1 files changed, 162 insertions, 0 deletions
diff --git a/arch/mn10300/lib/do_csum.S b/arch/mn10300/lib/do_csum.S
new file mode 100644
index 00000000000..e138994e166
--- /dev/null
+++ b/arch/mn10300/lib/do_csum.S
@@ -0,0 +1,162 @@
+/* Optimised simple memory checksum
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#include <asm/cache.h>
+
+        .section .text
+        .balign	L1_CACHE_BYTES
+
+###############################################################################
+#
+# unsigned int do_csum(const unsigned char *buff, size_t len)
+#
+###############################################################################
+	.globl	do_csum
+        .type	do_csum,@function
+do_csum:
+	movm	[d2,d3],(sp)
+	mov	d0,(12,sp)
+	mov	d1,(16,sp)
+	mov	d1,d2				# count
+	mov	d0,a0				# buff
+	clr	d1				# accumulator
+
+	cmp	+0,d2
+	beq	do_csum_done			# return if zero-length buffer
+
+	# 4-byte align the buffer pointer
+	btst	+3,a0
+	beq	do_csum_now_4b_aligned
+
+	btst	+1,a0
+	beq	do_csum_addr_not_odd
+	movbu	(a0),d0
+	inc	a0
+	asl	+8,d0
+	add	d0,d1
+	addc	+0,d1
+	add	-1,d2
+do_csum_addr_not_odd:
+
+	cmp	+2,d2
+	bcs	do_csum_fewer_than_4
+	btst	+2,a0
+	beq	do_csum_now_4b_aligned
+	movhu	(a0+),d0
+	add	d0,d1
+	addc	+0,d1
+	add	-2,d2
+	cmp	+4,d2
+	bcs	do_csum_fewer_than_4
+
+do_csum_now_4b_aligned:
+	# we want to checksum as much as we can in chunks of 32 bytes
+	cmp	+31,d2
+	bls	do_csum_remainder		# 4-byte aligned remainder
+
+	add	-32,d2
+	mov	+32,d3
+
+do_csum_loop:
+	mov	(a0+),d0
+	add	d0,d1
+	mov	(a0+),e0
+	addc	e0,d1
+	mov	(a0+),e1
+	addc	e1,d1
+	mov	(a0+),e3
+	addc	e3,d1
+	mov	(a0+),d0
+	addc	d0,d1
+	mov	(a0+),e0
+	addc	e0,d1
+	mov	(a0+),e1
+	addc	e1,d1
+	mov	(a0+),e3
+	addc	e3,d1
+	addc	+0,d1
+
+	sub	d3,d2
+	bcc	do_csum_loop
+
+	add	d3,d2
+	beq	do_csum_done
+
+do_csum_remainder:
+	# cut 16-31 bytes down to 0-15
+	cmp	+16,d2
+	bcs	do_csum_fewer_than_16
+	mov	(a0+),d0
+	add	d0,d1
+	mov	(a0+),e0
+	addc	e0,d1
+	mov	(a0+),e1
+	addc	e1,d1
+	mov	(a0+),e3
+	addc	e3,d1
+	addc	+0,d1
+	add	-16,d2
+	beq	do_csum_done
+
+do_csum_fewer_than_16:
+	# copy the remaining whole words
+	cmp	+4,d2
+	bcs	do_csum_fewer_than_4
+	cmp	+8,d2
+	bcs	do_csum_one_word
+	cmp	+12,d2
+	bcs	do_csum_two_words
+	mov	(a0+),d0
+	add	d0,d1
+	addc	+0,d1
+do_csum_two_words:
+	mov	(a0+),d0
+	add	d0,d1
+	addc	+0,d1
+do_csum_one_word:
+	mov	(a0+),d0
+	add	d0,d1
+	addc	+0,d1
+
+do_csum_fewer_than_4:
+	and	+3,d2
+	beq	do_csum_done
+	xor_cmp	d0,d0,+2,d2
+	bcs	do_csum_fewer_than_2
+	movhu	(a0+),d0
+do_csum_fewer_than_2:
+	and	+1,d2
+	beq	do_csum_add_last_bit
+	movbu	(a0),d3
+	add	d3,d0
+do_csum_add_last_bit:
+	add	d0,d1
+	addc	+0,d1
+
+do_csum_done:
+	# compress the checksum down to 16 bits
+	mov	+0xffff0000,d2
+	and	d1,d2
+	asl	+16,d1
+	add	d2,d1,d0
+	addc	+0xffff,d0
+	lsr	+16,d0
+
+	# flip the halves of the word result if the buffer was oddly aligned
+	mov	(12,sp),d1
+	and	+1,d1
+	beq	do_csum_not_oddly_aligned
+	swaph	d0,d0				# exchange bits 15:8 with 7:0
+
+do_csum_not_oddly_aligned:
+	ret	[d2,d3],8
+
+do_csum_end:
+	.size	do_csum, do_csum_end-do_csum