bitops.h

/*
 * Bitops Module
 *
 * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
 *
 * Mostly inspired by (stolen from) linux/bitmap.h and linux/bitops.h
 *
 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
 * See the COPYING.LIB file in the top-level directory.
 */

#ifndef BITOPS_H
#define BITOPS_H

#include "qemu-common.h"

#define BITS_PER_BYTE           CHAR_BIT
#define BITS_PER_LONG           (sizeof (unsigned long) * BITS_PER_BYTE)

#define BIT(nr)			(1UL << (nr))
#define BIT_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
#define BIT_WORD(nr)		((nr) / BITS_PER_LONG)
#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))

/**
 * bitops_ffs - find first bit in word.
 * @word: The word to search
 *
 * Undefined if no bit exists, so code should check against 0 first.
 */
static unsigned long bitops_ffsl(unsigned long word)
{
	int num = 0;

#if LONG_MAX > 0x7FFFFFFF
	if ((word & 0xffffffff) == 0) {
		num += 32;
		word >>= 32;
	}
#endif
	if ((word & 0xffff) == 0) {
		num += 16;
		word >>= 16;
	}
	if ((word & 0xff) == 0) {
		num += 8;
		word >>= 8;
	}
	if ((word & 0xf) == 0) {
		num += 4;
		word >>= 4;
	}
	if ((word & 0x3) == 0) {
		num += 2;
		word >>= 2;
	}
	if ((word & 0x1) == 0) {
		num += 1;
        }
	return num;
}

/**
 * bitops_fls - find last (most-significant) set bit in a long word
 * @word: the word to search
 *
 * Undefined if no set bit exists, so code should check against 0 first.
 */
static inline unsigned long bitops_flsl(unsigned long word)
{
	int num = BITS_PER_LONG - 1;

#if LONG_MAX > 0x7FFFFFFF
	if (!(word & (~0ul << 32))) {
		num -= 32;
		word <<= 32;
	}
#endif
	if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
		num -= 16;
		word <<= 16;
	}
	if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
		num -= 8;
		word <<= 8;
	}
	if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
		num -= 4;
		word <<= 4;
	}
	if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
		num -= 2;

		word <<= 2;
	}
	if (!(word & (~0ul << (BITS_PER_LONG-1))))
		num -= 1;
	return num;
}

/**
 * ffz - find first zero in word.
 * @word: The word to search
 *
 * Undefined if no zero exists, so code should check against ~0UL first.
 */
static inline unsigned long ffz(unsigned long word)
{
    return bitops_ffsl(~word);
}

/**
 * set_bit - Set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 */
static inline void set_bit(int nr, unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
        unsigned long *p = addr + BIT_WORD(nr);

	*p  |= mask;
}

/**
 * clear_bit - Clears a bit in memory
 * @nr: Bit to clear
 * @addr: Address to start counting from
 */
static inline void clear_bit(int nr, unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
        unsigned long *p = addr + BIT_WORD(nr);

	*p &= ~mask;
}

/**
 * change_bit - Toggle a bit in memory
 * @nr: Bit to change
 * @addr: Address to start counting from
 */
static inline void change_bit(int nr, unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
        unsigned long *p = addr + BIT_WORD(nr);

	*p ^= mask;
}

/**
 * test_and_set_bit - Set a bit and return its old value
 * @nr: Bit to set
 * @addr: Address to count from
 */
static inline int test_and_set_bit(int nr, unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
        unsigned long *p = addr + BIT_WORD(nr);
	unsigned long old = *p;

	*p = old | mask;
	return (old & mask) != 0;
}

/**
 * test_and_clear_bit - Clear a bit and return its old value
 * @nr: Bit to clear
 * @addr: Address to count from
 */
static inline int test_and_clear_bit(int nr, unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
        unsigned long *p = addr + BIT_WORD(nr);
	unsigned long old = *p;

	*p = old & ~mask;
	return (old & mask) != 0;
}

/**
 * test_and_change_bit - Change a bit and return its old value
 * @nr: Bit to change
 * @addr: Address to count from
 */
static inline int test_and_change_bit(int nr, unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
        unsigned long *p = addr + BIT_WORD(nr);
	unsigned long old = *p;

	*p = old ^ mask;
	return (old & mask) != 0;
}

/**
 * test_bit - Determine whether a bit is set
 * @nr: bit number to test
 * @addr: Address to start counting from
 */
static inline int test_bit(int nr, const unsigned long *addr)
{
	return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
}

/**
 * find_last_bit - find the last set bit in a memory region
 * @addr: The address to start the search at
 * @size: The maximum size to search
 *
 * Returns the bit number of the first set bit, or size.
 */
unsigned long find_last_bit(const unsigned long *addr,
                            unsigned long size);

