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107 lines
2.8 KiB
ArmAsm
107 lines
2.8 KiB
ArmAsm
/* Copyright (C) 1996-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Richard Henderson (rth@tamu.edu)
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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/* Copy no more than COUNT bytes of the null-terminated string from
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SRC to DST. If SRC does not cover all of COUNT, the balance is
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zeroed. Return the address of the terminating null in DEST, if
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any, else DEST + COUNT. */
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#include <sysdep.h>
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.set noat
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.set noreorder
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.text
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ENTRY(__stpncpy)
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ldgp gp, 0(pv)
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#ifdef PROF
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lda AT, _mcount
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jsr AT, (AT), _mcount
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#endif
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.prologue 1
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beq a2, $zerocount
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jsr t9, __stxncpy # do the work of the copy
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and t8, 0xf0, t3 # binary search for byte offset of the
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and t8, 0xcc, t2 # last byte written.
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and t8, 0xaa, t1
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andnot a0, 7, v0
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cmovne t3, 4, t3
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cmovne t2, 2, t2
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cmovne t1, 1, t1
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addq v0, t3, v0
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addq t1, t2, t1
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addq v0, t1, v0
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bne a2, $multiword # do we have full words left?
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.align 3
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zapnot t0, t8, t4 # e0 : was last byte a null?
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subq t8, 1, t2 # .. e1 :
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addq v0, 1, t5 # e0 :
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subq t10, 1, t3 # .. e1 :
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or t2, t8, t2 # e0 : clear the bits between the last
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or t3, t10, t3 # .. e1 : written byte and the last byte in
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andnot t3, t2, t3 # e0 : COUNT
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cmovne t4, t5, v0 # .. e1 : if last written wasnt null, inc v0
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zap t0, t3, t0 # e0 :
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stq_u t0, 0(a0) # e1 :
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ret # .. e1 :
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.align 3
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$multiword:
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subq t8, 1, t7 # e0 : clear the final bits in the prev
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or t7, t8, t7 # e1 : word
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zapnot t0, t7, t0 # e0 :
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subq a2, 1, a2 # .. e1 :
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stq_u t0, 0(a0) # e0 :
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addq a0, 8, a0 # .. e1 :
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beq a2, 1f # e1 :
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blbc a2, 0f # e1 :
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stq_u zero, 0(a0) # e0 : zero one word
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subq a2, 1, a2 # .. e1 :
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addq a0, 8, a0 # e0 :
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beq a2, 1f # .. e1 :
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0: stq_u zero, 0(a0) # e0 : zero two words
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subq a2, 2, a2 # .. e1 :
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stq_u zero, 8(a0) # e0 :
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addq a0, 16, a0 # .. e1 :
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bne a2, 0b # e1 :
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unop
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1: ldq_u t0, 0(a0) # e0 : clear the leading bits in the final
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subq t10, 1, t7 # .. e1 : word
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or t7, t10, t7 # e0 :
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zap t0, t7, t0 # e1 (stall)
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stq_u t0, 0(a0) # e0 :
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ret # .. e1 :
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$zerocount:
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mov a0, v0
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ret
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END(__stpncpy)
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libc_hidden_def (__stpncpy)
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weak_alias (__stpncpy, stpncpy)
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