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/* Optimized version of the standard strncpy() function.
This file is part of the GNU C Library.
Copyright (C) 2000-2021 Free Software Foundation, Inc.
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/>. */
/* Return: dest
Inputs:
in0: dest
in1: src
in2: len
In this form, it assumes little endian mode.
*/
#include <sysdep.h>
#undef ret
#define saved_lc r15
#define saved_pr r16
#define thresh r17
#define dest r18
#define dest2 r19
#define src r20
#define len r21
#define asrc r22
#define tmp r23
#define pos r24
#define w0 r25
#define w1 r26
#define c r27
#define sh2 r28
#define sh1 r29
#define loopcnt r30
#define value r31
ENTRY(strncpy)
.prologue
alloc r2 = ar.pfs, 3, 0, 29, 32
#define MEMLAT 2
.rotr r[MEMLAT + 2]
.rotp p[MEMLAT + 1]
mov ret0 = in0 // return value = dest
.save pr, saved_pr
mov saved_pr = pr // save the predicate registers
.save ar.lc, saved_lc
mov saved_lc = ar.lc // save the loop counter
mov ar.ec = 0 // ec is not guaranteed to
// be zero upon function entry
.body
cmp.geu p6, p5 = 24, in2
(p6) br.cond.spnt .short_len
sub tmp = r0, in0 ;; // tmp = -dest
mov len = in2 // len
mov dest = in0 // dest
mov src = in1 // src
and tmp = 7, tmp ;; // loopcnt = -dest % 8
cmp.eq p6, p7 = tmp, r0
adds loopcnt = -1, tmp // --loopcnt
(p6) br.cond.sptk .dest_aligned ;;
sub len = len, tmp // len -= -dest % 8
mov ar.lc = loopcnt
.l1: // copy -dest % 8 bytes
(p5) ld1 c = [src], 1 // c = *src++
;;
st1 [dest] = c, 1 // *dest++ = c
cmp.ne p5, p7 = c, r0
br.cloop.dptk .l1 ;;
(p7) br.cond.dpnt .found0_align
.dest_aligned: // p7 should be cleared here
shr.u c = len, 3 // c = len / 8
and sh1 = 7, src // sh1 = src % 8
and asrc = -8, src ;; // asrc = src & -OPSIZ -- align src
adds c = (MEMLAT-1), c // c = (len / 8) + MEMLAT - 1
sub thresh = 8, sh1
mov pr.rot = 1 << 16 // set rotating predicates
shl sh1 = sh1, 3 ;; // sh1 = 8 * (src % 8)
mov ar.lc = c // "infinite" loop
sub sh2 = 64, sh1 // sh2 = 64 - sh1
cmp.eq p6, p0 = sh1, r0 // is the src aligned?
(p6) br.cond.sptk .src_aligned
adds c = -(MEMLAT-1), c ;; // c = (len / 8)
ld8 r[1] = [asrc],8
mov ar.lc = c ;;
.align 32
.l2:
(p6) st8 [dest] = value, 8 // store val to dest
ld8.s r[0] = [asrc], 8
shr.u value = r[1], sh1 ;; // value = w0 >> sh1
czx1.r pos = value ;; // do we have an "early" zero
cmp.lt p7, p0 = pos, thresh // in w0 >> sh1?
