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/* Copyright (C) 1996-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<https://www.gnu.org/licenses/>. */
/* Bytewise compare two null-terminated strings. */
#include <sysdep.h>
.set noat
.set noreorder
.text
ENTRY(strcmp)
#ifdef PROF
ldgp gp, 0(pv)
lda AT, _mcount
jmp AT, (AT), _mcount
.prologue 1
#else
.prologue 0
#endif
ldq_u t0, 0(a0) # e0 : give cache time to catch up
xor a0, a1, t2 # .. e1 : are s1 and s2 co-aligned?
ldq_u t1, 0(a1) # e0 :
and t2, 7, t2 # .. e1 :
lda t3, -1 # e0 :
bne t2, $unaligned # .. e1 :
/* On entry to this basic block:
t0 == the first destination word for masking back in
t1 == the first source word.
t3 == -1. */
$aligned:
mskqh t3, a0, t3 # e0 :
nop # .. e1 :
ornot t1, t3, t1 # e0 :
ornot t0, t3, t0 # .. e1 :
cmpbge zero, t1, t7 # e0 : bits set iff null found
bne t7, $eos # e1 (zdb)
/* Aligned compare main loop.
On entry to this basic block:
t0 == an s1 word.
t1 == an s2 word not containing a null. */
$a_loop:
xor t0, t1, t2 # e0 :
bne t2, $wordcmp # .. e1 (zdb)
ldq_u t1, 8(a1) # e0 :
ldq_u t0, 8(a0) # .. e1 :
addq a1, 8, a1 # e0 :
addq a0, 8, a0 # .. e1 :
cmpbge zero, t1, t7 # e0 :
beq t7, $a_loop # .. e1 (zdb)
br $eos # e1 :
/* The two strings are not co-aligned. Align s1 and cope. */
$unaligned:
and a0, 7, t4 # e0 : find s1 misalignment
and a1, 7, t5 # .. e1 : find s2 misalignment
subq a1, t4, a1 # e0 :
/* If s2 misalignment is larger than s2 misalignment, we need
extra startup checks to avoid SEGV. */
cmplt t4, t5, t8 # .. e1 :
beq t8, $u_head # e1 :
mskqh t3, t5, t3 # e0 :
ornot t1, t3, t3 # e0 :
cmpbge zero, t3, t7 # e1 : is there a zero?
beq t7, $u_head # e1 :
/* We've found a zero in the first partial word of s2. Align
our current s1 and s2 words and compare what we've got. */
extql t1, t5, t1 # e0 :
extql t0, a0, t0 # e0 :
cmpbge zero, t1, t7 # .. e1 : find that zero again
br $eos # e1 : and finish up
.align 3
$u_head:
/* We know just enough now to be able to assemble the first
full word of s2. We can still find a zero at the end of it.
On entry to this basic block:
t0 == first word of s1
t1 == first partial word of s2. */
ldq_u t2, 8(a1) # e0 : load second partial s2 word
lda t3, -1 # .. e1 : create leading garbage mask
extql t1, a1, t1 # e0 : create first s2 word
mskqh t3, a0, t3 # e0 :
extqh t2, a1, t4 # e0 :
ornot t0, t3, t0 # .. e1 : kill s1 garbage
or t1, t4, t1 # e0 : s2 word now complete
cmpbge zero, t0, t7 # .. e1 : find zero in first s1 word
ornot t1, t3, t1 # e0 : kill s2 garbage
lda t3, -1 # .. e1 :
mskql t3, a1, t3 # e0 : mask for s2[1] bits we have seen
bne t7, $eos # .. e1 :
xor t0, t1, t4 # e0 : compare aligned words
bne t4, $wordcmp # .. e1 (zdb)
or t2, t3, t3 # e0 :
cmpbge zero, t3, t7 # e1 :
bne t7, $u_final
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