/*
 * 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 <stdint.h>
#include <assert.h>

#include "host-utils.h"
#include "atomic.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))

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

    *p  |= mask;
}

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

    atomic_or(p, mask);
}

/**
 * clear_bit - Clears a bit in memory
 * @nr: Bit to clear
 * @addr: Address to start counting from
 */
static inline void clear_bit(long 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(long 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(long 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(long 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(long 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(long 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)
{
    unsigned long result, tmp;

    for (result = 0; result < size; result += BITS_PER_LONG) {
        tmp = *addr++;
        if (tmp) {
            result += ctzl(tmp);
            return result < size ? result : size;
        }
    }
    /* Not found */
    return size;
}

/**
 * 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;
}

/**
 * rol8 - rotate an 8-bit value left
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint8_t rol8(uint8_t word, unsigned int shift)
{
    return (word << shift) | (word >> (8 - shift));
}

/**
 * ror8 - rotate an 8-bit value right
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint8_t ror8(uint8_t word, unsigned int shift)
{
    return (word >> shift) | (word << (8 - shift));
}

/**
 * rol16 - rotate a 16-bit value left
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint16_t rol16(uint16_t word, unsigned int shift)
{
    return (word << shift) | (word >> (16 - shift));
}

/**
 * ror16 - rotate a 16-bit value right
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint16_t ror16(uint16_t word, unsigned int shift)
{
    return (word >> shift) | (word << (16 - shift));
}

/**
 * rol32 - rotate a 32-bit value left
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint32_t rol32(uint32_t word, unsigned int shift)
{
    return (word << shift) | (word >> (32 - shift));
}

/**
 * ror32 - rotate a 32-bit value right
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint32_t ror32(uint32_t word, unsigned int shift)
{
    return (word >> shift) | (word << (32 - shift));
}

/**
 * rol64 - rotate a 64-bit value left
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint64_t rol64(uint64_t word, unsigned int shift)
{
    return (word << shift) | (word >> (64 - shift));
}

/**
 * ror64 - rotate a 64-bit value right
 * @word: value to rotate
 * @shift: bits to roll
 */
static inline uint64_t ror64(uint64_t word, unsigned int shift)
{
    return (word >> shift) | (word << (64 - shift));
}

/**
 * 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));
}

/**
 * sextract32:
 * @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, sign extended to
 * an int32_t (ie with the most significant bit of the field propagated
 * to all the upper bits of the return value). 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 sign extended value of the bit field extracted from the
 * input value.
 */
static inline int32_t sextract32(uint32_t value, int start, int length)
{
    assert(start >= 0 && length > 0 && length <= 32 - start);
    /* Note that this implementation relies on right shift of signed
     * integers being an arithmetic shift.
     */
    return ((int32_t)(value << (32 - length - start))) >> (32 - length);
}

/**
 * sextract64:
 * @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, sign extended to
 * an int64_t (ie with the most significant bit of the field propagated
 * to all the upper bits of the return value). 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 sign extended value of the bit field extracted from the
 * input value.
 */
static inline int64_t sextract64(uint64_t value, int start, int length)
{
    assert(start >= 0 && length > 0 && length <= 64 - start);
    /* Note that this implementation relies on right shift of signed
     * integers being an arithmetic shift.
     */
    return ((int64_t)(value << (64 - length - start))) >> (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