/**
 * find_next_bit - find the next set bit in a memory region
 * @addr: The address to base the search on
 * @offset: The bitnumber to start searching at
 * @size: The bitmap size in bits
 */
unsigned long find_next_bit(const unsigned long *addr,
				   unsigned long size, unsigned long offset);

/**
 * find_next_zero_bit - find the next cleared bit in a memory region
 * @addr: The address to base the search on
 * @offset: The bitnumber to start searching at
 * @size: The bitmap size in bits
 */

unsigned long find_next_zero_bit(const unsigned long *addr,
                                 unsigned long size,
                                 unsigned long offset);

/**
 * find_first_bit - find the first set bit in a memory region
 * @addr: The address to start the search at
 * @size: The maximum size to search
 *
 * Returns the bit number of the first set bit.
 */
static inline unsigned long find_first_bit(const unsigned long *addr,
                                           unsigned long size)
{
    return find_next_bit(addr, size, 0);
}

/**
 * find_first_zero_bit - find the first cleared bit in a memory region
 * @addr: The address to start the search at
 * @size: The maximum size to search
 *
 * Returns the bit number of the first cleared bit.
 */
static inline unsigned long find_first_zero_bit(const unsigned long *addr,
                                                unsigned long size)
{
    return find_next_zero_bit(addr, size, 0);
}

static inline unsigned long hweight_long(unsigned long w)
{
    unsigned long count;

    for (count = 0; w; w >>= 1) {
        count += w & 1;
    }
    return count;
}

/**
 * extract32:
 * @value: the value to extract the bit field from
 * @start: the lowest bit in the bit field (numbered from 0)
 * @length: the length of the bit field
 *
 * Extract from the 32 bit input @value the bit field specified by the
 * @start and @length parameters, and return it. The bit field must
 * lie entirely within the 32 bit word. It is valid to request that
 * all 32 bits are returned (ie @length 32 and @start 0).
 *
 * Returns: the value of the bit field extracted from the input value.
 */
static inline uint32_t extract32(uint32_t value, int start, int length)
{
    assert(start >= 0 && length > 0 && length <= 32 - start);
    return (value >> start) & (~0U >> (32 - length));
}

/**
 * extract64:
 * @value: the value to extract the bit field from
 * @start: the lowest bit in the bit field (numbered from 0)
 * @length: the length of the bit field
 *
 * Extract from the 64 bit input @value the bit field specified by the
 * @start and @length parameters, and return it. The bit field must
 * lie entirely within the 64 bit word. It is valid to request that
 * all 64 bits are returned (ie @length 64 and @start 0).
 *
 * Returns: the value of the bit field extracted from the input value.
 */
static inline uint64_t extract64(uint64_t value, int start, int length)
{
    assert(start >= 0 && length > 0 && length <= 64 - start);
    return (value >> start) & (~0ULL >> (64 - length));
}

/**
 * deposit32:
 * @value: initial value to insert bit field into
 * @start: the lowest bit in the bit field (numbered from 0)
 * @length: the length of the bit field
 * @fieldval: the value to insert into the bit field
 *
 * Deposit @fieldval into the 32 bit @value at the bit field specified
 * by the @start and @length parameters, and return the modified
 * @value. Bits of @value outside the bit field are not modified.
 * Bits of @fieldval above the least significant @length bits are
 * ignored. The bit field must lie entirely within the 32 bit word.
 * It is valid to request that all 32 bits are modified (ie @length
 * 32 and @start 0).
 *
 * Returns: the modified @value.
 */
static inline uint32_t deposit32(uint32_t value, int start, int length,
                                 uint32_t fieldval)
{
    uint32_t mask;
    assert(start >= 0 && length > 0 && length <= 32 - start);
    mask = (~0U >> (32 - length)) << start;
    return (value & ~mask) | ((fieldval << start) & mask);
}

/**
 * deposit64:
 * @value: initial value to insert bit field into
 * @start: the lowest bit in the bit field (numbered from 0)
 * @length: the length of the bit field
 * @fieldval: the value to insert into the bit field
 *
 * Deposit @fieldval into the 64 bit @value at the bit field specified
 * by the @start and @length parameters, and return the modified
 * @value. Bits of @value outside the bit field are not modified.
 * Bits of @fieldval above the least significant @length bits are
 * ignored. The bit field must lie entirely within the 64 bit word.
 * It is valid to request that all 64 bits are modified (ie @length
 * 64 and @start 0).
 *
 * Returns: the modified @value.
 */
static inline uint64_t deposit64(uint64_t value, int start, int length,
                                 uint64_t fieldval)
{
    uint64_t mask;
    assert(start >= 0 && length > 0 && length <= 64 - start);
    mask = (~0ULL >> (64 - length)) << start;
    return (value & ~mask) | ((fieldval << start) & mask);
}

#endif