| // 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) |