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1/*
2 * A fast checksum+copy routine using movem
3 * Copyright (c) 1998, 2001 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 ;; check for breakeven length between movem and normal word looping versions
20 ;; we also do _NOT_ want to compute a checksum over more than the
21 ;; actual length when length < 40
22
23 cmpu.w 80, $r12
24 blo _word_loop
25 nop
26
27 ;; need to save the registers we use below in the movem loop
28 ;; this overhead is why we have a check above for breakeven length
29 ;; only r0 - r8 have to be saved, the other ones are clobber-able
30 ;; according to the ABI
31
32 subq 9*4, $sp
33 movem $r8, [$sp]
34
35 ;; do a movem copy and checksum
36
37 subq 10*4, $r12 ; update length for the first loop
38
39_mloop: movem [$r10+],$r9 ; read 10 longwords
401: ;; A failing userspace access will have this as PC.
41 movem $r9,[$r11+] ; write 10 longwords
42
43 ;; perform dword checksumming on the 10 longwords
44
45 add.d $r0,$r13
46 ax
47 add.d $r1,$r13
48 ax
49 add.d $r2,$r13
50 ax
51 add.d $r3,$r13
52 ax
53 add.d $r4,$r13
54 ax
55 add.d $r5,$r13
56 ax
57 add.d $r6,$r13
58 ax
59 add.d $r7,$r13
60 ax
61 add.d $r8,$r13
62 ax
63 add.d $r9,$r13
64
65 ;; fold the carry into the checksum, to avoid having to loop the carry
66 ;; back into the top
67
68 ax
69 addq 0,$r13
70
71 subq 10*4,$r12
72 bge _mloop
73 nop
74
75 addq 10*4,$r12 ; compensate for last loop underflowing length
76
77 movem [$sp+],$r8 ; restore regs
78
79_word_loop:
80 ;; only fold if there is anything to fold.
81
82 cmpq 0,$r13
83 beq _no_fold
84
85 ;; fold 32-bit checksum into a 16-bit checksum, to avoid carries below
86 ;; r9 can be used as temporary.
87
88 move.d $r13,$r9
89 lsrq 16,$r9 ; r0 = checksum >> 16
90 and.d 0xffff,$r13 ; checksum = checksum & 0xffff
91 add.d $r9,$r13 ; checksum += r0
92
93_no_fold:
94 cmpq 2,$r12
95 blt _no_words
96 nop
97
98 ;; copy and checksum the rest of the words
99
100 subq 2,$r12
101
102_wloop: move.w [$r10+],$r9
1032: ;; A failing userspace access will have this as PC.
104 addu.w $r9,$r13
105 subq 2,$r12
106 bge _wloop
107 move.w $r9,[$r11+]
108
109 addq 2,$r12
110
111_no_words:
112 ;; see if we have one odd byte more
113 cmpq 1,$r12
114 beq _do_byte
115 nop
116 ret
117 move.d $r13, $r10
118
119_do_byte:
120 ;; copy and checksum the last byte
121 move.b [$r10],$r9
1223: ;; A failing userspace access will have this as PC.
123 addu.b $r9,$r13
124 move.b $r9,[$r11]
125 ret
126 move.d $r13, $r10
1/*
2 * A fast checksum+copy routine using movem
3 * Copyright (c) 1998, 2001 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 ;; check for breakeven length between movem and normal word looping versions
20 ;; we also do _NOT_ want to compute a checksum over more than the
21 ;; actual length when length < 40
22
23 cmpu.w 80, $r12
24 blo _word_loop
25 nop
26
27 ;; need to save the registers we use below in the movem loop
28 ;; this overhead is why we have a check above for breakeven length
29 ;; only r0 - r8 have to be saved, the other ones are clobber-able
30 ;; according to the ABI
31
32 subq 9*4, $sp
33 movem $r8, [$sp]
34
35 ;; do a movem copy and checksum
36
37 subq 10*4, $r12 ; update length for the first loop
38
39_mloop: movem [$r10+],$r9 ; read 10 longwords
401: ;; A failing userspace access will have this as PC.
41 movem $r9,[$r11+] ; write 10 longwords
42
43 ;; perform dword checksumming on the 10 longwords
44
45 add.d $r0,$r13
46 ax
47 add.d $r1,$r13
48 ax
49 add.d $r2,$r13
50 ax
51 add.d $r3,$r13
52 ax
53 add.d $r4,$r13
54 ax
55 add.d $r5,$r13
56 ax
57 add.d $r6,$r13
58 ax
59 add.d $r7,$r13
60 ax
61 add.d $r8,$r13
62 ax
63 add.d $r9,$r13
64
65 ;; fold the carry into the checksum, to avoid having to loop the carry
66 ;; back into the top
67
68 ax
69 addq 0,$r13
70
71 subq 10*4,$r12
72 bge _mloop
73 nop
74
75 addq 10*4,$r12 ; compensate for last loop underflowing length
76
77 movem [$sp+],$r8 ; restore regs
78
79_word_loop:
80 ;; only fold if there is anything to fold.
81
82 cmpq 0,$r13
83 beq _no_fold
84
85 ;; fold 32-bit checksum into a 16-bit checksum, to avoid carries below
86 ;; r9 can be used as temporary.
87
88 move.d $r13,$r9
89 lsrq 16,$r9 ; r0 = checksum >> 16
90 and.d 0xffff,$r13 ; checksum = checksum & 0xffff
91 add.d $r9,$r13 ; checksum += r0
92
93_no_fold:
94 cmpq 2,$r12
95 blt _no_words
96 nop
97
98 ;; copy and checksum the rest of the words
99
100 subq 2,$r12
101
102_wloop: move.w [$r10+],$r9
1032: ;; A failing userspace access will have this as PC.
104 addu.w $r9,$r13
105 subq 2,$r12
106 bge _wloop
107 move.w $r9,[$r11+]
108
109 addq 2,$r12
110
111_no_words:
112 ;; see if we have one odd byte more
113 cmpq 1,$r12
114 beq _do_byte
115 nop
116 ret
117 move.d $r13, $r10
118
119_do_byte:
120 ;; copy and checksum the last byte
121 move.b [$r10],$r9
1223: ;; A failing userspace access will have this as PC.
123 addu.b $r9,$r13
124 move.b $r9,[$r11]
125 ret
126 move.d $r13, $r10