1 /*
2 *
3 * Copyright 2015 Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * Alternatively, this software may be distributed under the terms of the
17 * GNU General Public License ("GPL") version 2 as published by the Free
18 * Software Foundation.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <libpayload.h>
34
35 /*
36 * Provide platform-independent backend implementation for __builtin_clz() in
37 * <libpayload.h> in case GCC does not have an assembly version for this arch.
38 */
39
40 int __clzsi2(u32 a);
__clzsi2(u32 a)41 int __clzsi2(u32 a)
42 {
43 static const u8 four_bit_table[] = {
44 [0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2,
45 [0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1,
46 [0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0,
47 [0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0,
48 };
49 int r = 0;
50
51 if (!(a & (0xffff << 16))) {
52 r += 16;
53 a <<= 16;
54 }
55
56 if (!(a & (0xff << 24))) {
57 r += 8;
58 a <<= 8;
59 }
60
61 if (!(a & (0xf << 28))) {
62 r += 4;
63 a <<= 4;
64 }
65
66 return r + four_bit_table[a >> 28];
67 }
68