mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 21:10:07 +00:00
111 lines
3.4 KiB
ArmAsm
111 lines
3.4 KiB
ArmAsm
/* Optimized rawmemchr implementation for PowerPC32/POWER7 using cmpb insn.
|
|
Copyright (C) 2010-2017 Free Software Foundation, Inc.
|
|
Contributed by Luis Machado <luisgpm@br.ibm.com>.
|
|
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 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>
|
|
|
|
/* int [r3] rawmemchr (void *s [r3], int c [r4]) */
|
|
.machine power7
|
|
ENTRY (__rawmemchr)
|
|
CALL_MCOUNT
|
|
dcbt 0,r3
|
|
clrrwi r8,r3,2 /* Align the address to word boundary. */
|
|
|
|
/* Replicate byte to word. */
|
|
insrwi r4,r4,8,16
|
|
insrwi r4,r4,16,0
|
|
|
|
/* Now r4 has a word of c bytes. */
|
|
|
|
rlwinm r6,r3,3,27,28 /* Calculate padding. */
|
|
lwz r12,0(r8) /* Load word from memory. */
|
|
cmpb r5,r12,r4 /* Compare each byte against c byte. */
|
|
#ifdef __LITTLE_ENDIAN__
|
|
srw r5,r5,r6
|
|
slw r5,r5,r6
|
|
#else
|
|
slw r5,r5,r6 /* Move left to discard ignored bits. */
|
|
srw r5,r5,r6 /* Bring the bits back as zeros. */
|
|
#endif
|
|
cmpwi cr7,r5,0 /* If r5 == 0, no c bytes have been found. */
|
|
bne cr7,L(done)
|
|
|
|
mtcrf 0x01,r8
|
|
|
|
/* Are we now aligned to a doubleword boundary? If so, skip to
|
|
the main loop. Otherwise, go through the alignment code. */
|
|
|
|
bt 29,L(loop)
|
|
|
|
/* Handle WORD2 of pair. */
|
|
lwzu r12,4(r8)
|
|
cmpb r5,r12,r4
|
|
cmpwi cr7,r5,0
|
|
bne cr7,L(done)
|
|
b L(loop) /* We branch here (rather than falling through)
|
|
to skip the nops due to heavy alignment
|
|
of the loop below. */
|
|
|
|
/* Main loop to look for the end of the string. Since it's a
|
|
small loop (< 8 instructions), align it to 32-bytes. */
|
|
.p2align 5
|
|
L(loop):
|
|
/* Load two words, compare and merge in a
|
|
single register for speed. This is an attempt
|
|
to speed up the byte-checking process for bigger strings. */
|
|
lwz r12,4(r8)
|
|
lwzu r11,8(r8)
|
|
cmpb r5,r12,r4
|
|
cmpb r6,r11,r4
|
|
or r7,r5,r6
|
|
cmpwi cr7,r7,0
|
|
beq cr7,L(loop)
|
|
|
|
/* OK, one (or both) of the words contains a 'c' byte. Check
|
|
the first word and decrement the address in case the first
|
|
word really contains a c byte. */
|
|
|
|
cmpwi cr6,r5,0
|
|
addi r8,r8,-4
|
|
bne cr6,L(done)
|
|
|
|
/* The 'c' byte must be in the second word. Adjust the address
|
|
again and move the result of cmpb to r10 so we can calculate the
|
|
pointer. */
|
|
mr r5,r6
|
|
addi r8,r8,4
|
|
|
|
/* r5 has the output of the cmpb instruction, that is, it contains
|
|
0xff in the same position as the 'c' byte in the original
|
|
word from the string. Use that fact to find out what is
|
|
the position of the byte inside the string. */
|
|
L(done):
|
|
#ifdef __LITTLE_ENDIAN__
|
|
addi r0,r5,-1
|
|
andc r0,r0,r5
|
|
popcntw r0,r0
|
|
#else
|
|
cntlzw r0,r5 /* Count leading zeros before the match. */
|
|
#endif
|
|
srwi r0,r0,3 /* Convert leading zeros to bytes. */
|
|
add r3,r8,r0 /* Return address of the matching char. */
|
|
blr
|
|
END (__rawmemchr)
|
|
weak_alias (__rawmemchr,rawmemchr)
|
|
libc_hidden_builtin_def (__rawmemchr)
|