148 lines
3.8 KiB
ArmAsm
148 lines
3.8 KiB
ArmAsm
/*
|
|
* 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 <variant/core.h>
|
|
|
|
/* Load or store instructions that may cause exceptions use the EX macro. */
|
|
|
|
#define EX(insn,reg1,reg2,offset,handler) \
|
|
9: insn reg1, reg2, offset; \
|
|
.section __ex_table, "a"; \
|
|
.word 9b, handler; \
|
|
.previous
|
|
|
|
/*
|
|
* 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
|
|
.align 4
|
|
.global __strnlen_user
|
|
.type __strnlen_user,@function
|
|
__strnlen_user:
|
|
entry sp, 16 # minimal stack frame
|
|
# 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(l32i, a9, a4, 4, lenfixup) # 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(l32i, a9, a4, 4, lenfixup) # 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
|
|
retw
|
|
|
|
# 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
|
|
retw
|
|
.Lz1: # byte 1 is zero
|
|
addi a4, a4, 1+1 # point just beyond zero byte
|
|
sub a2, a4, a2 # subtract to get length
|
|
retw
|
|
.Lz2: # byte 2 is zero
|
|
addi a4, a4, 2+1 # point just beyond zero byte
|
|
sub a2, a4, a2 # subtract to get length
|
|
retw
|
|
|
|
.L1mod2: # address is odd
|
|
EX(l8ui, a9, a4, 4, lenfixup) # 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(l32i, a9, a4, 0, lenfixup) # 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
|
|
retw
|
|
|
|
.section .fixup, "ax"
|
|
.align 4
|
|
lenfixup:
|
|
movi a2, 0
|
|
retw
|