/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/
/
/
/
/
/ char *
/ strcpy(char *s1, const char *s2)
/ {
/ char *os1 = s1;
/
/ while (*s1++ = *s2++)
/ ;
/ return (os1);
/ }
/
/ In this assembly language version, the following expression is used
/ to check if a 32-bit word data contains a null byte or not:
/ (((A & 0x7f7f7f7f) + 0x7f7f7f7f) | A) & 0x80808080
/ If the above expression geneates a value other than 0x80808080,
/ that means the 32-bit word data contains a null byte.
/
#include "SYS.h"
ENTRY(strcpy)
push %edi / save reg as per calling cvntn
mov 12(%esp), %ecx / src ptr
mov 8(%esp), %edi / dst ptr
mov %ecx, %eax / src
sub %edi, %ecx / src - dst
and $3, %eax / check src alignment
jz load
sub $4, %eax
byte_loop:
movb (%edi, %ecx, 1), %dl / load src byte
movb %dl, (%edi) / load dest byte
inc %edi / increment src and dest
testb %dl, %dl / is src zero?
jz done
inc %eax / check src alignment
jnz byte_loop
jmp load
store:
mov %eax, (%edi) / store word
add $4, %edi / incrment src and dest by 4
load:
mov (%edi, %ecx, 1), %eax / load word
lea -0x01010101(%eax), %edx / (word - 0x01010101)
not %eax / ~word
and %eax, %edx / (word - 0x01010101) & ~word
not %eax / word
and $0x80808080, %edx / (wd - 0x01010101) & ~wd & 0x80808080
jz store / store word w/o zero byte
has_zero_byte:
movb %al, (%edi) / store first byte
testb %al, %al / check first byte for zero
jz done
movb %ah, 1(%edi) / continue storing and checking
testb %ah, %ah
jz done
shr $16, %eax / grab last two bytes
movb %al, 2(%edi)
testb %al, %al
jz done
movb %ah, 3(%edi)
done:
mov 8(%esp), %eax / return ptr to dest
pop %edi / restore as per calling cvntn
ret
SET_SIZE(strcpy)