mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-12 11:03:57 +08:00
258 lines
8.6 KiB
ArmAsm
258 lines
8.6 KiB
ArmAsm
/* strcat(dest, src) -- Append SRC on the end of DEST.
|
|
Optimized for x86-64.
|
|
Copyright (C) 2002-2013 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Andreas Jaeger <aj@suse.de>, 2002.
|
|
|
|
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 "asm-syntax.h"
|
|
|
|
|
|
.text
|
|
ENTRY (strcat)
|
|
movq %rdi, %rcx /* Dest. register. */
|
|
andl $7, %ecx /* mask alignment bits */
|
|
movq %rdi, %rax /* Duplicate destination pointer. */
|
|
movq $0xfefefefefefefeff,%r8
|
|
|
|
/* First step: Find end of destination. */
|
|
jz 4f /* aligned => start loop */
|
|
|
|
neg %ecx /* We need to align to 8 bytes. */
|
|
addl $8,%ecx
|
|
/* Search the first bytes directly. */
|
|
0: cmpb $0x0,(%rax) /* is byte NUL? */
|
|
je 2f /* yes => start copy */
|
|
incq %rax /* increment pointer */
|
|
decl %ecx
|
|
jnz 0b
|
|
|
|
|
|
|
|
/* Now the source is aligned. Scan for NUL byte. */
|
|
.p2align 4
|
|
4:
|
|
/* First unroll. */
|
|
movq (%rax), %rcx /* get double word (= 8 bytes) in question */
|
|
addq $8,%rax /* adjust pointer for next word */
|
|
movq %r8, %rdx /* magic value */
|
|
addq %rcx, %rdx /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 3f /* highest byte is NUL => return pointer */
|
|
xorq %rcx, %rdx /* (word+magic)^word */
|
|
orq %r8, %rdx /* set all non-carry bits */
|
|
incq %rdx /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
jnz 3f /* found NUL => return pointer */
|
|
|
|
/* Second unroll. */
|
|
movq (%rax), %rcx /* get double word (= 8 bytes) in question */
|
|
addq $8,%rax /* adjust pointer for next word */
|
|
movq %r8, %rdx /* magic value */
|
|
addq %rcx, %rdx /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 3f /* highest byte is NUL => return pointer */
|
|
xorq %rcx, %rdx /* (word+magic)^word */
|
|
orq %r8, %rdx /* set all non-carry bits */
|
|
incq %rdx /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
jnz 3f /* found NUL => return pointer */
|
|
|
|
/* Third unroll. */
|
|
movq (%rax), %rcx /* get double word (= 8 bytes) in question */
|
|
addq $8,%rax /* adjust pointer for next word */
|
|
movq %r8, %rdx /* magic value */
|
|
addq %rcx, %rdx /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 3f /* highest byte is NUL => return pointer */
|
|
xorq %rcx, %rdx /* (word+magic)^word */
|
|
orq %r8, %rdx /* set all non-carry bits */
|
|
incq %rdx /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
jnz 3f /* found NUL => return pointer */
|
|
|
|
/* Fourth unroll. */
|
|
movq (%rax), %rcx /* get double word (= 8 bytes) in question */
|
|
addq $8,%rax /* adjust pointer for next word */
|
|
movq %r8, %rdx /* magic value */
|
|
addq %rcx, %rdx /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 3f /* highest byte is NUL => return pointer */
|
|
xorq %rcx, %rdx /* (word+magic)^word */
|
|
orq %r8, %rdx /* set all non-carry bits */
|
|
incq %rdx /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
jz 4b /* no NUL found => continue loop */
|
|
|
|
.p2align 4 /* Align, it's a jump target. */
|
|
3: subq $8,%rax /* correct pointer increment. */
|
|
|
|
testb %cl, %cl /* is first byte NUL? */
|
|
jz 2f /* yes => return */
|
|
incq %rax /* increment pointer */
|
|
|
|
testb %ch, %ch /* is second byte NUL? */
|
|
jz 2f /* yes => return */
|
|
incq %rax /* increment pointer */
|
|
|
|
testl $0x00ff0000, %ecx /* is third byte NUL? */
|
|
jz 2f /* yes => return pointer */
|
|
incq %rax /* increment pointer */
|
|
|
|
testl $0xff000000, %ecx /* is fourth byte NUL? */
|
|
jz 2f /* yes => return pointer */
|
|
incq %rax /* increment pointer */
|
|
|
|
shrq $32, %rcx /* look at other half. */
|
|
|
|
testb %cl, %cl /* is first byte NUL? */
|
|
jz 2f /* yes => return */
|
|
incq %rax /* increment pointer */
|
|
|
|
testb %ch, %ch /* is second byte NUL? */
|
|
jz 2f /* yes => return */
|
|
incq %rax /* increment pointer */
|
|
|
|
testl $0xff0000, %ecx /* is third byte NUL? */
