1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (C) 2005-2017 Andes Technology Corporation 3 4 #include <linux/linkage.h> 5 6 .text 7 ENTRY(memset) 8 move $r5, $r0 ! Return value 9 beqz $r2, end_memset ! Exit when len = 0 10 srli $p1, $r2, 2 ! $p1 is how many words to copy 11 andi $r2, $r2, 3 ! How many bytes are less than a word 12 beqz $p1, byte_set ! When n is less than a word 13 14 ! set $r1 from ??????ab to abababab 15 andi $r1, $r1, #0x00ff ! $r1 = 000000ab 16 slli $p0, $r1, #8 ! $p0 = 0000ab00 17 or $r1, $r1, $p0 ! $r1 = 0000abab 18 slli $p0, $r1, #16 ! $p0 = abab0000 19 or $r1, $r1, $p0 ! $r1 = abababab 20 word_set: 21 addi $p1, $p1, #-1 ! How many words left to copy 22 smw.bim $r1, [$r0], $r1 ! Copy the word to det 23 bnez $p1, word_set ! Still words to set, continue looping 24 beqz $r2, end_memset ! No left byte to set 25 byte_set: ! Less than 4 bytes left to set 26 addi $r2, $r2, #-1 ! Decrease len by 1 27 sbi.bi $r1, [$r0], #1 ! Set data of the next byte to $r1 28 bnez $r2, byte_set ! Still bytes left to set 29 end_memset: 30 move $r0, $r5 31 ret 32 33 ENDPROC(memset) 34