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https://github.com/autc04/Retro68.git
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203 lines
5.1 KiB
ArmAsm
203 lines
5.1 KiB
ArmAsm
/*
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Copyright (c) 2015, Synopsys, Inc. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1) Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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2) Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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3) Neither the name of the Synopsys, Inc., nor the names of its contributors
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may be used to endorse or promote products derived from this software
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without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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/* This implementation is optimized for performance. For code size a generic
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implementation of this function from newlib/libc/string/strchr.c will be
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used. */
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#if !defined (__OPTIMIZE_SIZE__) && !defined (PREFER_SIZE_OVER_SPEED)
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#include "asm.h"
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/* In order to search for a zero in a W, we calculate
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X := (W - 0x01010101) & ~W & 0x80808080;
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In the little endian case:
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If no byte in W is zero, X will be zero; otherwise, the least significant
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byte of X which is nonzero indicates the least significant byte of W that
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is zero.
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In the big endian case:
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X will be zero iff no byte in W is zero.
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If X is nonzero, to find out which is the most significant zero byte
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in W, we calculate:
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Y := ~(((W | 0x80808080) - 0x01010101) | W) & 0x80808080;
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Each byte in Y is 0x80 if the the corresponding byte in
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W is zero, otherwise that byte of Y is 0. */
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#if defined (__ARC_BARREL_SHIFTER__) && \
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(defined (__ARC600__) || (!defined (__ARC_NORM__) && !defined (__ARC601__)))
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ENTRY (strchr)
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bmsk.f r2,r0,1
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mov_s r3,0x01010101
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extb_s r1,r1
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asl r5,r1,8
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or r5,r5,r1
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beq.d .Laligned
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asl r4,r5,16
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sub_s r0,r0,r2
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asl_s r2,r2,3
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#ifdef __LITTLE_ENDIAN__
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asl r7,r3,r2
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#else
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lsr r7,r3,r2
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#endif
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ld_s r2,[r0]
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or r5,r5,r4
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ror r4,r3
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sub r12,r2,r7
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bic_s r12,r12,r2
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and r12,r12,r4
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brne.d r12,0,.Lfound0_ua
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xor r6,r2,r5
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ld.a r2,[r0,4]
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sub r12,r6,r7
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bic r12,r12,r6
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#ifdef __LITTLE_ENDIAN__
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and.f r7,r12,r4
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sub r12,r2,r3
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bic_s r12,r12,r2
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beq.d .Loop
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and r12,r12,r4
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b.d .Lfound_char_ua
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btst r7,7
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#else
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and.f r8,r12,r4
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sub r12,r2,r3
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bic_s r12,r12,r2
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beq.d .Loop
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and r12,r12,r4
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bic r12,r7,r6
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asl_s r12,r12,7
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and.f r2,r8,r12
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b.d .Lfound_char_ua
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sub_s r0,r0,4
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#endif
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.balign 4
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.Laligned:
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ld_s r2,[r0]
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or r5,r5,r4
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ror r4,r3
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sub r12,r2,r3
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bic_s r12,r12,r2
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and r12,r12,r4
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.Loop:
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brne.d r12,0,.Lfound0
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xor r6,r2,r5
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ld.a r2,[r0,4]
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sub r12,r6,r3
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bic r12,r12,r6
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and.f r7,r12,r4
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sub r12,r2,r3
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bic_s r12,r12,r2
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beq.d .Loop
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and r12,r12,r4
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; Found searched-for character. r0 has already advanced to next word.
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#ifdef __LITTLE_ENDIAN__
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/* We only need the information about the first matching byte
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(i.e. the least significant matching byte) to be exact,
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hence there is no problem with carry effects. */
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.Lfound_char:
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btst r7,7
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.Lfound_char_ua:
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sub_s r0,r0,4
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add.eq r0,r0,1
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btst.eq r7,15
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add.eq r0,r0,1
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btst.eq r7,23
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j_s.d [blink]
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add.eq r0,r0,1
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.balign 4
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.Lfound0_ua:
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mov_l r3,r7
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.Lfound0:
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sub r2,r6,r3
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bic r2,r2,r6
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and r2,r2,r4
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or r3,r12,r2
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sub_s r12,r3,1
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xor_s r3,r3,r12
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tst_s r2,r3
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lsr r2,r3,31
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lsr r12,r3,16
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jeq.d [blink]
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mov.eq r0,0
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lsr r3,r3,8
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sub_s r2,r2,r12
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sub_s r2,r2,r3
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bmsk_s r2,r2,1
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j_s.d [blink]
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add_s r0,r0,r2
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#else /* BIG ENDIAN */
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.Lfound_char:
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asl r6,r6,7
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sub_s r0,r0,4
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bic.f r2,r7,r6
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.Lfound_char_ua:
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add.pl r0,r0,1
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jmi.d [blink]
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btst_s r2,23
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add.eq r0,r0,1
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btst.eq r2,15
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j_s.d [blink]
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add.eq r0,r0,1
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; N.B. if we searched for a char zero and found it in the MSB,
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; and ignored matches are identical, we will take the early exit
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; like for an ordinary found zero - except for the extra stalls at jhi -
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; but still compute the right result.
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.Lfound0_ua:
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mov_s r3,r7
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.Lfound0:
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asl_s r2,r2,7
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or r7,r6,r4
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bic_s r12,r12,r2
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sub r2,r7,r3
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or r2,r2,r6
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bic r2,r4,r2
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cmp r12,r2
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mov.hi r0,0
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btst.ls r2,31
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jhi.d [blink]
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add.eq r0,r0,1
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btst.eq r2,23
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add.eq r0,r0,1
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btst.eq r2,15
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j_s.d [blink]
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add.eq r0,r0,1
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#endif /* ENDIAN */
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ENDFUNC (strchr)
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#endif /* __ARC_BARREL_SHIFTER__ &&
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(__ARC600__ || (!__ARC_NORM__ && !__ARC601__)) */
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#endif /* !__OPTIMIZE_SIZE__ && !PREFER_SIZE_OVER_SPEED */
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