1 /*- 2 * BSD LICENSE 3 * 4 * Copyright(c) Intel Corporation. All rights reserved. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * * Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * * Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * * Neither the name of Intel Corporation nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 24 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 25 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 27 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 31 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include "spdk/stdinc.h" 35 #include "spdk/util.h" 36 #include "spdk/assert.h" 37 38 /* The following will automatically generate several version of 39 * this function, targeted at different architectures. This 40 * is only supported by GCC 6 or newer. */ 41 #if defined(__GNUC__) && __GNUC__ >= 6 && !defined(__clang__) \ 42 && (defined(__i386__) || defined(__x86_64__)) \ 43 && defined(__ELF__) 44 __attribute__((target_clones("bmi", "arch=core2", "arch=atom", "default"))) 45 #endif 46 uint32_t 47 spdk_u32log2(uint32_t x) 48 { 49 if (x == 0) { 50 /* log(0) is undefined */ 51 return 0; 52 } 53 SPDK_STATIC_ASSERT(sizeof(x) == sizeof(unsigned int), "Incorrect size"); 54 return 31u - __builtin_clz(x); 55 } 56 57 /* The following will automatically generate several version of 58 * this function, targeted at different architectures. This 59 * is only supported by GCC 6 or newer. */ 60 #if defined(__GNUC__) && __GNUC__ >= 6 && !defined(__clang__) \ 61 && (defined(__i386__) || defined(__x86_64__)) \ 62 && defined(__ELF__) 63 __attribute__((target_clones("bmi", "arch=core2", "arch=atom", "default"))) 64 #endif 65 uint64_t 66 spdk_u64log2(uint64_t x) 67 { 68 if (x == 0) { 69 /* log(0) is undefined */ 70 return 0; 71 } 72 SPDK_STATIC_ASSERT(sizeof(x) == sizeof(unsigned long long), "Incorrect size"); 73 return 63u - __builtin_clzll(x); 74 } 75