277 lines
8.0 KiB
C
277 lines
8.0 KiB
C
/*
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* Bitops Module
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*
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* Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
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*
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* Mostly inspired by (stolen from) linux/bitmap.h and linux/bitops.h
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*/
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#ifndef BITOPS_H
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#define BITOPS_H
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#include "qemu-common.h"
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#include "host-utils.h"
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#define BITS_PER_BYTE CHAR_BIT
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#define BITS_PER_LONG (sizeof (unsigned long) * BITS_PER_BYTE)
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#define BIT(nr) (1UL << (nr))
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#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
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#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
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#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
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/**
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* set_bit - Set a bit in memory
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* @nr: the bit to set
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* @addr: the address to start counting from
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*/
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static inline void set_bit(int nr, unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = addr + BIT_WORD(nr);
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*p |= mask;
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}
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/**
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* clear_bit - Clears a bit in memory
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* @nr: Bit to clear
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* @addr: Address to start counting from
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*/
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static inline void clear_bit(int nr, unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = addr + BIT_WORD(nr);
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*p &= ~mask;
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}
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/**
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* change_bit - Toggle a bit in memory
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* @nr: Bit to change
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* @addr: Address to start counting from
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*/
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static inline void change_bit(int nr, unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = addr + BIT_WORD(nr);
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*p ^= mask;
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}
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/**
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* test_and_set_bit - Set a bit and return its old value
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* @nr: Bit to set
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* @addr: Address to count from
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*/
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static inline int test_and_set_bit(int nr, unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = addr + BIT_WORD(nr);
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unsigned long old = *p;
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*p = old | mask;
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return (old & mask) != 0;
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}
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/**
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* test_and_clear_bit - Clear a bit and return its old value
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* @nr: Bit to clear
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* @addr: Address to count from
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*/
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static inline int test_and_clear_bit(int nr, unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = addr + BIT_WORD(nr);
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unsigned long old = *p;
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*p = old & ~mask;
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return (old & mask) != 0;
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}
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/**
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* test_and_change_bit - Change a bit and return its old value
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* @nr: Bit to change
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* @addr: Address to count from
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*/
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static inline int test_and_change_bit(int nr, unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = addr + BIT_WORD(nr);
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unsigned long old = *p;
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*p = old ^ mask;
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return (old & mask) != 0;
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}
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/**
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* test_bit - Determine whether a bit is set
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* @nr: bit number to test
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* @addr: Address to start counting from
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*/
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static inline int test_bit(int nr, const unsigned long *addr)
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{
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return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
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}
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/**
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* find_last_bit - find the last set bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum size to search
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*
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* Returns the bit number of the first set bit, or size.
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*/
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unsigned long find_last_bit(const unsigned long *addr,
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unsigned long size);
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/**
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* find_next_bit - find the next set bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The bitmap size in bits
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*/
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unsigned long find_next_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset);
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/**
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* find_next_zero_bit - find the next cleared bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The bitmap size in bits
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*/
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unsigned long find_next_zero_bit(const unsigned long *addr,
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unsigned long size,
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unsigned long offset);
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/**
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* find_first_bit - find the first set bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum size to search
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*
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* Returns the bit number of the first set bit.
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*/
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static inline unsigned long find_first_bit(const unsigned long *addr,
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unsigned long size)
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{
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return find_next_bit(addr, size, 0);
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}
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/**
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* find_first_zero_bit - find the first cleared bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum size to search
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*
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* Returns the bit number of the first cleared bit.
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*/
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static inline unsigned long find_first_zero_bit(const unsigned long *addr,
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unsigned long size)
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{
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return find_next_zero_bit(addr, size, 0);
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}
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static inline unsigned long hweight_long(unsigned long w)
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{
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unsigned long count;
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for (count = 0; w; w >>= 1) {
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count += w & 1;
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}
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return count;
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}
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/**
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* extract32:
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* @value: the value to extract the bit field from
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* @start: the lowest bit in the bit field (numbered from 0)
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* @length: the length of the bit field
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*
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* Extract from the 32 bit input @value the bit field specified by the
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* @start and @length parameters, and return it. The bit field must
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* lie entirely within the 32 bit word. It is valid to request that
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* all 32 bits are returned (ie @length 32 and @start 0).
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*
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* Returns: the value of the bit field extracted from the input value.
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*/
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static inline uint32_t extract32(uint32_t value, int start, int length)
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{
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assert(start >= 0 && length > 0 && length <= 32 - start);
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return (value >> start) & (~0U >> (32 - length));
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}
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/**
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* extract64:
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* @value: the value to extract the bit field from
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* @start: the lowest bit in the bit field (numbered from 0)
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* @length: the length of the bit field
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*
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* Extract from the 64 bit input @value the bit field specified by the
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* @start and @length parameters, and return it. The bit field must
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* lie entirely within the 64 bit word. It is valid to request that
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* all 64 bits are returned (ie @length 64 and @start 0).
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*
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* Returns: the value of the bit field extracted from the input value.
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*/
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static inline uint64_t extract64(uint64_t value, int start, int length)
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{
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assert(start >= 0 && length > 0 && length <= 64 - start);
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return (value >> start) & (~0ULL >> (64 - length));
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}
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/**
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* deposit32:
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* @value: initial value to insert bit field into
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* @start: the lowest bit in the bit field (numbered from 0)
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* @length: the length of the bit field
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* @fieldval: the value to insert into the bit field
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*
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* Deposit @fieldval into the 32 bit @value at the bit field specified
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* by the @start and @length parameters, and return the modified
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* @value. Bits of @value outside the bit field are not modified.
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* Bits of @fieldval above the least significant @length bits are
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* ignored. The bit field must lie entirely within the 32 bit word.
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* It is valid to request that all 32 bits are modified (ie @length
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* 32 and @start 0).
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*
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* Returns: the modified @value.
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*/
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static inline uint32_t deposit32(uint32_t value, int start, int length,
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uint32_t fieldval)
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{
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uint32_t mask;
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assert(start >= 0 && length > 0 && length <= 32 - start);
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mask = (~0U >> (32 - length)) << start;
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return (value & ~mask) | ((fieldval << start) & mask);
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}
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/**
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* deposit64:
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* @value: initial value to insert bit field into
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* @start: the lowest bit in the bit field (numbered from 0)
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* @length: the length of the bit field
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* @fieldval: the value to insert into the bit field
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*
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* Deposit @fieldval into the 64 bit @value at the bit field specified
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* by the @start and @length parameters, and return the modified
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* @value. Bits of @value outside the bit field are not modified.
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* Bits of @fieldval above the least significant @length bits are
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* ignored. The bit field must lie entirely within the 64 bit word.
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* It is valid to request that all 64 bits are modified (ie @length
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* 64 and @start 0).
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*
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* Returns: the modified @value.
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*/
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static inline uint64_t deposit64(uint64_t value, int start, int length,
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uint64_t fieldval)
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{
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uint64_t mask;
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assert(start >= 0 && length > 0 && length <= 64 - start);
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mask = (~0ULL >> (64 - length)) << start;
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return (value & ~mask) | ((fieldval << start) & mask);
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}
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#endif
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