FreeCalypso > hg > fc-selenite

annotate src/libsys/bzero.S @ 112:fdecfb3bd860

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
.../drv_app/r2d/r2d_*.c: LCD include case fixes from Magnetite R2D is not used in Selenite, but we strive to keep the two source trees in sync as much as possible to reduce the diffs.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 13 Oct 2018 16:56:22 +0000
parents 425ab6d987f3
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
86
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
1 /*
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
2 * This ARM implementation of bzero() has been derived from:
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
3 *
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4 * linux/arch/arm/lib/memzero.S
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
5 *
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
6 * Copyright (C) 1995-2000 Russell King
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
7 *
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
8 * This program is free software; you can redistribute it and/or modify
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
9 * it under the terms of the GNU General Public License version 2 as
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
10 * published by the Free Software Foundation.
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11 */
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13 .text
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14 .code 32
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
15 .globl bzero
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
16
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
17 /*
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
18 * Align the pointer in r0. r3 contains the number of bytes that we are
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
19 * mis-aligned by, and r1 is the number of bytes. If r1 < 4, then we
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
20 * don't bother; we use byte stores instead.
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
21 */
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
22 1: subs r1, r1, #4 @ 1 do we have enough
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
23 blt 5f @ 1 bytes to align with?
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
24 cmp r3, #2 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
25 strltb r2, [r0], #1 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
26 strleb r2, [r0], #1 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
27 strb r2, [r0], #1 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
28 add r1, r1, r3 @ 1 (r1 = r1 - (4 - r3))
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
29 /*
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
30 * The pointer is now aligned and the length is adjusted. Try doing the
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
31 * bzero again.
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
32 */
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
33
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
34 bzero:
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
35 mov r2, #0 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
36 ands r3, r0, #3 @ 1 unaligned?
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
37 bne 1b @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
38 /*
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
39 * r3 = 0, and we know that the pointer in r0 is aligned to a word boundary.
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
40 */
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
41 3: subs r1, r1, #4
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
42 strge r2, [r0], #4
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
43 bgt 3b @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
44 bxeq lr @ 1/2 quick exit
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
45 /*
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
46 * No need to correct the count; we're only testing bits from now on
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
47 *
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
48 * When we get here, we've got less than 4 bytes to zero. We
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
49 * may have an unaligned pointer as well.
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
50 */
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
51 5: tst r1, #2 @ 1 2 bytes or more?
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
52 strneb r2, [r0], #1 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
53 strneb r2, [r0], #1 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
54 tst r1, #1 @ 1 a byte left over
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
55 strneb r2, [r0], #1 @ 1
425ab6d987f3 src/libsys: pieced together from Citrine
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
56 bx lr @ 1