-/* stpncpy -- copy no more then N bytes from SRC to DEST, returning the
- address of the terminating '\0' in DEST.
-For Intel 80x86, x>=3.
-Copyright (C) 1994, 1995, 1996 Free Software Foundation, Inc.
-Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>
-Some bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>
- - original wrote n+1 chars in some cases.
- - stpncpy() ought to behave like strncpy() ie. not null-terminate
- if limited by n. glibc-1.09 stpncpy() does this.
-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 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. */
+/* copy no more than N bytes from SRC to DEST, returning the address of
+ the terminating '\0' in DEST.
+ For Intel 80x86, x>=3.
+ Copyright (C) 1994-2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>
+ Some bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>
+ - original wrote n+1 chars in some cases.
+ - stpncpy() ought to behave like strncpy() ie. not null-terminate
+ if limited by n. glibc-1.09 stpncpy() does this.
+
+ 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 <sysdep.h>
#include "asm-syntax.h"
-/*
- INPUT PARAMETERS:
- dest (sp + 4)
- src (sp + 8)
- maxlen (sp + 12)
-*/
+#define PARMS 4+4 /* space for 1 saved reg */
+#define RTN PARMS
+#define DEST RTN
+#define SRC DEST+4
+#define LEN SRC+4
.text
ENTRY (__stpncpy)
pushl %esi
+ cfi_adjust_cfa_offset (4)
- movl 8(%esp), %eax /* load destination pointer */
- movl 12(%esp), %esi /* load source pointer */
- movl 16(%esp), %ecx /* load maximal length */
+ movl DEST(%esp), %eax
+ movl SRC(%esp), %esi
+ cfi_rel_offset (esi, 0)
+ movl LEN(%esp), %ecx
subl %eax, %esi /* magic: reduce number of loop variants
to one using addressing mode */
- jmp L1 /* jump to loop "head" */
+ jmp L(1) /* jump to loop "head" */
ALIGN(4)
/* Four times unfolded loop with two loop counters. We get the
- the third value (the source address) by using the index+base
- adressing mode. */
-L2: movb (%eax,%esi), %dl /* load current char */
+ third value (the source address) by using the index+base
+ addressing mode. */
+L(2): movb (%eax,%esi), %dl /* load current char */
movb %dl, (%eax) /* and store it */
testb %dl, %dl /* was it NUL? */
- jz L7 /* yes, then exit */
+ jz L(7) /* yes, then exit */
movb 1(%eax,%esi), %dl /* load current char */
movb %dl, 1(%eax) /* and store it */
testb %dl, %dl /* was it NUL? */
- jz L6 /* yes, then exit */
+ jz L(6) /* yes, then exit */
movb 2(%eax,%esi), %dl /* load current char */
movb %dl, 2(%eax) /* and store it */
testb %dl, %dl /* was it NUL? */
- jz L5 /* yes, then exit */
+ jz L(5) /* yes, then exit */
movb 3(%eax,%esi), %dl /* load current char */
movb %dl, 3(%eax) /* and store it */
testb %dl, %dl /* was it NUL? */
- jz L4 /* yes, then exit */
+ jz L(4) /* yes, then exit */
addl $4, %eax /* increment loop counter for full round */
-L1: subl $4, %ecx /* still more than 4 bytes allowed? */
- jae L2 /* yes, then go to start of loop */
+L(1): subl $4, %ecx /* still more than 4 bytes allowed? */
+ jae L(2) /* yes, then go to start of loop */
/* The maximal remaining 15 bytes are not processed in a loop. */
addl $4, %ecx /* correct above subtraction */
- jz L9 /* maximal allowed char reached => go to end */
+ jz L(9) /* maximal allowed char reached => go to end */
movb (%eax,%esi), %dl /* load current char */
movb %dl, (%eax) /* and store it */
testb %dl, %dl /* was it NUL? */
- jz L3 /* yes, then exit */
+ jz L(3) /* yes, then exit */
incl %eax /* increment pointer */
decl %ecx /* decrement length counter */
- jz L9 /* no more allowed => exit */
+ jz L(9) /* no more allowed => exit */
movb (%eax,%esi), %dl /* load current char */
movb %dl, (%eax) /* and store it */
testb %dl, %dl /* was it NUL? */
- jz L3 /* yes, then exit */
+ jz L(3) /* yes, then exit */
incl %eax /* increment pointer */
decl %ecx /* decrement length counter */
- jz L9 /* no more allowed => exit */
+ jz L(9) /* no more allowed => exit */
movb (%eax,%esi), %dl /* load current char */
movb %dl, (%eax) /* and store it */
testb %dl, %dl /* was it NUL? */
- jz L3 /* yes, then exit */
+ jz L(3) /* yes, then exit */
incl %eax /* increment pointer */
- jmp L9 /* we don't have to test for counter underflow
+ jmp L(9) /* we don't have to test for counter underflow
because we know we had a most 3 bytes
remaining => exit */
/* When coming from the main loop we have to adjust the pointer. */
-L4: decl %ecx /* decrement counter */
+L(4): decl %ecx /* decrement counter */
incl %eax /* increment pointer */
-L5: decl %ecx /* increment pointer */
+L(5): decl %ecx /* increment pointer */
incl %eax /* increment pointer */
-L6: decl %ecx /* increment pointer */
+L(6): decl %ecx /* increment pointer */
incl %eax /* increment pointer */
-L7:
+L(7):
addl $3, %ecx /* correct pre-decrementation of counter
at the beginning of the loop; but why 3
and not 4? Very simple, we have to count
the NUL char we already wrote. */
- jz L9 /* counter is also 0 => exit */
+ jz L(9) /* counter is also 0 => exit */
/* We now have to fill the rest of the buffer with NUL. This
- is done in a tricky way. Please note that the adressing mode
+ is done in a tricky way. Please note that the addressing mode
used below is not the same we used above. Here we use the
%ecx register. */
-L8:
+L(8):
movb $0, (%ecx,%eax) /* store NUL char */
-L3: decl %ecx /* all bytes written? */
- jnz L8 /* no, then again */
+L(3): decl %ecx /* all bytes written? */
+ jnz L(8) /* no, then again */
-L9: popl %esi /* restore saved register content */
+L(9): popl %esi /* restore saved register content */
+ cfi_adjust_cfa_offset (-4)
+ cfi_restore (esi)
ret
-PSEUDO_END (__stpncpy)
+END (__stpncpy)
+libc_hidden_def (__stpncpy)
weak_alias (__stpncpy, stpncpy)
projects / thirdparty / glibc.git / blobdiff