Annotation of sys/lib/libkern/arch/m68k/memset.S, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: memset.S,v 1.2 2003/06/02 23:28:08 millert Exp $ */
2:
3: /*-
4: * Copyright (c) 1990 The Regents of the University of California.
5: * All rights reserved.
6: *
7: * This code is derived from software contributed to Berkeley by
8: * the Systems Programming Group of the University of Utah Computer
9: * Science Department.
10: *
11: * Redistribution and use in source and binary forms, with or without
12: * modification, are permitted provided that the following conditions
13: * are met:
14: * 1. Redistributions of source code must retain the above copyright
15: * notice, this list of conditions and the following disclaimer.
16: * 2. Redistributions in binary form must reproduce the above copyright
17: * notice, this list of conditions and the following disclaimer in the
18: * documentation and/or other materials provided with the distribution.
19: * 3. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #include "DEFS.h"
37:
38: #if defined(LIBC_SCCS)
39: .text
40: .asciz "$OpenBSD: memset.S,v 1.2 2003/06/02 23:28:08 millert Exp $"
41: #endif /* LIBC_SCCS */
42:
43: /*
44: * This is probably not the best we can do, but it is still much
45: * faster than the C version in the portable gen directory.
46: *
47: * Things that might help:
48: * - unroll the longword loop (might not be good for a 68020)
49: * - longword, as opposed to word, align when possible (only on the 68020)
50: * - use nested DBcc instructions or use one and limit size to 64K
51: */
52: ENTRY(memset)
53: movl d2,sp@-
54: movl sp@(8),a0 | destination
55: movl sp@(16),d0 | count
56: beq bzdone | nothing to do
57: movb sp@(15),d2 | character
58: movl a0,d1
59: btst #0,d1 | address odd?
60: beq bzeven | no, skip alignment
61: movb d2,a0@+ | set one byte
62: subql #1,d0 | adjust count
63: beq bzdone | if zero, all done
64: bzeven:
65: cmpl #15,d0
66: ble bzbloop | too small to be worthwhile
67: clrl d1 | replicate byte to fill longword
68: movb d2,d1
69: movl d1,d2
70: lsll #8,d1
71: orl d1,d2
72: lsll #8,d1
73: orl d1,d2
74: lsll #8,d1
75: orl d1,d2
76: movl d0,d1 | convert to longword count
77: lsrl #2,d1
78: #ifdef DEBUG
79: moveml #0xffff,sp@-
80: movl d2,sp@-
81: movl d1,sp@-
82: movl d0,sp@-
83: movl a0,sp@-
84: movl #foo,sp@-
85: jsr _printf
86: addl #20,sp
87: moveml sp@+,#0xffff
88: #endif
89: bzlloop:
90: movl d2,a0@+ | set one longword
91: subql #1,d1 | adjust count
92: bne bzlloop | still more, keep going
93: andl #3,d0 | what remains
94: beq bzdone | nothing, all done
95: bzbloop:
96: movb d2,a0@+ | set one byte
97: subql #1,d0 | adjust count
98: bne bzbloop | still more, keep going
99: bzdone:
100: movl sp@(8),d0 | return destination
101: movl sp@+,d2
102: rts
103:
104: #ifdef DEBUG
105: .globl _printf
106: foo:
107: .asciz "a0=%08x d0=%08x d1=%08x d2=%08x\n"
108: #endif
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