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1/*
2 * A fast checksum+copy routine using movem
3 * Copyright (c) 1998-2007 Axis Communications AB
4 *
5 * Authors:	Bjorn Wesen
6 *
7 * csum_partial_copy_nocheck(const char *src, char *dst,
8 *		             int len, unsigned int sum)
9 */
10
11	.globl	csum_partial_copy_nocheck
12csum_partial_copy_nocheck:
13
14	;; r10 - src
15	;; r11 - dst
16	;; r12 - length
17	;; r13 - checksum
18
19	;; Optimized for large packets
20	subq	10*4, $r12
21	blt	_word_loop
22	move.d	$r12, $acr
23
24	subq	9*4,$sp
25	clearf	c
26	movem	$r8,[$sp]
27
28	;; do a movem copy and checksum
291:	;; A failing userspace access (the read) will have this as PC.
30_mloop:	movem	[$r10+],$r9	; read 10 longwords
31	addoq	-10*4, $acr, $acr ; loop counter in latency cycle
32	movem	$r9,[$r11+]	; write 10 longwords
33
34	;; perform dword checksumming on the 10 longwords
35	addc	$r0,$r13
36	addc	$r1,$r13
37	addc	$r2,$r13
38	addc	$r3,$r13
39	addc	$r4,$r13
40	addc	$r5,$r13
41	addc	$r6,$r13
42	addc	$r7,$r13
43	addc	$r8,$r13
44	addc	$r9,$r13
45
46	;; test $acr, without trashing carry.
47	move.d	$acr, $acr
48	bpl	_mloop
49	;; r12 <= acr  is needed after mloop and in the exception handlers.
50	move.d	$acr, $r12
51
52	;; fold the last carry into r13
53	addc	0, $r13
54	movem	[$sp+],$r8	; restore regs
55
56_word_loop:
57	addq	10*4,$r12	; compensate for last loop underflowing length
58
59	;; fold 32-bit checksum into a 16-bit checksum, to avoid carries below
60	;; r9 can be used as temporary.
61	move.d	$r13,$r9
62	lsrq	16,$r9		; r0 = checksum >> 16
63	and.d	0xffff,$r13	; checksum = checksum & 0xffff
64
65	subq	2, $r12
66	blt	_no_words
67	add.d	$r9,$r13	; checksum += r0
68
69	;; copy and checksum the rest of the words
702:	;; A failing userspace access for the read below will have this as PC.
71_wloop:	move.w	[$r10+],$r9
72	addu.w	$r9,$r13
73	subq	2,$r12
74	bge	_wloop
75	move.w	$r9,[$r11+]
76
77_no_words:
78	addq	2,$r12
79	bne	_do_byte
80	nop
81	ret
82	move.d	$r13,$r10
83
84_do_byte:
85	;; copy and checksum the last byte
863:	;; A failing userspace access for the read below will have this as PC.
87	move.b	[$r10],$r9
88	addu.b	$r9,$r13
89	move.b	$r9,[$r11]
90	ret
91	move.d	$r13,$r10
92