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/* Copyright (C) 1996-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson <rth@tamu.edu>, 1996.
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/>. */
/* Append no more than COUNT characters from the null-terminated string SRC
to the null-terminated string DST. Always null-terminate the new DST. */
#include <sysdep.h>
.text
ENTRY(strncat)
ldgp gp, 0(pv)
#ifdef PROF
.set noat
lda AT, _mcount
jsr AT, (AT), _mcount
.set at
#endif
.prologue 1
mov a0, v0 # set up return value
beq a2, $zerocount
/* Find the end of the string. */
ldq_u t0, 0(a0) # load first quadword (a0 may be misaligned)
lda t1, -1(zero)
insqh t1, a0, t1
andnot a0, 7, a0
or t1, t0, t0
cmpbge zero, t0, t1 # t1 <- bitmask: bit i == 1 <==> i-th byte == 0
bne t1, $found
$loop: ldq t0, 8(a0)
addq a0, 8, a0 # addr += 8
cmpbge zero, t0, t1
beq t1, $loop
$found: negq t1, t2 # clear all but least set bit
and t1, t2, t1
and t1, 0xf0, t2 # binary search for that set bit
and t1, 0xcc, t3
and t1, 0xaa, t4
cmovne t2, 4, t2
cmovne t3, 2, t3
cmovne t4, 1, t4
addq t2, t3, t2
addq a0, t4, a0
addq a0, t2, a0
/* Now do the append. */
jsr t9, __stxncpy
/* Worry about the null termination. */
zapnot t0, t8, t1 # was last byte a null?
bne t1, 0f
ret
0: and t10, 0x80, t1
bne t1, 1f
/* Here there are bytes left in the current word. Clear one. */
addq t10, t10, t10 # end-of-count bit <<= 1
zap t0, t10, t0
stq_u t0, 0(a0)
ret
1: /* Here we must read the next DST word and clear the first byte. */
ldq_u t0, 8(a0)
zap t0, 1, t0
stq_u t0, 8(a0)
$zerocount:
ret
END(strncat)
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