1fb7df12dSIngo Molnar /* SPDX-License-Identifier: GPL-2.0 */ 2de1e17b1SArnaldo Carvalho de Melo #ifndef _ASM_GENERIC_BITOPS_FLS_H_ 3de1e17b1SArnaldo Carvalho de Melo #define _ASM_GENERIC_BITOPS_FLS_H_ 4de1e17b1SArnaldo Carvalho de Melo 5de1e17b1SArnaldo Carvalho de Melo /** 6de1e17b1SArnaldo Carvalho de Melo * fls - find last (most-significant) bit set 7de1e17b1SArnaldo Carvalho de Melo * @x: the word to search 8de1e17b1SArnaldo Carvalho de Melo * 9de1e17b1SArnaldo Carvalho de Melo * This is defined the same way as ffs. 10de1e17b1SArnaldo Carvalho de Melo * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. 11de1e17b1SArnaldo Carvalho de Melo */ 12de1e17b1SArnaldo Carvalho de Melo fls(unsigned int x)13*3fc2579eSMatthew Wilcoxstatic __always_inline int fls(unsigned int x) 14de1e17b1SArnaldo Carvalho de Melo { 15de1e17b1SArnaldo Carvalho de Melo int r = 32; 16de1e17b1SArnaldo Carvalho de Melo 17de1e17b1SArnaldo Carvalho de Melo if (!x) 18de1e17b1SArnaldo Carvalho de Melo return 0; 19de1e17b1SArnaldo Carvalho de Melo if (!(x & 0xffff0000u)) { 20de1e17b1SArnaldo Carvalho de Melo x <<= 16; 21de1e17b1SArnaldo Carvalho de Melo r -= 16; 22de1e17b1SArnaldo Carvalho de Melo } 23de1e17b1SArnaldo Carvalho de Melo if (!(x & 0xff000000u)) { 24de1e17b1SArnaldo Carvalho de Melo x <<= 8; 25de1e17b1SArnaldo Carvalho de Melo r -= 8; 26de1e17b1SArnaldo Carvalho de Melo } 27de1e17b1SArnaldo Carvalho de Melo if (!(x & 0xf0000000u)) { 28de1e17b1SArnaldo Carvalho de Melo x <<= 4; 29de1e17b1SArnaldo Carvalho de Melo r -= 4; 30de1e17b1SArnaldo Carvalho de Melo } 31de1e17b1SArnaldo Carvalho de Melo if (!(x & 0xc0000000u)) { 32de1e17b1SArnaldo Carvalho de Melo x <<= 2; 33de1e17b1SArnaldo Carvalho de Melo r -= 2; 34de1e17b1SArnaldo Carvalho de Melo } 35de1e17b1SArnaldo Carvalho de Melo if (!(x & 0x80000000u)) { 36de1e17b1SArnaldo Carvalho de Melo x <<= 1; 37de1e17b1SArnaldo Carvalho de Melo r -= 1; 38de1e17b1SArnaldo Carvalho de Melo } 39de1e17b1SArnaldo Carvalho de Melo return r; 40de1e17b1SArnaldo Carvalho de Melo } 41de1e17b1SArnaldo Carvalho de Melo 42de1e17b1SArnaldo Carvalho de Melo #endif /* _ASM_GENERIC_BITOPS_FLS_H_ */ 43