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* libc/machine/arm/strcmp-arm-tiny.S: New file. 

* libc/machine/arm/strcmp-armv4.S: New file.
	* libc/machine/arm/strcmp-armv4t.S: New file.
	* libc/machine/arm/strcmp-armv6.S: New file.
	* libc/machine/arm/strcmp-armv7.S: New file.
	* libc/machine/arm/strcmp-armv7m.S: New file.
	* libc/machine/arm/strcmp.S: Replace with wrapper for various
	implementations.
	* libc/machine/arm/Makefile.am (strcmp.o, strcmp.obj): Add
	dependencies.
	* libc/machine/arm/Makefile.in: Regenerated.
This commit is contained in:
Richard Earnshaw 2014-04-22 12:16:22 +00:00
parent 93a1517f68
commit 742e729664
10 changed files with 1859 additions and 743 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
newlib/ChangeLog
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@ -1,3 +1,17 @@
2014-04-22 Richard Earnshaw <rearnsha@arm.com>
* libc/machine/arm/strcmp-arm-tiny.S: New file.
* libc/machine/arm/strcmp-armv4.S: New file.
* libc/machine/arm/strcmp-armv4t.S: New file.
* libc/machine/arm/strcmp-armv6.S: New file.
* libc/machine/arm/strcmp-armv7.S: New file.
* libc/machine/arm/strcmp-armv7m.S: New file.
* libc/machine/arm/strcmp.S: Replace with wrapper for various
implementations.
* libc/machine/arm/Makefile.am (strcmp.o, strcmp.obj): Add
dependencies.
* libc/machine/arm/Makefile.in: Regenerated.
2014-04-14 Sebastian Huber <sebastian.huber@embedded-brains.de> 2014-04-14 Sebastian Huber <sebastian.huber@embedded-brains.de>
* libc/sys/rtems/sys/cpuset.h (CPU_SET_S): Add const qualifier. * libc/sys/rtems/sys/cpuset.h (CPU_SET_S): Add const qualifier.

6
newlib/libc/machine/arm/Makefile.am
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@ -18,7 +18,13 @@ ACLOCAL_AMFLAGS = -I ../../.. -I ../../../..
CONFIG_STATUS_DEPENDENCIES = $(newlib_basedir)/configure.host CONFIG_STATUS_DEPENDENCIES = $(newlib_basedir)/configure.host
MEMCPY_DEP=memcpy-armv7a.S memcpy-armv7m.S MEMCPY_DEP=memcpy-armv7a.S memcpy-armv7m.S
STRCMP_DEP=strcmp-arm-tiny.S strcmp-armv4.S strcmp-armv4t.S strcmp-armv6.S \
strcmp-armv7.S strcmp-armv7m.S
$(lpfx)memcpy.o: $(MEMCPY_DEP) $(lpfx)memcpy.o: $(MEMCPY_DEP)
$(lpfx)memcpy.obj: $(MEMCPY_DEP) $(lpfx)memcpy.obj: $(MEMCPY_DEP)
$(lpfx)strcmp.o: $(STRCMP_DEP)
$(lpfx)strcmp.obj: $(STRCMP_DEP)

7
newlib/libc/machine/arm/Makefile.in
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@ -209,6 +209,9 @@ lib_a_CFLAGS = $(AM_CFLAGS)
ACLOCAL_AMFLAGS = -I ../../.. -I ../../../.. ACLOCAL_AMFLAGS = -I ../../.. -I ../../../..
CONFIG_STATUS_DEPENDENCIES = $(newlib_basedir)/configure.host CONFIG_STATUS_DEPENDENCIES = $(newlib_basedir)/configure.host
MEMCPY_DEP = memcpy-armv7a.S memcpy-armv7m.S MEMCPY_DEP = memcpy-armv7a.S memcpy-armv7m.S
STRCMP_DEP = strcmp-arm-tiny.S strcmp-armv4.S strcmp-armv4t.S strcmp-armv6.S \
strcmp-armv7.S strcmp-armv7m.S
all: all-am all: all-am
.SUFFIXES: .SUFFIXES:
@ -508,6 +511,10 @@ $(lpfx)memcpy.o: $(MEMCPY_DEP)
$(lpfx)memcpy.obj: $(MEMCPY_DEP) $(lpfx)memcpy.obj: $(MEMCPY_DEP)
$(lpfx)strcmp.o: $(STRCMP_DEP)
$(lpfx)strcmp.obj: $(STRCMP_DEP)
# Tell versions [3.59,3.63) of GNU make to not export all variables. # Tell versions [3.59,3.63) of GNU make to not export all variables.
# Otherwise a system limit (for SysV at least) may be exceeded. # Otherwise a system limit (for SysV at least) may be exceeded.
.NOEXPORT: .NOEXPORT:

46
newlib/libc/machine/arm/strcmp-arm-tiny.S Normal file
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@ -0,0 +1,46 @@
/*
* Copyright (c) 2012-2014 ARM Ltd
* All rights reserved.
*
* 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. The name of the company may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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.
*/
/* Tiny version of strcmp in ARM state. Used only when optimizing
for size. Also supports Thumb-2. */
.syntax unified
def_fn strcmp
.cfi_startproc
1:
ldrb r2, [r0], #1
ldrb r3, [r1], #1
cmp r2, #1
it cs
cmpcs r2, r3
beq 1b
2:
subs r0, r2, r3
RETURN
.cfi_endproc
.size strcmp, . - strcmp

381
newlib/libc/machine/arm/strcmp-armv4.S Normal file
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@ -0,0 +1,381 @@
/*
* Copyright (c) 2012-2014 ARM Ltd
* All rights reserved.
*
* 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. The name of the company may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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.
*/
/* Basic ARM implementation. This should run on anything except
for ARMv6-M, but there are better implementations for later
revisions of the architecture. This version can support ARMv4T
ARM/Thumb interworking. */
/* Parameters and result. */
#define src1 r0
#define src2 r1
#define result r0 /* Overlaps src1. */
/* Internal variables. */
#define data1 r2
#define data2 r3
#define magic1 r4
#define tmp2 r5
#define tmp1 r12
#define syndrome r12 /* Overlaps tmp1 */
.arm
def_fn strcmp
.cfi_startproc
eor tmp1, src1, src2
tst tmp1, #3
/* Strings not at same byte offset from a word boundary. */
bne .Lstrcmp_unaligned
ands tmp1, src1, #3
bic src1, src1, #3
bic src2, src2, #3
ldr data1, [src1], #4
ldreq data2, [src2], #4
beq 1f
/* Although s1 and s2 have identical initial alignment, they are
not currently word aligned. Rather than comparing bytes,
make sure that any bytes fetched from before the addressed
bytes are forced to 0xff. Then they will always compare
equal. */
eor tmp1, tmp1, #3
mvn data2, #MSB
lsl tmp1, tmp1, #3
S2LO tmp1, data2, tmp1
ldr data2, [src2], #4
orr data1, data1, tmp1
orr data2, data2, tmp1
1:
/* Load the 'magic' constant 0x01010101. */
str r4, [sp, #-4]!
