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/* Compare two strings for differences.
For SPARC v9.
Copyright (C) 2011 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by David S. Miller <davem@davemloft.net>
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/asi.h>
#ifndef XCC
.register %g2, #scratch
.register %g3, #scratch
.register %g6, #scratch
#endif
#define rSTR1 %o0
#define rSTR2 %o1
#define r0101 %o2 /* 0x0101010101010101 */
#define r8080 %o3 /* 0x8080808080808080 */
#define rSTRXOR %o4
#define rWORD1 %o5
#define rTMP1 %g1
#define rTMP2 %g2
#define rWORD2 %g3
#define rSLL %g4
#define rSRL %g5
#define rBARREL %g6
/* There are two cases, either the two pointers are aligned
* identically or they are not. If they have the same
* alignment we can use the normal full speed loop. Otherwise
* we have to use the barrel-shifter version.
*/
.text
.align 32
ENTRY(strcmp)
or rSTR2, rSTR1, rTMP1
sethi %hi(0x80808080), r8080
andcc rTMP1, 0x7, %g0
bne,pn %icc, .Lmaybe_barrel_shift
or r8080, %lo(0x80808080), r8080
ldx [rSTR1], rWORD1
sub rSTR2, rSTR1, rSTR2
sllx r8080, 32, rTMP1
ldx [rSTR1 + rSTR2], rWORD2
or r8080, rTMP1, r8080
ba,pt %xcc, .Laligned_loop_entry
srlx r8080, 7, r0101
.align 32
.Laligned_loop_entry:
.Laligned_loop:
add rSTR1, 8, rSTR1
sub rWORD1, r0101, rTMP2
xorcc rWORD1, rWORD2, rSTRXOR
bne,pn %xcc, .Lcommon_endstring
andn r8080, rWORD1, rTMP1
ldxa [rSTR1] ASI_PNF, rWORD1
andcc rTMP1, rTMP2, %g0
be,a,pt %xcc, .Laligned_loop
ldxa [rSTR1 + rSTR2] ASI_PNF, rWORD2
.Lcommon_equal:
retl
mov 0, %o0
/* All loops terminate here once they find an unequal word.
* If a zero byte appears in the word before the first unequal
* byte, we must report zero. Otherwise we report '1' or '-1'
* depending upon whether the first mis-matching byte is larger
* in the first string or the second, respectively.
*
* First we compute a 64-bit mask value that has "0x01" in
* each byte where a zero exists in rWORD1. rSTRXOR holds the
* value (rWORD1 ^ rWORD2). Therefore, if considered as an
* unsigned quantity, our "0x01" mask value is "greater than"
* rSTRXOR then a zero terminating byte comes first and
* therefore we report '0'.
*
* The formula for this mask is:
*
* mask_tmp1 = ~rWORD1 & 0x8080808080808080;
* mask_tmp2 = ((rWORD1 & 0x7f7f7f7f7f7f7f7f) +
* 0x7f7f7f7f7f7f7f7f);
*
* mask = ((mask_tmp1 & ~mask_tmp2) >> 7);
*/
.Lcommon_endstring:
andn rWORD1, r8080, rTMP2
or r8080, 1, %o1
mov 1, %o0
sub rTMP2, %o1, rTMP2
cmp rWORD1, rWORD2
andn rTMP1, rTMP2, rTMP1
movleu %xcc, -1, %o0
srlx rTMP1, 7, rTMP1
/* In order not to be influenced by bytes after the zero byte, we
* have to retain only the highest bit in the mask for the comparison
* with rSTRXOR to work properly.
*/
mov 0, rTMP2
andcc rTMP1, 0x0100, %g0
movne %xcc, 8, rTMP2
sllx rTMP1, 63 - 16, %o1
movrlz %o1, 16, rTMP2
sllx rTMP1, 63 - 24, %o1
movrlz %o1, 24, rTMP2
sllx rTMP1, 63 - 32, %o1
movrlz %o1, 32, rTMP2
sllx rTMP1, 63 - 40, %o1
movrlz %o1, 40, rTMP2
sllx rTMP1, 63 - 48, %o1
movrlz %o1, 48, rTMP2
sllx rTMP1, 63 - 56, %o1
movrlz %o1, 56, rTMP2
srlx rTMP1, rTMP2, rTMP1
sllx rTMP1, rTMP2, rTMP1
cmp rTMP1, rSTRXOR
retl
movgu %xcc, 0, %o0
.Lmaybe_barrel_shift:
sub rSTR2, rSTR1, rSTR2
sllx r8080, 32, rTMP1
or r8080, rTMP1, r8080
and rSTR1, 0x7, rTMP2
srlx r8080, 7, r0101
andn rSTR1, 0x7, rSTR1
ldxa [rSTR1] ASI_PNF, rWORD1
andcc rSTR2, 0x7, rSLL
sll rTMP2, 3, rSTRXOR
bne,pn %icc, .Lneed_barrel_shift
mov -1, rTMP1
ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
srlx rTMP1, rSTRXOR, rTMP2
orn rWORD1, rTMP2, rWORD1
ba,pt %xcc, .Laligned_loop_entry
orn rBARREL, rTMP2, rWORD2
.Lneed_barrel_shift:
sllx rSLL, 3, rSLL
andn rSTR2, 0x7, rSTR2
ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
mov 64, rTMP2
sub rTMP2, rSLL, rSRL
srlx rTMP1, rSTRXOR, rTMP1
add rSTR2, 8, rSTR2
orn rWORD1, rTMP1, rWORD1
sllx rBARREL, rSLL, rWORD2
ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
add rSTR1, 8, rSTR1
sub rWORD1, r0101, rTMP2
srlx rBARREL, rSRL, rSTRXOR
or rWORD2, rSTRXOR, rWORD2
orn rWORD2, rTMP1, rWORD2
ba,pt %xcc, .Lbarrel_shift_loop_entry
andn r8080, rWORD1, rTMP1
.Lbarrel_shift_loop:
sllx rBARREL, rSLL, rWORD2
ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
add rSTR1, 8, rSTR1
sub rWORD1, r0101, rTMP2
srlx rBARREL, rSRL, rSTRXOR
andn r8080, rWORD1, rTMP1
or rWORD2, rSTRXOR, rWORD2
.Lbarrel_shift_loop_entry:
xorcc rWORD1, rWORD2, rSTRXOR
bne,pn %xcc, .Lcommon_endstring
andcc rTMP1, rTMP2, %g0
be,a,pt %xcc, .Lbarrel_shift_loop
ldxa [rSTR1] ASI_PNF, rWORD1
retl
mov 0, %o0
END(strcmp)
libc_hidden_builtin_def (strcmp)
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