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142 lines
3.6 KiB
ArmAsm
142 lines
3.6 KiB
ArmAsm
/* Copyright (C) 2010-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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/*
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Assumes:
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ARMv6T2, AArch32
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*/
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#include <arm-features.h>
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#include <sysdep.h>
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#ifdef __ARMEB__
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#define S2LO lsl
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#define S2HI lsr
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#else
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#define S2LO lsr
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#define S2HI lsl
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#endif
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/* This code is best on Thumb. */
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.thumb
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/* Parameters and result. */
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#define srcin r0
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#define result r0
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/* Internal variables. */
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#define src r1
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#define data1a r2
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#define data1b r3
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#define const_m1 r12
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#define const_0 r4
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#define tmp1 r4 /* Overlaps const_0 */
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#define tmp2 r5
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.text
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.p2align 6
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ENTRY(strlen)
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pld [srcin, #0]
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strd r4, r5, [sp, #-8]!
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cfi_adjust_cfa_offset (8)
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cfi_rel_offset (r4, 0)
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cfi_rel_offset (r5, 4)
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cfi_remember_state
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bic src, srcin, #7
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mvn const_m1, #0
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ands tmp1, srcin, #7 /* (8 - bytes) to alignment. */
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pld [src, #32]
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bne.w .Lmisaligned8
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mov const_0, #0
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mov result, #-8
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.Lloop_aligned:
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/* Bytes 0-7. */
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ldrd data1a, data1b, [src]
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pld [src, #64]
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add result, result, #8
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.Lstart_realigned:
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uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
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sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
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uadd8 data1b, data1b, const_m1
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sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
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cbnz data1b, .Lnull_found
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/* Bytes 8-15. */
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ldrd data1a, data1b, [src, #8]
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uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
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add result, result, #8
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sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
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uadd8 data1b, data1b, const_m1
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sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
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cbnz data1b, .Lnull_found
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/* Bytes 16-23. */
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ldrd data1a, data1b, [src, #16]
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uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
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add result, result, #8
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sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
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uadd8 data1b, data1b, const_m1
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sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
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cbnz data1b, .Lnull_found
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/* Bytes 24-31. */
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ldrd data1a, data1b, [src, #24]
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add src, src, #32
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uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
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add result, result, #8
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sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
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uadd8 data1b, data1b, const_m1
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sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
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cmp data1b, #0
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beq .Lloop_aligned
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.Lnull_found:
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cmp data1a, #0
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itt eq
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addeq result, result, #4
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moveq data1a, data1b
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#ifndef __ARMEB__
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rev data1a, data1a
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#endif
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clz data1a, data1a
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ldrd r4, r5, [sp], #8
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cfi_adjust_cfa_offset (-8)
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cfi_restore (r4)
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cfi_restore (r5)
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add result, result, data1a, lsr #3 /* Bits -> Bytes. */
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DO_RET(lr)
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.Lmisaligned8:
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cfi_restore_state
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ldrd data1a, data1b, [src]
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and tmp2, tmp1, #3
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rsb result, tmp1, #0
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lsl tmp2, tmp2, #3 /* Bytes -> bits. */
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tst tmp1, #4
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pld [src, #64]
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S2HI tmp2, const_m1, tmp2
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orn data1a, data1a, tmp2
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itt ne
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ornne data1b, data1b, tmp2
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movne data1a, const_m1
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mov const_0, #0
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b .Lstart_realigned
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END(strlen)
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libc_hidden_builtin_def (strlen)
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