.cfi_def_cfa_offset 4
.cfi_offset 4, -4
mov magic1, #1
orr magic1, magic1, magic1, lsl #8
orr magic1, magic1, magic1, lsl #16
.p2align 2
4:
sub syndrome, data1, magic1
cmp data1, data2
/* check for any zero bytes in first word */
biceq syndrome, syndrome, data1
tsteq syndrome, magic1, lsl #7
ldreq data1, [src1], #4
ldreq data2, [src2], #4
beq 4b
2:
/* There's a zero or a different byte in the word */
S2HI result, data1, #24
S2LO data1, data1, #8
cmp result, #1
cmpcs result, data2, S2HI #24
S2LOEQ data2, data2, #8
beq 2b
/* On a big-endian machine, RESULT contains the desired byte in bits
0-7; on a little-endian machine they are in bits 24-31. In
both cases the other bits in RESULT are all zero. For DATA2 the
interesting byte is at the other end of the word, but the
other bits are not necessarily zero. We need a signed result
representing the differnece in the unsigned bytes, so for the
little-endian case we can't just shift the interesting bits
up. */
#ifdef __ARM_BIG_ENDIAN
sub result, result, data2, lsr #24
#else
and data2, data2, #255
rsb result, data2, result, lsr #24
#endif
ldr r4, [sp], #4
.cfi_restore 4
.cfi_def_cfa_offset 0
RETURN
#if 0
/* The assembly code below is based on the following alogrithm. */
#ifdef __ARM_BIG_ENDIAN
#define RSHIFT <<
#define LSHIFT >>
#else
#define RSHIFT >>
#define LSHIFT <<
#endif
#define body(shift) \
mask = 0xffffffffU RSHIFT shift; \
data1 = *src1++; \
data2 = *src2++; \
do \
{ \
tmp2 = data1 & mask; \
if (__builtin_expect(tmp2 != data2 RSHIFT shift, 0)) \
{ \
data2 RSHIFT= shift; \
break; \
} \
if (__builtin_expect(((data1 - b1) & ~data1) & (b1 << 7), 0)) \
{ \
/* See comment in assembler below re syndrome on big-endian */\
if ((((data1 - b1) & ~data1) & (b1 << 7)) & mask) \
data2 RSHIFT= shift; \
else \
{ \
data2 = *src2; \
tmp2 = data1 RSHIFT (32 - shift); \
data2 = (data2 LSHIFT (32 - shift)) RSHIFT (32 - shift); \
} \
break; \
} \
data2 = *src2++; \
tmp2 ^= data1; \
if (__builtin_expect(tmp2 != data2 LSHIFT (32 - shift), 0)) \
{ \
tmp2 = data1 >> (32 - shift); \
data2 = (data2 << (32 - shift)) RSHIFT (32 - shift); \
break; \
} \
data1 = *src1++; \
} while (1)
const unsigned* src1;
const unsigned* src2;
unsigned data1, data2;
unsigned mask;
unsigned shift;
unsigned b1 = 0x01010101;
char c1, c2;
unsigned tmp2;
while (((unsigned) s1) & 3)
{
c1 = *s1++;
c2 = *s2++;
if (c1 == 0 || c1 != c2)
return c1 - (int)c2;
}
src1 = (unsigned*) (((unsigned)s1) & ~3);
src2 = (unsigned*) (((unsigned)s2) & ~3);
tmp2 = ((unsigned) s2) & 3;
if (tmp2 == 1)
{
body(8);
}
else if (tmp2 == 2)
{
body(16);
}
else
{
body (24);
}
do
{
#ifdef __ARM_BIG_ENDIAN
c1 = (char) tmp2 >> 24;
c2 = (char) data2 >> 24;
#else /* not __ARM_BIG_ENDIAN */
c1 = (char) tmp2;
c2 = (char) data2;
#endif /* not __ARM_BIG_ENDIAN */
tmp2 RSHIFT= 8;
data2 RSHIFT= 8;
} while (c1 != 0 && c1 == c2);
return c1 - c2;
#endif /* 0 */
/* First of all, compare bytes until src1(sp1) is word-aligned. */
.Lstrcmp_unaligned:
tst src1, #3
beq 2f
ldrb data1, [src1], #1
ldrb data2, [src2], #1
cmp data1, #1
cmpcs data1, data2
beq .Lstrcmp_unaligned
sub result, data1, data2
RETURN
2:
stmfd sp!, {r4, r5}
.cfi_def_cfa_offset 8
.cfi_offset 4, -8
.cfi_offset 5, -4
mov magic1, #1
orr magic1, magic1, magic1, lsl #8
orr magic1, magic1, magic1, lsl #16
ldr data1, [src1], #4
and tmp2, src2, #3
bic src2, src2, #3
ldr data2, [src2], #4
cmp tmp2, #2
beq .Loverlap2
bhi .Loverlap1
/* Critical inner Loop: Block with 3 bytes initial overlap */
.p2align 2
.Loverlap3:
bic tmp2, data1, #MSB
cmp tmp2, data2, S2LO #8
sub syndrome, data1, magic1
bic syndrome, syndrome, data1
bne 4f
ands syndrome, syndrome, magic1, lsl #7
ldreq data2, [src2], #4
bne 5f
eor tmp2, tmp2, data1
cmp tmp2, data2, S2HI #24
bne 6f
ldr data1, [src1], #4
b .Loverlap3
4:
S2LO data2, data2, #8
b .Lstrcmp_tail
5:
#ifdef __ARM_BIG_ENDIAN
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00. */
tst data1, #0xff000000
tstne data1, #0x00ff0000
tstne data1, #0x0000ff00
beq .Lstrcmp_done_equal
#else
bics syndrome, syndrome, #0xff000000
bne .Lstrcmp_done_equal
#endif
ldrb data2, [src2]
S2LO tmp2, data1, #24
#ifdef __ARM_BIG_ENDIAN
lsl data2, data2, #24
#endif
b .Lstrcmp_tail
6:
S2LO tmp2, data1, #24
and data2, data2, #LSB
b .Lstrcmp_tail
/* Critical inner Loop: Block with 2 bytes initial overlap. */
.p2align 2
.Loverlap2:
S2HI tmp2, data1, #16
sub syndrome, data1, magic1
S2LO tmp2, tmp2, #16
bic syndrome, syndrome, data1
cmp tmp2, data2, S2LO #16
bne 4f
ands syndrome, syndrome, magic1, lsl #7
ldreq data2, [src2], #4
bne 5f
eor tmp2, tmp2, data1
cmp tmp2, data2, S2HI #16
bne 6f
ldr data1, [src1], #4
b .Loverlap2
5:
#ifdef __ARM_BIG_ENDIAN
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00 */
tst data1, #0xff000000
tstne data1, #0x00ff0000
beq .Lstrcmp_done_equal
#else
lsls syndrome, syndrome, #16
bne .Lstrcmp_done_equal
#endif
ldrh data2, [src2]
S2LO tmp2, data1, #16
#ifdef __ARM_BIG_ENDIAN
lsl data2, data2, #16
#endif
b .Lstrcmp_tail
6:
S2HI data2, data2, #16
S2LO tmp2, data1, #16
4:
S2LO data2, data2, #16
b .Lstrcmp_tail
/* Critical inner Loop: Block with 1 byte initial overlap. */
.p2align 2
.Loverlap1:
and tmp2, data1, #LSB
cmp tmp2, data2, S2LO #24
sub syndrome, data1, magic1
bic syndrome, syndrome, data1
bne 4f
ands syndrome, syndrome, magic1, lsl #7
ldreq data2, [src2], #4
bne 5f
eor tmp2, tmp2, data1
cmp tmp2, data2, S2HI #8
bne 6f
ldr data1, [src1], #4
b .Loverlap1
4:
S2LO data2, data2, #24
b .Lstrcmp_tail
5:
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00. */
tst data1, #LSB
beq .Lstrcmp_done_equal
ldr data2, [src2], #4
6:
S2LO tmp2, data1, #8
bic data2, data2, #MSB
b .Lstrcmp_tail
.Lstrcmp_done_equal:
mov result, #0
.cfi_remember_state
ldmfd sp!, {r4, r5}
.cfi_restore 4
.cfi_restore 5
.cfi_def_cfa_offset 0
RETURN
.Lstrcmp_tail:
.cfi_restore_state
and r2, tmp2, #LSB
and result, data2, #LSB
cmp result, #1
cmpcs result, r2
S2LOEQ tmp2, tmp2, #8
S2LOEQ data2, data2, #8
beq .Lstrcmp_tail
sub result, r2, result
ldmfd sp!, {r4, r5}
.cfi_restore 4
.cfi_restore 5
.cfi_def_cfa_offset 0
RETURN
.cfi_endproc
.size strcmp, . - strcmp

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newlib/libc/machine/arm/strcmp-armv4t.S Normal file
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/*
* Copyright (c) 2012-2014 ARM Ltd
* All rights reserved.
*
* 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. The name of the company may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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.
*/
/* This version is only used when we want a very basic Thumb1
implementation or for size, otherwise we use the base ARMv4
version. This is also suitable for ARMv6-M. */
.thumb
.syntax unified
.arch armv4t
.eabi_attribute Tag_also_compatible_with, "\006\013" /* ARMv6-M. */
.eabi_attribute Tag_ARM_ISA_use, 0
def_fn strcmp
.cfi_startproc
1:
ldrb r2, [r0]
ldrb r3, [r1]
cmp r2, #0
beq 2f
adds r0, r0, #1
adds r1, r1, #1
cmp r2, r3
beq 1b
2:
subs r0, r2, r3
bx lr
.cfi_endproc
.size strcmp, . - strcmp

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newlib/libc/machine/arm/strcmp-armv6.S Normal file
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@ -0,0 +1,469 @@
/*
* Copyright (c) 2012-2014 ARM Ltd
* All rights reserved.
*
* 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. The name of the company may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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.
*/
/* Implementation of strcmp for ARMv6. Use ldrd to support wider
loads, provided the data is sufficiently aligned. Use
saturating arithmetic to optimize the compares. */
/* Build Options:
STRCMP_NO_PRECHECK: Don't run a quick pre-check of the first
byte in the string. If comparing completely random strings
the pre-check will save time, since there is a very high
probability of a mismatch in the first character: we save
significant overhead if this is the common case. However,
if strings are likely to be identical (eg because we're
verifying a hit in a hash table), then this check is largely
redundant. */
.arm
/* Parameters and result. */
#define src1 r0
#define src2 r1
#define result r0 /* Overlaps src1. */
/* Internal variables. */
#define tmp1 r4
#define tmp2 r5
#define const_m1 r12
/* Additional internal variables for 64-bit aligned data. */
#define data1a r2
#define data1b r3
#define data2a r6
#define data2b r7
#define syndrome_a tmp1
#define syndrome_b tmp2
/* Additional internal variables for 32-bit aligned data. */
#define data1 r2
#define data2 r3
#define syndrome tmp2
/* Macro to compute and return the result value for word-aligned
cases. */
.macro strcmp_epilogue_aligned synd d1 d2 restore_r6
#ifdef __ARM_BIG_ENDIAN
/* If data1 contains a zero byte, then syndrome will contain a 1 in
bit 7 of that byte. Otherwise, the highest set bit in the
syndrome will highlight the first different bit. It is therefore
sufficient to extract the eight bits starting with the syndrome
bit. */
clz tmp1, \synd
lsl r1, \d2, tmp1
.if \restore_r6
ldrd r6, r7, [sp, #8]
.endif
.cfi_restore 6
.cfi_restore 7
lsl \d1, \d1, tmp1
.cfi_remember_state
lsr result, \d1, #24
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
sub result, result, r1, lsr #24
bx lr
#else
/* To use the big-endian trick we'd have to reverse all three words.
that's slower than this approach. */
rev \synd, \synd
clz tmp1, \synd
bic tmp1, tmp1, #7
lsr r1, \d2, tmp1
.cfi_remember_state
.if \restore_r6
ldrd r6, r7, [sp, #8]
.endif
.cfi_restore 6
.cfi_restore 7
lsr \d1, \d1, tmp1
and result, \d1, #255
and r1, r1, #255
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
sub result, result, r1
bx lr
#endif
.endm
.text
.p2align 5
.Lstrcmp_start_addr:
#ifndef STRCMP_NO_PRECHECK
.Lfastpath_exit:
sub r0, r2, r3
bx lr
#endif
def_fn strcmp
#ifndef STRCMP_NO_PRECHECK
ldrb r2, [src1]
ldrb r3, [src2]
cmp r2, #1
cmpcs r2, r3
bne .Lfastpath_exit
#endif
.cfi_startproc
strd r4, r5, [sp, #-16]!
