmsk.f  0,r1,23
        j_s.d   [blink]
        add.eq  r0,r0,1
#else /* BIG ENDIAN */
#ifdef __OPTIMIZE_SIZE__
1:      ldb_s   r1,[r3]
        breq_s  r1,0,0f
        ldb.a   r1,[r3,1]
        breq_s  r1,0,0f
        ldb.a   r1,[r3,1]
        breq_s  r1,0,0f
        add_s   r3,r3,1
0:      j_s.d   [blink]
        sub     r0,r3,r0

#define SPECIAL_EARLY_END
.Learly_end:
        mov_s   r3,r0
        b_s     1b
#elif 0 /* Need more information about pipeline to assess if this is faster.  */
        mov.eq  r2,r6
        and     r2,r2,r5
        sub1    r2,r4,r2
        mov.eq  r1,r12
        bic.f   r1,r1,r2
        sub     r0,r3,r0
        add.pl  r0,r0,1
        btst.pl r1,23
        add.eq  r0,r0,1
        btst.eq r1,15
        j_s.d   [blink]
        add.eq  r0,r0,1
#else /* !__OPTIMIZE_SIZE__ */
        /* Need carry clear here.  */
        mov.eq  r2,r6
1:      bmsk    r1,r2,23
        breq    r1,r2,0f
        bmsk    r2,r1,15
        breq.d  r1,r2,0f
        add_s   r3,r3,1
        cmp     r2,0x100
        add_s   r3,r3,2
0:      j_s.d   [blink]
        sbc     r0,r3,r0

#define SPECIAL_EARLY_END
.Learly_end:
        sub_s.ne r1,r1,r1
        mov_s   r12,0
        bset    r12,r12,r7
        sub1    r2,r2,r12
        b.d     .Lend
        sub1.ne r6,r6,r12
#endif /* !__OPTIMIZE_SIZE__ */
#endif /* ENDIAN */

#ifndef SPECIAL_EARLY_END
        .balign 4
.Learly_end:
        b.d     .Lend
        sub_s.ne r1,r1,r1
#endif /* !SPECIAL_EARLY_END */
ENDFUNC (strlen)
#endif /* __ARC601__ || !__ARC_BARREL_SHIFTER__*/

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