71 lines
2.0 KiB
ArmAsm
71 lines
2.0 KiB
ArmAsm
|
// SPDX-License-Identifier: GPL-2.0
|
||
|
|
// Copyright (C) 2005-2017 Andes Technology Corporation
|
||
|
|
|
||
|
|
#include <linux/linkage.h>
|
||
|
|
|
||
|
|
/*
|
||
|
|
void *memmove(void *dst, const void *src, int n);
|
||
|
|
|
||
|
|
dst: $r0
|
||
|
|
src: $r1
|
||
|
|
n : $r2
|
||
|
|
ret: $r0 - pointer to the memory area dst.
|
||
|
|
*/
|
||
|
|
.text
|
||
|
|
|
||
|
|
ENTRY(memmove)
|
||
|
|
move $r5, $r0 ! Set return value = det
|
||
|
|
beq $r0, $r1, exit_memcpy ! Exit when det = src
|
||
|
|
beqz $r2, exit_memcpy ! Exit when n = 0
|
||
|
|
pushm $t0, $t1 ! Save reg
|
||
|
|
srli $p1, $r2, #2 ! $p1 is how many words to copy
|
||
|
|
|
||
|
|
! Avoid data lost when memory overlap
|
||
|
|
! Copy data reversely when src < dst
|
||
|
|
slt $p0, $r0, $r1 ! check if $r0 < $r1
|
||
|
|
beqz $p0, do_reverse ! branch if dst > src
|
||
|
|
|
||
|
|
! No reverse, dst < src
|
||
|
|
andi $r2, $r2, #3 ! How many bytes are less than a word
|
||
|
|
li $t0, #1 ! Determining copy direction in byte_cpy
|
||
|
|
beqz $p1, byte_cpy ! When n is less than a word
|
||
|
|
|
||
|
|
word_cpy:
|
||
|
|
lmw.bim $p0, [$r1], $p0 ! Read a word from src
|
||
|
|
addi $p1, $p1, #-1 ! How many words left to copy
|
||
|
|
smw.bim $p0, [$r0], $p0 ! Copy the word to det
|
||
|
|
bnez $p1, word_cpy ! If remained words > 0
|
||
|
|
beqz $r2, end_memcpy ! No left bytes to copy
|
||
|
|
b byte_cpy
|
||
|
|
|
||
|
|
do_reverse:
|
||
|
|
add $r0, $r0, $r2 ! Start with the end of $r0
|
||
|
|
add $r1, $r1, $r2 ! Start with the end of $r1
|
||
|
|
andi $r2, $r2, #3 ! How many bytes are less than a word
|
||
|
|
li $t0, #-1 ! Determining copy direction in byte_cpy
|
||
|
|
beqz $p1, reverse_byte_cpy ! When n is less than a word
|
||
|
|
|
||
|
|
reverse_word_cpy:
|
||
|
|
lmw.adm $p0, [$r1], $p0 ! Read a word from src
|
||
|
|
addi $p1, $p1, #-1 ! How many words left to copy
|
||
|
|
smw.adm $p0, [$r0], $p0 ! Copy the word to det
|
||
|
|
bnez $p1, reverse_word_cpy ! If remained words > 0
|
||
|
|
beqz $r2, end_memcpy ! No left bytes to copy
|
||
|
|
|
||
|
|
reverse_byte_cpy:
|
||
|
|
addi $r0, $r0, #-1
|
||
|
|
addi $r1, $r1, #-1
|
||
|
|
byte_cpy: ! Less than 4 bytes to copy now
|
||
|
|
lb.bi $p0, [$r1], $t0 ! Read a byte from src
|
||
|
|
addi $r2, $r2, #-1 ! How many bytes left to copy
|
||
|
|
sb.bi $p0, [$r0], $t0 ! copy the byte to det
|
||
|
|
bnez $r2, byte_cpy ! If remained bytes > 0
|
||
|
|
|
||
|
|
end_memcpy:
|
||
|
|
popm $t0, $t1
|
||
|
|
exit_memcpy:
|
||
|
|
move $r0, $r5
|
||
|
|
ret
|
||
|
|
|
||
|
|
ENDPROC(memmove)
|