2019-01-21 15:23:28 +08:00
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/*
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2019-01-24 14:11:10 +08:00
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2019 Western Digital Corporation or its affiliates.
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2019-01-21 15:23:28 +08:00
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*
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* Authors:
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* Atish Patra<atish.patra@wdc.com>
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*/
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#ifndef __SBI_BITOPS_H__
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#define __SBI_BITOPS_H__
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#include <sbi/sbi_bits.h>
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#include <sbi/riscv_asm.h>
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/**
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* ffs - Find first bit set
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* @x: the word to search
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*
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* This is defined the same way as
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* the libc and compiler builtin ffs routines, therefore
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* differs in spirit from the above ffz (man ffs).
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*/
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static inline int ffs(int x)
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{
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int r = 1;
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if (!x)
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return 0;
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if (!(x & 0xffff)) {
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x >>= 16;
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r += 16;
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}
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if (!(x & 0xff)) {
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x >>= 8;
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r += 8;
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}
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if (!(x & 0xf)) {
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x >>= 4;
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r += 4;
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}
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if (!(x & 3)) {
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x >>= 2;
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r += 2;
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}
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if (!(x & 1)) {
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x >>= 1;
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r += 1;
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}
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return r;
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}
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/**
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* __ffs - find first bit in word.
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* @word: The word to search
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*
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* Undefined if no bit exists, so code should check against 0 first.
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*/
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static inline int __ffs(unsigned long word)
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{
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int num = 0;
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#if BITS_PER_LONG == 64
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if ((word & 0xffffffff) == 0) {
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num += 32;
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word >>= 32;
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}
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#endif
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if ((word & 0xffff) == 0) {
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num += 16;
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word >>= 16;
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}
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if ((word & 0xff) == 0) {
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num += 8;
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word >>= 8;
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}
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if ((word & 0xf) == 0) {
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num += 4;
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word >>= 4;
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}
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if ((word & 0x3) == 0) {
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num += 2;
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word >>= 2;
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}
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if ((word & 0x1) == 0)
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num += 1;
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return num;
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}
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/*
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* ffz - find first zero in word.
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* @word: The word to search
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*
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* Undefined if no zero exists, so code should check against ~0UL first.
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*/
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2019-04-11 08:41:52 +08:00
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#define ffz(x) __ffs(~(x))
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2019-01-21 15:23:28 +08:00
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2019-11-25 15:33:47 +08:00
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/**
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* fls - find last (most-significant) bit set
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* @x: the word to search
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*
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* This is defined the same way as ffs.
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* Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
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*/
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static inline int fls(int x)
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{
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int r = 32;
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if (!x)
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return 0;
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if (!(x & 0xffff0000u)) {
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x <<= 16;
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r -= 16;
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}
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if (!(x & 0xff000000u)) {
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x <<= 8;
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r -= 8;
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}
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if (!(x & 0xf0000000u)) {
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x <<= 4;
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r -= 4;
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}
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if (!(x & 0xc0000000u)) {
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x <<= 2;
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r -= 2;
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}
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if (!(x & 0x80000000u)) {
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x <<= 1;
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r -= 1;
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}
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return r;
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}
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/**
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* __fls - find last (most-significant) set bit in a long word
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* @word: the word to search
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*
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* Undefined if no set bit exists, so code should check against 0 first.
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*/
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static inline unsigned long __fls(unsigned long word)
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{
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int num = BITS_PER_LONG - 1;
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#if BITS_PER_LONG == 64
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if (!(word & (~0ul << 32))) {
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num -= 32;
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word <<= 32;
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}
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#endif
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if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
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num -= 16;
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word <<= 16;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
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num -= 8;
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word <<= 8;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
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num -= 4;
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word <<= 4;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
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num -= 2;
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word <<= 2;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-1))))
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num -= 1;
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return num;
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}
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2019-01-21 15:23:28 +08:00
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#endif
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