mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-27 13:10:29 +00:00
170 lines
4.5 KiB
ArmAsm
170 lines
4.5 KiB
ArmAsm
/* Optimized memchr implementation for PowerPC32/POWER7 using cmpb insn.
|
|
Copyright (C) 2010 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>
|
|
#include <bp-sym.h>
|
|
#include <bp-asm.h>
|
|
|
|
/* int [r3] memchr (char *s [r3], int byte [r4], int size [r5]) */
|
|
.machine power7
|
|
ENTRY (BP_SYM (__memchr))
|
|
CALL_MCOUNT
|
|
dcbt 0,r3
|
|
clrrwi r8,r3,2
|
|
rlwimi r4,r4,8,16,23
|
|
rlwimi r4,r4,16,0,15
|
|
add r7,r3,r5 /* Calculate the last acceptable address. */
|
|
cmplwi r5,16
|
|
ble L(small_range)
|
|
|
|
cmplw cr7,r3,r7 /* Is the address equal or less than r3? If
|
|
it's equal or less, it means size is either 0
|
|
or a negative number. */
|
|
ble cr7,L(proceed)
|
|
|
|
li r7,-1 /* Make r11 the biggest if r4 <= 0. */
|
|
L(proceed):
|
|
rlwinm r6,r3,3,27,28 /* Calculate padding. */
|
|
lwz r12,0(r8) /* Load word from memory. */
|
|
cmpb r10,r12,r4 /* Check for BYTE's in WORD1. */
|
|
slw r10,r10,r6
|
|
srw r10,r10,r6
|
|
cmplwi cr7,r10,0 /* If r10 == 0, no BYTE's have been found. */
|
|
bne cr7,L(done)
|
|
|
|
/* Are we done already? */
|
|
addi r9,r8,4
|
|
cmplw cr6,r9,r7
|
|
bge cr6,L(null)
|
|
|
|
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_setup)
|
|
|
|
/* Handle WORD2 of pair. */
|
|
lwzu r12,4(r8)
|
|
cmpb r10,r12,r4
|
|
cmplwi cr7,r10,0
|
|
bne cr7,L(done)
|
|
|
|
/* Are we done already? */
|
|
addi r9,r8,4
|
|
cmplw cr6,r9,r7
|
|
bge cr6,L(null)
|
|
|
|
L(loop_setup):
|
|
sub r5,r7,r9
|
|
srwi r6,r5,3 /* Number of loop iterations. */
|
|
mtctr r6 /* Setup the counter. */
|
|
b L(loop)
|
|
/* Main loop to look for BYTE backwards in 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 r10,r12,r4
|
|
cmpb r9,r11,r4
|
|
or r5,r9,r10 /* Merge everything in one word. */
|
|
cmplwi cr7,r5,0
|
|
bne cr7,L(found)
|
|
bdnz L(loop)
|
|
/* We're here because the counter reached 0, and that means we
|
|
didn't have any matches for BYTE in the whole range. Just
|
|
return the original range. */
|
|
addi r9,r8,4
|
|
cmplw cr6,r9,r7
|
|
blt cr6,L(loop_small)
|
|
b L(null)
|
|
|
|
/* OK, one (or both) of the words contains BYTE. Check
|
|
the first word and decrement the address in case the first
|
|
word really contains BYTE. */
|
|
.align 4
|
|
L(found):
|
|
cmplwi cr6,r10,0
|
|
addi r8,r8,-4
|
|
bne cr6,L(done)
|
|
|
|
/* 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 r10,r9
|
|
addi r8,r8,4
|
|
|
|
/* r10 has the output of the cmpb instruction, that is, it contains
|
|
0xff in the same position as BYTE in the original
|
|
word from the string. Use that to calculate the pointer.
|
|
We need to make sure BYTE is *before* the end of the
|
|
range. */
|
|
L(done):
|
|
cntlzw r0,r10 /* Count leading zeroes before the match. */
|
|
srwi r0,r0,3 /* Convert leading zeroes to bytes. */
|
|
add r3,r8,r0
|
|
cmplw r3,r7
|
|
bge L(null)
|
|
blr
|
|
|
|
.align 4
|
|
L(null):
|
|
li r3,0
|
|
blr
|
|
|
|
/* Deals with size <= 16. */
|
|
.align 4
|
|
L(small_range):
|
|
cmplwi r5,0
|
|
beq L(null)
|
|
|
|
rlwinm r6,r3,3,27,28 /* Calculate padding. */
|
|
lwz r12,0(r8) /* Load word from memory. */
|
|
cmpb r10,r12,r4 /* Check for BYTE in DWORD1. */
|
|
slw r10,r10,r6
|
|
srw r10,r10,r6
|
|
cmplwi cr7,r10,0
|
|
bne cr7,L(done)
|
|
|
|
/* Are we done already? */
|
|
addi r9,r8,4
|
|
cmplw r9,r7
|
|
bge L(null)
|
|
b L(loop_small)
|
|
|
|
.p2align 5
|
|
L(loop_small):
|
|
lwzu r12,4(r8)
|
|
cmpb r10,r12,r4
|
|
addi r9,r8,4
|
|
cmplwi cr6,r10,0
|
|
bne cr6,L(done)
|
|
cmplw r9,r7
|
|
bge L(null)
|
|
b L(loop_small)
|
|
|
|
END (BP_SYM (__memchr))
|
|
weak_alias (BP_SYM (__memchr), BP_SYM(memchr))
|
|
libc_hidden_builtin_def (memchr)
|