mirror of https://gitee.com/openkylin/linux.git
124 lines
2.5 KiB
ArmAsm
124 lines
2.5 KiB
ArmAsm
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/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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/* ARC700 has a relatively long pipeline and branch prediction, so we want
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to avoid branches that are hard to predict. On the other hand, the
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presence of the norm instruction makes it easier to operate on whole
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words branch-free. */
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#include <asm/linkage.h>
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ARC_ENTRY strchr
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extb_s r1,r1
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asl r5,r1,8
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bmsk r2,r0,1
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or r5,r5,r1
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mov_s r3,0x01010101
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breq.d r2,r0,.Laligned
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asl r4,r5,16
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sub_s r0,r0,r2
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asl r7,r2,3
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ld_s r2,[r0]
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#ifdef __LITTLE_ENDIAN__
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asl r7,r3,r7
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#else
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lsr r7,r3,r7
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#endif
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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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and r7,r12,r4
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breq r7,0,.Loop ; For speed, we want this branch to be unaligned.
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b .Lfound_char ; Likewise this one.
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; /* We require this code address to be unaligned for speed... */
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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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; /* ... so that this code address is aligned, for itself and ... */
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.Loop:
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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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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 r7,r12,r4
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breq r7,0,.Loop /* ... so that this branch is unaligned. */
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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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sub r3,r7,1
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bic r3,r3,r7
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norm r2,r3
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sub_s r0,r0,1
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asr_s r2,r2,3
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j.d [blink]
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sub_s r0,r0,r2
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.balign 4
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.Lfound0_ua:
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mov r3,r7
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.Lfound0:
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sub r3,r6,r3
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bic r3,r3,r6
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and r2,r3,r4
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or_s r12,r12,r2
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sub_s r3,r12,1
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bic_s r3,r3,r12
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norm r3,r3
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add_s r0,r0,3
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asr_s r12,r3,3
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asl.f 0,r2,r3
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sub_s r0,r0,r12
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j_s.d [blink]
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mov.pl r0,0
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#else /* BIG ENDIAN */
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.Lfound_char:
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lsr r7,r7,7
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bic r2,r7,r6
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norm r2,r2
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sub_s r0,r0,4
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asr_s r2,r2,3
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j.d [blink]
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add_s r0,r0,r2
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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 r12,r2,r12
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bic.f r3,r4,r12
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norm r3,r3
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add.pl r3,r3,1
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asr_s r12,r3,3
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asl.f 0,r2,r3
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add_s r0,r0,r12
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j_s.d [blink]
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mov.mi r0,0
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#endif /* ENDIAN */
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ARC_EXIT strchr
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