.cfi_def_cfa_offset 16
.cfi_offset 4, -16
.cfi_offset 5, -12
orr tmp1, src1, src2
strd r6, r7, [sp, #8]
.cfi_offset 6, -8
.cfi_offset 7, -4
mvn const_m1, #0
tst tmp1, #7
beq .Lloop_aligned8
.Lnot_aligned:
eor tmp1, src1, src2
tst tmp1, #7
bne .Lmisaligned8
/* Deal with mutual misalignment by aligning downwards and then
masking off the unwanted loaded data to prevent a difference. */
and tmp1, src1, #7
bic src1, src1, #7
and tmp2, tmp1, #3
bic src2, src2, #7
lsl tmp2, tmp2, #3 /* Bytes -> bits. */
ldrd data1a, data1b, [src1], #16
tst tmp1, #4
ldrd data2a, data2b, [src2], #16
/* In ARM code we can't use ORN, but with do have MVN with a
register shift. */
mvn tmp1, const_m1, S2HI tmp2
orr data1a, data1a, tmp1
orr data2a, data2a, tmp1
beq .Lstart_realigned8
orr data1b, data1b, tmp1
mov data1a, const_m1
orr data2b, data2b, tmp1
mov data2a, const_m1
b .Lstart_realigned8
/* Unwind the inner loop by a factor of 2, giving 16 bytes per
pass. */
.p2align 5,,12 /* Don't start in the tail bytes of a cache line. */
.p2align 2 /* Always word aligned. */
.Lloop_aligned8:
ldrd data1a, data1b, [src1], #16
ldrd data2a, data2b, [src2], #16
.Lstart_realigned8:
uadd8 syndrome_b, data1a, const_m1 /* Only want GE bits, */
eor syndrome_a, data1a, data2a
sel syndrome_a, syndrome_a, const_m1
uadd8 syndrome_b, data1b, const_m1 /* Only want GE bits. */
eor syndrome_b, data1b, data2b
sel syndrome_b, syndrome_b, const_m1
orrs syndrome_b, syndrome_b, syndrome_a /* Only need if s_a == 0 */
bne .Ldiff_found
ldrd data1a, data1b, [src1, #-8]
ldrd data2a, data2b, [src2, #-8]
uadd8 syndrome_b, data1a, const_m1 /* Only want GE bits, */
eor syndrome_a, data1a, data2a
sel syndrome_a, syndrome_a, const_m1
uadd8 syndrome_b, data1b, const_m1 /* Only want GE bits. */
eor syndrome_b, data1b, data2b
sel syndrome_b, syndrome_b, const_m1
orrs syndrome_b, syndrome_b, syndrome_a /* Only need if s_a == 0 */
beq .Lloop_aligned8
.Ldiff_found:
cmp syndrome_a, #0
bne .Ldiff_in_a
.Ldiff_in_b:
strcmp_epilogue_aligned syndrome_b, data1b, data2b 1
.Ldiff_in_a:
.cfi_restore_state
strcmp_epilogue_aligned syndrome_a, data1a, data2a 1
.cfi_restore_state
.Lmisaligned8:
tst tmp1, #3
bne .Lmisaligned4
ands tmp1, src1, #3
bne .Lmutual_align4
/* Unrolled by a factor of 2, to reduce the number of post-increment
operations. */
.Lloop_aligned4:
ldr data1, [src1], #8
ldr data2, [src2], #8
.Lstart_realigned4:
uadd8 syndrome, data1, const_m1 /* Only need GE bits. */
eor syndrome, data1, data2
sel syndrome, syndrome, const_m1
cmp syndrome, #0
bne .Laligned4_done
ldr data1, [src1, #-4]
ldr data2, [src2, #-4]
uadd8 syndrome, data1, const_m1
eor syndrome, data1, data2
sel syndrome, syndrome, const_m1
cmp syndrome, #0
beq .Lloop_aligned4
.Laligned4_done:
strcmp_epilogue_aligned syndrome, data1, data2, 0
.Lmutual_align4:
.cfi_restore_state
/* Deal with mutual misalignment by aligning downwards and then
masking off the unwanted loaded data to prevent a difference. */
lsl tmp1, tmp1, #3 /* Bytes -> bits. */
bic src1, src1, #3
ldr data1, [src1], #8
bic src2, src2, #3
ldr data2, [src2], #8
/* In ARM code we can't use ORN, but with do have MVN with a
register shift. */
mvn tmp1, const_m1, S2HI tmp1
orr data1, data1, tmp1
orr data2, data2, tmp1
b .Lstart_realigned4
.Lmisaligned4:
ands tmp1, src1, #3
beq .Lsrc1_aligned
sub src2, src2, tmp1
bic src1, src1, #3
lsls tmp1, tmp1, #31
ldr data1, [src1], #4
beq .Laligned_m2
bcs .Laligned_m1
#ifdef STRCMP_NO_PRECHECK
ldrb data2, [src2, #1]
uxtb tmp1, data1, ror #BYTE1_OFFSET
cmp tmp1, #1
cmpcs tmp1, data2
bne .Lmisaligned_exit
.Laligned_m2:
ldrb data2, [src2, #2]
uxtb tmp1, data1, ror #BYTE2_OFFSET
cmp tmp1, #1
cmpcs tmp1, data2
bne .Lmisaligned_exit
.Laligned_m1:
ldrb data2, [src2, #3]
uxtb tmp1, data1, ror #BYTE3_OFFSET
cmp tmp1, #1
cmpcs tmp1, data2
beq .Lsrc1_aligned
#else /* STRCMP_NO_PRECHECK */
/* If we've done the pre-check, then we don't need to check the
first byte again here. */
ldrb data2, [src2, #2]
uxtb tmp1, data1, ror #BYTE2_OFFSET
cmp tmp1, #1
cmpcs tmp1, data2
bne .Lmisaligned_exit
.Laligned_m2:
ldrb data2, [src2, #3]
uxtb tmp1, data1, ror #BYTE3_OFFSET
cmp tmp1, #1
cmpcs tmp1, data2
beq .Laligned_m1
#endif
.Lmisaligned_exit:
.cfi_remember_state
sub result, tmp1, data2
ldr r4, [sp], #16
.cfi_restore 4
bx lr
#ifndef STRCMP_NO_PRECHECK
.Laligned_m1:
add src2, src2, #4
#endif
.Lsrc1_aligned:
.cfi_restore_state
/* src1 is word aligned, but src2 has no common alignment
with it. */
ldr data1, [src1], #4
lsls tmp1, src2, #31 /* C=src2[1], Z=src2[0]. */
bic src2, src2, #3
ldr data2, [src2], #4
bhi .Loverlap1 /* C=1, Z=0 => src2[1:0] = 0b11. */
bcs .Loverlap2 /* C=1, Z=1 => src2[1:0] = 0b10. */
/* (overlap3) C=0, Z=0 => src2[1:0] = 0b01. */
.Loverlap3:
bic tmp1, data1, #MSB
uadd8 syndrome, data1, const_m1
eors syndrome, tmp1, data2, S2LO #8
sel syndrome, syndrome, const_m1
bne 4f
cmp syndrome, #0
ldreq data2, [src2], #4
bne 5f
eor tmp1, tmp1, data1
cmp tmp1, data2, S2HI #24
bne 6f
ldr data1, [src1], #4
b .Loverlap3
4:
S2LO data2, data2, #8
b .Lstrcmp_tail
5:
bics syndrome, syndrome, #MSB
bne .Lstrcmp_done_equal
/* We can only get here if the MSB of data1 contains 0, so
fast-path the exit. */
ldrb result, [src2]
.cfi_remember_state
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
/* R6/7 Not used in this sequence. */
.cfi_restore 6
.cfi_restore 7
neg result, result
bx lr
6:
.cfi_restore_state
S2LO data1, data1, #24
and data2, data2, #LSB
b .Lstrcmp_tail
.p2align 5,,12 /* Ensure at least 3 instructions in cache line. */
.Loverlap2:
and tmp1, data1, const_m1, S2LO #16
uadd8 syndrome, data1, const_m1
eors syndrome, tmp1, data2, S2LO #16
sel syndrome, syndrome, const_m1
bne 4f
cmp syndrome, #0
ldreq data2, [src2], #4
bne 5f
eor tmp1, tmp1, data1
cmp tmp1, data2, S2HI #16
bne 6f
ldr data1, [src1], #4
b .Loverlap2
4:
S2LO data2, data2, #16
b .Lstrcmp_tail
5:
ands syndrome, syndrome, const_m1, S2LO #16
bne .Lstrcmp_done_equal
ldrh data2, [src2]
S2LO data1, data1, #16
#ifdef __ARM_BIG_ENDIAN
lsl data2, data2, #16
#endif
b .Lstrcmp_tail
6:
S2LO data1, data1, #16
and data2, data2, const_m1, S2LO #16
b .Lstrcmp_tail
.p2align 5,,12 /* Ensure at least 3 instructions in cache line. */
.Loverlap1:
and tmp1, data1, #LSB
uadd8 syndrome, data1, const_m1
eors syndrome, tmp1, data2, S2LO #24
sel syndrome, syndrome, const_m1
bne 4f
cmp syndrome, #0
ldreq data2, [src2], #4
bne 5f
eor tmp1, tmp1, data1
cmp tmp1, data2, S2HI #8
bne 6f
ldr data1, [src1], #4
b .Loverlap1
4:
S2LO data2, data2, #24
b .Lstrcmp_tail
5:
tst syndrome, #LSB
bne .Lstrcmp_done_equal
ldr data2, [src2]
6:
S2LO data1, data1, #8
bic data2, data2, #MSB
b .Lstrcmp_tail
.Lstrcmp_done_equal:
mov result, #0
.cfi_remember_state
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
/* R6/7 not used in this sequence. */
.cfi_restore 6
.cfi_restore 7
bx lr
.Lstrcmp_tail:
.cfi_restore_state
#ifndef __ARM_BIG_ENDIAN
rev data1, data1
rev data2, data2
/* Now everything looks big-endian... */
#endif
uadd8 tmp1, data1, const_m1
eor tmp1, data1, data2
sel syndrome, tmp1, const_m1
clz tmp1, syndrome
lsl data1, data1, tmp1
lsl data2, data2, tmp1
lsr result, data1, #24
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
/* R6/7 not used in this sequence. */
.cfi_restore 6
.cfi_restore 7
sub result, result, data2, lsr #24
bx lr
.cfi_endproc
.size strcmp, . - .Lstrcmp_start_addr

468
newlib/libc/machine/arm/strcmp-armv7.S Normal file
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/*
* Copyright (c) 2012-2014 ARM Ltd
* All rights reserved.
