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/* Copyright (c) 2017 SiFive Inc. All rights reserved.
This copyrighted material is made available to anyone wishing to use,
modify, copy, or redistribute it subject to the terms and conditions
of the BSD License. This program is distributed in the hope that
it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
including the implied warranties of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. A copy of this license is available at
http://www.opensource.org/licenses.
*/
#include <sys/asm.h>
#if BYTE_ORDER != LITTLE_ENDIAN
# error
#endif
.text
.globl strcmp
.type strcmp, @function
strcmp:
or a4, a0, a1
li t2, -1
and a4, a4, SZREG-1
bnez a4, .Lmisaligned
#if SZREG == 4
li a5, 0x7f7f7f7f
#else
ld a5, mask
#endif
.macro check_one_word i n
REG_L a2, \i*SZREG(a0)
REG_L a3, \i*SZREG(a1)
and t0, a2, a5
or t1, a2, a5
add t0, t0, a5
or t0, t0, t1
bne t0, t2, .Lnull\i
.if \i+1-\n
bne a2, a3, .Lmismatch
.else
add a0, a0, \n*SZREG
add a1, a1, \n*SZREG
beq a2, a3, .Lloop
# fall through to .Lmismatch
.endif
.endm
.macro foundnull i n
.ifne \i
.Lnull\i:
add a0, a0, \i*SZREG
add a1, a1, \i*SZREG
.ifeq \i-1
.Lnull0:
.endif
bne a2, a3, .Lmisaligned
li a0, 0
ret
.endif
.endm
.Lloop:
# examine full words at a time, favoring strings of a couple dozen chars
#if __riscv_xlen == 32
check_one_word 0 5
check_one_word 1 5
check_one_word 2 5
check_one_word 3 5
check_one_word 4 5
#else
check_one_word 0 3
check_one_word 1 3
check_one_word 2 3
#endif
# backwards branch to .Lloop contained above
.Lmismatch:
# words don't match, but a2 has no null byte.
#if __riscv_xlen == 64
sll a4, a2, 48
sll a5, a3, 48
bne a4, a5, .Lmismatch_upper
sll a4, a2, 32
sll a5, a3, 32
bne a4, a5, .Lmismatch_upper
#endif
sll a4, a2, 16
sll a5, a3, 16
bne a4, a5, .Lmismatch_upper
srl a4, a2, 8*SZREG-16
srl a5, a3, 8*SZREG-16
sub a0, a4, a5
and a1, a0, 0xff
bnez a1, 1f
ret
.Lmismatch_upper:
srl a4, a4, 8*SZREG-16
srl a5, a5, 8*SZREG-16
sub a0, a4, a5
and a1, a0, 0xff
bnez a1, 1f
ret
1:and a4, a4, 0xff
and a5, a5, 0xff
sub a0, a4, a5
ret
.Lmisaligned:
# misaligned
lbu a2, 0(a0)
lbu a3, 0(a1)
add a0, a0, 1
add a1, a1, 1
bne a2, a3, 1f
bnez a2, .Lmisaligned
1:
sub a0, a2, a3
ret
# cases in which a null byte was detected
#if __riscv_xlen == 32
foundnull 0 5
foundnull 1 5
foundnull 2 5
foundnull 3 5
foundnull 4 5
#else
foundnull 0 3
foundnull 1 3
foundnull 2 3
#endif
.size strcmp, .-strcmp
#if SZREG == 8
.section .srodata.cst8,"aM",@progbits,8
.align 3
mask:
.dword 0x7f7f7f7f7f7f7f7f
#endif
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