adds len = -8, len // len -= 8
(p7) br.cond.dpnt .nonalign_found0
chk.s r[0], .recovery2 // it is safe to do that only
.back2: // after the previous test
shl tmp = r[0], sh2 // tmp = w1 << sh2
;;
or value = value, tmp ;; // value |= tmp
czx1.r pos = value ;;
cmp.ne p7, p6 = 8, pos
(p7) br.cond.dpnt .nonalign_found0
br.ctop.dptk .l2 ;;
adds len = 8, len
br.cond.sptk .not_found0 ;;
.nonalign_found0:
cmp.gtu p6, p0 = -8, len
(p6) br.cond.dptk .found0
adds len = 8, len
br.cond.sptk .not_found0 ;;
.align 32
.src_aligned:
.l3:
(p[0]) ld8.s r[0] = [src], 8
(p[MEMLAT]) chk.s r[MEMLAT], .recovery3
.back3:
(p[MEMLAT]) mov value = r[MEMLAT]
(p[MEMLAT]) czx1.r pos = r[MEMLAT] ;;
(p[MEMLAT]) cmp.ne p7, p0 = 8, pos
(p[MEMLAT]) adds len = -8, len // len -= 8
(p7) br.cond.dpnt .found0
(p[MEMLAT]) st8 [dest] = r[MEMLAT], 8
br.ctop.dptk .l3 ;;
chk.s r[MEMLAT-1], .recovery4
.back4:
mov value = r[MEMLAT-1]
.not_found0:
cmp.eq p5, p6 = len, r0
adds len = -1, len
(p5) br.cond.dptk .restore_and_exit ;;
mov ar.lc = len
.l4:
(p6) extr.u c = value, 0, 8 // c = value & 0xff
(p6) shr.u value = value, 8 ;;
st1 [dest] = c, 1
cmp.ne p6, p0 = c, r0
br.cloop.dptk .l4
br.cond.sptk .restore_and_exit
.found0_align:
mov pos = 0
adds len = -8, len
mov value = 0 ;;
.found0:
shl tmp = pos, 3
shr.u loopcnt = len, 4 // loopcnt = len / 16
mov c = -1 ;;
cmp.eq p6, p0 = loopcnt, r0
adds loopcnt = -1, loopcnt
shl c = c, tmp ;;
and len = 0xf, len
andcm value = value, c
mov ar.lc = loopcnt ;;
cmp.le p7, p0 = 8, len
adds dest2 = 16, dest
st8 [dest] = value, 8
and len = 0x7, len
(p6) br.cond.dpnt .l6 ;;
.l5:
st8 [dest] = r0, 16
st8 [dest2] = r0, 16
br.cloop.dptk .l5 ;;
.l6:
(p7) st8 [dest] = r0, 8
cmp.eq p5, p0 = len, r0
adds len = -1, len
(p5) br.cond.dptk .restore_and_exit ;;
mov ar.lc = len ;;
.l7:
st1 [dest] = r0, 1
br.cloop.dptk .l7 ;;
.restore_and_exit:
mov ar.lc = saved_lc // restore the loop counter
mov pr = saved_pr, -1 // restore the predicate registers
br.ret.sptk.many b0
.short_len:
cmp.eq p5, p0 = in2, r0
adds loopcnt = -1, in2
(p5) br.cond.spnt .restore_and_exit ;;
mov ar.lc = loopcnt // p6 should be set when we get here
.l8:
(p6) ld1 c = [in1], 1 // c = *src++
;;
st1 [in0] = c, 1 // *dest++ = c
(p6) cmp.ne p6, p0 = c, r0
br.cloop.dptk .l8
;;
mov ar.lc = saved_lc // restore the loop counter
mov pr = saved_pr, -1 // restore the predicate registers
br.ret.sptk.many b0
.recovery2:
add c = 8, len
add tmp = -8, asrc ;;
cmp.gtu p8, p5 = c, thresh ;;
(p8) ld8 r[0] = [tmp]
(p5) mov r[0] = r0
br.cond.sptk .back2
.recovery3:
add tmp = -(MEMLAT + 1) * 8, src ;;
ld8 r[MEMLAT] = [tmp]
br.cond.sptk .back3
.recovery4:
cmp.eq p5, p6 = len, r0
add tmp = -MEMLAT * 8, src ;;
(p6) ld8 r[MEMLAT - 1] = [tmp]
(p5) mov r[MEMLAT - 1] = r0
br.cond.sptk .back4
END(strncpy)
libc_hidden_builtin_def (strncpy)
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