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/* Vector optimized 32/64 bit S/390 version of strncpy.
Copyright (C) 2015-2025 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/>. */
#include <ifunc-strncpy.h>
#include "sysdep.h"
#include "asm-syntax.h"
.text
#if HAVE_STRNCPY_Z13
/* char * strncpy (const char *dest, const char *src, size_t n)
Copy at most n characters of string src to dest.
Register usage:
-r0=dest pointer for return
-r1=tmp, zero byte index
-r2=dest
-r3=src
-r4=n
-r5=current_len
-r6=tmp, loaded bytes
-r7=tmp, border
-v16=part of src
-v17=index of zero
-v18=part of src
-v31=register save area for r6, r7
*/
ENTRY(STRNCPY_Z13)
.machine "z13"
.machinemode "zarch_nohighgprs"
# if !defined __s390x__
llgfr %r4,%r4
# endif /* !defined __s390x__ */
clgfi %r4,0
ber %r14 /* Nothing to do, if n == 0. */
lgr %r0,%r2 /* Save destination pointer for return. */
vlvgp %v31,%r6,%r7 /* Save registers. */
vlbb %v16,0(%r3),6 /* Load s until next 4k-byte boundary. */
lcbb %r6,0(%r3),6 /* Get bytes to 4k-byte boundary or 16. */
llgfr %r6,%r6 /* Convert 32bit to 64bit. */
lghi %r5,0 /* current_len = 0. */
clgrjle %r4,%r6,.Lremaining_v16 /* If n <= loaded-bytes
-> process remaining. */
/* n > loaded-byte-count. */
vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
clrjl %r1,%r6,.Lfound_v16_store /* Found zero within loaded bytes,
copy and return. */
/* Align s to 16 byte. */
risbgn %r7,%r3,60,128+63,0 /* %r3 = bits 60-63 of %r2 'and' 15. */
lghi %r5,15 /* current_len = 15. */
slr %r5,%r7 /* Compute highest index to 16byte boundary. */
/* Zero not found and n > loaded-byte-count. */
vstl %v16,%r5,0(%r2) /* Copy loaded characters - no zero. */
ahi %r5,1 /* Start loop at next character. */
/* Now we are 16byte aligned, so we can load
a full vreg without page fault. */
lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
aghi %r1,64
clgrjl %r1,%r4,.Lloop64
vl %v16,0(%r5,%r3) /* Load s. */
clgijl %r4,17,.Lremaining_v16 /* If n <= 16, process remaining
bytes. */
.Llt64:
lgr %r7,%r4
slgfi %r7,16 /* border_len = n - 16. */
clgrjhe %r5,%r7,.Lremaining_v16 /* If current_len >= border
then process remaining bytes. */
vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
je .Lfound_v16 /* Jump away if zero was found. */
vl %v18,16(%r5,%r3) /* Load next part of s. */
vst %v16,0(%r5,%r2) /* Store previous part without zero to dst. */
aghi %r5,16
clgrjhe %r5,%r7,.Lremaining_v18
vfenezbs %v17,%v18,%v18
je .Lfound_v18
vl %v16,16(%r5,%r3)
vst %v18,0(%r5,%r2)
aghi %r5,16
clgrjhe %r5,%r7,.Lremaining_v16
vfenezbs %v17,%v16,%v16
je .Lfound_v16
vl %v18,16(%r5,%r3)
vst %v16,0(%r5,%r2)
aghi %r5,16
.Lremaining_v18:
vlr %v16,%v18
.Lremaining_v16:
/* v16 contains the remaining bytes [1...16].
Store remaining bytes and append string-termination. */
vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
slgrk %r7,%r4,%r5 /* Remaining bytes = maxlen - current_len. */
aghi %r7,-1 /* vstl needs highest index. */
la %r2,0(%r5,%r2) /* vstl has no index register. */
vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
/* Zero in remaining bytes? -> jump away (zero-index < max-index)
Do not jump away if zero-index == max-index,
but simply copy zero with vstl below. */
clrjl %r1,%r7,.Lfound_v16_store
vstl %v16,%r7,0(%r2) /* Store remaining bytes without null
termination!. */
.Lend:
/* Restore saved registers. */
vlgvg %r6,%v31,0
vlgvg %r7,%v31,1
lgr %r2,%r0 /* Load saved dest-ptr. */
br %r14
.Lfound_v16_32:
aghi %r5,32
j .Lfound_v16
.Lfound_v18_48:
aghi %r5,32
.Lfound_v18_16:
aghi %r5,16
.Lfound_v18:
vlr %v16,%v18
.Lfound_v16:
/* v16 contains a zero. Store remaining bytes to zero. current_len
has not reached border, thus checking for n is not needed! */
vlgvb %r1,%v17,7 /* Load byte index of zero. */
la %r2,0(%r5,%r2) /* vstl has no support for index-register. */
.Lfound_v16_store:
vstl %v16,%r1,0(%r2) /* Copy characters including zero. */
/* Fill remaining bytes with zero - remaining count always > 0. */
algr %r5,%r1 /* Remaining bytes (=%r4) = ... */
slgr %r4,%r5 /* = n - (current_len + zero_index + 1). */
la %r2,0(%r1,%r2) /* Pointer to zero. start filling beyond. */
aghi %r4,-2 /* mvc with exrl needs count - 1.
(additional -1, see remaining bytes above) */
srlg %r6,%r4,8 /* Split into 256 byte blocks. */
ltgr %r6,%r6
je .Lzero_lt256
.Lzero_loop256:
mvc 1(256,%r2),0(%r2) /* Fill 256 zeros at once. */
la %r2,256(%r2)
brctg %r6,.Lzero_loop256 /* Loop until all blocks are processed. */
.Lzero_lt256:
exrl %r4,.Lmvc_lt256
j .Lend
.Lmvc_lt256:
mvc 1(1,%r2),0(%r2)
.Lloop64:
vl %v16,0(%r5,%r3) /* Load s. */
vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
je .Lfound_v16 /* Jump away if zero was found. */
vl %v18,16(%r5,%r3) /* Load next part of s. */
vst %v16,0(%r5,%r2) /* Store previous part without zero to dst. */
vfenezbs %v17,%v18,%v18
je .Lfound_v18_16
vl %v16,32(%r5,%r3)
vst %v18,16(%r5,%r2)
vfenezbs %v17,%v16,%v16
je .Lfound_v16_32
vl %v18,48(%r5,%r3)
vst %v16,32(%r5,%r2)
vfenezbs %v17,%v18,%v18
je .Lfound_v18_48
vst %v18,48(%r5,%r2)
aghi %r5,64
lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
aghi %r1,64
clgrjl %r1,%r4,.Lloop64
vl %v16,0(%r5,%r3) /* Load s. */
j .Llt64
END(STRNCPY_Z13)
# if ! HAVE_STRNCPY_IFUNC
strong_alias (STRNCPY_Z13, strncpy)
# endif
# if ! HAVE_STRNCPY_Z900_G5 && defined SHARED && IS_IN (libc)
strong_alias (STRNCPY_Z13, __GI_strncpy)
# endif
#endif
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