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/*
* 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
* or http://www.opensolaris.org/os/licensing.
* 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.
*/
.file "strchr.s"
#include "SYS.h"
ENTRY(strchr)
mov 4(%esp), %ecx / src string here
mov 8(%esp), %edx / character to find
mov %ecx, %eax / save src
and $3, %ecx / check if src is aligned
jz prepword / search wordwise if it is
cmpb %dl, (%eax) / src == char?
jz done
cmpb $0, (%eax) / src == 0?
jz not_found
add $1, %eax / increment src
cmp $3, %ecx / check alignment
jz prepword
cmpb %dl, (%eax) / src byte contains char?
jz done
cmpb $0, (%eax) / src byte == 0?
jz not_found
add $1, %eax / increment src ptr
cmp $2, %ecx / check alignment
jz prepword
cmpb %dl, (%eax) / check this byte
jz done
cmpb $0, (%eax) / is byte zero?
jz not_found
add $1, %eax / increment src ptr
prepword:
push %ebx / save regs per calling convention
push %esi
and $0xff, %edx / only want 1st byte
mov %edx, %ebx / copy character across all bytes in wd
shl $8, %edx
or %ebx, %edx
mov %edx, %ebx
shl $16, %edx
or %ebx, %edx
.align 16 / align loop for max performance
searchchar:
mov (%eax), %esi / load src word
add $4, %eax / increment src by four
mov %esi, %ebx / copy word
lea -0x01010101(%esi), %ecx / (word - 0x01010101)
xor %edx, %ebx / tmpword = word ^ char
not %esi / ~word
and $0x80808080, %esi / ~word & 0x80808080
and %ecx, %esi / (wd - 0x01010101) & ~wd & 0x80808080
jnz has_zero_byte
lea -0x01010101(%ebx), %ecx / repeat with tmpword
not %ebx
and $0x80808080, %ebx
and %ecx, %ebx
jz searchchar / repeat if char not found
found_char:
add $0x01010101, %ecx / restore tmpword
pop %esi / restore esi ebx as per calling cvntn
pop %ebx
test $0x000000ff, %ecx / look for character's position in word
jz done0
test $0x0000ff00, %ecx
jz done1
test $0x00ff0000, %ecx
jz done2
done3:
sub $1, %eax
ret
done2:
sub $2, %eax
ret
done1:
sub $3, %eax
ret
done0:
sub $4, %eax
ret
has_zero_byte:
add $0x01010101, %ecx / restore registers here
pop %esi
pop %ebx
cmpb %dl, %cl / check for character
je done0
testb %cl, %cl / check for null byte
jz not_found
cmpb %dh, %ch / continue checking for char, null
je done1
testb %ch, %ch
jz not_found
shr $16, %ecx / put bytes 2,3 into 8-but registers
cmpb %dl, %cl
je done2
testb %cl, %cl
jz not_found
cmpb %dh, %ch / repeat checking last 2 bytes
je done3
testb %ch, %ch
jz not_found
sub $1, %eax / correct for last loop iteration
done:
ret
not_found:
xor %eax, %eax
ret
SET_SIZE(strchr)
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