riscv: assembler versions of memcpy, memmove, memset
Provide optimized versions of memcpy(), memmove(), memset() copied from
the Linux kernel.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/arch/riscv/lib/memmove.S b/arch/riscv/lib/memmove.S
new file mode 100644
index 0000000..07d1d21
--- /dev/null
+++ b/arch/riscv/lib/memmove.S
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+
+ENTRY(__memmove)
+WEAK(memmove)
+ move t0, a0
+ move t1, a1
+
+ beq a0, a1, exit_memcpy
+ beqz a2, exit_memcpy
+ srli t2, a2, 0x2
+
+ slt t3, a0, a1
+ beqz t3, do_reverse
+
+ andi a2, a2, 0x3
+ li t4, 1
+ beqz t2, byte_copy
+
+word_copy:
+ lw t3, 0(a1)
+ addi t2, t2, -1
+ addi a1, a1, 4
+ sw t3, 0(a0)
+ addi a0, a0, 4
+ bnez t2, word_copy
+ beqz a2, exit_memcpy
+ j byte_copy
+
+do_reverse:
+ add a0, a0, a2
+ add a1, a1, a2
+ andi a2, a2, 0x3
+ li t4, -1
+ beqz t2, reverse_byte_copy
+
+reverse_word_copy:
+ addi a1, a1, -4
+ addi t2, t2, -1
+ lw t3, 0(a1)
+ addi a0, a0, -4
+ sw t3, 0(a0)
+ bnez t2, reverse_word_copy
+ beqz a2, exit_memcpy
+
+reverse_byte_copy:
+ addi a0, a0, -1
+ addi a1, a1, -1
+
+byte_copy:
+ lb t3, 0(a1)
+ addi a2, a2, -1
+ sb t3, 0(a0)
+ add a1, a1, t4
+ add a0, a0, t4
+ bnez a2, byte_copy
+
+exit_memcpy:
+ move a0, t0
+ move a1, t1
+ ret
+END(__memmove)