*
* 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. The name of the company may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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.
*/
/* Implementation of strcmp for ARMv7 when DSP instructions are
available. Use ldrd to support wider loads, provided the data
is sufficiently aligned. Use saturating arithmetic to optimize
the compares. */
/* Build Options:
STRCMP_NO_PRECHECK: Don't run a quick pre-check of the first
byte in the string. If comparing completely random strings
the pre-check will save time, since there is a very high
probability of a mismatch in the first character: we save
significant overhead if this is the common case. However,
if strings are likely to be identical (eg because we're
verifying a hit in a hash table), then this check is largely
redundant. */
/* This version uses Thumb-2 code. */
.thumb
.syntax unified
/* Parameters and result. */
#define src1 r0
#define src2 r1
#define result r0 /* Overlaps src1. */
/* Internal variables. */
#define tmp1 r4
#define tmp2 r5
#define const_m1 r12
/* Additional internal variables for 64-bit aligned data. */
#define data1a r2
#define data1b r3
#define data2a r6
#define data2b r7
#define syndrome_a tmp1
#define syndrome_b tmp2
/* Additional internal variables for 32-bit aligned data. */
#define data1 r2
#define data2 r3
#define syndrome tmp2
/* Macro to compute and return the result value for word-aligned
cases. */
.macro strcmp_epilogue_aligned synd d1 d2 restore_r6
#ifdef __ARM_BIG_ENDIAN
/* If data1 contains a zero byte, then syndrome will contain a 1 in
bit 7 of that byte. Otherwise, the highest set bit in the
syndrome will highlight the first different bit. It is therefore
sufficient to extract the eight bits starting with the syndrome
bit. */
clz tmp1, \synd
lsl r1, \d2, tmp1
.if \restore_r6
ldrd r6, r7, [sp, #8]
.endif
.cfi_restore 6
.cfi_restore 7
lsl \d1, \d1, tmp1
.cfi_remember_state
lsr result, \d1, #24
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
sub result, result, r1, lsr #24
bx lr
#else
/* To use the big-endian trick we'd have to reverse all three words.
that's slower than this approach. */
rev \synd, \synd
clz tmp1, \synd
bic tmp1, tmp1, #7
lsr r1, \d2, tmp1
.cfi_remember_state
.if \restore_r6
ldrd r6, r7, [sp, #8]
.endif
.cfi_restore 6
.cfi_restore 7
lsr \d1, \d1, tmp1
and result, \d1, #255
and r1, r1, #255
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
sub result, result, r1
bx lr
#endif
.endm
.text
.p2align 5
.Lstrcmp_start_addr:
#ifndef STRCMP_NO_PRECHECK
.Lfastpath_exit:
sub r0, r2, r3
bx lr
nop
#endif
def_fn strcmp
#ifndef STRCMP_NO_PRECHECK
ldrb r2, [src1]
ldrb r3, [src2]
cmp r2, #1
it cs
cmpcs r2, r3
bne .Lfastpath_exit
#endif
.cfi_startproc
strd r4, r5, [sp, #-16]!
.cfi_def_cfa_offset 16
.cfi_offset 4, -16
.cfi_offset 5, -12
orr tmp1, src1, src2
strd r6, r7, [sp, #8]
.cfi_offset 6, -8
.cfi_offset 7, -4
mvn const_m1, #0
lsl r2, tmp1, #29
cbz r2, .Lloop_aligned8
.Lnot_aligned:
eor tmp1, src1, src2
tst tmp1, #7
bne .Lmisaligned8
/* Deal with mutual misalignment by aligning downwards and then
masking off the unwanted loaded data to prevent a difference. */
and tmp1, src1, #7
bic src1, src1, #7
and tmp2, tmp1, #3
bic src2, src2, #7
lsl tmp2, tmp2, #3 /* Bytes -> bits. */
ldrd data1a, data1b, [src1], #16
tst tmp1, #4
ldrd data2a, data2b, [src2], #16
/* In thumb code we can't use MVN with a register shift, but
we do have ORN. */
S2HI tmp1, const_m1, tmp2
orn data1a, data1a, tmp1
orn data2a, data2a, tmp1
beq .Lstart_realigned8
orn data1b, data1b, tmp1
mov data1a, const_m1
orn data2b, data2b, tmp1
mov data2a, const_m1
b .Lstart_realigned8
/* Unwind the inner loop by a factor of 2, giving 16 bytes per
pass. */
.p2align 5,,12 /* Don't start in the tail bytes of a cache line. */
.p2align 2 /* Always word aligned. */
.Lloop_aligned8:
ldrd data1a, data1b, [src1], #16
ldrd data2a, data2b, [src2], #16
.Lstart_realigned8:
uadd8 syndrome_b, data1a, const_m1 /* Only want GE bits, */
eor syndrome_a, data1a, data2a
sel syndrome_a, syndrome_a, const_m1
cbnz syndrome_a, .Ldiff_in_a
uadd8 syndrome_b, data1b, const_m1 /* Only want GE bits. */
eor syndrome_b, data1b, data2b
sel syndrome_b, syndrome_b, const_m1
cbnz syndrome_b, .Ldiff_in_b
ldrd data1a, data1b, [src1, #-8]
ldrd data2a, data2b, [src2, #-8]
uadd8 syndrome_b, data1a, const_m1 /* Only want GE bits, */
eor syndrome_a, data1a, data2a
sel syndrome_a, syndrome_a, const_m1
uadd8 syndrome_b, data1b, const_m1 /* Only want GE bits. */
eor syndrome_b, data1b, data2b
sel syndrome_b, syndrome_b, const_m1
/* Can't use CBZ for backwards branch. */
orrs syndrome_b, syndrome_b, syndrome_a /* Only need if s_a == 0 */
beq .Lloop_aligned8
.Ldiff_found:
cbnz syndrome_a, .Ldiff_in_a
.Ldiff_in_b:
strcmp_epilogue_aligned syndrome_b, data1b, data2b 1
.Ldiff_in_a:
.cfi_restore_state
strcmp_epilogue_aligned syndrome_a, data1a, data2a 1
.cfi_restore_state
.Lmisaligned8:
tst tmp1, #3
bne .Lmisaligned4
ands tmp1, src1, #3
bne .Lmutual_align4
/* Unrolled by a factor of 2, to reduce the number of post-increment
operations. */
.Lloop_aligned4:
ldr data1, [src1], #8
ldr data2, [src2], #8
.Lstart_realigned4:
uadd8 syndrome, data1, const_m1 /* Only need GE bits. */
eor syndrome, data1, data2
sel syndrome, syndrome, const_m1
cbnz syndrome, .Laligned4_done
ldr data1, [src1, #-4]
ldr data2, [src2, #-4]
uadd8 syndrome, data1, const_m1
eor syndrome, data1, data2
sel syndrome, syndrome, const_m1
cmp syndrome, #0
beq .Lloop_aligned4
.Laligned4_done:
strcmp_epilogue_aligned syndrome, data1, data2, 0
.Lmutual_align4:
.cfi_restore_state
/* Deal with mutual misalignment by aligning downwards and then
masking off the unwanted loaded data to prevent a difference. */
lsl tmp1, tmp1, #3 /* Bytes -> bits. */
bic src1, src1, #3
ldr data1, [src1], #8
bic src2, src2, #3
ldr data2, [src2], #8
/* In thumb code we can't use MVN with a register shift, but
we do have ORN. */
S2HI tmp1, const_m1, tmp1
orn data1, data1, tmp1
orn data2, data2, tmp1
b .Lstart_realigned4
.Lmisaligned4:
ands tmp1, src1, #3
beq .Lsrc1_aligned
sub src2, src2, tmp1
bic src1, src1, #3
lsls tmp1, tmp1, #31
ldr data1, [src1], #4
beq .Laligned_m2
bcs .Laligned_m1
#ifdef STRCMP_NO_PRECHECK
ldrb data2, [src2, #1]
uxtb tmp1, data1, ror #BYTE1_OFFSET
subs tmp1, tmp1, data2
bne .Lmisaligned_exit
cbz data2, .Lmisaligned_exit
.Laligned_m2:
ldrb data2, [src2, #2]
uxtb tmp1, data1, ror #BYTE2_OFFSET
subs tmp1, tmp1, data2
bne .Lmisaligned_exit
cbz data2, .Lmisaligned_exit
.Laligned_m1:
ldrb data2, [src2, #3]
uxtb tmp1, data1, ror #BYTE3_OFFSET
subs tmp1, tmp1, data2
bne .Lmisaligned_exit
add src2, src2, #4
cbnz data2, .Lsrc1_aligned
#else /* STRCMP_NO_PRECHECK */
/* If we've done the pre-check, then we don't need to check the
first byte again here. */
ldrb data2, [src2, #2]
uxtb tmp1, data1, ror #BYTE2_OFFSET
subs tmp1, tmp1, data2
bne .Lmisaligned_exit
cbz data2, .Lmisaligned_exit
.Laligned_m2:
ldrb data2, [src2, #3]
uxtb tmp1, data1, ror #BYTE3_OFFSET
subs tmp1, tmp1, data2
bne .Lmisaligned_exit
cbnz data2, .Laligned_m1
#endif
.Lmisaligned_exit:
.cfi_remember_state
mov result, tmp1
ldr r4, [sp], #16
