projects / mirror_ubuntu-jammy-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| ace02e2b GH |
1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | // Copyright (C) 2005-2017 Andes Technology Corporation | |
| 3 | ||
| 4 | #include <linux/linkage.h> | |
| 5 | ||
| 6 | /* | |
| 7 | void *memmove(void *dst, const void *src, int n); | |
| 8 | ||
| 9 | dst: $r0 | |
| 10 | src: $r1 | |
| 11 | n : $r2 | |
| 12 | ret: $r0 - pointer to the memory area dst. | |
| 13 | */ | |
| 14 | .text | |
| 15 | ||
| 16 | ENTRY(memmove) | |
| 17 | move $r5, $r0 ! Set return value = det | |
| 18 | beq $r0, $r1, exit_memcpy ! Exit when det = src | |
| 19 | beqz $r2, exit_memcpy ! Exit when n = 0 | |
| 20 | pushm $t0, $t1 ! Save reg | |
| 21 | srli $p1, $r2, #2 ! $p1 is how many words to copy | |
| 22 | ||
| 23 | ! Avoid data lost when memory overlap | |
| 24 | ! Copy data reversely when src < dst | |
| 25 | slt $p0, $r0, $r1 ! check if $r0 < $r1 | |
| 26 | beqz $p0, do_reverse ! branch if dst > src | |
| 27 | ||
| 28 | ! No reverse, dst < src | |
| 29 | andi $r2, $r2, #3 ! How many bytes are less than a word | |
| 30 | li $t0, #1 ! Determining copy direction in byte_cpy | |
| 31 | beqz $p1, byte_cpy ! When n is less than a word | |
| 32 | ||
| 33 | word_cpy: | |
| 34 | lmw.bim $p0, [$r1], $p0 ! Read a word from src | |
| 35 | addi $p1, $p1, #-1 ! How many words left to copy | |
| 36 | smw.bim $p0, [$r0], $p0 ! Copy the word to det | |
| 37 | bnez $p1, word_cpy ! If remained words > 0 | |
| 38 | beqz $r2, end_memcpy ! No left bytes to copy | |
| 39 | b byte_cpy | |
| 40 | ||
| 41 | do_reverse: | |
| 42 | add $r0, $r0, $r2 ! Start with the end of $r0 | |
| 43 | add $r1, $r1, $r2 ! Start with the end of $r1 | |
| 44 | andi $r2, $r2, #3 ! How many bytes are less than a word | |
| 45 | li $t0, #-1 ! Determining copy direction in byte_cpy | |
| 46 | beqz $p1, reverse_byte_cpy ! When n is less than a word | |
| 47 | ||
| 48 | reverse_word_cpy: | |
| 49 | lmw.adm $p0, [$r1], $p0 ! Read a word from src | |
| 50 | addi $p1, $p1, #-1 ! How many words left to copy | |
| 51 | smw.adm $p0, [$r0], $p0 ! Copy the word to det | |
| 52 | bnez $p1, reverse_word_cpy ! If remained words > 0 | |
| 53 | beqz $r2, end_memcpy ! No left bytes to copy | |
| 54 | ||
| 55 | reverse_byte_cpy: | |
| 56 | addi $r0, $r0, #-1 | |
| 57 | addi $r1, $r1, #-1 | |
| 58 | byte_cpy: ! Less than 4 bytes to copy now | |
| 59 | lb.bi $p0, [$r1], $t0 ! Read a byte from src | |
| 60 | addi $r2, $r2, #-1 ! How many bytes left to copy | |
| 61 | sb.bi $p0, [$r0], $t0 ! copy the byte to det | |
| 62 | bnez $r2, byte_cpy ! If remained bytes > 0 | |
| 63 | ||
| 64 | end_memcpy: | |
| 65 | popm $t0, $t1 | |
| 66 | exit_memcpy: | |
| 67 | move $r0, $r5 | |
| 68 | ret | |
| 69 | ||
| 70 | ENDPROC(memmove) |