1 /* SPDX-License-Identifier: BSD-3-Clause
2 * Copyright (C) 2019 Intel Corporation. All rights reserved.
3 * All rights reserved.
4 */
5
6 #include "spdk/stdinc.h"
7 #include "spdk/util.h"
8 #include "spdk/assert.h"
9
10 /* The following will automatically generate several version of
11 * this function, targeted at different architectures. This
12 * is only supported by GCC 6 or newer. */
13 #if defined(__GNUC__) && __GNUC__ >= 6 && !defined(__clang__) \
14 && (defined(__i386__) || defined(__x86_64__)) \
15 && defined(__ELF__)
16 __attribute__((target_clones("bmi", "arch=core2", "arch=atom", "default")))
17 #endif
18 uint32_t
spdk_u32log2(uint32_t x)19 spdk_u32log2(uint32_t x)
20 {
21 if (x == 0) {
22 /* log(0) is undefined */
23 return 0;
24 }
25 SPDK_STATIC_ASSERT(sizeof(x) == sizeof(unsigned int), "Incorrect size");
26 return 31u - __builtin_clz(x);
27 }
28
29 /* The following will automatically generate several version of
30 * this function, targeted at different architectures. This
31 * is only supported by GCC 6 or newer. */
32 #if defined(__GNUC__) && __GNUC__ >= 6 && !defined(__clang__) \
33 && (defined(__i386__) || defined(__x86_64__)) \
34 && defined(__ELF__)
35 __attribute__((target_clones("bmi", "arch=core2", "arch=atom", "default")))
36 #endif
37 uint64_t
spdk_u64log2(uint64_t x)38 spdk_u64log2(uint64_t x)
39 {
40 if (x == 0) {
41 /* log(0) is undefined */
42 return 0;
43 }
44 SPDK_STATIC_ASSERT(sizeof(x) == sizeof(unsigned long long), "Incorrect size");
45 return 63u - __builtin_clzll(x);
46 }
47