.cfi_restore 4
bx lr
#ifndef STRCMP_NO_PRECHECK
.Laligned_m1:
add src2, src2, #4
#endif
.Lsrc1_aligned:
.cfi_restore_state
/* src1 is word aligned, but src2 has no common alignment
with it. */
ldr data1, [src1], #4
lsls tmp1, src2, #31 /* C=src2[1], Z=src2[0]. */
bic src2, src2, #3
ldr data2, [src2], #4
bhi .Loverlap1 /* C=1, Z=0 => src2[1:0] = 0b11. */
bcs .Loverlap2 /* C=1, Z=1 => src2[1:0] = 0b10. */
/* (overlap3) C=0, Z=0 => src2[1:0] = 0b01. */
.Loverlap3:
bic tmp1, data1, #MSB
uadd8 syndrome, data1, const_m1
eors syndrome, tmp1, data2, S2LO #8
sel syndrome, syndrome, const_m1
bne 4f
cbnz syndrome, 5f
ldr data2, [src2], #4
eor tmp1, tmp1, data1
cmp tmp1, data2, S2HI #24
bne 6f
ldr data1, [src1], #4
b .Loverlap3
4:
S2LO data2, data2, #8
b .Lstrcmp_tail
5:
bics syndrome, syndrome, #MSB
bne .Lstrcmp_done_equal
/* We can only get here if the MSB of data1 contains 0, so
fast-path the exit. */
ldrb result, [src2]
.cfi_remember_state
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
/* R6/7 Not used in this sequence. */
.cfi_restore 6
.cfi_restore 7
neg result, result
bx lr
6:
.cfi_restore_state
S2LO data1, data1, #24
and data2, data2, #LSB
b .Lstrcmp_tail
.p2align 5,,12 /* Ensure at least 3 instructions in cache line. */
.Loverlap2:
and tmp1, data1, const_m1, S2LO #16
uadd8 syndrome, data1, const_m1
eors syndrome, tmp1, data2, S2LO #16
sel syndrome, syndrome, const_m1
bne 4f
cbnz syndrome, 5f
ldr data2, [src2], #4
eor tmp1, tmp1, data1
cmp tmp1, data2, S2HI #16
bne 6f
ldr data1, [src1], #4
b .Loverlap2
4:
S2LO data2, data2, #16
b .Lstrcmp_tail
5:
ands syndrome, syndrome, const_m1, S2LO #16
bne .Lstrcmp_done_equal
ldrh data2, [src2]
S2LO data1, data1, #16
#ifdef __ARM_BIG_ENDIAN
lsl data2, data2, #16
#endif
b .Lstrcmp_tail
6:
S2LO data1, data1, #16
and data2, data2, const_m1, S2LO #16
b .Lstrcmp_tail
.p2align 5,,12 /* Ensure at least 3 instructions in cache line. */
.Loverlap1:
and tmp1, data1, #LSB
uadd8 syndrome, data1, const_m1
eors syndrome, tmp1, data2, S2LO #24
sel syndrome, syndrome, const_m1
bne 4f
cbnz syndrome, 5f
ldr data2, [src2], #4
eor tmp1, tmp1, data1
cmp tmp1, data2, S2HI #8
bne 6f
ldr data1, [src1], #4
b .Loverlap1
4:
S2LO data2, data2, #24
b .Lstrcmp_tail
5:
tst syndrome, #LSB
bne .Lstrcmp_done_equal
ldr data2, [src2]
6:
S2LO data1, data1, #8
bic data2, data2, #MSB
b .Lstrcmp_tail
.Lstrcmp_done_equal:
mov result, #0
.cfi_remember_state
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
/* R6/7 not used in this sequence. */
.cfi_restore 6
.cfi_restore 7
bx lr
.Lstrcmp_tail:
.cfi_restore_state
#ifndef __ARM_BIG_ENDIAN
rev data1, data1
rev data2, data2
/* Now everything looks big-endian... */
#endif
uadd8 tmp1, data1, const_m1
eor tmp1, data1, data2
sel syndrome, tmp1, const_m1
clz tmp1, syndrome
lsl data1, data1, tmp1
lsl data2, data2, tmp1
lsr result, data1, #24
ldrd r4, r5, [sp], #16
.cfi_restore 4
.cfi_restore 5
/* R6/7 not used in this sequence. */
.cfi_restore 6
.cfi_restore 7
sub result, result, data2, lsr #24
bx lr
.cfi_endproc
.size strcmp, . - .Lstrcmp_start_addr

377
newlib/libc/machine/arm/strcmp-armv7m.S Normal file
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/*
* Copyright (c) 2012-2014 ARM Ltd
* All rights reserved.
*
* 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. The name of the company may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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.
*/
/* Very similar to the generic code, but uses Thumb2 as implemented
in ARMv7-M. */
/* Parameters and result. */
#define src1 r0
#define src2 r1
#define result r0 /* Overlaps src1. */
/* Internal variables. */
#define data1 r2
#define data2 r3
#define tmp2 r5
#define tmp1 r12
#define syndrome r12 /* Overlaps tmp1 */
.thumb
.syntax unified
def_fn strcmp
.cfi_startproc
eor tmp1, src1, src2
tst tmp1, #3
/* Strings not at same byte offset from a word boundary. */
bne .Lstrcmp_unaligned
ands tmp1, src1, #3
bic src1, src1, #3
bic src2, src2, #3
ldr data1, [src1], #4
it eq
ldreq data2, [src2], #4
beq 4f
/* Although s1 and s2 have identical initial alignment, they are
not currently word aligned. Rather than comparing bytes,
make sure that any bytes fetched from before the addressed
bytes are forced to 0xff. Then they will always compare
equal. */
eor tmp1, tmp1, #3
mvn data2, #MSB
lsl tmp1, tmp1, #3
S2LO tmp1, data2, tmp1
ldr data2, [src2], #4
orr data1, data1, tmp1
orr data2, data2, tmp1
.p2align 2
/* Critical loop. */
4:
sub syndrome, data1, #0x01010101
cmp data1, data2
/* check for any zero bytes in first word */
itttt eq
biceq syndrome, syndrome, data1
tsteq syndrome, #0x80808080
ldreq data1, [src1], #4
ldreq data2, [src2], #4
beq 4b
2:
/* There's a zero or a different byte in the word */
S2HI result, data1, #24
S2LO data1, data1, #8
cmp result, #1
it cs
cmpcs result, data2, S2HI #24
it eq
S2LOEQ data2, data2, #8
beq 2b
/* On a big-endian machine, RESULT contains the desired byte in bits
0-7; on a little-endian machine they are in bits 24-31. In
both cases the other bits in RESULT are all zero. For DATA2 the
interesting byte is at the other end of the word, but the
other bits are not necessarily zero. We need a signed result
representing the differnece in the unsigned bytes, so for the
little-endian case we can't just shift the interesting bits
up. */
#ifdef __ARM_BIG_ENDIAN
sub result, result, data2, lsr #24
#else
and data2, data2, #255
lsrs result, result, #24
subs result, result, data2
#endif
RETURN
#if 0
/* The assembly code below is based on the following alogrithm. */
#ifdef __ARM_BIG_ENDIAN
#define RSHIFT <<
#define LSHIFT >>
#else
#define RSHIFT >>
#define LSHIFT <<
#endif
#define body(shift) \
mask = 0xffffffffU RSHIFT shift; \
data1 = *src1++; \
data2 = *src2++; \
do \
{ \
tmp2 = data1 & mask; \
if (__builtin_expect(tmp2 != data2 RSHIFT shift, 0)) \
{ \
data2 RSHIFT= shift; \
break; \
} \
if (__builtin_expect(((data1 - b1) & ~data1) & (b1 << 7), 0)) \
{ \
/* See comment in assembler below re syndrome on big-endian */\
if ((((data1 - b1) & ~data1) & (b1 << 7)) & mask) \
data2 RSHIFT= shift; \
else \
{ \
data2 = *src2; \
tmp2 = data1 RSHIFT (32 - shift); \
data2 = (data2 LSHIFT (32 - shift)) RSHIFT (32 - shift); \
} \
break; \
} \
data2 = *src2++; \
tmp2 ^= data1; \
if (__builtin_expect(tmp2 != data2 LSHIFT (32 - shift), 0)) \
{ \
tmp2 = data1 >> (32 - shift); \
data2 = (data2 << (32 - shift)) RSHIFT (32 - shift); \
break; \
} \
data1 = *src1++; \
} while (1)
const unsigned* src1;
const unsigned* src2;
unsigned data1, data2;
unsigned mask;
unsigned shift;
unsigned b1 = 0x01010101;
char c1, c2;
unsigned tmp2;
while (((unsigned) s1) & 3)
{
c1 = *s1++;
c2 = *s2++;
if (c1 == 0 || c1 != c2)
return c1 - (int)c2;
}
src1 = (unsigned*) (((unsigned)s1) & ~3);
src2 = (unsigned*) (((unsigned)s2) & ~3);
tmp2 = ((unsigned) s2) & 3;
if (tmp2 == 1)
{
body(8);
}
else if (tmp2 == 2)
{
body(16);
}
else
{
body (24);
}
do
{
#ifdef __ARM_BIG_ENDIAN
c1 = (char) tmp2 >> 24;
c2 = (char) data2 >> 24;
#else /* not __ARM_BIG_ENDIAN */
c1 = (char) tmp2;
c2 = (char) data2;
#endif /* not __ARM_BIG_ENDIAN */
tmp2 RSHIFT= 8;
data2 RSHIFT= 8;
} while (c1 != 0 && c1 == c2);
