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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
143 lines
4.3 KiB
ArmAsm
143 lines
4.3 KiB
ArmAsm
/* copy no more than N bytes from SRC to DEST, returning the address of
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the terminating '\0' in DEST.
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For Intel 80x86, x>=3.
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Copyright (C) 1994-2021 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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#include <sysdep.h>
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#include "asm-syntax.h"
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#define PARMS 4+4 /* space for 1 saved reg */
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#define RTN PARMS
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#define DEST RTN
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#define SRC DEST+4
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#define LEN SRC+4
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.text
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ENTRY (__stpncpy)
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pushl %esi
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cfi_adjust_cfa_offset (4)
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movl DEST(%esp), %eax
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movl SRC(%esp), %esi
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cfi_rel_offset (esi, 0)
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movl LEN(%esp), %ecx
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subl %eax, %esi /* magic: reduce number of loop variants
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to one using addressing mode */
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jmp L(1) /* jump to loop "head" */
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ALIGN(4)
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/* Four times unfolded loop with two loop counters. We get the
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third value (the source address) by using the index+base
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addressing mode. */
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L(2): movb (%eax,%esi), %dl /* load current char */
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movb %dl, (%eax) /* and store it */
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testb %dl, %dl /* was it NUL? */
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jz L(7) /* yes, then exit */
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movb 1(%eax,%esi), %dl /* load current char */
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movb %dl, 1(%eax) /* and store it */
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testb %dl, %dl /* was it NUL? */
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jz L(6) /* yes, then exit */
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movb 2(%eax,%esi), %dl /* load current char */
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movb %dl, 2(%eax) /* and store it */
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testb %dl, %dl /* was it NUL? */
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jz L(5) /* yes, then exit */
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movb 3(%eax,%esi), %dl /* load current char */
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movb %dl, 3(%eax) /* and store it */
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testb %dl, %dl /* was it NUL? */
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jz L(4) /* yes, then exit */
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addl $4, %eax /* increment loop counter for full round */
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L(1): subl $4, %ecx /* still more than 4 bytes allowed? */
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jae L(2) /* yes, then go to start of loop */
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/* The maximal remaining 15 bytes are not processed in a loop. */
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addl $4, %ecx /* correct above subtraction */
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jz L(9) /* maximal allowed char reached => go to end */
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movb (%eax,%esi), %dl /* load current char */
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movb %dl, (%eax) /* and store it */
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testb %dl, %dl /* was it NUL? */
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jz L(3) /* yes, then exit */
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incl %eax /* increment pointer */
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decl %ecx /* decrement length counter */
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jz L(9) /* no more allowed => exit */
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movb (%eax,%esi), %dl /* load current char */
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movb %dl, (%eax) /* and store it */
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testb %dl, %dl /* was it NUL? */
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jz L(3) /* yes, then exit */
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incl %eax /* increment pointer */
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decl %ecx /* decrement length counter */
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jz L(9) /* no more allowed => exit */
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movb (%eax,%esi), %dl /* load current char */
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movb %dl, (%eax) /* and store it */
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testb %dl, %dl /* was it NUL? */
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jz L(3) /* yes, then exit */
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incl %eax /* increment pointer */
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jmp L(9) /* we don't have to test for counter underflow
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because we know we had a most 3 bytes
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remaining => exit */
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/* When coming from the main loop we have to adjust the pointer. */
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L(4): decl %ecx /* decrement counter */
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incl %eax /* increment pointer */
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L(5): decl %ecx /* increment pointer */
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incl %eax /* increment pointer */
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L(6): decl %ecx /* increment pointer */
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incl %eax /* increment pointer */
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L(7):
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addl $3, %ecx /* correct pre-decrementation of counter
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at the beginning of the loop; but why 3
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and not 4? Very simple, we have to count
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the NUL char we already wrote. */
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jz L(9) /* counter is also 0 => exit */
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/* We now have to fill the rest of the buffer with NUL. This
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is done in a tricky way. Please note that the addressing mode
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used below is not the same we used above. Here we use the
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%ecx register. */
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L(8):
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movb $0, (%ecx,%eax) /* store NUL char */
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L(3): decl %ecx /* all bytes written? */
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jnz L(8) /* no, then again */
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L(9): popl %esi /* restore saved register content */
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cfi_adjust_cfa_offset (-4)
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cfi_restore (esi)
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ret
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END (__stpncpy)
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libc_hidden_def (__stpncpy)
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weak_alias (__stpncpy, stpncpy)
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