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/* strncpy - copy at most n characters from a string from source to
destination. For IBM S390
This file is part of the GNU C Library.
Copyright (C) 2000, 2001 Free Software Foundation, Inc.
Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
The GNU C Library is free software ; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation ; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/*
* R2 = address of destination (dst)
* R3 = address of source (src)
* R4 = max of bytes to copy
*/
#include "sysdep.h"
#include "asm-syntax.h"
ENTRY(strncpy)
.text
st %r2,24(%r15) # save dst pointer
slr %r2,%r3 # %r3 points to src, %r2+%r3 to dst
lhi %r1,3
nr %r1,%r4 # last 2 bits of # bytes
srl %r4,2
ltr %r4,%r4 # less than 4 bytes to copy ?
jz .L1
bras %r5,.L0 # enter loop & load address of a 0
.long 0
.L0: icm %r0,8,0(%r3) # first byte
jz .L3
icm %r0,4,1(%r3) # second byte
jz .L4
icm %r0,2,2(%r3) # third byte
jz .L5
icm %r0,1,3(%r3) # fourth byte
jz .L6
st %r0,0(%r2,%r3) # store all four to dest.
la %r3,4(%r3)
brct %r4,.L0
.L1: ltr %r1,%r1
jz .Lexit
.L2: icm %r0,1,0(%r3)
stc %r0,0(%r2,%r3)
la %r3,1(%r3)
jz .L7
brct %r1,.L2
j .Lexit
.L3: icm %r0,4,0(%r5)
.L4: icm %r0,2,0(%r5)
.L5: icm %r0,1,0(%r5)
.L6: st %r0,0(%r2,%r3)
la %r3,4(%r3)
ahi %r4,-1
j .L8
.L7: ahi %r1,-1
.L8: sll %r4,2
alr %r4,%r1
alr %r2,%r3 # start of dst area to be zeroed
lr %r3,%r4
slr %r4,%r4
slr %r5,%r5
.L9: mvcle %r2,%r4,0 # pad dst with zeroes
jo .L9
.Lexit: l %r2,24(%r15) # return dst pointer
br %r14
END(strncpy)
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