return c1 - c2;
#endif /* 0 */
/* First of all, compare bytes until src1(sp1) is word-aligned. */
.Lstrcmp_unaligned:
tst src1, #3
beq 2f
ldrb data1, [src1], #1
ldrb data2, [src2], #1
cmp data1, #1
it cs
cmpcs data1, data2
beq .Lstrcmp_unaligned
sub result, data1, data2
bx lr
2:
stmfd sp!, {r5}
.cfi_def_cfa_offset 4
.cfi_offset 5, -4
ldr data1, [src1], #4
and tmp2, src2, #3
bic src2, src2, #3
ldr data2, [src2], #4
cmp tmp2, #2
beq .Loverlap2
bhi .Loverlap1
/* Critical inner Loop: Block with 3 bytes initial overlap */
.p2align 2
.Loverlap3:
bic tmp2, data1, #MSB
cmp tmp2, data2, S2LO #8
sub syndrome, data1, #0x01010101
bic syndrome, syndrome, data1
bne 4f
ands syndrome, syndrome, #0x80808080
it eq
ldreq data2, [src2], #4
bne 5f
eor tmp2, tmp2, data1
cmp tmp2, data2, S2HI #24
bne 6f
ldr data1, [src1], #4
b .Loverlap3
4:
S2LO data2, data2, #8
b .Lstrcmp_tail
5:
#ifdef __ARM_BIG_ENDIAN
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00. */
tst data1, #0xff000000
itt ne
tstne data1, #0x00ff0000
tstne data1, #0x0000ff00
beq .Lstrcmp_done_equal
#else
bics syndrome, syndrome, #0xff000000
bne .Lstrcmp_done_equal
#endif
ldrb data2, [src2]
S2LO tmp2, data1, #24
#ifdef __ARM_BIG_ENDIAN
lsl data2, data2, #24
#endif
b .Lstrcmp_tail
6:
S2LO tmp2, data1, #24
and data2, data2, #LSB
b .Lstrcmp_tail
/* Critical inner Loop: Block with 2 bytes initial overlap. */
.p2align 2
.Loverlap2:
S2HI tmp2, data1, #16
sub syndrome, data1, #0x01010101
S2LO tmp2, tmp2, #16
bic syndrome, syndrome, data1
cmp tmp2, data2, S2LO #16
bne 4f
ands syndrome, syndrome, #0x80808080
it eq
ldreq data2, [src2], #4
bne 5f
eor tmp2, tmp2, data1
cmp tmp2, data2, S2HI #16
bne 6f
ldr data1, [src1], #4
b .Loverlap2
5:
#ifdef __ARM_BIG_ENDIAN
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00 */
tst data1, #0xff000000
it ne
tstne data1, #0x00ff0000
beq .Lstrcmp_done_equal
#else
lsls syndrome, syndrome, #16
bne .Lstrcmp_done_equal
#endif
ldrh data2, [src2]
S2LO tmp2, data1, #16
#ifdef __ARM_BIG_ENDIAN
lsl data2, data2, #16
#endif
b .Lstrcmp_tail
6:
S2HI data2, data2, #16
S2LO tmp2, data1, #16
4:
S2LO data2, data2, #16
b .Lstrcmp_tail
/* Critical inner Loop: Block with 1 byte initial overlap. */
.p2align 2
.Loverlap1:
and tmp2, data1, #LSB
cmp tmp2, data2, S2LO #24
sub syndrome, data1, #0x01010101
bic syndrome, syndrome, data1
bne 4f
ands syndrome, syndrome, #0x80808080
it eq
ldreq data2, [src2], #4
bne 5f
eor tmp2, tmp2, data1
cmp tmp2, data2, S2HI #8
bne 6f
ldr data1, [src1], #4
b .Loverlap1
4:
S2LO data2, data2, #24
b .Lstrcmp_tail
5:
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00. */
tst data1, #LSB
beq .Lstrcmp_done_equal
ldr data2, [src2], #4
6:
S2LO tmp2, data1, #8
bic data2, data2, #MSB
b .Lstrcmp_tail
.Lstrcmp_done_equal:
mov result, #0
.cfi_remember_state
ldmfd sp!, {r5}
.cfi_restore 5
.cfi_def_cfa_offset 0
RETURN
.Lstrcmp_tail:
.cfi_restore_state
and r2, tmp2, #LSB
and result, data2, #LSB
cmp result, #1
it cs
cmpcs result, r2
itt eq
S2LOEQ tmp2, tmp2, #8
S2LOEQ data2, data2, #8
beq .Lstrcmp_tail
sub result, r2, result
ldmfd sp!, {r5}
.cfi_restore 5
.cfi_def_cfa_offset 0
RETURN
.cfi_endproc
.size strcmp, . - strcmp

781
newlib/libc/machine/arm/strcmp.S
View File

@ -1,5 +1,5 @@
/* /*
* Copyright (c) 2012 ARM Ltd * Copyright (c) 2012-2014 ARM Ltd
* All rights reserved. * All rights reserved.
* *
* Redistribution and use in source and binary forms, with or without * Redistribution and use in source and binary forms, with or without
@ -26,769 +26,64 @@
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/ */
/* Wrapper for the various implementations of strcmp. */
#include "arm_asm.h" #include "arm_asm.h"
#ifdef __ARMEB__ #ifdef __ARM_BIG_ENDIAN
#define S2LOMEM lsl #define S2LO lsl
#define S2LOMEMEQ lsleq #define S2LOEQ lsleq
#define S2HIMEM lsr #define S2HI lsr
#define MSB 0x000000ff #define MSB 0x000000ff
#define LSB 0xff000000 #define LSB 0xff000000
#define BYTE0_OFFSET 24 #define BYTE0_OFFSET 24
#define BYTE1_OFFSET 16 #define BYTE1_OFFSET 16
#define BYTE2_OFFSET 8 #define BYTE2_OFFSET 8
#define BYTE3_OFFSET 0 #define BYTE3_OFFSET 0
#else /* not __ARMEB__ */ #else /* not __ARM_BIG_ENDIAN */
#define S2LOMEM lsr #define S2LO lsr
#define S2LOMEMEQ lsreq #define S2LOEQ lsreq
#define S2HIMEM lsl #define S2HI lsl
#define BYTE0_OFFSET 0 #define BYTE0_OFFSET 0
#define BYTE1_OFFSET 8 #define BYTE1_OFFSET 8
#define BYTE2_OFFSET 16 #define BYTE2_OFFSET 16
#define BYTE3_OFFSET 24 #define BYTE3_OFFSET 24
#define MSB 0xff000000 #define MSB 0xff000000
#define LSB 0x000000ff #define LSB 0x000000ff
#endif /* not __ARMEB__ */ #endif /* not __ARM_BIG_ENDIAN */
.syntax unified .macro def_fn f p2align=0
.text
.p2align \p2align
.global \f
.type \f, %function
\f:
.endm
#if defined (__thumb__) #if defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED) \
.thumb || (__ARM_ARCH == 6 && __ARM_ARCH_PROFILE == 'M')
.thumb_func
#if !defined (__thumb2__)
/* If we have thumb1 only, we need to explictly mark the
compatibility. */
.arch armv4t
.eabi_attribute Tag_also_compatible_with, "\006\013" /* v6-M. */
.eabi_attribute Tag_ARM_ISA_use, 0
#endif
#endif
.global strcmp
.type strcmp, %function
strcmp:
#if (defined (__thumb__) && !defined (__thumb2__)) # if defined (__thumb__) && !defined (__thumb2__)
1: /* Thumb1 only variant. */
ldrb r2, [r0] # include "strcmp-armv4t.S"
ldrb r3, [r1] # else
adds r0, r0, #1 # include "strcmp-arm-tiny.S"
adds r1, r1, #1 # endif
cmp r2, #0
beq 2f
cmp r2, r3
beq 1b
2:
subs r0, r2, r3
bx lr
#elif (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
1:
ldrb r2, [r0], #1
ldrb r3, [r1], #1
cmp r2, #1
it cs
cmpcs r2, r3
beq 1b
subs r0, r2, r3
RETURN
#elif __ARM_ARCH >= 7
#elif (defined (_ISA_THUMB_2) || defined (_ISA_ARM_6)) # ifdef __ARM_FEATURE_SIMD32
/* Use LDRD whenever possible. */ # include "strcmp-armv7.S"
# else
# include "strcmp-armv7m.S"
# endif
/* The main thing to look out for when comparing large blocks is that #elif __ARM_ARCH >= 6
the loads do not cross a page boundary when loading past the index
of the byte with the first difference or the first string-terminator.
For example, if the strings are identical and the string-terminator # include "strcmp-armv6.S"
is at index k, byte by byte comparison will not load beyond address
s1+k and s2+k; word by word comparison may load up to 3 bytes beyond
k; double word - up to 7 bytes. If the load of these bytes crosses
a page boundary, it might cause a memory fault (if the page is not mapped)
that would not have happened in byte by byte comparison.
If an address is (double) word aligned, then a load of a (double) word
from that address will not cross a page boundary.
Therefore, the algorithm below considers word and double-word alignment
of strings separately. */
/* High-level description of the algorithm.
* The fast path: if both strings are double-word aligned,
use LDRD to load two words from each string in every loop iteration.
* If the strings have the same offset from a word boundary,
use LDRB to load and compare byte by byte until
the first string is aligned to a word boundary (at most 3 bytes).
This is optimized for quick return on short unaligned strings.
