nds32: Library functions
This patch add support for various library functions.
Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/nds32/lib/memset.S b/arch/nds32/lib/memset.S
new file mode 100644
index 0000000..193cb6c
--- /dev/null
+++ b/arch/nds32/lib/memset.S
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/linkage.h>
+
+ .text
+ENTRY(memset)
+ move $r5, $r0 ! Return value
+ beqz $r2, end_memset ! Exit when len = 0
+ srli $p1, $r2, 2 ! $p1 is how many words to copy
+ andi $r2, $r2, 3 ! How many bytes are less than a word
+ beqz $p1, byte_set ! When n is less than a word
+
+ ! set $r1 from ??????ab to abababab
+ andi $r1, $r1, #0x00ff ! $r1 = 000000ab
+ slli $p0, $r1, #8 ! $p0 = 0000ab00
+ or $r1, $r1, $p0 ! $r1 = 0000abab
+ slli $p0, $r1, #16 ! $p0 = abab0000
+ or $r1, $r1, $p0 ! $r1 = abababab
+word_set:
+ addi $p1, $p1, #-1 ! How many words left to copy
+ smw.bim $r1, [$r0], $r1 ! Copy the word to det
+ bnez $p1, word_set ! Still words to set, continue looping
+ beqz $r2, end_memset ! No left byte to set
+byte_set: ! Less than 4 bytes left to set
+ addi $r2, $r2, #-1 ! Decrease len by 1
+ sbi.bi $r1, [$r0], #1 ! Set data of the next byte to $r1
+ bnez $r2, byte_set ! Still bytes left to set
+end_memset:
+ move $r0, $r5
+ ret
+
+ENDPROC(memset)