Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/arch/nds32/lib/memmove.S b/arch/nds32/lib/memmove.S
new file mode 100644
index 000000000..c823aada2
--- /dev/null
+++ b/arch/nds32/lib/memmove.S
@@ -0,0 +1,70 @@
+// 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)