forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
141 lines
3.6 KiB
141 lines
3.6 KiB
/* |
|
* arch/xtensa/lib/strnlen_user.S |
|
* |
|
* This file is subject to the terms and conditions of the GNU General |
|
* Public License. See the file "COPYING" in the main directory of |
|
* this archive for more details. |
|
* |
|
* Returns strnlen, including trailing zero terminator. |
|
* Zero indicates error. |
|
* |
|
* Copyright (C) 2002 Tensilica Inc. |
|
*/ |
|
|
|
#include <linux/linkage.h> |
|
#include <asm/asmmacro.h> |
|
#include <asm/core.h> |
|
|
|
/* |
|
* size_t __strnlen_user(const char *s, size_t len) |
|
*/ |
|
|
|
#ifdef __XTENSA_EB__ |
|
# define MASK0 0xff000000 |
|
# define MASK1 0x00ff0000 |
|
# define MASK2 0x0000ff00 |
|
# define MASK3 0x000000ff |
|
#else |
|
# define MASK0 0x000000ff |
|
# define MASK1 0x0000ff00 |
|
# define MASK2 0x00ff0000 |
|
# define MASK3 0xff000000 |
|
#endif |
|
|
|
# Register use: |
|
# a2/ src |
|
# a3/ len |
|
# a4/ tmp |
|
# a5/ mask0 |
|
# a6/ mask1 |
|
# a7/ mask2 |
|
# a8/ mask3 |
|
# a9/ tmp |
|
# a10/ tmp |
|
|
|
.text |
|
ENTRY(__strnlen_user) |
|
|
|
abi_entry_default |
|
# a2/ s, a3/ len |
|
addi a4, a2, -4 # because we overincrement at the end; |
|
# we compensate with load offsets of 4 |
|
movi a5, MASK0 # mask for byte 0 |
|
movi a6, MASK1 # mask for byte 1 |
|
movi a7, MASK2 # mask for byte 2 |
|
movi a8, MASK3 # mask for byte 3 |
|
bbsi.l a2, 0, .L1mod2 # if only 8-bit aligned |
|
bbsi.l a2, 1, .L2mod4 # if only 16-bit aligned |
|
|
|
/* |
|
* String is word-aligned. |
|
*/ |
|
.Laligned: |
|
srli a10, a3, 2 # number of loop iterations with 4B per loop |
|
#if XCHAL_HAVE_LOOPS |
|
loopnez a10, .Ldone |
|
#else |
|
beqz a10, .Ldone |
|
slli a10, a10, 2 |
|
add a10, a10, a4 # a10 = end of last 4B chunk |
|
#endif /* XCHAL_HAVE_LOOPS */ |
|
.Loop: |
|
EX(10f) l32i a9, a4, 4 # get next word of string |
|
addi a4, a4, 4 # advance string pointer |
|
bnone a9, a5, .Lz0 # if byte 0 is zero |
|
bnone a9, a6, .Lz1 # if byte 1 is zero |
|
bnone a9, a7, .Lz2 # if byte 2 is zero |
|
bnone a9, a8, .Lz3 # if byte 3 is zero |
|
#if !XCHAL_HAVE_LOOPS |
|
blt a4, a10, .Loop |
|
#endif |
|
|
|
.Ldone: |
|
EX(10f) l32i a9, a4, 4 # load 4 bytes for remaining checks |
|
|
|
bbci.l a3, 1, .L100 |
|
# check two more bytes (bytes 0, 1 of word) |
|
addi a4, a4, 2 # advance string pointer |
|
bnone a9, a5, .Lz0 # if byte 0 is zero |
|
bnone a9, a6, .Lz1 # if byte 1 is zero |
|
.L100: |
|
bbci.l a3, 0, .L101 |
|
# check one more byte (byte 2 of word) |
|
# Actually, we don't need to check. Zero or nonzero, we'll add one. |
|
# Do not add an extra one for the NULL terminator since we have |
|
# exhausted the original len parameter. |
|
addi a4, a4, 1 # advance string pointer |
|
.L101: |
|
sub a2, a4, a2 # compute length |
|
abi_ret_default |
|
|
|
# NOTE that in several places below, we point to the byte just after |
|
# the zero byte in order to include the NULL terminator in the count. |
|
|
|
.Lz3: # byte 3 is zero |
|
addi a4, a4, 3 # point to zero byte |
|
.Lz0: # byte 0 is zero |
|
addi a4, a4, 1 # point just beyond zero byte |
|
sub a2, a4, a2 # subtract to get length |
|
abi_ret_default |
|
.Lz1: # byte 1 is zero |
|
addi a4, a4, 1+1 # point just beyond zero byte |
|
sub a2, a4, a2 # subtract to get length |
|
abi_ret_default |
|
.Lz2: # byte 2 is zero |
|
addi a4, a4, 2+1 # point just beyond zero byte |
|
sub a2, a4, a2 # subtract to get length |
|
abi_ret_default |
|
|
|
.L1mod2: # address is odd |
|
EX(10f) l8ui a9, a4, 4 # get byte 0 |
|
addi a4, a4, 1 # advance string pointer |
|
beqz a9, .Lz3 # if byte 0 is zero |
|
bbci.l a4, 1, .Laligned # if string pointer is now word-aligned |
|
|
|
.L2mod4: # address is 2 mod 4 |
|
addi a4, a4, 2 # advance ptr for aligned access |
|
EX(10f) l32i a9, a4, 0 # get word with first two bytes of string |
|
bnone a9, a7, .Lz2 # if byte 2 (of word, not string) is zero |
|
bany a9, a8, .Laligned # if byte 3 (of word, not string) is nonzero |
|
# byte 3 is zero |
|
addi a4, a4, 3+1 # point just beyond zero byte |
|
sub a2, a4, a2 # subtract to get length |
|
abi_ret_default |
|
|
|
ENDPROC(__strnlen_user) |
|
|
|
.section .fixup, "ax" |
|
.align 4 |
|
10: |
|
movi a2, 0 |
|
abi_ret_default
|
|
|