* If the strings have the same offset from a double-word boundary,
use LDRD to load two words from each string in every loop iteration, as in the fast path.
* If the strings do not have the same offset from a double-word boundary,
load a word from the second string before the loop to initialize the queue.
Use LDRD to load two words from every string in every loop iteration.
Inside the loop, load the second word from the second string only after comparing
the first word, using the queued value, to guarantee safety across page boundaries.
* If the strings do not have the same offset from a word boundary,
use LDR and a shift queue. Order of loads and comparisons matters,
similarly to the previous case.
* Use UADD8 and SEL to compare words, and use REV and CLZ to compute the return value.
* The only difference between ARM and Thumb modes is the use of CBZ instruction.
* The only difference between big and little endian is the use of REV in little endian
to compute the return value, instead of MOV.
* No preload. [TODO.]
*/
.macro m_cbz reg label
#ifdef __thumb2__
cbz \reg, \label
#else /* not defined __thumb2__ */
cmp \reg, #0
beq \label
#endif /* not defined __thumb2__ */
.endm /* m_cbz */
.macro m_cbnz reg label
#ifdef __thumb2__
cbnz \reg, \label
#else /* not defined __thumb2__ */
cmp \reg, #0
bne \label
#endif /* not defined __thumb2__ */
.endm /* m_cbnz */
.macro init
/* Macro to save temporary registers and prepare magic values. */
subs sp, sp, #16
strd r4, r5, [sp, #8]
strd r6, r7, [sp]
mvn r6, #0 /* all F */
mov r7, #0 /* all 0 */
.endm /* init */
.macro magic_compare_and_branch w1 w2 label
/* Macro to compare registers w1 and w2 and conditionally branch to label. */
cmp \w1, \w2 /* Are w1 and w2 the same? */
magic_find_zero_bytes \w1
it eq
cmpeq ip, #0 /* Is there a zero byte in w1? */
bne \label
.endm /* magic_compare_and_branch */
.macro magic_find_zero_bytes w1
/* Macro to find all-zero bytes in w1, result is in ip. */
#if (defined (__ARM_FEATURE_DSP))
uadd8 ip, \w1, r6
sel ip, r7, r6
#else /* not defined (__ARM_FEATURE_DSP) */
/* __ARM_FEATURE_DSP is not defined for some Cortex-M processors.
Coincidently, these processors only have Thumb-2 mode, where we can use the
the (large) magic constant available directly as an immediate in instructions.
Note that we cannot use the magic constant in ARM mode, where we need
to create the constant in a register. */
sub ip, \w1, #0x01010101
bic ip, ip, \w1
and ip, ip, #0x80808080
#endif /* not defined (__ARM_FEATURE_DSP) */
.endm /* magic_find_zero_bytes */
.macro setup_return w1 w2
#ifdef __ARMEB__
mov r1, \w1
mov r2, \w2
#else /* not __ARMEB__ */
rev r1, \w1
rev r2, \w2
#endif /* not __ARMEB__ */
.endm /* setup_return */
/*
optpld r0, #0
optpld r1, #0
*/
/* Are both strings double-word aligned? */
orr ip, r0, r1
tst ip, #7
bne .Ldo_align
/* Fast path. */
init
.Ldoubleword_aligned:
/* Get here when the strings to compare are double-word aligned. */
/* Compare two words in every iteration. */
.p2align 2
2:
/*
optpld r0, #16
optpld r1, #16
*/
/* Load the next double-word from each string. */
ldrd r2, r3, [r0], #8
ldrd r4, r5, [r1], #8
magic_compare_and_branch w1=r2, w2=r4, label=.Lreturn_24
magic_compare_and_branch w1=r3, w2=r5, label=.Lreturn_35
b 2b
.Ldo_align:
/* Is the first string word-aligned? */
ands ip, r0, #3
beq .Lword_aligned_r0
/* Fast compare byte by byte until the first string is word-aligned. */
/* The offset of r0 from a word boundary is in ip. Thus, the number of bytes
to read until the next word boudnary is 4-ip. */
bic r0, r0, #3
ldr r2, [r0], #4
lsls ip, ip, #31
beq .Lbyte2
bcs .Lbyte3
.Lbyte1:
ldrb ip, [r1], #1
uxtb r3, r2, ror #BYTE1_OFFSET
subs ip, r3, ip
bne .Lfast_return
m_cbz reg=r3, label=.Lfast_return
.Lbyte2:
ldrb ip, [r1], #1
uxtb r3, r2, ror #BYTE2_OFFSET
subs ip, r3, ip
bne .Lfast_return
m_cbz reg=r3, label=.Lfast_return
.Lbyte3:
ldrb ip, [r1], #1
uxtb r3, r2, ror #BYTE3_OFFSET
subs ip, r3, ip
bne .Lfast_return
m_cbnz reg=r3, label=.Lword_aligned_r0
.Lfast_return:
mov r0, ip
bx lr
.Lword_aligned_r0:
init
/* The first string is word-aligned. */
/* Is the second string word-aligned? */
ands ip, r1, #3
bne .Lstrcmp_unaligned
.Lword_aligned:
/* The strings are word-aligned. */
/* Is the first string double-word aligned? */
tst r0, #4
beq .Ldoubleword_aligned_r0
/* If r0 is not double-word aligned yet, align it by loading
and comparing the next word from each string. */
ldr r2, [r0], #4
ldr r4, [r1], #4
magic_compare_and_branch w1=r2 w2=r4 label=.Lreturn_24
.Ldoubleword_aligned_r0:
/* Get here when r0 is double-word aligned. */
/* Is r1 doubleword_aligned? */
tst r1, #4
beq .Ldoubleword_aligned
/* Get here when the strings to compare are word-aligned,
r0 is double-word aligned, but r1 is not double-word aligned. */
/* Initialize the queue. */
ldr r5, [r1], #4
/* Compare two words in every iteration. */
.p2align 2
3:
/*
optpld r0, #16
optpld r1, #16
*/
/* Load the next double-word from each string and compare. */
ldrd r2, r3, [r0], #8
magic_compare_and_branch w1=r2 w2=r5 label=.Lreturn_25
ldrd r4, r5, [r1], #8
magic_compare_and_branch w1=r3 w2=r4 label=.Lreturn_34
b 3b
.macro miscmp_word offsetlo offsethi
/* Macro to compare misaligned strings. */
/* r0, r1 are word-aligned, and at least one of the strings
is not double-word aligned. */
/* Compare one word in every loop iteration. */
/* OFFSETLO is the original bit-offset of r1 from a word-boundary,
OFFSETHI is 32 - OFFSETLO (i.e., offset from the next word). */
/* Initialize the shift queue. */
ldr r5, [r1], #4
/* Compare one word from each string in every loop iteration. */
.p2align 2
7:
ldr r3, [r0], #4
S2LOMEM r5, r5, #\offsetlo
magic_find_zero_bytes w1=r3
cmp r7, ip, S2HIMEM #\offsetlo
and r2, r3, r6, S2LOMEM #\offsetlo
it eq
cmpeq r2, r5
bne .Lreturn_25
ldr r5, [r1], #4
cmp ip, #0
eor r3, r2, r3
S2HIMEM r2, r5, #\offsethi
it eq
cmpeq r3, r2
bne .Lreturn_32
b 7b
.endm /* miscmp_word */
.Lstrcmp_unaligned:
/* r0 is word-aligned, r1 is at offset ip from a word. */
/* Align r1 to the (previous) word-boundary. */
bic r1, r1, #3
/* Unaligned comparison word by word using LDRs. */
cmp ip, #2
beq .Lmiscmp_word_16 /* If ip == 2. */
bge .Lmiscmp_word_24 /* If ip == 3. */
miscmp_word offsetlo=8 offsethi=24 /* If ip == 1. */
.Lmiscmp_word_16: miscmp_word offsetlo=16 offsethi=16
.Lmiscmp_word_24: miscmp_word offsetlo=24 offsethi=8
.Lreturn_32:
setup_return w1=r3, w2=r2
b .Ldo_return
.Lreturn_34:
setup_return w1=r3, w2=r4
b .Ldo_return
.Lreturn_25:
setup_return w1=r2, w2=r5
b .Ldo_return
.Lreturn_35:
setup_return w1=r3, w2=r5
b .Ldo_return
.Lreturn_24:
setup_return w1=r2, w2=r4
.Ldo_return:
#ifdef __ARMEB__
mov r0, ip
#else /* not __ARMEB__ */
rev r0, ip
#endif /* not __ARMEB__ */
/* Restore temporaries early, before computing the return value. */
ldrd r6, r7, [sp]
ldrd r4, r5, [sp, #8]
adds sp, sp, #16
/* There is a zero or a different byte between r1 and r2. */
/* r0 contains a mask of all-zero bytes in r1. */
/* Using r0 and not ip here because cbz requires low register. */
m_cbz reg=r0, label=.Lcompute_return_value
clz r0, r0
/* r0 contains the number of bits on the left of the first all-zero byte in r1. */
rsb r0, r0, #24
/* Here, r0 contains the number of bits on the right of the first all-zero byte in r1. */
lsr r1, r1, r0
lsr r2, r2, r0
.Lcompute_return_value:
movs r0, #1
cmp r1, r2
/* The return value is computed as follows.
If r1>r2 then (C==1 and Z==0) and LS doesn't hold and r0 is #1 at return.
If r1<r2 then (C==0 and Z==0) and we execute SBC with carry_in=0,
which means r0:=r0-r0-1 and r0 is #-1 at return.
If r1=r2 then (C==1 and Z==1) and we execute SBC with carry_in=1,
which means r0:=r0-r0 and r0 is #0 at return.
