blob: bc02e39629b7f90def42c76a8c22b4359b197e30 [file] [log] [blame]
David Howellsb920de12008-02-08 04:19:31 -08001/* Optimised simple memory fill
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11#include <asm/cache.h>
12
13 .section .text
14 .balign L1_CACHE_BYTES
15
16###############################################################################
17#
18# void *memset(void *dst, int c, size_t n)
19#
20###############################################################################
21 .globl memset
22 .type memset,@function
23memset:
24 movm [d2,d3],(sp)
25 mov d0,(12,sp)
26 mov d1,(16,sp)
27 mov (20,sp),d2 # count
28 mov d0,a0 # dst
29 mov d0,e3 # the return value
30
31 cmp +0,d2
32 beq memset_done # return if zero-length fill
33
34 # see if the region parameters are four-byte aligned
35 or d0,d2,d3
36 and +3,d3
37 bne memset_1 # jump if not
38
39 extbu d1
40 mov_asl d1,d3,8,d1
41 or_asl d1,d3,8,d1
42 or_asl d1,d3,8,d1
43 or d3,d1
44
45 # we want to transfer as much as we can in chunks of 32 bytes
46 cmp +31,d2
47 bls memset_4_remainder # 4-byte aligned remainder
48
49 add -32,d2
50 mov +32,d3
51
52memset_4_loop:
53 mov d1,(a0+)
54 mov d1,(a0+)
55 mov d1,(a0+)
56 mov d1,(a0+)
57 mov d1,(a0+)
58 mov d1,(a0+)
59 mov d1,(a0+)
60 mov d1,(a0+)
61
62 sub d3,d2
63 bcc memset_4_loop
64
65 add d3,d2
66 beq memset_4_no_remainder
67
68memset_4_remainder:
69 # cut 4-7 words down to 0-3
70 cmp +16,d2
71 bcs memset_4_three_or_fewer_words
72 mov d1,(a0+)
73 mov d1,(a0+)
74 mov d1,(a0+)
75 mov d1,(a0+)
76 add -16,d2
77 beq memset_4_no_remainder
78
79 # copy the remaining 1, 2 or 3 words
80memset_4_three_or_fewer_words:
81 cmp +8,d2
82 bcs memset_4_one_word
83 beq memset_4_two_words
84 mov d1,(a0+)
85memset_4_two_words:
86 mov d1,(a0+)
87memset_4_one_word:
88 mov d1,(a0+)
89
90memset_4_no_remainder:
91 # check we set the correct amount
92 # TODO: REMOVE CHECK
93 sub e3,a0,d2
94 mov (20,sp),d1
95 cmp d2,d1
96 beq memset_done
97 break
98 break
99 break
100
101memset_done:
102 mov e3,a0
103 ret [d2,d3],8
104
105 # handle misaligned copying
106memset_1:
107 add -1,d2
108 mov +1,d3
109 setlb # setlb requires the next insns
110 # to occupy exactly 4 bytes
111
112 sub d3,d2
113 movbu d1,(a0)
114 inc a0
115 lcc
116
117 mov e3,a0
118 ret [d2,d3],8
119
120memset_end:
121 .size memset, memset_end-memset