131 lines
3.9 KiB
ArmAsm
131 lines
3.9 KiB
ArmAsm
/* Optimized strchr implementation for PowerPC.
|
|
Copyright (C) 1997, 1999, 2000 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Library General Public License as
|
|
published by the Free Software Foundation; either version 2 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
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If not,
|
|
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include <sysdep.h>
|
|
#include <bp-sym.h>
|
|
#include <bp-asm.h>
|
|
|
|
/* See strlen.s for comments on how this works. */
|
|
|
|
/* char * [r3] strchr (const char *s [r3] , int c [r4] ) */
|
|
|
|
ENTRY (BP_SYM (strchr))
|
|
|
|
#define rTMP1 r0
|
|
#define rRTN r3 /* outgoing result */
|
|
#if __BOUNDED_POINTERS__
|
|
# define rSTR r4
|
|
# define rCHR r5 /* byte we're looking for, spread over the whole word */
|
|
# define rWORD r8 /* the current word */
|
|
#else
|
|
# define rSTR r3 /* current word pointer */
|
|
# define rCHR r4 /* byte we're looking for, spread over the whole word */
|
|
# define rWORD r5 /* the current word */
|
|
#endif
|
|
#define rCLZB rCHR /* leading zero byte count */
|
|
#define rFEFE r6 /* constant 0xfefefeff (-0x01010101) */
|
|
#define r7F7F r7 /* constant 0x7f7f7f7f */
|
|
#define rTMP2 r9
|
|
#define rIGN r10 /* number of bits we should ignore in the first word */
|
|
#define rMASK r11 /* mask with the bits to ignore set to 0 */
|
|
#define rTMP3 r12
|
|
|
|
CHECK_BOUNDS_LOW (rSTR, rTMP1, rTMP2)
|
|
STORE_RETURN_BOUNDS (rTMP1, rTMP2)
|
|
|
|
rlwimi rCHR, rCHR, 8, 16, 23
|
|
li rMASK, -1
|
|
rlwimi rCHR, rCHR, 16, 0, 15
|
|
rlwinm rIGN, rSTR, 3, 27, 28
|
|
lis rFEFE, -0x101
|
|
lis r7F7F, 0x7f7f
|
|
clrrwi rSTR, rSTR, 2
|
|
addi rFEFE, rFEFE, -0x101
|
|
addi r7F7F, r7F7F, 0x7f7f
|
|
/* Test the first (partial?) word. */
|
|
lwz rWORD, 0(rSTR)
|
|
srw rMASK, rMASK, rIGN
|
|
orc rWORD, rWORD, rMASK
|
|
add rTMP1, rFEFE, rWORD
|
|
nor rTMP2, r7F7F, rWORD
|
|
and. rTMP1, rTMP1, rTMP2
|
|
xor rTMP3, rCHR, rWORD
|
|
orc rTMP3, rTMP3, rMASK
|
|
b L(loopentry)
|
|
|
|
/* The loop. */
|
|
|
|
L(loop):lwzu rWORD, 4(rSTR)
|
|
and. rTMP1, rTMP1, rTMP2
|
|
/* Test for 0. */
|
|
add rTMP1, rFEFE, rWORD
|
|
nor rTMP2, r7F7F, rWORD
|
|
bne L(foundit)
|
|
and. rTMP1, rTMP1, rTMP2
|
|
/* Start test for the bytes we're looking for. */
|
|
xor rTMP3, rCHR, rWORD
|
|
L(loopentry):
|
|
add rTMP1, rFEFE, rTMP3
|
|
nor rTMP2, r7F7F, rTMP3
|
|
beq L(loop)
|
|
/* There is a zero byte in the word, but may also be a matching byte (either
|
|
before or after the zero byte). In fact, we may be looking for a
|
|
zero byte, in which case we return a match. We guess that this hasn't
|
|
happened, though. */
|
|
L(missed):
|
|
and. rTMP1, rTMP1, rTMP2
|
|
li rSTR, 0
|
|
STORE_RETURN_VALUE (rSTR)
|
|
beqlr
|
|
/* It did happen. Decide which one was first...
|
|
I'm not sure if this is actually faster than a sequence of
|
|
rotates, compares, and branches (we use it anyway because it's shorter). */
|
|
and rFEFE, r7F7F, rWORD
|
|
or rMASK, r7F7F, rWORD
|
|
and rTMP1, r7F7F, rTMP3
|
|
or rIGN, r7F7F, rTMP3
|
|
add rFEFE, rFEFE, r7F7F
|
|
add rTMP1, rTMP1, r7F7F
|
|
nor rWORD, rMASK, rFEFE
|
|
nor rTMP2, rIGN, rTMP1
|
|
cmplw rWORD, rTMP2
|
|
bgtlr
|
|
cntlzw rCLZB, rTMP2
|
|
srwi rCLZB, rCLZB, 3
|
|
add rSTR, rSTR, rCLZB
|
|
CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
|
|
STORE_RETURN_VALUE (rSTR)
|
|
blr
|
|
|
|
L(foundit):
|
|
and rTMP1, r7F7F, rTMP3
|
|
or rIGN, r7F7F, rTMP3
|
|
add rTMP1, rTMP1, r7F7F
|
|
nor rTMP2, rIGN, rTMP1
|
|
cntlzw rCLZB, rTMP2
|
|
subi rSTR, rSTR, 4
|
|
srwi rCLZB, rCLZB, 3
|
|
add rSTR, rSTR, rCLZB
|
|
CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
|
|
STORE_RETURN_VALUE (rSTR)
|
|
blr
|
|
END (BP_SYM (strchr))
|
|
|
|
weak_alias (BP_SYM (strchr), BP_SYM (index))
|