|
|
jz 2f /* yes => return pointer */
|
|
incq %rax /* increment pointer */
|
|
|
|
2:
|
|
/* Second step: Copy source to destination. */
|
|
|
|
movq %rsi, %rcx /* duplicate */
|
|
andl $7,%ecx /* mask alignment bits */
|
|
movq %rax, %rdx /* move around */
|
|
jz 22f /* aligned => start loop */
|
|
|
|
neg %ecx /* align to 8 bytes. */
|
|
addl $8, %ecx
|
|
/* Align the source pointer. */
|
|
21:
|
|
movb (%rsi), %al /* Fetch a byte */
|
|
testb %al, %al /* Is it NUL? */
|
|
movb %al, (%rdx) /* Store it */
|
|
jz 24f /* If it was NUL, done! */
|
|
incq %rsi
|
|
incq %rdx
|
|
decl %ecx
|
|
jnz 21b
|
|
|
|
/* Now the sources is aligned. Unfortunatly we cannot force
|
|
to have both source and destination aligned, so ignore the
|
|
alignment of the destination. */
|
|
.p2align 4
|
|
22:
|
|
/* 1st unroll. */
|
|
movq (%rsi), %rax /* Read double word (8 bytes). */
|
|
addq $8, %rsi /* Adjust pointer for next word. */
|
|
movq %rax, %r9 /* Save a copy for NUL finding. */
|
|
addq %r8, %r9 /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 23f /* highest byte is NUL => return pointer */
|
|
xorq %rax, %r9 /* (word+magic)^word */
|
|
orq %r8, %r9 /* set all non-carry bits */
|
|
incq %r9 /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
|
|
jnz 23f /* found NUL => return pointer */
|
|
|
|
movq %rax, (%rdx) /* Write value to destination. */
|
|
addq $8, %rdx /* Adjust pointer. */
|
|
|
|
/* 2nd unroll. */
|
|
movq (%rsi), %rax /* Read double word (8 bytes). */
|
|
addq $8, %rsi /* Adjust pointer for next word. */
|
|
movq %rax, %r9 /* Save a copy for NUL finding. */
|
|
addq %r8, %r9 /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 23f /* highest byte is NUL => return pointer */
|
|
xorq %rax, %r9 /* (word+magic)^word */
|
|
orq %r8, %r9 /* set all non-carry bits */
|
|
incq %r9 /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
|
|
jnz 23f /* found NUL => return pointer */
|
|
|
|
movq %rax, (%rdx) /* Write value to destination. */
|
|
addq $8, %rdx /* Adjust pointer. */
|
|
|
|
/* 3rd unroll. */
|
|
movq (%rsi), %rax /* Read double word (8 bytes). */
|
|
addq $8, %rsi /* Adjust pointer for next word. */
|
|
movq %rax, %r9 /* Save a copy for NUL finding. */
|
|
addq %r8, %r9 /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 23f /* highest byte is NUL => return pointer */
|
|
xorq %rax, %r9 /* (word+magic)^word */
|
|
orq %r8, %r9 /* set all non-carry bits */
|
|
incq %r9 /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
|
|
jnz 23f /* found NUL => return pointer */
|
|
|
|
movq %rax, (%rdx) /* Write value to destination. */
|
|
addq $8, %rdx /* Adjust pointer. */
|
|
|
|
/* 4th unroll. */
|
|
movq (%rsi), %rax /* Read double word (8 bytes). */
|
|
addq $8, %rsi /* Adjust pointer for next word. */
|
|
movq %rax, %r9 /* Save a copy for NUL finding. */
|
|
addq %r8, %r9 /* add the magic value to the word. We get
|
|
carry bits reported for each byte which
|
|
is *not* 0 */
|
|
jnc 23f /* highest byte is NUL => return pointer */
|
|
xorq %rax, %r9 /* (word+magic)^word */
|
|
orq %r8, %r9 /* set all non-carry bits */
|
|
incq %r9 /* add 1: if one carry bit was *not* set
|
|
the addition will not result in 0. */
|
|
|
|
jnz 23f /* found NUL => return pointer */
|
|
|
|
movq %rax, (%rdx) /* Write value to destination. */
|
|
addq $8, %rdx /* Adjust pointer. */
|
|
jmp 22b /* Next iteration. */
|
|
|
|
/* Do the last few bytes. %rax contains the value to write.
|
|
The loop is unrolled twice. */
|
|
.p2align 4
|
|
23:
|
|
movb %al, (%rdx) /* 1st byte. */
|
|
testb %al, %al /* Is it NUL. */
|
|
jz 24f /* yes, finish. */
|
|
incq %rdx /* Increment destination. */
|
|
movb %ah, (%rdx) /* 2nd byte. */
|
|
testb %ah, %ah /* Is it NUL?. */
|
|
jz 24f /* yes, finish. */
|
|
incq %rdx /* Increment destination. */
|
|
shrq $16, %rax /* Shift... */
|
|
jmp 23b /* and look at next two bytes in %rax. */
|
|
|
|
|
|
24:
|
|
movq %rdi, %rax /* Source is return value. */
|
|
retq
|
|
END (strcat)
|
|
libc_hidden_builtin_def (strcat)
|