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authorRoland McGrath <roland@gnu.org>1995-10-16 01:37:51 +0000
committerRoland McGrath <roland@gnu.org>1995-10-16 01:37:51 +0000
commit8f5ca04bc7fd53741d80117df992995ace8f6d2d (patch)
treee39c13fc198b22ec55647259a8080051988e8c69 /sysdeps/i386/stpncpy.S
parent5d82cf5c55f56ae10d3b0a205d1fcc7de1cf56a0 (diff)
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Sat Oct 14 02:52:36 1995 Ulrich Drepper <drepper@ipd.info.uni-karlsruhe.de>
* malloc/malloc.c (_malloc_internal): Performance fix. Move if statement out of loop. * stdio/_itoa.c, stdio/_itoa.h: Complete rewrite. Much faster implementation using GMP functions. Contributed by Torbjorn Granlund and Ulrich Drepper. * stdio/test_rdwr.c: Include <errno.h>. * sysdeps/i386/i586/Implies: New file. New highly optimized string functions for i[345]86. * sysdeps/i386/memchr.S, sysdeps/i386/memcmp.S: New files. * sysdeps/i386/stpcpy.S, sysdeps/i386/stpncpy.S: New files. * sysdeps/i386/strchr.S, sysdeps/i386/strcspn.S: New files. * sysdeps/i386/strpbrk.S, sysdeps/i386/strrchr.S: New files. * sysdeps/i386/strspn.S, sysdeps/i386/i486/strcat.S: New files. * sysdeps/i386/i486/strlen.S, sysdeps/i386/i586/strchr.S: New files. * sysdeps/i386/i586/strlen.S: New file. * sysdeps/i386/memchr.c: Removed. There is now an assembler version. * sysdeps/i386/i586/memcopy.h (WORD_COPY_BWD): Parameters did not correspond to used values. * sysdeps/unix/sysv/linux/nfs/nfs.h: New file. Simply a wrapper around a kernel header file. * sysdeps/unix/sysv/linux/Dist: Add it. * sysdeps/unix/sysv/linux/Makefile [$(subdir)=sunrpc] (headers): Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Rewrite. Instead of defining ourself we use a kernel header file. * sysdeps/unix/sysv/linux/i386/sysdep.h (DO_CALL): Optimize system call handler for i586. * sysdeps/unix/sysv/linux/sys/param.h: Add copyright and clean up. Sat Oct 14 02:52:36 1995 Ulrich Drepper <drepper@ipd.info.uni-karlsruhe.de> * malloc/malloc.c (_malloc_internal): Performance fix. Move if statement out of loop. * stdio/_itoa.c, stdio/_itoa.h: Complete rewrite. Much faster implementation using GMP functions. Contributed by Torbjorn Granlund and Ulrich Drepper. * stdio/test_rdwr.c: Include <errno.h>. * sysdeps/i386/i586/Implies: New file. New highly optimized string functions for i[345]86. * sysdeps/i386/memchr.S, sysdeps/i386/memcmp.S: New files. * sysdeps/i386/stpcpy.S, sysdeps/i386/stpncpy.S: New files. * sysdeps/i386/strchr.S, sysdeps/i386/strcspn.S: New files. * sysdeps/i386/strpbrk.S, sysdeps/i386/strrchr.S: New files. * sysdeps/i386/strspn.S, sysdeps/i386/i486/strcat.S: New files. * sysdeps/i386/i486/strlen.S, sysdeps/i386/i586/strchr.S: New files. * sysdeps/i386/i586/strlen.S: New file. * sysdeps/i386/memchr.c: Removed. There is now an assembler version. * sysdeps/i386/i586/memcopy.h (WORD_COPY_BWD): Parameters did not correspond to used values. * sysdeps/unix/sysv/linux/nfs/nfs.h: New file. Simply a wrapper around a kernel header file. * sysdeps/unix/sysv/linux/Dist: Add it. * sysdeps/unix/sysv/linux/Makefile [$(subdir)=sunrpc] (headers): Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Rewrite. Instead of defining ourself we use a kernel header file. * sysdeps/unix/sysv/linux/i386/sysdep.h (DO_CALL): Optimize system call handler for i586. * sysdeps/unix/sysv/linux/sys/param.h: Add copyright and clean up.
Diffstat (limited to 'sysdeps/i386/stpncpy.S')
-rw-r--r--sysdeps/i386/stpncpy.S143
1 files changed, 143 insertions, 0 deletions
diff --git a/sysdeps/i386/stpncpy.S b/sysdeps/i386/stpncpy.S
new file mode 100644
index 0000000000..59192e66c9
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+++ b/sysdeps/i386/stpncpy.S
@@ -0,0 +1,143 @@
+/* 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 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. */
+
+#include <sysdep.h>
+#include "asm-syntax.h"
+
+/*
+ INPUT PARAMETERS:
+ dest (sp + 4)
+ src (sp + 8)
+ maxlen (sp + 12)
+*/
+
+ .text
+ENTRY (__stpncpy)
+
+ pushl %esi
+
+ movl 8(%esp), %eax /* load destination pointer */
+ movl 12(%esp), %esi /* load source pointer */
+ movl 16(%esp), %ecx /* load maximal length */
+
+ subl %eax, %esi /* magic: reduce number of loop variants
+ to one using addressing mode */
+ jmp L1 /* 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 */
+ movb %dl, (%eax) /* and store it */
+ testb %dl, %dl /* was it NUL? */
+ jz L7 /* 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 */
+
+ 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 */
+
+ 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 */
+
+ 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 */
+
+ /* 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 */
+
+ movb (%eax,%esi), %dl /* load current char */
+ movb %dl, (%eax) /* and store it */
+ testb %dl, %dl /* was it NUL? */
+ jz L3 /* yes, then exit */
+
+ incl %eax /* increment pointer */
+ decl %ecx /* decrement length counter */
+ jz L9 /* 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 */
+
+ incl %eax /* increment pointer */
+ decl %ecx /* decrement length counter */
+ jz L9 /* 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 */
+
+ incl %eax /* increment pointer */
+ jmp L9 /* 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 */
+ incl %eax /* increment pointer */
+
+L5: decl %ecx /* increment pointer */
+ incl %eax /* increment pointer */
+
+L6: decl %ecx /* increment pointer */
+ incl %eax /* increment pointer */
+L7:
+
+ 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 */
+
+ /* 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
+ used below is not the same we used above. Here we use the
+ %ecx register. */
+L8:
+ movb $0, (%ecx,%eax) /* store NUL char */
+L3: decl %ecx /* all bytes written? */
+ jnz L8 /* no, then again */
+
+L9: popl %esi /* restore saved register content */
+
+ ret
+
+weak_alias (__stpncpy, stpncpy)