(C==0 and Z==1) cannot happen because the carry bit is "not borrow". */
it ls
sbcls r0, r0, r0
bx lr
#else /* !(defined (_ISA_THUMB_2) || defined (_ISA_ARM_6)
defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED) ||
(defined (__thumb__) && !defined (__thumb2__))) */
/* Use LDR whenever possible. */
#ifdef __thumb2__
#define magic1(REG) 0x01010101
#define magic2(REG) 0x80808080
#else #else
#define magic1(REG) REG
#define magic2(REG) REG, lsl #7 # include "strcmp-armv4.S"
#endif #endif
optpld r0
optpld r1
eor r2, r0, r1
tst r2, #3
/* Strings not at same byte offset from a word boundary. */
bne .Lstrcmp_unaligned
ands r2, r0, #3
bic r0, r0, #3
bic r1, r1, #3
ldr ip, [r0], #4
it eq
ldreq r3, [r1], #4
beq 1f
/* Although s1 and s2 have identical initial alignment, they are
not currently word aligned. Rather than comparing bytes,
make sure that any bytes fetched from before the addressed
bytes are forced to 0xff. Then they will always compare
equal. */
eor r2, r2, #3
lsl r2, r2, #3
mvn r3, MSB
S2LOMEM r2, r3, r2
ldr r3, [r1], #4
orr ip, ip, r2
orr r3, r3, r2
1:
#ifndef __thumb2__
/* Load the 'magic' constant 0x01010101. */
str r4, [sp, #-4]!
mov r4, #1
orr r4, r4, r4, lsl #8
orr r4, r4, r4, lsl #16
#endif
.p2align 2
4:
optpld r0, #8
optpld r1, #8
sub r2, ip, magic1(r4)
cmp ip, r3
itttt eq
/* check for any zero bytes in first word */
biceq r2, r2, ip
tsteq r2, magic2(r4)
ldreq ip, [r0], #4
ldreq r3, [r1], #4
beq 4b
2:
/* There's a zero or a different byte in the word */
S2HIMEM r0, ip, #24
S2LOMEM ip, ip, #8
cmp r0, #1
it cs
cmpcs r0, r3, S2HIMEM #24
it eq
S2LOMEMEQ r3, r3, #8
beq 2b
/* On a big-endian machine, r0 contains the desired byte in bits
0-7; on a little-endian machine they are in bits 24-31. In
both cases the other bits in r0 are all zero. For r3 the
interesting byte is at the other end of the word, but the
other bits are not necessarily zero. We need a signed result
representing the differnece in the unsigned bytes, so for the
little-endian case we can't just shift the interesting bits
up. */
#ifdef __ARMEB__
sub r0, r0, r3, lsr #24
#else
and r3, r3, #255
#ifdef __thumb2__
/* No RSB instruction in Thumb2 */
lsr r0, r0, #24
sub r0, r0, r3
#else
rsb r0, r3, r0, lsr #24
#endif
#endif
#ifndef __thumb2__
ldr r4, [sp], #4
#endif
RETURN
.Lstrcmp_unaligned:
#if 0
/* The assembly code below is based on the following alogrithm. */
#ifdef __ARMEB__
#define RSHIFT <<
#define LSHIFT >>
#else
#define RSHIFT >>
#define LSHIFT <<
#endif
#define body(shift) \
mask = 0xffffffffU RSHIFT shift; \
w1 = *wp1++; \
w2 = *wp2++; \
do \
{ \
t1 = w1 & mask; \
if (__builtin_expect(t1 != w2 RSHIFT shift, 0)) \
{ \
w2 RSHIFT= shift; \
break; \
} \
if (__builtin_expect(((w1 - b1) & ~w1) & (b1 << 7), 0)) \
{ \
/* See comment in assembler below re syndrome on big-endian */\
if ((((w1 - b1) & ~w1) & (b1 << 7)) & mask) \
w2 RSHIFT= shift; \
else \
{ \
w2 = *wp2; \
t1 = w1 RSHIFT (32 - shift); \
w2 = (w2 LSHIFT (32 - shift)) RSHIFT (32 - shift); \
} \
break; \
} \
w2 = *wp2++; \
t1 ^= w1; \
if (__builtin_expect(t1 != w2 LSHIFT (32 - shift), 0)) \
{ \
t1 = w1 >> (32 - shift); \
w2 = (w2 << (32 - shift)) RSHIFT (32 - shift); \
break; \
} \
w1 = *wp1++; \
} while (1)
const unsigned* wp1;
const unsigned* wp2;
unsigned w1, w2;
unsigned mask;
unsigned shift;
unsigned b1 = 0x01010101;
char c1, c2;
unsigned t1;
while (((unsigned) s1) & 3)
{
c1 = *s1++;
c2 = *s2++;
if (c1 == 0 || c1 != c2)
return c1 - (int)c2;
}
wp1 = (unsigned*) (((unsigned)s1) & ~3);
wp2 = (unsigned*) (((unsigned)s2) & ~3);
t1 = ((unsigned) s2) & 3;
if (t1 == 1)
{
body(8);
}
else if (t1 == 2)
{
body(16);
}
else
{
body (24);
}
do
{
#ifdef __ARMEB__
c1 = (char) t1 >> 24;
c2 = (char) w2 >> 24;
#else /* not __ARMEB__ */
c1 = (char) t1;
c2 = (char) w2;
#endif /* not __ARMEB__ */
t1 RSHIFT= 8;
w2 RSHIFT= 8;
} while (c1 != 0 && c1 == c2);
return c1 - c2;
#endif /* 0 */
wp1 .req r0
wp2 .req r1
b1 .req r2
w1 .req r4
w2 .req r5
t1 .req ip
@ r3 is scratch
/* First of all, compare bytes until wp1(sp1) is word-aligned. */
1:
tst wp1, #3
beq 2f
ldrb r2, [wp1], #1
ldrb r3, [wp2], #1
cmp r2, #1
it cs
cmpcs r2, r3
beq 1b
sub r0, r2, r3
RETURN
2:
str r5, [sp, #-4]!
str r4, [sp, #-4]!
//stmfd sp!, {r4, r5}
mov b1, #1
orr b1, b1, b1, lsl #8
orr b1, b1, b1, lsl #16
and t1, wp2, #3
bic wp2, wp2, #3
ldr w1, [wp1], #4
ldr w2, [wp2], #4
cmp t1, #2
beq 2f
bhi 3f
/* Critical inner Loop: Block with 3 bytes initial overlap */
.p2align 2
1:
bic t1, w1, MSB
cmp t1, w2, S2LOMEM #8
sub r3, w1, b1
bic r3, r3, w1
bne 4f
ands r3, r3, b1, lsl #7
it eq
ldreq w2, [wp2], #4
bne 5f
eor t1, t1, w1
cmp t1, w2, S2HIMEM #24
bne 6f
ldr w1, [wp1], #4
b 1b
4:
S2LOMEM w2, w2, #8
b 8f
5:
#ifdef __ARMEB__
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00 */
tst w1, #0xff000000
itt ne
tstne w1, #0x00ff0000
tstne w1, #0x0000ff00
beq 7f
#else
bics r3, r3, #0xff000000
bne 7f
#endif
ldrb w2, [wp2]
S2LOMEM t1, w1, #24
#ifdef __ARMEB__
lsl w2, w2, #24
#endif
b 8f
6:
S2LOMEM t1, w1, #24
and w2, w2, LSB
b 8f
/* Critical inner Loop: Block with 2 bytes initial overlap */
.p2align 2
2:
S2HIMEM t1, w1, #16
sub r3, w1, b1
S2LOMEM t1, t1, #16
bic r3, r3, w1
cmp t1, w2, S2LOMEM #16
bne 4f
ands r3, r3, b1, lsl #7
it eq
ldreq w2, [wp2], #4
bne 5f
eor t1, t1, w1
cmp t1, w2, S2HIMEM #16
bne 6f
ldr w1, [wp1], #4
b 2b
5:
#ifdef __ARMEB__
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00 */
tst w1, #0xff000000
it ne
tstne w1, #0x00ff0000
beq 7f
#else
lsls r3, r3, #16
bne 7f
#endif
ldrh w2, [wp2]
S2LOMEM t1, w1, #16
#ifdef __ARMEB__
lsl w2, w2, #16
#endif
b 8f
6:
S2HIMEM w2, w2, #16
S2LOMEM t1, w1, #16
4:
S2LOMEM w2, w2, #16
b 8f
/* Critical inner Loop: Block with 1 byte initial overlap */
.p2align 2
3:
and t1, w1, LSB
cmp t1, w2, S2LOMEM #24
sub r3, w1, b1
bic r3, r3, w1
bne 4f
ands r3, r3, b1, lsl #7
it eq
ldreq w2, [wp2], #4
bne 5f
eor t1, t1, w1
cmp t1, w2, S2HIMEM #8
bne 6f
ldr w1, [wp1], #4
b 3b
4:
S2LOMEM w2, w2, #24
b 8f
5:
/* The syndrome value may contain false ones if the string ends
with the bytes 0x01 0x00 */
tst w1, LSB
beq 7f
ldr w2, [wp2], #4
6:
S2LOMEM t1, w1, #8
bic w2, w2, MSB
b 8f
7:
mov r0, #0
//ldmfd sp!, {r4, r5}
ldr r4, [sp], #4
ldr r5, [sp], #4
RETURN
8:
and r2, t1, LSB
and r0, w2, LSB
cmp r0, #1
it cs
cmpcs r0, r2
itt eq
S2LOMEMEQ t1, t1, #8
S2LOMEMEQ w2, w2, #8
beq 8b
sub r0, r2, r0
//ldmfd sp!, {r4, r5}
ldr r4, [sp], #4
ldr r5, [sp], #4
RETURN
#endif /* !(defined (_ISA_THUMB_2) || defined (_ISA_ARM_6)
defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED) ||
(defined (__thumb__) && !defined (__thumb2__))) */