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Diffstat (limited to 'sysdeps/i386/stpncpy.S')
| -rw-r--r-- | sysdeps/i386/stpncpy.S | 147 |
1 files changed, 0 insertions, 147 deletions
diff --git a/sysdeps/i386/stpncpy.S b/sysdeps/i386/stpncpy.S deleted file mode 100644 index 46f2aba713..0000000000 --- a/sysdeps/i386/stpncpy.S +++ /dev/null @@ -1,147 +0,0 @@ -/* 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) 1994-2017 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 - <http://www.gnu.org/licenses/>. */ - -#include <sysdep.h> -#include "asm-syntax.h" - -#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 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 L(1) /* jump to loop "head" */ - - ALIGN(4) - - /* Four times unfolded loop with two loop counters. We get the - 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 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 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 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 L(4) /* yes, then exit */ - - addl $4, %eax /* increment loop counter for full round */ - -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 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 L(3) /* yes, then exit */ - - incl %eax /* increment pointer */ - decl %ecx /* decrement length counter */ - 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 L(3) /* yes, then exit */ - - incl %eax /* increment pointer */ - decl %ecx /* decrement length counter */ - 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 L(3) /* yes, then exit */ - - incl %eax /* increment pointer */ - 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. */ -L(4): decl %ecx /* decrement counter */ - incl %eax /* increment pointer */ - -L(5): decl %ecx /* increment pointer */ - incl %eax /* increment pointer */ - -L(6): decl %ecx /* increment pointer */ - incl %eax /* increment pointer */ -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 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 addressing mode - used below is not the same we used above. Here we use the - %ecx register. */ -L(8): - movb $0, (%ecx,%eax) /* store NUL char */ -L(3): decl %ecx /* all bytes written? */ - jnz L(8) /* no, then again */ - -L(9): popl %esi /* restore saved register content */ - cfi_adjust_cfa_offset (-4) - cfi_restore (esi) - - ret -END (__stpncpy) - -libc_hidden_def (__stpncpy) -weak_alias (__stpncpy, stpncpy) |