Macro buffer_fixed 

macro_rules! buffer_fixed {
    (
        $(#[$attr:meta])*
        $v:vis struct $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        impl: $($trait_name:ident)*;
    ) => { ... };
    (
        $(#[$attr:meta])*
        $v:vis struct $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        oid: $oid:literal;
        impl: $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        ;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        FixedHashTraits $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        MacTraits $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        ResetMacTraits $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        BaseFixedTraits $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        Debug $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        AlgorithmName $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        BlockSizeUser $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        OutputSizeUser $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        CoreProxy $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        Update $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        FixedOutput $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        Default $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        CustomizedInit $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        Clone $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        HashMarker $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        MacMarker $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        InnerInit $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        KeyInit $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        Reset $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        FixedOutputReset $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        SerializableState $($trait_name:ident)*;
    ) => { ... };
    (
        impl_inner: $name:ident
        $(< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)?
        ($core_ty:ty);
        ZeroizeOnDrop $($trait_name:ident)*;
    ) => { ... };
}

Creates a buffered wrapper around block-level “core” type which implements fixed output size traits.