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Commit ab244c1a authored by Akira Takeuchi's avatar Akira Takeuchi Committed by David Howells
Browse files

MN10300: Optimise do_csum() 



Optimise do_csum() to gang up the loads so they're less likely to get
interruptions between.

Signed-off-by: default avatarAkira Takeuchi <takeuchi.akr@jp.panasonic.com>
Signed-off-by: default avatarKiyoshi Owada <owada.kiyoshi@jp.panasonic.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 4f81ca13

arch/mn10300/lib/do_csum.S

+22 −27
Original line number Diff line number Diff line
@@ -15,21 +15,20 @@ 


###############################################################################

#

# unsigned int do_csum(const unsigned char *buff, size_t len)

# unsigned int do_csum(const unsigned char *buff, int 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

	mov	a0,a1

	clr	d1				# accumulator



	cmp	+0,d2

	beq	do_csum_done			# return if zero-length buffer

	ble	do_csum_done			# check for zero length or negative



	# 4-byte align the buffer pointer

	btst	+3,a0
@@ -41,17 +40,15 @@ do_csum: 
	inc	a0

	asl	+8,d0

	add	d0,d1

	addc	+0,d1

	add	-1,d2

do_csum_addr_not_odd:



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
@@ -66,20 +63,20 @@ do_csum_now_4b_aligned: 


do_csum_loop:

	mov	(a0+),d0

	add	d0,d1

	mov	(a0+),e0

	addc	e0,d1

	mov	(a0+),e1

	addc	e1,d1

	mov	(a0+),e3

	add	d0,d1

	addc	e0,d1

	addc	e1,d1

	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	d0,d1

	addc	e0,d1

	addc	e1,d1

	addc	e3,d1

	addc	+0,d1
@@ -94,12 +91,12 @@ do_csum_remainder: 
	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

	add	d0,d1

	addc	e0,d1

	addc	e1,d1

	addc	e3,d1

	addc	+0,d1

	add	-16,d2
@@ -131,9 +128,9 @@ do_csum_fewer_than_4: 
	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

do_csum_fewer_than_2:

	movbu	(a0),d3

	add	d3,d0

do_csum_add_last_bit:
@@ -142,21 +139,19 @@ do_csum_add_last_bit: 


do_csum_done:

	# compress the checksum down to 16 bits

	mov	+0xffff0000,d2

	and	d1,d2

	mov	+0xffff0000,d0

	and	d1,d0

	asl	+16,d1

	add	d2,d1,d0

	add	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

	and	+1,a1

	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
 
	.size	do_csum, .-do_csum