newlib-cygwin/newlib/libc/machine/arc/strchr.S

209 lines
5.2 KiB
ArmAsm

/*
Copyright (c) 2015, Synopsys, Inc. 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) Neither the name of the Synopsys, 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER OR CONTRIBUTORS 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 implementation is optimized for performance. For code size a generic
implementation of this function from newlib/libc/string/strchr.c will be
used. */
#if !defined (__OPTIMIZE_SIZE__) && !defined (PREFER_SIZE_OVER_SPEED)
#include "asm.h"
/* In order to search for a zero in a W, we calculate
X := (W - 0x01010101) & ~W & 0x80808080;
In the little endian case:
If no byte in W is zero, X will be zero; otherwise, the least significant
byte of X which is nonzero indicates the least significant byte of W that
is zero.
In the big endian case:
X will be zero iff no byte in W is zero.
If X is nonzero, to find out which is the most significant zero byte
in W, we calculate:
Y := ~(((W | 0x80808080) - 0x01010101) | W) & 0x80808080;
Each byte in Y is 0x80 if the the corresponding byte in
W is zero, otherwise that byte of Y is 0. */
#if defined (__ARC601__) || !defined (__ARC_BARREL_SHIFTER__)
ENTRY (strchr)
bmsk.f r2,r0,1
mov_s r3,0x01010101
extb_s r1,r1
mov r8,0
add3 r5,r8,r1
add3 r5,r8,r5
add2 r5,r1,r5
add3 r4,r8,r5
add3 r4,r8,r4
add3 r4,r8,r4
add3 r4,r8,r4
beq.d .Laligned
add3 r4,r8,r4
sub_s r0,r0,r2
#ifdef __LITTLE_ENDIAN__
add3.f r2,-1,r2
bmsk r7,r3,r2
rsub.pl r7,r7,r3
#else
mov_s r12,31
sub3 r2,r12,r2
bmsk r7,r3,r2
#endif
ld_s r2,[r0]
add1 r5,r5,r4
ror r4,r3
sub r12,r2,r7
bic_s r12,r12,r2
and r12,r12,r4
brne.d r12,0,.Lfound0_ua
xor r6,r2,r5
ld.a r2,[r0,4]
sub r12,r6,r7
bic r12,r12,r6
#ifdef __LITTLE_ENDIAN__
and.f r7,r12,r4
sub r12,r2,r3
bic_s r12,r12,r2
beq.d .Loop
and r12,r12,r4
b.d .Lfound_char_ua
btst r7,7
#else
and.f r8,r12,r4
sub r12,r2,r3
bic_s r12,r12,r2
beq.d .Loop
and r12,r12,r4
bic r12,r7,r6
bic r2,r3,r12
sub1 r2,r3,r2
sub_s r0,r0,4
b.d .Lfound_char_ua
bic.f r2,r8,r2
#endif
.balign 4
.Laligned:
ld_s r2,[r0]
add1 r5,r5,r4
ror r4,r3
sub r12,r2,r3
bic_s r12,r12,r2
and r12,r12,r4
.Loop:
brne.d r12,0,.Lfound0
xor r6,r2,r5
ld.a r2,[r0,4]
sub r12,r6,r3
bic r12,r12,r6
and.f r7,r12,r4
sub r12,r2,r3
bic_s r12,r12,r2
beq.d .Loop
and r12,r12,r4
; Found searched-for character. r0 has already advanced to next word.
#ifdef __LITTLE_ENDIAN__
/* We only need the information about the first matching byte
(i.e. the least significant matching byte) to be exact,
hence there is no problem with carry effects. */
.Lfound_char:
btst r7,7
.Lfound_char_ua:
sub_s r0,r0,4
add.eq r0,r0,1
btst.eq r7,15
add.eq r0,r0,1
btst.eq r7,23
j_s.d [blink]
add.eq r0,r0,1
.balign 4
.Lfound0_ua:
mov_l r3,r7
.Lfound0:
sub r2,r6,r3
bic r2,r2,r6
and r2,r2,r4
or r3,r12,r2
sub_s r12,r3,1
xor_s r3,r3,r12
cmp 0xffff,r3
; cmp uses limm ; ARC600 would do: asl.f 0,r3,9
tst_s r2,r3
mov.eq r0,0
add.mi r0,r0,1
btst.ne r3,15
j_s.d [blink]
adc.ne r0,r0,1
#else /* BIG ENDIAN */
.Lfound_char:
and r2,r6,r3
sub1 r2,r3,r2
sub_s r0,r0,4
bic.f r2,r7,r2
.Lfound_char_ua:
add.pl r0,r0,1
jmi.d [blink]
btst_s r2,23
add.eq r0,r0,1
btst.eq r2,15
j_s.d [blink]
add.eq r0,r0,1
; N.B. if we searched for a char zero and found it in the MSB,
; and ignored matches are identical, we will take the early exit
; like for an ordinary found zero - except for the extra stalls at jhi -
; but still compute the right result.
.Lfound0_ua:
mov_s r3,r7
.Lfound0:
and_s r2,r2,r3
sub1 r2,r3,r2
or r7,r6,r4
bic_s r12,r12,r2
sub r2,r7,r3
or r2,r2,r6
bic r2,r4,r2
cmp_s r12,r2
mov.hi r0,0
btst.ls r2,31
jhi.d [blink]
add.eq r0,r0,1
btst.eq r2,23
add.eq r0,r0,1
btst.eq r2,15
j_s.d [blink]
add.eq r0,r0,1
#endif /* ENDIAN */
ENDFUNC (strchr)
#endif /* __ARC601__ || !__ARC_BARREL_SHIFTER__ */
#endif /* !__OPTIMIZE_SIZE__ && !PREFER_SIZE_OVER_SPEED */