newlib-cygwin/newlib/libc/machine/mips/strcmp.S

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/*
* Copyright (c) 2014
* Imagination Technologies Limited.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the MIPS Technologies, Inc., nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY IMAGINATION TECHNOLOGIES LIMITED ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL IMAGINATION TECHNOLOGIES LIMITED BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifdef ANDROID_CHANGES
# include "machine/asm.h"
# include "machine/regdef.h"
#elif _COMPILING_NEWLIB
# include "machine/asm.h"
# include "machine/regdef.h"
#else
# include <regdef.h>
# include <sys/asm.h>
#endif
/* Technically strcmp should not read past the end of the strings being
compared. We will read a full word that may contain excess bits beyond
the NULL string terminator but unless ENABLE_READAHEAD is set, we will not
read the next word after the end of string. Setting ENABLE_READAHEAD will
improve performance but is technically illegal based on the definition of
strcmp. */
#ifdef ENABLE_READAHEAD
# define DELAY_READ
#else
# define DELAY_READ nop
#endif
/* Testing on a little endian machine showed using CLZ was a
performance loss, so we are not turning it on by default. */
#if defined(ENABLE_CLZ) && (__mips_isa_rev > 1)
# define USE_CLZ
#endif
/* Some asm.h files do not have the L macro definition. */
#ifndef L
# if _MIPS_SIM == _ABIO32
# define L(label) $L ## label
# else
# define L(label) .L ## label
# endif
#endif
/* Some asm.h files do not have the PTR_ADDIU macro definition. */
#ifndef PTR_ADDIU
# ifdef USE_DOUBLE
# define PTR_ADDIU daddiu
# else
# define PTR_ADDIU addiu
# endif
#endif
/* Allow the routine to be named something else if desired. */
#ifndef STRCMP_NAME
# define STRCMP_NAME strcmp
#endif
#ifdef ANDROID_CHANGES
LEAF(STRCMP_NAME, 0)
#else
LEAF(STRCMP_NAME)
#endif
.set nomips16
.set noreorder
or t0, a0, a1
andi t0,0x3
bne t0, zero, L(byteloop)
/* Both strings are 4 byte aligned at this point. */
lui t8, 0x0101
ori t8, t8, 0x0101
lui t9, 0x7f7f
ori t9, 0x7f7f
#define STRCMP32(OFFSET) \
lw v0, OFFSET(a0); \
lw v1, OFFSET(a1); \
subu t0, v0, t8; \
bne v0, v1, L(worddiff); \
nor t1, v0, t9; \
and t0, t0, t1; \
bne t0, zero, L(returnzero)
L(wordloop):
STRCMP32(0)
DELAY_READ
STRCMP32(4)
DELAY_READ
STRCMP32(8)
DELAY_READ
STRCMP32(12)
DELAY_READ
STRCMP32(16)
DELAY_READ
STRCMP32(20)
DELAY_READ
STRCMP32(24)
DELAY_READ
STRCMP32(28)
PTR_ADDIU a0, a0, 32
b L(wordloop)
PTR_ADDIU a1, a1, 32
L(returnzero):
j ra
move v0, zero
L(worddiff):
#ifdef USE_CLZ
subu t0, v0, t8
nor t1, v0, t9
and t1, t0, t1
xor t0, v0, v1
or t0, t0, t1
# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
wsbh t0, t0
rotr t0, t0, 16
# endif
clz t1, t0
and t1, 0xf8
# if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
neg t1
addu t1, 24
# endif
rotrv v0, v0, t1
rotrv v1, v1, t1
and v0, v0, 0xff
and v1, v1, 0xff
j ra
subu v0, v0, v1
#else /* USE_CLZ */
# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
andi t0, v0, 0xff
beq t0, zero, L(wexit01)
andi t1, v1, 0xff
bne t0, t1, L(wexit01)
srl t8, v0, 8
srl t9, v1, 8
andi t8, t8, 0xff
beq t8, zero, L(wexit89)
andi t9, t9, 0xff
bne t8, t9, L(wexit89)
srl t0, v0, 16
srl t1, v1, 16
andi t0, t0, 0xff
beq t0, zero, L(wexit01)
andi t1, t1, 0xff
bne t0, t1, L(wexit01)
srl t8, v0, 24
srl t9, v1, 24
# else /* __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ */
srl t0, v0, 24
beq t0, zero, L(wexit01)
srl t1, v1, 24
bne t0, t1, L(wexit01)
srl t8, v0, 16
srl t9, v1, 16
andi t8, t8, 0xff
beq t8, zero, L(wexit89)
andi t9, t9, 0xff
bne t8, t9, L(wexit89)
srl t0, v0, 8
srl t1, v1, 8
andi t0, t0, 0xff
beq t0, zero, L(wexit01)
andi t1, t1, 0xff
bne t0, t1, L(wexit01)
andi t8, v0, 0xff
andi t9, v1, 0xff
# endif /* __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ */
L(wexit89):
j ra
subu v0, t8, t9
L(wexit01):
j ra
subu v0, t0, t1
#endif /* USE_CLZ */
/* It might seem better to do the 'beq' instruction between the two 'lbu'
instructions so that the nop is not needed but testing showed that this
code is actually faster (based on glibc strcmp test). */
#define BYTECMP01(OFFSET) \
lbu v0, OFFSET(a0); \
lbu v1, OFFSET(a1); \
beq v0, zero, L(bexit01); \
nop; \
bne v0, v1, L(bexit01)
#define BYTECMP89(OFFSET) \
lbu t8, OFFSET(a0); \
lbu t9, OFFSET(a1); \
beq t8, zero, L(bexit89); \
nop; \
bne t8, t9, L(bexit89)
L(byteloop):
BYTECMP01(0)
BYTECMP89(1)
BYTECMP01(2)
BYTECMP89(3)
BYTECMP01(4)
BYTECMP89(5)
BYTECMP01(6)
BYTECMP89(7)
PTR_ADDIU a0, a0, 8
b L(byteloop)
PTR_ADDIU a1, a1, 8
L(bexit01):
j ra
subu v0, v0, v1
L(bexit89):
j ra
subu v0, t8, t9
.set at
.set reorder
END(STRCMP_NAME)