On 5/29/2024 12:59, Tong Ho wrote:> Add inlined functions to obtain a mask of
changed bits. 3 flavors
> are added: toggled, changed to 1, changed to 0.
>
> These newly added utilities aid common device behaviors where
> actions are taken only when a register's bit(s) are changed.
>
> Signed-off-by: Tong Ho <tong...@amd.com>
> ---
> include/qemu/bitops.h | 33 +++++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
> index 2c0a2fe751..7a701474ea 100644
> --- a/include/qemu/bitops.h
> +++ b/include/qemu/bitops.h
> @@ -148,6 +148,39 @@ static inline int test_bit(long nr, const unsigned long
> *addr)
> return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
> }
>
> +/**
> + * find_bits_changed - Returns a mask of bits changed.
> + * @ref_bits: the reference bits against which the test is made.
> + * @chk_bits: the bits to be checked.
> + */
> +static inline unsigned long find_bits_changed(unsigned long ref_bits,
> + unsigned long chk_bits)
> +{
> + return ref_bits ^ chk_bits;
> +}
> +
> +/**
> + * find_bits_to_1 - Returns a mask of bits changed from 0 to 1.
> + * @ref_bits: the reference bits against which the test is made.
> + * @chk_bits: the bits to be checked.
> + */
> +static inline unsigned long find_bits_to_1(unsigned long ref_bits,
> + unsigned long chk_bits)
> +{
> + return find_bits_changed(ref_bits, chk_bits) & chk_bits;
> +}
> +
> +/**
> + * find_bits_to_0 - Returns a mask of bits changed from 1 to 0.
> + * @ref_bits: the reference bits against which the test is made.
> + * @chk_bits: the bits to be checked.
> + */
> +static inline unsigned long find_bits_to_0(unsigned long ref_bits,
> + unsigned long chk_bits)
> +{
> + return find_bits_to_1(chk_bits, ref_bits);
> +}
> +
> /**
> * find_last_bit - find the last set bit in a memory region
> * @addr: The address to start the search at
Reviewed-by: Lei Wang <lei4.w...@intel.com>
